Bones Hi - Fi

Commercially Produced Electrically Recorded Sound Is Turning 100 This Year

2025-12-30T12:41:00.000-08:00

Commercially produced electrically recorded sound is turning 100 this year, will it still be around for the next 100 years?

Various experiments with electrical recording actually began back to 1919. This system was perfected at the Bell Telephone Laboratories back in 1924 and the first commercial electric recordings were issued by Victor and Columbia back in 1925. The electrical recording that birthed the multi-million dollar music industry we know today is a system that used a microphone at the performing end. The microphone generated tiny electrical impulses that represented a replica of the original sound; a thermionic / vacuum tube based amplifier increased the strength of the signal picked up by the microphone so the electrical impulses can be strong enough to power the cutting head or a recording stylus.

Although the early results of the electrical recording system were characterized as strident in comparison to the earlier acoustic recording system, they boasted the then impressive frequency range of 100 Hz to 5,000 Hz. One of the editorials by Compton Mackenzie on the November 1925 issue of Gramophone magazine on the introduction of electrical recording goes: “the exaggeration of sibilants by the new method is abominable, and there is often a harshness which recalls some of the worst excesses of the past. The recording of massed strings is atrocious from an impressionistic standpoint.” Having read about this back in 1995, Compton Mackenzie’s comments on the first batch of commercially produced electrical recordings back in 1995 reminds me of criticisms of the sound quality of Redbook CDs in comparison to vinyl records during the heyday of the mid 1990s vinyl records revival.

Given that the electrical recording system allowed the manufacture of recorded sound a lot less expensive in comparison to the Edison era acoustic recording system, in 1925, the Brunswick Company marketed the first all electric phonograph. The Radio Corporation of America (RCA) purchased the Victor Corporation in 1928 and a year later, RCA converted the Victor plant largely to the manufacture of radio sets, while Edison discontinued production of all phonographs and records. During the first years of the Great Depression that began during the last quarter of 1929, the phonograph and record business dwindled but later took an upswing during the 1930s. Record playing attachments for plugging into 1930s era radio sets were introduced which also made the 1930s to be known as the “Golden Age Of Radio”. Also, juke boxes – first developed by Edison – also enjoyed a vogue during this time.

Early electrical recordings - also known as 78 rpm shellacs - that are now “celebrating” their 100^th Anniversary were largely ignored by enthusiasts during the start of the 1990s vinyl records revival because “younger” audio enthusiasts who grew up listening to vinyl back in the 1960s and 1970s were largely ignorant on how to play “pre World War II era” shellacs. Thanks to “older” audiophiles giving advice on how to play 78 rpm shellacs back in the 1990s, younger audiophiles can begin collecting 78 rpm shellacs as a hobby. Back then the Garrard 401 turntable was the most cost effective way to play older shellacs. Columbia records first batch of electrical recordings were recorded at 80 rpm until the late 1920s and thus an 80 rpm capable Garrard 401 populating the second hand record shops back in the 1990s came as a “godsend”.

Does Age Related Hearing Loss Matters?

2021-08-19T12:02:00.000-07:00

Given the popularity of age related audiological tests on You Tube, does age related hearing loss actually matters in practice?

By: Ringo Bones

As a true blue audiophile, you may have already checked out those You Tube channels that has audiological tests designed to determine the so-called age of your ears. Whether via click-bait or the fact that the de-facto audio bandwidth of You Tube doesn’t go beyond 16,000 Hz, those tests are just too intriguing to ignore. Whether it gave you a sobering realization that there are sound frequencies you can no longer hear now, unlike back when you are still 18, probably got you cringing after spending 10,000 US dollars on a hi-fi loudspeaker you can finally afford but has doubts whether your ears are “healthy” enough to appreciate them, fear not because there are others like me who now harbors doubts whether age related hearing loss really matter in practice – as in real life listening to audio systems and live concert events.

Virtually all acoustic / audio related literature and online fact-sites lists the human auditory range – i.e. the frequency of sounds we can hear – at 20 Hz (lowest frequency) to 20,000 Hz (highest frequency often abbreviated to 20 KHz) give or take a few hertz up or below this. Sadly, age related hearing loss is an inescapable fact of life. But have you noticed how the tests are done – i.e. using low distortion sine waves, usually below 0.1 percent THD – and they are quite revealing when if you are in your mid to late 40s and you can no longer hear those high frequency sine waves above 15,000 Hz. Sobering, yes, but does it matter in real life? Let me cite a couple of broad examples.

As the lockdown eased in my neighborhood a month ago and our local hi fi store started demoing its latest stock of Focal Kanta Number 2 loudspeakers, it sounded quite impressive when playing Chesky audiophile LPs. But when a Mobile Fidelity Sound Lab reissue of Saturday Night Fever soundtrack LP was played in the VPI turntable, most listeners – i.e. audiophiles who turned 18 back in 1975 and who are now in their 60s – complained that the Bee Gees sounded “too bright” when played to the Focal Kanta speakers while those listeners under 25 years of age where impressed on how the Focals sound as if there were cymbals and horns playing in the hi fi store. Given that those older folks – who even probably old enough to have actually been in a Bee Gees concert back in the 1970s complained on how the Kanta sounded too bright despite of their age related hearing degradation preferring instead on 1970s era JBLs or Altec Lansing Voice of the Theater speakers, while the younger listeners were awed by the way the Focal Kantas sound as if the cymbals and horns were actually playing live in the hi fi store, instead of a playback from an LP only highlights my doubts on how age related hearing loss really plays out in practice. And another thing, if age related hearing loss really does matter in practice, how come drummers 50 years and older not ditching their Zildjian cymbals for brighter sounding Paiste cymbals? As long as your presbycusis – i.e. age related hearing loss – doesn’t prevent you from having a normal conversation with your fellow human being, it’s probably best to just sit back and enjoy the music or the concert.

Headphones: Less Than Ideal Hi-Fi Gear?

2020-09-30T02:56:00.000-07:00

Even though it was deemed an indispensible component when the Sony Walkman became king back in the 1980s, are headphones, until now, has always been a less than ideal way to listen to music?

By: Ringo Bones

Dubbed by conservatives as the most antisocial way to listen to music back when Sony’s Walkman was new, the shortcomings of the ubiquitous headphones has recently been brought back into the spotlight after the shortcomings of a flagship Apple product – i.e. the Apple AirPods wireless headphones and their Mainland Chinese made knockoffs – as early users complained of excessive background hiss, not to mention early users old enough to remember 1980s era cassette tapes saying that the hiss levels are worse than that of dubbing a copy of a copy of a prerecorded cassette tape album. But are headphones really the weakest link of all the sound producing transducers in our high fidelity audio hobby?

Despite its shortcomings, audio enthusiasts old enough to have taken sound quality seriously back in the 1980s had surprisingly managed to make due of listening to music via headphones. Weird between-the-ears stereo soundstage when listening to plain vanilla 2-channel stereo cassette recordings and producing more background hiss in comparison to conventional loudspeakers notwithstanding. But let us explore more on the headphone’s hiss issue given that, especially when listening to prerecorded cassette tape albums as your primary music source, is already inherently hissy in the first place.

Hiss is more noticeable through headphones than speakers for several reasons. Since headphones lie closer to the ears of the listener in comparison to loudspeakers, any hiss that the headphones’ produce is readily transferred to the eardrums. Headphones are more sensitive than loudspeakers – i.e. headphone sensitivity are typically measured in decibels per milliwatt as opposed to decibels per watt when measuring loudspeaker sensitivity – so headphones are more likely to pick-up the faint residual hiss produced by your audio rig, like that in the preamplifier stage. And headphone models that isolate your ears from outside sounds can also prevent such sounds from masking hiss, denying the user from using Mother Nature’s naturally generated dither noise.

Linaeum Tweeters: Exotic Tweeter For The Masses?

2020-09-22T02:31:00.000-07:00

Often described as the lowest cost alternative for budget conscious audiophiles disenfranchised with the dome-tweeter sound, is the Linaeum Tweeter a true-blue “exotic tweeter” for the masses?

By: Ringo Bones

When RadioShack collaborated with Mystical Audio Limited to release their Optimus PRO series of hi-fi loudspeakers back in the mid-1990s, it was hailed by audio experts and reviewers as the “best sounding loudspeakers they have ever heard in the $300 to $500 price range”. While actual audiophiles who can’t afford ribbon-tweeter and planar-magnetic tweeter equipped exotica in the four-figure to five-figure price range had hailed the RadioShack Optimus PRO series as a veritable godsend at the time. I mean hearing what an actual 1990s era grunge guitar band produced in a budget-conscious audiophile’s listening room after concluding budget dome-tweeters seem to just don’t cut it sonic wise can be a revelation back then.

Sadly, the bass and lower midrange sound quality of the RadioShack Optimus PRO series was sonically below par in a side-by-side comparison to their old-fashioned dome-tweeter equipped competition in the $250 to $1,000 price-range. Not to mention that the inherent nature of the Linaeum Tweeter design will produce a harsh high frequency sound quality if operated below 3,000-Hz in the audio spectrum. But what makes the Linaeum Tweeter a value-for-money alternative to the good old-fashioned dome-tweeter in the entry-level hi-fi loudspeaker market?

What’s so special about the Linaeum Tweeter? In a conventional tweeter, a coil of wire is suspended between the circular poles of a ring-shaped magnet that moves a cone or a dome-shaped diaphragm backwards and forwards according to the dictates of the electrical signal, allowing it to produce audible sound from the power amplifier’s electrical signal. In the Linaeum Tweeter, there is still a voice coil, but this time it is flattened into a vertical shape and suspended between opposed rectangular magnetic poles. The voice coil still moves backwards and forwards, but instead of driving a cone or dome-shaped diaphragm, it pushes and pulls the vertical joining point of two semi-cylindrical 3-inch long sheets of stiff plastic film, each of which is fixed at its own end. Imagine two empty beer cans side-by-side, the point where they touch is where the voice coil is attached. Under the influence of the electrical signal from the power amplifier, the two semi-cylinders rotate back and forth, the resultant traveling waves producing sound.

The advantages of the Linaeum Tweeter design over a conventional cone and dome-shaped tweeter design are a uniformly wide horizontal dispersion pattern of the produced sound and good linearity, both of which lend the Linaeum Tweeter some of the attributes of a good, but far more expensive, planar drive unit. If as in the RadioShack Optimus PRO LX series, two sets of diaphragms are placed back-to-back with a common magnet structure, sharing a common voice coil, those at the rear pull when the front one’s push. The resulting sound radiation to the rear should produce an enhanced feeling of “airiness” to the loudspeaker’s sound in all but the most “acoustically dead” –I .e. unreflective – of listening rooms.

