DIY Audio Projects - Hi-Fi Blog for DIY Audiophiles

Cello Speakers - Lawrence Audio - CES 2012

2012-01-10T00:00:00.001-06:00

CES 2012 doesn't officially kick off until tomorrow, but today I decided to check out the layout of the High-Performance Audio floors at the Venetian. All the exhibitors were very busy setting up their exhibit rooms and it was nice to chat to them before the large crowds arrive tomorrow. Secretly my real intent of visiting the show a day before the official start was that I was hoping to get some private listening opportunities. While walking down one of the hallways the seductive voice of Rebecca Pidgeon pulled me into the Lawrence Audio room who are based out of Taiwan. Just my luck, their system was ready to play and my private listening session was just moments away. While it was the voice of Rebbeca that initially caught my attention, I was immediately struck the unique looking speakers on display and the wonderful sound emanating from them.

Lawrence Audio Cello and Violin Speakers at CES 2012

In the photo above are the new Cello speakers (larger, inside) and the Violin speakers (smaller, outside). The Violin ($7500US) speakers won an Innovations award at CES last year and this year the Cello ($20,000) speaker have received an Innovations award this year. The unique looking speakers resemble the instrument that they are named after which really is a refreshing change from typical boxy speaker designs. The Cello speakers each use five drivers to make a 3.5-way floor standing loudspeaker. The loudspeaker employs an air motion tweeter and an air motion mid-treble. The woofer and subwoofer units are 8-inch aluminum framed drivers with a non-woven carbon fiber cone. There is also a rear firing ribbon tweeter which I quickly identified as an Aurum Cantis G2Si. The crossover frequencies are set at 700Hz, 1.7kHz, 2.6kHz and 9kHz with preimum crossover components used throughout. The speakers have a nominal impedance of 4 ohms (3.2 ohms minimum) with a frequency response noted as 32Hz to 40kHz and a sensitivity of 90dB. The loudspeaker enclosures are vented at the bottom. Shown below with the Cello speaker is Lawrence Liao who is the acoustic designer and founder of Lawrence Audio.

Lawrence Liao of Lawrence Audio with Cello Speakers

The private listening session with Rebbeca Pidgeon and the Cello speakers was wonderful. I am very familiar The Raven recording and the Cello speakers did a fabulous job reproducing this excellent Rebbeca Pidgeon recording. The Cello speakers produced a very wide and deep soundstage. Most impressive was the focus and the deep bass. With closed eyes one can distinctly pick out all the instruments in the recording. With it's unique looks and excellent sound reproduction, I'm sure many will be wrting about these speakers at CES 2012. For more information see the Cello Loudspeaker at Lawrence Audio.

More CES 2012 Show Coverage

2012 CES, Las Vegas - diyAudioProjects.com Show Coverage thread

CES 2012

2012-01-09T01:14:00.000-06:00

I hope that all our readers had a great holiday season and best wishes for the new year. We are kicking off 2012 with a bang - a trip to Las Vegas and attendance at CES 2012. While I have been to Las Vegas many times, this will be my first time attending CES. Thumbing through the exhibitors list it certainly looks like almost all the Hi-Fi manufacturers will be represented at the show. The high-performance audio exhibits will be located at the Venetian Hotel. Floor plans for the High-Performance Audio suites are shown below (click floor plan images to enlarge).

Floor 29 - High-Performance Audio Exhibitors at CES 2012

Floor 30 - High-Performance Audio Exhibitors at CES 2012

Floor 31 - High-Performance Audio Exhibitors at CES 2012

Floors 34 and 35 - High-Performance Audio Exhibitors at CES 2012

As you can see, the show is huge, so naturally I won't be able to provide complete coverage from all the exhibitors. We will try check out most of the exhibitors and we will report back on the DIY parts suppliers in attendance and also on some of the new and interesting commercial hi-fi products on display. Updates and coverage from CES 2012 will be posted on this blog and also in the 2012 CES, Las Vegas - diyAudioProjects.com Show Coverage thread on the forum. I'm looking forward to hearing some very expensive Hi-Fi setups. It will be interesting to compare the sound from the high-end systems to that of my modest and predominately DIY system.