The Linaeum Tweeter further gained its reputation as the “exotic tweeter for the masses” after RadioShack decides to discontinue the Optimus PRO LX series and sold them heavily discounted – including the after-market replacement Linaeum tweeters – around after 9/11. Some RadioShack outlets had even sold the Linaeum Tweeter as low as $15 per pair further on. Now virtually impossible to find outside of heavily inflated priced working ones offered on e-bay, adventurous hi-fi enthusiasts had managed to experiment with them during the first two decades of the 21^st Century. If operated above 3,000-Hz, Linaeum Tweeters offer more natural and realistic sounding high frequencies that dome tweeters in the $100 to $500 price range. When operated at 6,000-Hz or higher as a super-tweeter, the Linaeum Tweeter can easily make a DIY loudspeaker sound as if it is 10 to 20 times the price of its actual purchase price.

What Does a 1990s Era Hi-Fi Sound Like?

2020-07-27T00:57:00.000-07:00

Did 1990s era hi-fi sounded like it should because hi-fi enthusiasts finally wanted to hear more of the music – instead of the audio gear?

By: Ringo Bones

Why did 1990s era high fidelity audio managed to cast such a long shadow that every well-reviewed audio gear are now commanding serious second-hand prices? Well, if you’re like me who got started to appreciate hi-fi audio as a hobby during the mid 1980s but only managed to acquire the disposable income needed to buy a much coveted kit during the early 1990s, it is safe to say that almost – if not all – well reviewed budget hi-fi gear, especially speakers, that entered the market between 2010 to 2019 is not that much different, sound wise, from their budget counterparts of the 1990s.

Maybe it is because 1990s era hi-fi enthusiasts finally decided to hear more of the music – instead of the hi-fi gear – that tonal neutrality and timbral accuracy finally managed to trickle down to budget hi-fi gear back then. Remember during the mid 1980s budget amplifiers, and signal sources – CD players, tape decks and turntables – were inherently designed to drive an inherently colored loudspeaker, that only a handful of 1980s era hi-fi gear are cherished compared to their rivals made a decade later.

During the latter half of the 1990s, even a relatively colored-sounding loudspeaker – like the Cabasse Farella 400 – especially the early model ones with an unmodified crossover network and driven with an entry-level Rotel RA-920AX integrated amp can manage to sound way more neutral and musically realistic when compared to an original JBL 4312 loudspeaker driven by an integrated amp manufactured In the mid 1980s. I mean to my ears at least – the Cabasse Farella 400 managed to produce a more realistic sounding acoustic guitar sound from a recording on a redbook spec CD than the late 1970s era JBL.

How Many Subwoofers Do You Actually Need?

2020-07-13T01:45:00.001-07:00

Even though you could get away with just one, how many subwoofers do you actually need to achieve natural sound at a reasonable cost?

By: Ringo Bones

Believe it or not, subwoofers were already sold by hi-fi retail stores around the mid 1970s. Sadly, those early subwoofers were very notorious for sounding as if an electric bass guitar connected to a loud bass guitar amp is playing along with the music in your listening room – even when playing small-scale chamber music. After the early design excesses were weaned out, subwoofer in the home has undergone a hiatus that made it desirable again in a few years time.

The subwoofer gained popularity again in the 1980s due to a great number of affordable small loudspeaker systems designed with very small woofers / main drivers – i.e. 5 to 7 inches or so and, sadly, most pain-in-the-ass interior decorators find them attractive. Sadder still, the growing impracticality for many hi-fi enthusiasts to own loudspeaker systems with 12-inch or 15-inch or larger main drivers for reasons of cost, space or room aesthetics (thanks to your pain-in-the-ass interior decorator) finally made subwoofers a viable option when it comes to system building.

During the early 1990s, a partial, but interesting solution to the problem was the introduction of the three-piece system. This generally consists of two quite small loudspeakers that cover the frequency range down to 100-Hz or so. Such a loudspeaker system with a 5-inch or 6-inch main driver are fairly easy an inexpensive to design and manufacture. But a loudspeaker system with the bottom two octaves missing is not very satisfying to the seasoned audiophile, so a third component is added – the subwoofer.

The rational of using a subwoofer is that the main front left and front right loudspeakers can be designed to give appreciable power output and have optimal performance at very low frequencies because the two main left and right front loudspeakers no longer has to reproduce the very low frequencies. And while the subwoofer no longer has to reproduce the higher frequencies assigned to the front left and right loudspeakers, that one subwoofer box can now – in theory – be placed in a more or less out-of-the-way location in the room since the low frequencies – i.e. below 100-Hz – have very little directionality. It was generally thought – since the mid 1960s – that a single monaural channel for frequencies below 100-Hz was needed and also because frequencies below 80-Hz were, allegedly, mixed to monaural anyway. This latter factor was a result of the limitations – and still is - of the mechanical reproduction process used in making vinyl records and back then, open-reel tapes are a way, way more expensive alternative to vinyl playback. But when properly connected, two subwoofers operating in stereo absolutely sounds more gorgeous that a system with just one, even in casual listening.

The assumptions that justified using a single subwoofer has some basis in fact because three piece systems have been, and are still popular when space and room styling (thanks pain-in-the-ass interior decorator) take precedence over other acoustic considerations. Audiophiles who preferably listen to rock music usually place the subwoofer to the left because the bass guitarist is usually mixed to the left of the soundstage, while those who listen to large scale Classical music place the subwoofer to the right because in a majority of orchestral recordings, the low frequency instruments tend to sound as if they are located on the right of the soundstage. However, over the years, I have some concerns and reservations about the technical justifications for the three-piece system.

It can also be quite a shocker to know that not all, or even most, loudspeaker setup absolutely needs a subwoofer or two to make them complete in the low bass. To my ears, it might be the wisest decision to get a truly full-range loudspeaker in the first place, since it will have been designed as a unit and have a smoothly balanced response over its full range. However, in the case of smaller bookshelf-type loudspeakers, considerable advantage can be had by removing the lower two octaves of the sound from the two main left and right loudspeakers and diverting them into a good subwoofer. The advantages are that the subwoofer now handles the hard-to reproduce very low frequencies due to much higher power requirements freeing the smaller loudspeakers from the greater power and displacement demands of reproducing the very low frequencies. This can result in lower distortion in the small loudspeakers and considerably improved sound quality from them. It also allows planning for system growth – that is if you first invest in a good, small pair of loudspeakers, you can augment them later by increasing bass capacity with a subwoofer.

But the question now is whether one, two or perhaps more, subwoofers should be added. If only one subwoofer is added, the result would be a three-piece system with monaural bass response below 80 or 100-Hz. If two subwoofers are added, the result is the two bookshelf-sized loudspeakers virtually becoming two full range loudspeaker system with a full stereo low bass capability. But does it matter if we have stereo or monaural low bass? To my ears and my over 30 years experience in being an audiophile, I believe that it does for at least two reasons. The first is that we have a much better program material today from the Redbook Compact Disc, various high resolution digital audio formats like DSD and 24-bit 192-KHZ sampled PCM audio – and even low rate data online streaming in MP3 and the like compared with entry level vinyl in the low bass frequencies.

The second reason is not quite so obvious, but very important if you want your system to accurately reproduce low bass frequencies in a timbrally accurate manner, whether it is from a Fender Mustang electric bass played through an Ampeg GS-12R equipped with 7591A output tubes, an upright acoustic bass, or even a full-sized church organ with 64-foot pipes. Believe it or not, there is considerable interaction between the room and the low frequency loudspeaker units. We all know that placing the bass loudspeakers in near a wall or in a corner of the room changes the amount and distribution of the bass frequencies in the room. At low frequencies, strong and widely spaced room modes are occurring. These modes manifest itself by the fact that as we move about the listening room, some locations have a lot of bass while other locations have a lack of bass. Also, the locations where more or less bass frequencies are heard also moves around the room when you shift the position of the low frequency loudspeaker.

The problem with a three=piece system is that we only have one loudspeaker producing the low frequencies, thus the room is only excited from one point and we have a set of modes – i.e. those parts in your room where the low frequencies are either too strong or too weak – that are quite audible. When two bass loudspeakers – or two subwoofers – are placed in a room and are excited by a full stereo bass signal, each will have its own set of modes. But the benefit this time is that it is not as likely that the lack or excess of bass from one loudspeaker will fall exactly the same point as for the other loudspeaker. This would result in a considerably better uniformity of bass response is obtained when the room is excited from two low frequency sources – in comparison when excited from just one low frequency source. But if using two subwoofers is better than using just one, would using more than two provide even far better results?

A fellow audiophile of mine has a set-up that uses eight REL Acoustics Q100E subwoofers in the frontal 60-degree arc of his hi-fi rig. Four were connected to the left channel and the other four were connected to the right. According to him, this set-up was a quantum leap in terms of performance from his previous set-up when he just used two REL Acoustics Stadium II subwoofers – about four times larger in terms of volume than the REL Q100E. But how does it sound? To my ears, it is probably the most timbrally accurate set-up when it comes to producing bass below 100-Hz. Not only that, on some minimalist chamber music recordings, it transformed his listening room into a medieval era chapel where the music was recorded!!! Probably due to the room modes are now vanishing low.

Drone Cones: Rotten Bass?

2020-03-31T03:42:00.000-07:00

Even though the theory behind passive radiator loudspeakers – i.e. drone cones - is persuasive and mathematically ordered, do they have a reputation of producing rotten sounding low frequencies?

By: Ringo Bones

Despite having a history that dates back to the early days of cone type loudspeakers, passive radiator equipped loudspeakers – i.e. drone cone equipped loudspeakers – probably gained widespread popularity around 1972 when Polk Audio founder Matthew S. Polk released his Polk Monitor 7 loudspeakers back in 1972, and since then, the global audiophile community developed a love / hate relationship around the idea behind drone cones / passive radiators. But do drone cones / passive radiators truly deserve the reputation for producing rotten sounding bass frequencies?

From a design standpoint, passive radiators are actually a form of vent substitute and thus tend to follow vented loudspeaker design methodology and design characteristics. Also known as “drone cones”, they have two very important advantages over bas reflex vent designs. First, they eliminate vent colorations – as in resonant pipe sounds – wind noises and the internal high frequency sound reflected out of the vent. Second, passive radiator / drone cone designs are practical for small enclosures – i.e. bookshelf sized hi-fi loudspeakers – when the resulting design equations call for vent lengths that exceed the internal box dimensions of the loudspeaker’s enclosure. From a design standpoint, passive radiators are also simpler to deal with, having fewer alignment algorithms that lead to calculation of losses. On the downside, passive radiators have a steeper cutoff – and this offer less transient stability – that vented / bass reflex designs (vented / bass reflex loudspeaker design already roll-off their lowest frequencies at 24 db / octave), a slightly higher cutoff frequency and greater overall losses (Q˪) than vented / bass reflex designs.

A widely popular misconception about passive radiators / drone cones is that they operate in the low frequency regions, mechanically crossing over to the main / active bass driver at a higher frequency and extend the bass of that driver. Actually, the passive radiator / drone cone operates in conjunction with the main active driver – or woofer – at low frequencies, sharing the acoustic load and reducing driver excursion, thus reducing the total harmonic distortion produced by the main bass driver. Working as a variant of a bass reflex vent, passive radiators / drone cones only add as much as they subtract. From a design standpoint, this implies that passive radiators have the same positive attributes as a bass reflex vent – such as higher power handling and lower resulting harmonic distortion.

From a historical standpoint, passive radiator loudspeaker designs were first described by Harry Olson in his patent “Loudspeaker and Method of Propagating Sound”, issued back in January 1935. Except for an article by Olson in 1954, very little was published about passive radiators / drone cones until Nomura and Kitamura in their IEEE paper in October 1973 and Richard Small’s Journal of the Audio Engineering Society paper in October 1974. At around this time, Polk audio became the well known manufacturer of passive radiator / drone cone equipped hi-fi loudspeakers when Matthew S. Polk released the Polk Monitor 7 with its famed 10-inch passive radiator / drone cone. Scores of other manufacturers have produced their own version of the passive radiator / drone cone hi-fi loudspeakers since then, like Bowers and Wilkins with their DM620i, Boston Acoustics with their compact HD9 monitor loudspeakers, Technics’ SB-M300 loudspeaker and the British – German hi fi collaborative effort ALR / Jordan Note 7 whose passive radiators / drone cones can have various weights attached to them to match their low frequencies to the listening room’s dimensions they are intended to be used. Given that, more or less, hi fi loudspeakers with passive radiators / drone cones produced to the years have more or less received favorable – and sometimes exemplar – reviews, then why do passive radiator equipped loudspeaker designs harbor the reputation of producing rotten, sluggish sounding bass?

Around the 1990s, almost all science enthusiasts – especially science enthusiasts who are also audiophiles – have read in various science journals, like Scientific American and their ilk, about how Mother Nature abhors three things the most – i.e. a singularity, a vacuum and an audio signal passing through a real-world capacitor. And given the steep cut-off of passive radiator/ drone cone designs, this only spells bad news from a sound quality perspective – especially in the pace, rhythm and timing department despite of their ability to produce prodigious quantity of bass in comparison to similarly sized hi fi loudspeakers.

I have an audio-buddy who has bought a second hand B&W DM620i loudspeakers back in the mid 1990s, he notices how the speakers lacked finesse when it comes to resolving subtle low bass to upper bass details. Even though I found the B&W DM629i’s overall presentation and adequate enough for casual listening of small-scale ensemble Classical Music like string quartets and the like, this won’t be the loudspeaker I’ll be using if I want to find out if a certain hair metal recording had its recording session engineer been using a dynamic range compressor with a sidechain access to “clean up the bottom end” by using the kickdrum as a “key” to limit the overall dynamics of the bass guitar – as in the compressor pushes the volume of the bass guitar down whenever the kickdrum is hit.

Loudspeakers With Rear-Firing Tweeters: The Least Room Fussy Hi-Fi Loudspeakers?

2020-03-09T16:35:00.000-07:00

For the budget audiophile skeptical about acoustically treating your listening room, are loudspeakers with rear-firing tweeters the best value-for-money solution?

By: Ringo Bones

Budget-conscious audiophiles had always been skeptical about “pricey” acoustic room treatments. They argue that their listening rooms …” is neither a recording studio, nor a mastering or recording post-production studio…” And both anecdotal and empirical evidence seems to reinforce this very idea by the time they manage to afford those relatively pricey second hand Quad electrostatic loudspeakers either the original ESL 57 from the 1950s or the newer one and far more common ESL 63 from the early 1980s. In practice, loudspeakers with rear-firing tweeters and their more elaborate counterparts – i.e. bipolar loudspeakers that radiate sound in both the front and the back – excel at sounding as if the very recorded acoustic event is actually happening in your listening room reproduced with timbral accuracy that conventional monopolar loudspeakers (i.e. those that radiate sound only in the frontal 180-degree arc) seem to lack. But in all things audiophile, not all bipolar / dipolar / loudspeakers with rear firing tweeters are not created equal.

Back when the late, great Audio Hall Of Fame speaker designer Arnie Nudell released the Eosone RSS series back in the early 1990s, many budget-conscious audiophiles got their first exposure of a budget loudspeaker that can reproduce the timbral accuracy of the cymbals in a basic rock combo drum-kit. But there are bigger, pricier ones that are found to be wanting from this time period.

Despite of the brownie points earned for a clean, full sound in a majority of hi fi magazine reviews, the Snell Type B loudspeaker was criticized by more than a few audiophiles as having its rear-firing tweeter for being a tad too loud. Some even suggested gluing a penny over the rear tweeter in order to make it sound better. Maybe a better solution is for the designer (s) of the Snell Type B to incorporate an l-pad attenuator / rheostat in the first place to attenuate the rear tweeter to make it around 12 dB SPL quieter than the front tweeter while preserving its high-pass filter crossover point or maybe include an on-off switch for the rear tweeter in “worst-case scenarios” for an overly bright listening room.

Bipolar loudspeakers – especially those manufactured by Mirage as in their Bipolar series - gained popularity back in the 1990s due to their rather “psychedelic phasiness” that they introduce to electric guitar recordings. Though criticized for not exactly accurate, they could take this effect too far by making those early Eric Clapton recordings when he’s playing through a small-ish tweed guitar amp, most bipolar loudspeakers tend to make tweed guitar amps sound acoustically small despite of the rich harmonics of the tone being produced. And sometimes bipolar loudspeakers exaggerate the “acoustical size” of some famous electric guitar recordings – i.e. that era when Eric Clapton preferred Gibson Explorers played through Marshall full stacks.

Open baffled loudspeakers – especially ones with an open baffle midrange configuration - are praised for reproducing female vocals with a timbral accuracy as if there was no microphone and onstage monitor loudspeakers - in short, the timbral accuracy of an unamplified female voice. Despite of their virtues, open baffle loudspeakers have one glaring shortcoming, they could sound devoid of any extraneous reverb bas in they sound drier than “Prohibition era Georgia” when paired with a very low jitter digital front end. This effect is very noticeable on electric guitar recordings that are injected directly into the mixing board with distortion and tonal effects only in the preamplifier level – as in the timbral roar of the 1980s era hair metal guitar solos championed by MTV.

The Walsh Type Tweeter: The Greatest Tweeter Most Audiophiles Never Heard Of?

2020-02-10T02:58:00.000-08:00

Given the rarity of still functional Infinity and Ohm Walsh loudspeakers in the 21^st Century, is the Walsh-type tweeter the greatest sounding tweeter that a new generation of audiophiles never even heard of?

By: Ringo Bones

During the 1970s, there was a legendary tweeter invented by famed audio pioneer Lincoln Walsh that was first widely used by the Ohm Loudspeaker Company given that they were the first ones to acquire the patents, Infinity then got permission to use these famed tweeters a few years later. Given that they were praised during their day as the “most realistic sounding” tweeter technology, how come the “Walsh Tweeter” is now largely forgotten?

For those who are lucky enough to still own a still functional pairs – though you can use Google to find out what are these kind of tweeters or what they look like – the Walsh Tweeter is that inverted gold cone on top of the Infinity loudspeaker box. The Walsh-type tweeter is essentially a standard tweeter motor with the voice coil and magnet attached to an ice-cream-cone-shaped thin metal with damping inside. Invented by Lincoln Walsh, the Walsh Tweeter is often associated with the Ohm Loudspeaker Company who acquired the patents on their Ohm Walsh series.

The technology seems rather simple: Instead of a traditional horizontal dome acting as a hemispherical piston facing the listener, the Walsh Tweeter was a vertical pump attempting a 360-degree sphere of high frequencies as in “omnidirectional radiation” of sound waves. Many audio manufacturers still covet the design – like Warren Gregoire and Associates with their Ikonoklast3 loudspeakers and MBL – though it struggled at higher frequencies because of its high moving mass and large shape, although the MBL’s tweeter design differs that from the Walsh-type tweeter because the MBL uses a flexible metal balloon instead of a rigid ice-cream-cone-shaped radiator. Both designs have trouble reaching past 12,000 Hz and is often used with a “conventional shaped” dome tweeter being used as a “super tweeter” to generate signals above 12,000 Hz.

Given their limitations, anyone lucky enough to own a still functional Ohm F loudspeaker swore that the Walsh Tweeters are the ideal tweeter for reproducing Classical string quartets or similar small ensemble Classical works, although some say Jimi Hendrix sounds “more interesting” on a pair of Ohm F loudspeakers. The same holographic front-to-back imaging thing also occurs on a pair of more recent Ikonoklast3 loudspeakers and similar MBL Radialstrahler 101 loudspeakers.

ELAC Debut 2.0 OW4.2: 21st Century Hi Fi Budget Wonder?

2019-12-27T15:23:00.000-08:00

When it comes to entry level hi fi loudspeakers in the 200 to 300 USD price range, is the ELAC 2.o OW4.2 represent the 21^st Century’s hi fi budget wonder?

By: Ringo Bones

Before ELAC’s designer Andrew Jones joined the German based hi fi manufacturing firm ELAC, he began work at KEF from 1983 until 1994. Then he later went on to Infinity and later with Sony and it was with the Japanese firm that he gained familiarity with designing hi fi loudspeakers using “exotic” materials like beryllium for tweeter diaphragms. But does his engineering experience translate to finally making an entry level budget loudspeaker in the 200 to 300 USD price range that would be universally loved by audiophiles the world over?

When I first heard of the ELAC Debut 2.0 OW4.2 last year, memories of budget loudspeakers of its price class made during the past 25 years came flooding in and begged for comparison. Fortunately, one of my audiobuddies kept his old Mission 731 LE loudspeakers bought back in 1995 – though he has moved on to much better speakers – i.e. his mega-buck albeit entry level Magneplanars. If 25 years of inflation is taken into account, the mission 731 LE would be much more expensive today than the ELAC Debut 2.0 OW4.2 and yet the 21^st Century ELAC’s raison d’être is to provide novice audiophiles a taste of the high end with a much lesser impact on the wallet.

The entry level ELAC’s Kevlar cones (Kevlar is the same aramid fiber used to make bullet proof vests) allows it to be played loud without breaking up and yet maintain reasonable efficiency, but unfortunately, there’s a somewhat broad suck-out in the midrange which if your idea of hi fi loudspeaker fidelity is how close it replicates hearing baritone Leo Nucci belting out the best parts of Verdi’s Rigoletto at La Scalla while sitting only 50 feet away without any electronic amplification, then you may find the entry level ELAC a little lacking in this department. If your loudspeakers you currently have can do that much better than the budget ELAC, then maybe you should spend your upgrade money in buying records and CDs instead. Nonetheless, the ELAC Debut 2.0 OW4.2 is very adept when it comes to mainstream pop and electronic dance music reproduction, albeit only up to a certain volume level and it serves as a gateway for millennials wanting a taste of high end at beer budget prices like the Mission 731 LE did for gen X’ers during the 1990s.

DNA: Music Recording And Playback Format Of The Future?

2019-02-17T14:35:00.000-08:00

With traditional independent record stores now closing and malls no longer selling Red Book Compact Discs, will DNA prove to be the “future-proof” music format of the future?

By: Ringo Bones

With traditional independent music stores – ones that sell vinyl LPs and Redbook 16-bit 44.1 KHz sampled compact discs closing and big malls no longer selling Redbook CDs, it seems that it would only be a matter of time that every Generation-Xers music collection could be consigned to the dustbin of history much sooner than expected. Thankfully, to celebrate the 20^th anniversary of the release of their most successful album, UK based electronic music group Massive Attack released their Mezzanine album on DNA back in October 2018.

Massive Attack worked with Andrew Melchior at the technology consultancy 3^rd Space Agency – the man who helped Bjӧrk convert her performance of “Stonemilker” into virtual reality for her 2015 MOMA show. According to Melchior: “The advantage with DNA is that our civilization could crash into dust and rebuild itself using entirely different technology, meaning they couldn’t access our computers or disks, since every human carries DNA, we can expect any future civilization to work out how to play back DNA-stored information. Which means the first thing a future civilization would learn about us might be Mezzanine.”

Using the DNA molecule to store vast amounts of digitally encoded information is more than just a science fiction pipe dream that was first popularly presented in the Superman movie franchise Man of Steel. The idea has first been published back in 1964 to 1965 when a Soviet era physicist named Mikhail Neiman published his work on the subject in the journal Radiotekhnika. But the first successful execution of encoding digital data onto a DNA molecule was back in 2012 when Harvard biologist George Church encoded one of his books onto a DNA molecule.

The electronic musicians Massive Attack worked with scientists at TurboBeads, a commercial spin-off from the Swiss science, engineering and mathematics university ETH Zurich, to adopt a technology pioneered by maverick US biotechnologists Craig Venter when he created a synthetic chromosome of a bacteria species in the laboratory with four “watermarks” written in the DNA. Robert Grass, professor at ETH Zurich’s Functional Materials Laboratory and his colleague Reinhard Heckel used similar chemical techniques to translate Mezzanine’s digital audio stream into genetic code. “We store digital information in a sequence of zeroes and ones, but biology stores genetic information using the four building blocks of DNA,” Grass explains. “We compressed Mezzanine’s digital audio then coded it as DNA molecules by converting the binary 0s and 1s into a quaternary code – with adenine representing 00, cytosine representing 01, guanine representing 10 and thymine representing 11. The resulting DNA resembles natural DNA in every way, although it contains no useful genetic information.”

According to Massive Attack band member Robert del Naja: “The storage potential of DNA is huge.” Indeed, one milligram of the DNA molecule could store the complete text of every book in the US Library of Congress and have room to spare. Del Naja also states: “If you think about DNA versus the ridiculous amounts of server farms that have got to be cooled 24/7 all around the world, this looks like a much better solution going forward. It allows us to archive music for hundreds of thousands of years.” Unfortunately as of late no word yet on the newfangled format’s sound quality.

MIT Terminator Network Loudspeaker Cables: A Misadvertized Audio Product That Actually Works?

2019-01-06T14:25:00.000-08:00

Despite of the rather “misleading” efficiency graphs in their adverts during the 1990s, does the MIT loudspeaker cables actually a “misadvertized” products that actually does its intended purpose – i.e. improve sound quality?

By: Ringo Bones

A few months ago, I was fortunate enough to rummage upon a used 1990s era MIT Terminator Network loudspeaker cable in a garage sale. Priced at around 20 US dollars a set, it was almost a steal. Even more fortunate, the former owner who is a radiologist used the box of the cable when testing a newly purchased CAT scan for a hospital and noted the values of the capacitors and inductors in the box from the X-Ray results – i.e. the component labels of the capacitors are clearly visible and the inductor’s values are determined by its dimensions and number of turns. I wonder why these products managed to improve the dynamics of solid-state amps by making them perform dynamic swings that has only been previously the domain reserved to classic McIntosh vacuum tube power amplifiers. With the LC filter component values sets its working frequency at around 45 Megahertz, I started to wonder if the working principle of how the MIT loudspeakers improve sound quality is similar to James Henriot’s Whest Dap 10 Processor – i.e. the elimination of the so-called “analog domain jitter”?

When Stereophile reviewer Jonathan Scull quoted Matthew Bond of TARA’s white paper on the difference between Musical Interface Technology’s products versus TARA’s from an August 1998 review of TARA Labs The One interconnect, loudspeaker cable and digital datalink. Most readers are familiar with cables that use network boxes in-line with the signal – i.e. MIT (Musical Interface Technology) Fadel Audio Art and Transparent Cable come to mind. According to Matthew Bond’s own view regarding these issues:

“These boxes contain low-pass filter networks that filter radio frequencies (RF) from the audio cables. These should not be confused with TARA’s Isolated Shield Matrix. The differences in both function and effectiveness are extreme.”

“A filter network removes RF from the audio signal by filtering out or rolling off all high-frequency energy above a certain range. This generally affects the upper end of the musical spectrum. Furthermore, these filter networks are directly in the signal path. When the signal is interrupted and fed through these low-pass filter networks, the cable’s electrical characteristics are changed to make a modified cable interface with limited and unnatural filter characteristics. The high-frequency bandwidth is reduced. The audio band is affected also, as it is subjected by the filter network to rippling, and slower rise time (in the case of the fourth-order Bessel low-pass filter). Furthermore, in a filter network RF modulation has not been addressed properly because of the heterodyning effect still occurs in the audio band. Additionally, the amplitude of the extremely high-frequency harmonics of the music are filtered off, along with the RF distortion, by generic capacitors and inductors in the network. The effects of a filter network are therefore subtractive and ultimately color the original signal. The Isolated Shield Matrix does not filter RF it grounds it outside of the signal path. It transfers RF and EMI energy from the cable without filtering the signal, thereby allowing ore high-frequency information to be passed through unaltered.”

The problem is unofficially known as “analog domain jitter” and even though Whest Audio founder James Henriot doesn’t understand the disease but thinks he’s found a cure while promoting his Whest Dap. 10 Processor featured in the July 2005 issue of Stereophile. Could Musical Interface Technologies MIT network cables manage to improve the sound by the same principle of eliminating “analog domain jitter”?

The Whest dap.10 works entirely in the analog domain above 30,000 Hz, far above the range of human hearing. It is also well above the 20,000 Hz limit at which your DAC’s filters curtail CD sound. According to James Henriot, frequencies you can’t hear affect the ones that you can hear. Other audio designers since the 1990s have stated the same thing and so have musicians talking about their instruments. Musical Fidelity founder Antony Michaelson who is also an accomplished musician who plays the piano and clarinet in a classical setting also stated that things occurring above the audible range have an effect on the sounds that you can hear.

According to James Henriot:“All amplifier circuits produce a set of harmonics related to the incoming signal. The output of a CD player is no different. Often referred to as “ghost images” in a Fast-Fourier Transform display result, the time shift causes minor ripples above 30,000 Hz. We think that these ripples have a profound negative impact on CD reproduction, possibly by beat interaction, which dribbles its way down into the audible frequency range. All electronic circuits – especially sold state ones – may have a way of knocking harmonics out of sync, resulting in a less musical and more electronic sound. Does this mean that building a musical sounding solid-state amplifier is akin to building a concert grand piano with all those string compensators?

Does Power Supply Electrolytic Capacitors Have a Finite Lifespan?

2017-12-05T07:58:00.000-08:00

They may last forever in so-called “textbook conditions”, but do capacitors used in real-world situations really have a finite lifespan?

By: Ringo Bones

The topic of capacitor mortality entered the conversation radar of my audiobuddies late last year when Sunfire founder Bob Carver voiced his concern after many of his Tracking Downconverter / PWM power supply equipped power amps “flooded” the online second hand market. And given a majority of these are from the mid to late 1990s and on average are 20 years old – or a bit older, Carver cautions the potential buyer to first service and / or troubleshoot these amps, especially check the power supply capacitors since given the pulse-width-modulation type power supply nature of these amps, the main electrolytic capacitors have a theoretically much shorter lifespan than power amps using conventional linear power supplies. Another power amp that’s very popular in the online second-hand market is the Musical Fidelity A1, which requires a careful main power supply capacitor examination since it runs hot at 50 to 65 degrees Celsius and the inside where the capacitor lies could get much hotter.

The power amplifier’s overall layout and operational temperature plays a very important part on the “mortality” of its main power supply filter capacitors since the leakage current of insulators and consequently all capacitor types, increases with temperature due to Arrhenius’s Law. The power dissipated in a capacitor subject to alternating current stress or ripple is a product of effective series resistance and RMS current. The effective series resistance and impedance of capacitors are both dependent on which frequency they operate and hence must be ascertained at the relevant frequencies. Assuming sinusoidal waveforms – as in a typical linear power supply – RMS current can be easily determined. With other waveforms – as in those Bob Carver power amplifier designs equipped with Tracking Downconverter / pulse width modulation type power supplies, the only accurate method requires the use of the Fourier analysis of the capacitor voltage waveform to determine the frequency components and hence permit calculation of the current for each harmonic involved. For those preferring to avoid the complications of Fourier analysis, a workable rule-of-thumb is to check the temperature rise of the capacitor case. If less than 5 degrees Celsius above the ambient temperature of inside the power amp’s casing of say 55 degrees Celsius maximum, leave well alone; if greater (as in hotter) – investigate immediately.

The normal failure mode of aluminum electrolytic capacitors is gradual parametric degradation after years of operation. But I’ve noticed to cool running power amp designs whose insides are only 3 to 5 degrees Celsius higher than the ambient room temperature, the main power supply electrolytic filter capacitors seem to measure within its parameters after 25 years of regular operation –i.e. 4 to 5 hours a day being played; Whereas for other capacitor types, normal failure mode is by short circuit. This parametric degradation results from the finite volume of electrolyte and the consumption of available oxygen.

The leakage current of normal capacitor operation consumes minute quantities of oxygen from the electrolyte, releasing a corresponding amount of hydrogen which is either reabsorbed in the electrolyte or escapes to the atmosphere. Excess quantities of gas result if: 1) the said capacitor is subjected to DC voltages way beyond its rated capacity. 2) The capacitor used in power supply filtering is subjected to alternating current for several minutes perhaps due to a short circuited rectifier diode and the power supply fuse not blowing. 3) The DC bias is externally reversed by circuit action and / or alternatively internal reverse DC bias due to excessive ripple or discharge currents. 4) Series or parallel connected capacitor banks not having suitable voltage or current sharing provisions.

When considering capacitor failures, it is essential to remember that all electrolytic capacitors comprise of two polarized capacitors back-to-back connected in series. This is implicit in the construction methods, both for polar and non-polar devices, which differ only in effective working voltage of the two capacitors. So if that Rubycon Black Gate electrolytic capacitor you installed in your power amp back in 1988 sill makes your low-power solid state design sound as if it is a single-ended triode tube amp, then it consider yourself lucky and keep it in place.

Can Graphene Semiconductors Make Future Solid State Audio Power Amps Sound Like Vacuum Tube Amps?

2016-05-16T07:22:00.000-07:00

Given that electrons can travel more than 100 times faster in graphene than in copper, will the upcoming graphene based semiconductors make solid state amps sound like vacuum tube amps?

By: Ringo Bones

Though they’ve been identified as far back as 1947 as being 207 times stronger than steel and make electrons travel 100 times faster through them than through copper wires, the carbon allotrope graphene was only manufactured / synthesized in significant amounts back in the 1970s by Manchester University physicists Prof. Andrei Geim and Konstantin Novoselov which made them the recipient of the 2010 Nobel Physics Prize. But more recently, various methods to manufacture graphene in higher volumes and far lower costs than before have recently made them economically viable enough for semiconductor applications. Given faster electron flow / electron mobility and high tensile strength, could upcoming graphene semiconductors someday make solid state hi-fi amplifiers sound like their famed vacuum tube counterparts?

During the 1990s many research articles were written about why hi-fi solid state power amplifiers sound different from their thermionic vacuum tube counterparts. But during the latter half of the 1990s, solid state integrated amplifiers that used “high electron mobility” semiconductors – i.e. solid state devices that used indium antimonide that are "blocked out" to protect the secret of their designs whose electron flow is up to 50 times that of copper wire and or power transistors enclosed in nonmagnetic packaging like TO-3 packaged 2N3055 NPN transistors in brass as opposed to the bog standard magnetic stainless steel. Even though these amps tend to be overpriced – average price between 3,000 to 5,000 US dollars each were their equivalent circuit counterparts using bog standard output devices tent to sell on average one-tenth of their price. Many audio engineers and hi-fi enthusiasts have wondered whether the difference in sound / timbre of solid state power amps and vacuum tube power amps is largely due to the speed of electrons travel through their output devices.

Electrons and electromagnetic waves propagate in vacuum at a maximum speed of 299, 792, 458 meters per second – usually rounded to 3-million meters per second or more famously known as 186,000 miles per second or 670-million miles per hour. A 12-gauge copper wire carrying a 10-ampere DC current, the speed of the electrons traveling through it is about 80 centimeters per hour – or about 0.0002 meters per second. A current traveling through a silicon-based semiconductor is about the same. While a velocity of an electron by the time it reaches the anode after being accelerated by the anode’s field is truly mind boggling by comparison. For example a vacuum tube with a fairly typical anode voltage of 450-volt DC, the electrons will hit the anode at approximately 12-million meters per second or 28 million miles per hour.

Remember those “overpriced” integrated amplifiers that use exotic high electron mobility solid state devices that sound like vacuum tube power amps? The average electron mobility rating of the active output devices that these amp use are 50 times that of typical silicon based output devices. Is electron mobility / electron speed the secret to better subjective sound quality? Well, electron flow in a typical indium antimonide semiconductor is around 0.01 meters per second and on graphene based semiconductors is 0.02 meters per second – quite a lot faster than a silicon semiconductor’s 0.0002 meters per second. Will high electron mobility spell improved subjective sound quality for upcoming graphene based solid state high fidelity audio amplifiers?

Are Physical Digital Formats Better Than Digital Downloads?

2016-04-10T17:11:00.000-07:00

From a sound quality perspective – are digitally downloaded music stored in solid state memory sounds inferior in comparison to their physical digital counterparts?

By: Ringo Bones

Ever since legal digital music downloads became a commercially viable reality that benefited both artists and record labels, it has been touted by environmentally concerned individuals as a “green” way of selling music around the world because this means that there are no shipping of CDs and other physical formats around the world that produce significant amounts of carbon dioxide emissions. Musical distribution carbon footprint would be limited to the power used by servers and PCs or other devices used to download the music and this could be much lower if those devices are powered by renewably-generated electricity. From an electronic engineering perspective, digital music stored in solid state memory has “supposedly” eliminated the problems of digital jitter in comparison to 120-centimeter CD or DVD discs played in a transport. But why is it that an increasing number of audiophiles have noticed that downloaded music, more often than not, sounded inferior in comparison to its physical counterparts?

Ever since the popularity of universal players that are able to play any 12-centimeter disc – whether it be 16-bit CDs, DVD-video, DVD-audio and Super Audio CDs – and digitally downloaded music via a USB slot, many budget conscious audiophiles, including me, had noticed that digitally downloaded music, even high resolution ones that are in FLAC (Free Lossless Audio Codec) format tend to sound inferior to their physical format. In my own experience, using a 150 US dollar Oppo universal player, physical Redbook 16-bit 44.1-KHz sampled CDs tend to sound better than their downloaded 24-bit 192-KHz FLAC encoded counterparts. The most common recordings that are usually available in both that can be compared side-by-side using a universal player are Miles Davis’ Kind of Blue album and Martin Taylor’s Spirit of Django album.

To my ears, it seems as if the downloaded versions sounds as if it has the sound quality of a typical 100 US dollar CD player while the physical versions sounds as if it has the sound quality of a typical 500 US dollar CD player. And to Stereophile magazine leaders, most downloaded music played on universal players priced between 150 to 500 US dollars via its USB slot has a digital sound that Stereophile contributor Michael Fremer used to describe back in the 1990s as “everything gets flattened out – including dynamics. Given that solid state storage devices supposedly doesn’t have the digital jitter inherent in CD / DVD / SACD drives, why is it that digitally downloaded music – even hi-rez ones – sound inferior to their physical counterparts? By the way, digitally downloaded music only started to sound as good as of better than their physical formats only after I’ve burned them into their requisite 12-centimeter recordable CD or DVD discs using a PC with Windows Media Player that can handle FLAC encoded music data.

Amazing Synchronicities In Hi-Fi and AV?

2016-03-07T04:20:00.000-08:00

Some of the other hi-fi and audio-video enthusiasts out there had been doing this for more than 20 years, but have you ever noticed the growing number of “amazing synchronicities”?

By: Ringo Bones

About 20 or so years ago when serious hi-fi enthusiasts who are “mere mortals” can finally afford DVD players that can seamlessly hook-up into their hi-fi rigs. They began experimenting on what they’ve found out on the internet that if you start Pink Floyd’s Dark Side of the Moon album at just the right moment while watching The Wizard of Oz, amazing synchronicities occur between what’s on the screen and what’s heard in the lyrics and music. I and countless others who have tried it during the past 20 years swear that it works. Since then, this specific hi-fi phenomenon has since been dubbed “Amazing Synchronicities” and has ever since fostered various websites and discussion posts on the internet since the 21^st Century began. When it comes to Pink Floyd’s Dark Side of the Moon album and The Wizard of Oz – “who knows witch is which….” Indeed. But did you know that there are other “startling coincidences” and “amazing synchronicities” that every hi-fi and AV enthusiasts can test out on their own systems?

Pink Floyd’s Wish You Were Here and Blade Runner also eerily synchs up like a music video. And also at the end of Stanley Kubrick’s science fiction classic 2001: A Space Odyssey where a 22-minute sequence titled “Jupiter and Beyond the Infinite” eerily synchs up with Pink Floyd’s Echoes, which is also 22-minutes long. Although Kubrick’s original score in “Jupiter” is already as good as it is. My stumbled upon favorite on You Tube was a video reenactment of the September 16, 2007 Nisour Square Massacre – that notorious Blackwater Security Consulting’s unwarranted shooting of unarmed Iraqi civilians where Tori Amos’ Precious Things (track number 5 of her Little Earthquakes album) eerily syncs in with the carnage - although this piece has been since taken out from You Tube. Maybe the maker didn't pay Tori Amos royalties and got a cease and desist order. And I bet every hi-fi enthusiasts the world over had tried probably almost anything since 1995 after discovering their first “amazing synchronicities” between Pink Floyd’s Dark Side of the Moon album and The Wizard of Oz movie.

Is Your Audio System Cat-Friendly?

2016-02-13T03:59:00.000-08:00

While early high fidelity audio systems got notoriety for “scaring away the horses” – is your current audio set-up cat-friendly?

By: Ringo Bones

Maybe we should blame cellist David Teie for this given that his Kickstarter funded research into feline-centric / species-appropriate music that recently got scientific verification by a recent independent study conducted by researchers at the University of Wisconsin and published in Applied Animal Behavior. Also, Teie’s Music for Cats compositions recently got scores of positive testimonials by early purchasers who tested Teie’s cat music recordings on their own cats noting that it actually had a relaxing effect on their own pets.

Cello player David Teie comes from a long line of musicians, composers and professional instrumentalists. Since 2014, he has been the conductor and music director of Washington D.C.’s premier chamber orchestra – the Eclipse Chamber Orchestra – and currently serves on the faculty at the University of Maryland’s School of Music. Teie’s career has spanned performing as a soloist with the National Symphony Orchestra under Russian maestro Mstislav Rostropovich. And also as the acting principal cellist of the San Francisco Symphony where Teie performed as cellist on Metallica’s 1999 album S&M. His research has been published in the Royal Society Biology Letters and in Evolution of Emotional Communication. His invention of species-specific music was described by the New York Times as the number one idea of 2009.

According to cellist David Teie, cats were our first choice because they’re widely kept as pets which allowed us to easily share music with them. Given that cats can hear audio frequencies way above the human hearing frequency limit of 20,000-Hz, can cats even appreciate those upper octaves of Teie’s music given that most entry-level audio systems have trouble playing at significant volume – never mind proper phase linearity – of audio signals above 20,000-Hz?

With the relatively wide availability and relative affordability of audio components and recordings capable of producing cleanly audio signals above 20,000-Hz – i.e. 24-Bit 192-KHz sampled PCM DVD Audio files and Super Audio CD recordings that can produce notes above 100,000-Hz and some moving coil cartridges like the Dynavector 17D2MkII Karat Diamond whose shorter 1.7-mm diamond cantilever allow it to have a high-frequency extension above 100,000-Hz and diamond coated tweeters that can cleanly play 100,000 Hz or higher audio frequencies – then it is now relatively easy to upgrade your audio system that can produce sounds that even cats, dogs and even bats can clearly hear.

Maybe it was due to the fact that he hanged out with Metallica for a relatively long time during rehearsals in comparison to us mere fans back in 1999 or whether he is already a Metallica fan back when bassist Cliff Burton was still alive that got me wondering how much Metallica was an influence to cellist David Teie upon hearing of Cozmo’s Air – one of the tracks of his Music for Cats – that it reminded me of the ambient into of Metallica’s Damage, Inc. – the last track on the Master of Puppets album. Well, at least Teie managed to make his “cat music” also interesting to hear for us human music lovers which will probably give Pet Sounds a whole new meaning to audiophiles around the world.

Transmission Line Loudspeakers: The Ultimate Domestic Hi-Fi Loudspeakers?

2016-02-01T03:10:00.000-08:00

Given its ability to produce unbelievable amounts of bass for its size, are transmission line loudspeakers qualify as the ultimate domestic hi-fi loudspeakers?

By: Ringo Bones

As of late, there has been discussion on how come hi-fi audio designer Arthur Radford’s electronics – especially his EL34 based audio power amplifiers like the Radford STA25 - get more recognition in comparison to his transmission line loudspeakers which despite being manufactured 50 or so years ago can still manage to hold its own in a side-by-side comparison to more recently manufactured hi-fi loudspeakers. Arthur Radford did a lot of work, both theoretical and practical, on transmission line loudspeaker design during the 1960s.The Radford Studio 90 which was also sold in the U.S. in kit form during the late 1960s as the Audionics TL90 – a ¼ wavelength 3-way transmission line loudspeaker equipped with Radford sourced drivers and crossover circuit. The Radford Studio 90 was the first commercially manufactured hi-fi transmission line loudspeaker based on A.R. Bailey’s papers and there are even larger models based on the same design. Even though they were a bit pricey when they first entered the market, enough of them were sold in the United States to establish a “cult following” of this legendary loudspeakers. Despite their excellent subjective sound quality, why are transmission line loudspeakers relatively rare in comparison to competing designs? But first, here’s an introduction on the theoretical and practical principles of transmission line loudspeakers.

Then and now, designers of closed-box / acoustic suspension and vented / bass reflex loudspeaker systems have long been able to make heavy use of computers, while transmission line systems had been designed by cut-and-try methods. Transmission line loudspeaker systems are more complicated to design because of their inherent distributed-parameter nature. By way of comparison, sealed / acoustic suspension and vented / bass reflex loudspeaker systems can be treated as a much simpler, lumped-parameter acoustic systems. Also, there is still a dearth of research literature regarding transmission line loudspeaker design to guide the prospective designer. But to those adventurous enough, they should check out Quick & Easy Transmission Line Speaker Design by Larry D. Sharp and those “white papers” published online by John Wright of TDL.

Transmission line loudspeakers are known for their deep, powerful bass and the way they grip a room, filling it with a full scale performance. But they have their downsides too, notably the difficulty of tuning the line, which appears to be the blackest of arts in the audio engineering world. A practical transmission line has two main effects that are advantageous to loudspeaker design. Firstly, the sound venting from the end of a quarter-wavelength transmission line is 90-degrees out of phase with the signal from the back of the cone which drives the line, which itself is 180-degrees out of phase with the front radiation. This ensures that sound radiation at lower frequencies is progressively moving into phase and it will add, rather than subtract, to the forward low frequency response. Also a practical transmission line loudspeaker is lined with acoustic felt and wool, so that a majority of upper bass and midrange energy is absorbed before it reaches the end of the line and the outside world. Lower frequency bass energy gets through, making low bass apparent. In electrical engineering terms, a transmission line port is a low pass filter with a 270-degrees plus phase shift.

An area where transmission line loudspeakers receive criticism is midrange coloration. To overcome this, various transmission line loudspeaker designers over the years adapted a number of sensible design features. If the transmission line vent length is made exactly ¼-wavelength in length, it tends to act like a tuned pipe which introduces coloration. Making the transmission line slightly shorter, a technique later adapted by John Wright of TDL during the late 1960s, reduces this coloration without adversely affecting bass quality.

In some transmission line loudspeaker designs where the line is folded quickly behind the cone, the strongly reflected sound wave from the cabinet wall can give that “clatter-type” coloration in the midrange. For this reason, in newer transmission line loudspeaker designs, the rear wall of the cabinet is kept as far back as possible and fitted with a generous covering of soft, absorbent carpet felt.

One great thing about a transmission line loudspeaker is that once the cabinet dimensions have been optimized and fixed, it can be subtly tuned to give the bass quality you want in your listening room just by altering the amount and density of long hair wool in the line. This makes transmission line loudspeakers extremely versatile for home constructors, which combined with their subjective performance explains why they’ve been making a comeback since the 1990s hi-fi boom.

Another great advantage, or possibly the greatest advantage, of transmission line loudspeakers – and probably why they’ve returned during the 1990s in conjunction with the zero negative feedback single-ended-triode audio amplification Renaissance of the period - is their highly damped impedance curve. Impedance varies little across the entire audio spectrum – especially in the upper bass and lower midrange region in comparison with vented / bass reflex and closed box / acoustic suspension loudspeakers. This makes transmission line loudspeakers much, much easier to drive with zero negative feedback single-ended triode audio amplifiers and other low feedback vacuum tube audio amplifier designs.

Phono Cartridge Stylus And Cantilever Construction Materials: What’s Best?

2016-01-10T16:11:00.000-08:00

Given that your phono cartridge has an overwhelming influence on the fidelity of the reproduction quality of your hi-fi rig, would the bits that make the first contact on the vinyl disc – the stylus and the cantilever have the most influence on sound quality?

By: Ringo Bones

For more than a decade and a half into the 21^st Century, it seems that the vinyl record had managed to hold its own as the playback medium that is better than Redbook CD – or those downloadable digital music on the internet – by a significantly wide margin in terms of sound quality. Despite being introduced a few years ago, three popular entry-level turntables: the Project Carbon Debut DC, the Pioneer PL-30-K and the Onkyo CP-1050 Direct Drive Turntable are still selling strong. But what about phono cartridges – has there technological progress being made since the early 1990s vinyl record revival?

Any phono cartridge faces a major problem: how to cover the full three-decade-wide bandwidth (20Hz to 20,000Hz) needed for high fidelity audio playback. High frequency resonances seems pretty well inevitable and mid-band “glitches” are difficult to avoid, too, as the frequency-response and vertical / lateral crosstalk sweeps with the use of test records showed. Not surprisingly, the success with which these are controlled is very closely linked to the cartridge’s overall sound quality.

Phono cartridge stylus and cantilever construction have significantly – even radically - improved since those osmium phonograph needles used during the introduction of electrically / electronically recorded records to the market back in November 1925. During the post World War II period that lead to the Golden Age of Stereo, stylus dimensions got smaller and smaller to better track the microscopic grooves of the vinyl long-paying record introduced by Peter Goldmark. First it was made of sapphire – a gem quality form of corundum with a hardness of 9 on the Mohs’ scale which was later replaced by micro-profiled elliptical diamond stylus for better sound quality reproduction. While during the Golden Age of Stereo – the material of choice for high quality phono cartridge cantilevers is the most rigid alloy of aluminum that is commercially available, which during the 1950s is typically aircraft / aerospace grade aluminum.

Then and now, the moving coil phono cartridge – despite of its low signal output - has been considered as the best when compared to its moving magnet counterparts due to its lack of frequency response problems in the upper midband and high frequencies. Traditionally, moving coil phono cartridges have had relatively incompliant cantilever hinges in comparison to its moving magnet counterpart which resulted in poor low frequency tracking. Anyone looking to preserve their record collection find this alarming. Remember those early Decca London phono cartridges with their tip resonances that are notorious for doing damage to vinyl records? So tip resonance control is also a factor in choice of materials in stylus and cantilever construction.

Ideally, the stylus should be constructed from the same materials to consistently control the inevitable resulting resonances. Given that the microscopic-dimensioned stylus is barely visible to the unaided naked eye and a modern phono cartridge stylus measures around 7.5-mm long or 5/16 of an inch long and 0.5 –mm thick or 1/32 of an inch thick constructing one from a single artificial produced diamond should not carry a prohibitive price premium. Dynavector’s 17D2 Mk. II diamond cantilever MC cartridge is one such beast. With a hardness of 10 on the Mohs’s Scale, solid diamond is the hardest possible material and supreme for cantilever use. And given that diamond is a good heat conductor, any heat friction generated during vinyl playback can easily be dissipated by the stylus and cantilever assembly because they are made of the same material. But since its introduction in the early 1990s, many competing phono cartridge makers have managed to create better sounding cartridges using both more exotic and tried and true materials.

Solid-boron-rod cantilevers constructed from the crystalline allotrope of the element boron that has a hardness of 9.5 on the Mohs’s Scale has been extensively used for moving coil phono cartridge construction during the latter half of the 1990s due to its subjectively better sound quality when compared to diamond. Used on the Van Den Hul Frog with a specially shaped Type 1S diamond stylus, this cartridge has the highest cantilever compliance and the lowest recommended tracking weight of all the commercially available cartridges and is notable for its ability to ignore vinyl scratches which is very important if you frequently purchase vinyl LPs and 45 RPM singles from used record shops. While the Clearaudio Signature uses a hollow boron cantilever variant.

Cantilevers made of sapphire or corundum – which has a hardness of 9 on the Mohs’s Scale - was also tried as far back as the late 1970s. The most famous example of these is the Bang & Olufsen MMC 20CL phono cartridge – which a diamond stylus is attached to a sapphire crystal cantilever that resulted in the elimination of audible tip resonance and thus eliminating distortion in music reproduction and it also means it won’t be destroying your precious vinyl records every time you play them. Enthusiasts back in 1981 praised its life-like ability to reproduce choral recordings like never before and it is probably the first cartridge that started the exotic materials construction wars.

As a go to material for phono cartridge cantilever construction, aluminum has held its own since the Golden Age of Stereo. The mid 1990s era Ortofon Rohman uses a tapered aluminum cantilever and still manages to gain converts unimpressed by the newfangled solid-boron-rod cantilever construction of competing cartridges. While the Lyra Parnassus DCt uses a more exotic diamond-coated, ceramic-reinforced aluminum cantilever said to be stiffer than ordinary aluminum alloys previously used in cantilever construction.

Sound quality wise, audiophiles weaned on the “dreaded” compact disc tend to gravitate towards boron cantilevered phono cartridges largely due to its wider perceived bandwidth in comparison to ones using aluminum alloy as a cantilever. While those Iron Maiden and Judas Priest fans who extensively listen to vinyl during the early part of the 1980s say that aluminum cantilevered phono cartridges are more neutral sounding in comparison to their boron, diamond or sapphire / corundum counterparts.

Are Light Emitting Diodes Too Noisy For High End High Fidelity Use?

2015-12-21T04:21:00.000-08:00

Though it has become ubiquitous as a power on indicator of consumer electronics since its introduction back in the 1960s, are light emitting diodes just too noisy for high end hi-fi use?

By: Ringo Bones

Ever since I started my audio equipment and musical instrument modifying business back in the early 1990s, I’ve noted that some audio equipment – especially very high gain solid state moving coil cartridge phono preamplifiers – will improve its noise floor when you replace the red or green LED power on indicator or light emitting diode power on indicator with a miniature tungsten filament power on indicator light bulb often used in older audio equipment. In my experience, the main beneficiaries from such moddings are vacuum tube based moving coil phono preamplifiers that use the ECC88 / 6DJ8 / 6922 small-signal vacuum tube and those iconing solid-state moving coil phono preamplifiers that use FETs and transistors or a mix of both like the DNM 3B and the Michell Iso and Michell Argo.

During the first decade of the 21^st Century, I also discovered that organic LEDs are noisier than their plain vanilla LED counterparts. Even though the invention of organic LEDs made possible those relatively affordable and indispensable part of 21^st Century home theater unnecessarily large video monitors, blue LEDs that had become fashionable add-ons of power conditioners like the MIT Z-Center, produce an audible buzz when used with critical high gain moving coil phono preamplifiers.

What’s weird about organic LEDs – even those green ones that emit a more vivid green light than their plain vanilla counterparts is that they can be as noisy as their blue colored counterparts. Weirder still, when viewed through a diffraction grading – either a CD or DVD surface – organic LEDs lack the monotonicity of their plain-vanilla counterparts. Ordinary green and red LEDs produce a pure green or and red light when viewed through a diffraction grating while their organic LED equivalents produced a distinctive rainbow streak. Though it is only noticeable in practice, do LEDs – organic and plain vanilla ones – produce more noise when compared with those tiny tungsten filament power on indicator lamps because LEDs are solid-state semiconductor devices and in the solid-state semiconductor world, noise is directly proportional to operational current?

Vinyl Records: An Extraordinary Playback Medium?

2015-11-07T08:36:00.002-08:00

Whether LPs or 45s, are vinyl records qualify as an “extraordinary” musical playback medium due to their capacity to “alleviate” screw-ups during the recorded music performance’s mastering stage?

By: Ringo Bones

Strange how those “wonderful” attributes of the analog vinyl records – whether they be 33 1/3 LPs or 45s - that Stereophile magazine columnist Michael Fremer had been describing about throughout the 1990s still holds true today, well into the second decade of the 21^st Century. With the Marantz TT-15 turntable back in 2004 and the more recent Onkyo CP-1050 turntable, one would think that both SACD and 24-bit 192-KHz DVD Audio would have consigned vinyl records to the “dustbin of history” during the first decade of the 21^st Century, unfortunately it didn’t. But what is it about vinyl records that managed to raise “more mysticism” than even its own 2-channel analog master tape?

Chesky Records founder David Chesky once remarked that there was something “magical” and inexplicable about the music generated by a stylus coursing through a record groove. Is the magic we love about vinyl records, whether they be 33 and 1/3 RPM LPs or 45 RPM singles, inherent in the analog nature of record playback, or is it something added by that process that allows vinyl records to create a sense of “reality” better than most commercially available prerecorded music mediums and including its 2-channel analog master tape? Or is it a combination of both?

In my own listening experience, I suspect it is mostly due to how vinyl record playback cartridges – both moving magnet and moving coil – make the vinyl record playback system like they are very transparent sounding analog “dynamic range expanders” due to the way vinyl records tend to sound “more dynamic” in side by side comparison to the first generation open reel copy of the master tape. Given that some of the master tapes of oft-mentioned classic pop rock studio albums recorded during the mid to late 1970s had been recorded with a little too much compression that even though they are multi-track analog studio recordings they sound as if they have that digital sound that Michael Fremer rails against – i.e. everything gets flattened out – including dynamics. Could the stylus and cantilever structure of a typical vinyl record playback cartridge acting as a “corrective dynamic range expander” that makes some over-compressed studio album recordings sound more natural on their vinyl pressing versions in comparison to either open reel tape and CD, SACD or 24-bit 192-KHz DVD Audio copies?

The ECF80 Triode-Pentode Vacuum Tube: The Integrated Circuit Vacuum Tube?

2015-10-26T03:07:00.000-07:00

Given that it contains two different thermionic amplifiers in a single enclosure, does the ECF80 triode-pentode vacuum tube qualify as an “integrated circuit vacuum tube?

By: Ringo Bones

Multiunit vacuum tubes may not be able to compete in size and component count with their solid-state integrated circuit counterparts, but if your hankering after that good old robust tone vacuum tube sound, post World War II era subminiature vacuum tubes offer those in a more reasonable sized package. The ECF80 triode-pentode vacuum tube is unusual in that this multiunit vacuum tube can run both its triode and pentode sections at about the same current. The ECF80 makes a great Mu-follower with the pentode strapped as a triode on top and it is often described as a medium Mu triode sharp cut-off pentode.

Even though it is not featured in the 1959 Mullard Tube Circuits For Audio Amplifiers, Mullard says that the ECF80 was designed for operation up to 220-MHz and it was first introduced back in 1954. As 1950s era television receivers tend to use the PCFnn 300-milliampere filament heater vacuum tubes, the production of the ECF80 with a 6.3 volt heater filament suggests that it was aimed at the 1950s era professional VHF communications market. In a typical VHF application of the ECF80, the triode section is often used as a Wien-Bridge oscillator and has to produce a 5-volt peak-to-peak signal which could allow the ECF80 to be used as the active transceiver tube in 1950s era walkie-talkies. The screen pentode is the mixer. The vacuum tube has two cathodes so the two independent amplifiers are enclosed in a single envelope. The twin anode construction is clearly visible with the triode occupying the much smaller anode. The two sections can be used separately if required and thus extending the versatility of this vacuum tube.

Given that post World War II subminiature vacuum tubes are primarily used as a cost saving preamplifier and phase-splitter sections of power amplifiers that use 1930s era output power tubes, the World Audio Design K6L6 Integrated Amplifier is probably the most famous application of the ECF80 triode-pentode vacuum tube where it was used as a “novel” phase-splitter. The problem with conventional double-triode phase-splitter, like the 12AX7 double-triode phase-splitter section of the ubiquitous Mullard 5-20, is that its high output capacitance caused by the Miller Effect. This causes high frequency loading on the input vacuum tube and reducing bandwidth, making it very difficult to use appreciable amounts of negative feedback without instability due to the phase shifts incurred. A pentode vacuum tube has a very low output capacitance and high gain due to the shielding effect of the screen grid. This means that the loading on the input vacuum tube is greatly reduced, increasing bandwidth and decreasing troublesome phase shifts. And the WAD K6L6 Integrated Amplifier’s use of the ECF80 triode-pentode vacuum tube as a phase-splitter also eliminated the need of an interstage phase-splitting transformer which also kept costs down.

The 6AU6 Low Noise RF Pentode: The Retro Vacuum Tube?

2015-10-25T09:59:00.001-07:00

Even though modern-manufacture vacuum tube makers have yet to reissue it, does the 6AU6 vacuum tube truly qualify as a “retro preamplifier vacuum tube”?

By: Ringo Bones

The NOS or new old stock versions were quite plentiful back in the 1990s when I first got serious into vacuum tube hi-fi as a hobby and even until today modern-manufacture tube makers like Electro-Harmonix, Svetlana and Sovtek still doesn’t have an economically viable need to manufacture their own version of the 6AU6 low-noise RF pentode vacuum tube. And from what I know so far in this hobby, I think the primary raison d’être of those subminiature vacuum tubes manufactured after World War II is to lower the build cost of the preamplifier and phase-splitter stages of power amplifiers that uses output vacuum tubes that date back from the 1930s.

The 6AU6 low noise radio-frequency pentode vacuum tube was developed by RCA Victor Co. Inc. of New York, New York and it is identical to the EF94. Entered into the Electron Tube Registration List back in October 25, 1945 and entered the Manufacturer’s Literature RCA Datasheet back in October 23, 1945. It has a miniature 7-pin base and was often used as the front end sections of radio and television receivers and it eventually gained widespread use in hi-fi audio towards the end of the 1950s. The 6AU6 is an indirectly heated small signal vacuum tube with a 6.3 volt filament and a 300-milliampere filament heater current. The 6AU6 was described as an RF-IF sharp cutoff amplifier for use in sets with series connected heaters and was eventually superseded by the 6AU6A since November 1956.

It gained popularity back in the 1990s to keep build costs down when used as first stage preamplifiers of power amplifiers that use power output tubes that dates back from the 1930s – like the 6L6 beam power tetrode – which was first manufactured back in 1936. One of the most popular applications of the 6AU6 low noise RF pentode was in the World Audio Design K6L6 integrated amplifier back in 1995. The WAD K6L6 circuit topology is similar to the ubiquitous Mullard 5-20 amplifier but the 6AU6 low noise RF pentode was configured as a high-gain single-ended amplifier stage. But the relative rarity of the use of the 6AU6 was that the original 1959 Mulalrd Tube Circuits For Audio Applications handbook never used the preamplifier tube in its construction guide of its ubiquitous Mullard 5-20 vacuum tube power amplifier.

The Type 85 Vacuum Tube: The Rescued From Obscurity Vacuum Tube?

2015-10-24T10:43:00.000-07:00

Even though it dates from the Golden Age of Radio, but did you know that despite it is still in current production, the Type 85 vacuum tube has been languishing in obscurity for almost forever?

By: Ringo Bones

Kara Chaffee of deHavilland Electric Amplifier Company has recently become a cause-célèbre in the audiophile world when she designed those keenly packaged and cleverly priced zero negative feedback preamplifiers that became well-loved by both critics and real-world audiophiles. Even though she had been designing zero negative feedback preamplifiers since the mid 1990s as the “gold channel” preamplifier circuit for recording studio and boutique audiophile label mastering establishments, Chaffee had earned the reverence of audiophiles the world over when she used an obscure but still in manufacture small-signal vacuum tube that dates back from the 1930s Golden Age of Radio – the Type 85 vacuum tube - and turned it into an excellent sounding preamplifier, the deHavilland Mercury preamplifier that even managed to regenerate a sense of wonder even to the most jaded high-end audio equipment reviewer. But to those unfamiliar with it, here’s a brief history of the Type 85 vacuum tube.

The Type 85 is a 6-pin dual-diode triode multiunit vacuum tube with its distinctive top metal cap – that is a vacuum tube containing several independently acting vacuum tubes in one envelope – as it is composed of twin triodes and two radio-frequency detector diodes in a single glass envelope. First manufactured during the 1930s, it was primarily used as a radio-frequency detector, automatic voltage controller and first stage audio amplifier in AC line operated AM receivers. It is also used as the phase inverter in several 1930s era public address amplifiers. The Type 85 is electrically identical to the octal based 6V7. The Type 85S is a spray-shield type made by Majestic.

The Type 85 has a maximum plate voltage rating of 250 volts though typical operation as an amplifier the plate voltage is around 135 volts, it has a maximum plate current of 8-milliamperes though in typical operation it is around 3.7-milliamperes, it has a maximum grid voltage rating of -20 volts though in typical use this is around -10.5 volts. Typical in its operation, its heater voltage is 6.3 volts and heater current is 300-milliamperes, amplification factor or mu is 8.3, transconductance or gm is 750 and a plate resistance of 11,000-ohms. By way of comparison, an ECC32 has a plate resistance of 14,500-ohms while the 6SN7 has a plate resistance of 7,300-ohms thus making the Type 85 as having higher output impedance that it’s closest rival preamplifier vacuum tubes. As mentioned previously, the Type 85 vacuum tube contains two diodes which are used as radio-frequency detectors like the 1904 era J. Ambrose Fleming’s radio-frequency detector diode.

Dating back to the 1930s Golden Age of Radio and it is still manufactured in “sufficient” quantities by Russian and Mainland Chinese vacuum tube manufacturing firms and even sold in antique radio hobby suppliers in South-East Asia at around 5 US dollars each, the Type 85 vacuum tube has never received any recognition in high end circles – unlike its audio and radio frequency power transmitter vacuum tube siblings like the Western Electric 300B, the 211, the 845 and the Russian GM70 transmitter vacuum tubes which became famous during the 1990s era hi-fi boom. The Type 85’s humble origins as a 1930s era audio frequency preamplifier tube did not solidify its image as a much coveted exotic vacuum tube back in the 1990s.

Internally, the Type 85 is composed of two R-F diodes and a single triode section housed in a single envelope. Such a “compaction” certainly facilitated the mass production of “affordable” 1930s era AM radio designs by combining the front-end R-F detector, amplifier and the automatic voltage controller into one stage. Sadly, this topology is not the sort of vacuum tube likely to engender a cult following either back in the 1930s or in the 1990s. It should be noted that the triode section is almost completely independent of the R-F detector diodes, the only shared element being a cathode sleeve. The top metal cap of the Type 85 vacuum tube is electrically connected to the ground and therefore does not represent a high voltage shock hazard and we should be thankful to Kara Chaffee of deHavilland for approaching this vacuum tube with an open mind and thus discovering its hidden sonic potential.

Sound wise, the Type 85 vacuum tube has a much more gorgeous and creamier midrange than its nearest competition – the 6SN7 vacuum tube – which Kara Chaffee also used in her famed deHavilland UltraVerve preamplifier. And on a side-by-side comparison, the Type 85 even excels the ability of the other famed 1930s era preamplifier tube – the ECC32 – in making modern over-bright over-equalized multi-track 24-bit 192-Khz pop-rock recordings much more pleasing to the typical hardened audiophile’s ears. Even though it is pricier than the ECC88 vacuum tube equipped Musical Fidelity X-Pre, the Type 85 vacuum tube equipped deHavilland Mercury preamplifier sounds much, much better – though the deHavilland Mercury is around 10 times the price of the 250-US dollar Musical Fidelity X-Pre. High cost be damned – or if you have the spare time and the ability to DIY a Type 85 vacuum tube equipped preamplifier – the deHavilland Mercury and its Type 85 ilk can make any reasonably good sounding solid-state power amplifier the ability to create a soundstage as if it is a zero-feedback single-ended triode vacuum tube power amplifier.

Though most modern vacuum tube reissue manufacturers - like the famed Electro-Harmonix and Svetlana - has yet to manufacture their own "audiophile grade" Type 85 vacuum tubes, the ones I currently have and used in my preliminary DIY work are from National Union (Made in USA) NOS ones that still register "OK" in my audio-buddy's small-signal vacuum tube checker and a newer Mainland Chinese one whose brand is written in Chinese characters. Both managed to sound great from a vacuum tube perspective and I think the tone produced by a preamplifier using the Type 85 vacuum tube will easily please "tone freaks".

Zero Negative Feedback Preamplifiers: An Audiophile Must Have?

2015-10-17T15:43:00.000-07:00

Given the deleterious effect of negative feedback circuits on sound reproduction, would a working zero negative feedback preamplifier soon become an audiophile must have?

By: Ringo Bones

Either by first-hand listening or by reading them in hi-fi oriented publications, negative feedback circuits “suspected” deleterious effect on music signals – like loss of natural timbre, a duller less expressive performance, increased aural fatigue and missing life and energy in reproduced sound – may be the primary consequences of the application of negative feedback. And even though modern electronic industry and the availability of modern solid-state amplification would be impossible without the application of negative feedback, many seasoned audiophiles have deplored its existence since its widespread use near the end of the 1920s. And some seasoned audiophiles even reasoned that the primary raison d’être of audiophile recordings is making solid-state hi-fi gear sound like they are made of vacuum tubes.

It is no secret that single-ended triode audio amplifiers with zero negative feed back have that magical quality of making less-than-pristine recordings – especially mainstream rock recordings – sounds as if they are made by boutique audiophile labels, literally!!! And it is also no secret that making zero negative feedback single-ended triode vacuum tube audio amplifiers as user-friendly as a typical packaged Bose Lifestyle Systems also makes them prohibitively expensive for the typical audiophile, never mind a first time one. So what would one do, would zero negative feedback vacuum tube preamplifiers provide a more economically viable option?

Ever since the Musical Fidelity X-Pre vacuum tube preamplifier during the latter half of the 1990s, many “working-class audiophiles” saw it as a godsend of making their real-world priced audiophile solid state amplifiers - like the Pioneer A-400 Power Amplifier – sound as if it is a single-ended vacuum tube audio amplifier, at least up to a point. But unknown to most audiophiles at the time, the vacuum tubes used on the 250 US dollar Musical Fidelity X-Pre are the same ones used on the 15,000 US dollar Conrad-Johnson ART preamplifier – the 6922 dual triode – the high-voltage Russian equivalent of the ECC88 / 6DJ8 dual triode preamplifier vacuum tube.

While the circuit on the Musical Fidelity X-Pre is not a zero feedback preamplifier, the negative feedback used is much lower than that typically used on most mass-market solid-state audio gear that, sound quality wise, the Musical Fidelity X-Pre managed to fly rings around comparably-priced solid-state audio gear in its price range at the time. Not to mention that it also has the ability to improve a bit the duff sound quality of most mainstream pop and rock recordings of the time – albeit just a hint of what a full-blown zero negative feedback vacuum tube gear can do.

Comprising just one stage: a true zero-feedback common cathode or anode follower preamplifier circuit employing paralleled 6922 / ECC88 / 6DJ8 dual triode vacuum tubes. And even though tube purists might argue that the choice of Conrad-Johnson to use 6922 / ECC88 / 6DJ8 dual triode vacuum tubes on their 15,000 US dollar ART preamplifier isn’t optimal, the non use of negative feedback made the Conrad-Johnson ART sound way better than the 250 US dollar Musical Fidelity X-Pre. But is there a potential to make a zero negative feedback amplifier that’s potentially better sounding that the ART and the X-Pre?

A few months ago, I managed to DIY a common cathode / anode follower zero feedback preamplifier that can use ECC32 / CV181 or other 6SN7 type dual triode vacuum tube provided the requisite biasing voltage adjustments are made. To make such a preamplifier that uses gigantic pre World War II vacuum tubes made before Dr. Harvey C. Rentschler managed to perfect how to manufacture acorn-sized miniature vacuum tubes like the 12AX7 run as noiselessly as a modern solid-state preamplifier necessitated an über-designed power supply with big choke filters and high-voltage capacitors. And just like the 15,000 US dollar Conrad-Johnson ART, it ended up as a two-box preamplifier. Sound wise, it has the ability to make duff recordings sound more audiophile up to a point and it can be connected to a real-world solid-state amplifier like the Pioneer A400 and make it sound really gorgeous. Though a 6SN7 / ECC32 based zero negative feedback preamplifier can never be manufactured and sold as inexpensively as the 250-US dollar Musical Fidelity X-Pre. Well, at least it sounded like a scaled-down ART.