More CES 2012 Show Coverage

Informal Comparison of Six Phono Preamps

2011-11-22T18:14:00.001-06:00

This is a project that sort of evolved from an interest to see how good a particular phonograph preamplifier was. Not the one I designed, but one from a DIY kit. If I would have known how difficult and possibly inconclusive it would become, I might have not done it. As it was, the experience was valuable in several ways. First let it be clear in everyone’s mind that this comparison is largely subjective and based on what I hear or can measure. It was concerned with only those preamps that I had available at the time and your thoughts and results could be quite different. The comparison demonstrated that without a top notch system nearly any preamp might be OK. The flip side was also true that in a top notch system, many preamps would be unacceptable. Another thing that came from the listening and testing is that compliance with RIAA equalization varies from company to company but in many cases might not be audible. My method for comparison had two parts. The first was to listen to various selections of music with each preamp and then score them on various things I felt meaningful. The second was to check various parameters with my test gear. The following six phonograph preamps were the ones compared:

Oatley Electronics K303, JFET based RIAA Preamp Kit
Jaycar KC5433, Opamp based Preamp Kit (upgraded with BurrBrown opamp and Wima caps)
Hafler DH101, Transistor based full complementary (upgraded capacitors)
Phonopreamps.com TC750 PRO, discrete devices (upgraded capacitors)
SimAudio Moon LP3, IC based high performance
Oddwatt Audio Groove, all valve three stage SRPP design

Left top, Moon LP3, left middle TC 750, left bottom Jaycar KC5433,
Right top, Groove, right middle K303, right bottom DH101

General

The various phonograph preamps cover a wide range of designs and prices. The lowest cost ones are approximately $50 (TC750) and the most costly more than 10 times as much (LP3). One has an undetermined price at this time (Groove) and is likely to be above the upper end of the group even in kit form. Design variations range from entirely IC to all tube. Some use single ended configurations on the active devices, one uses fully complementary differential style (DH101) and one SRPP (Groove). All are designed as stand alone devices with the exception of the DH101 which is a complete preamp. All are MM/MI compatible with the LP3 also covering MC applications. All, but one, are solid state devices. There will be two phases, bench testing and listening.

Equipment Used For The Listening Portion

Pro-ject Debut III turntable with acrylic platter and Speedbox
Dynavector 10X5 high output MC cartridge (re-tipped with ruby cantilever by Sound Smith)
80-Step Passive preamp (1% precision resistors)
Oddwatt KT88 Monoblock valve power amplifiers
Martin Logan Vista electrostatic speakers (operating full range)
Marchand electronic crossover (50 Hz low pass / 24 dB per octave to subs only)
AudioSource Amp 100 dual 50 watt RMS solid state power amplifier (for the sub)
Custom designed 7 cubic foot subwoofers, 15" drivers (F3 = 22 Hz)
APC H10 AC line power conditioner

Listening Tests

Listening tests were performed first to avoid prejudging performance based on what the test measurements might indicate. Music selections consisted of new and older records. The music selected was varied and covered a wide range of genre. Different selections might have provided different results, but I tried to span a wide range. There were acoustic stringed instruments, male and female vocals (duets too), classic rock music, music with keyboards, solo jazz singers and big band. Each preamplifier was played in turn with the order mixed up with the same selection.

The listening performance was subjective and the various ratings are solely those of the tester. Scoring was as follows: Numeric grade of 1 to 10 with 10 being the best. 10 = among the best I have ever heard, 8 = excellent performance, 6 = average performance, 5 = minor deficiencies, below 5 increasing levels of unsatisfactory performance. Areas rated were: Signal to noise – both hum and / or background noise (only in bench testing unless one is obviously deficient during the listening tests), treble response, mid range response, base response, image centering, low level detail, sound stage width, and overall involvement of the sound.

(click to enlarge)

Listening Test Results

It seems that price and to a certain degree complexity matters. The three most pricy or complex designs were clearly better than the lower cost three. All of the top three excelled in some areas. There is a different flavor to each that shows up in how they rendered the different musical tracks. The Groove was a clear standout in the bass region. Solid, deep and well controlled bass was noted in all cases. Other preamps occasionally got into the sub 50 Hertz range, but none with such authority. The LP3 was second in this area and was clean and well controlled, but not nearly as authoritative. The DH101 had deeper bass than the LP3, but it was not as clean and well controlled. At the opposite end of the range, the LP3 had a slight edge on all others in treble presentation. The Groove was a close second and often they were tied. In the areas of inner detail, imaging and sound stage width the differences were often linked to the particular music being reproduced. It was largely a toss up between the LP3 and Groove with the edge going to the Groove. The primary difference between the top two preamps is one of flavor. The LP3 has a crisp clean leaning toward neutral sound and the Groove a warmer more delicate sound. Either would be satisfactory in many systems. The DH101 fell slightly short of the performance of the top two, but was in most areas a rather nice sounding preamp. The three preamps in the “budget” category were sort of a mixed bunch. They clearly were in a different category from the top performers. In some cases they would be good entry level preamps for someone just starting in vinyl. The TC750 even with upgraded components was at the bottom of the group. It performed in what I would generally characterize as less than average manner. It really has no place in a quality system. The other two (Jaycar KC5433 and the K303) are fairly well matched. Each is slightly above the average level, but well short of the top performers. Generally their shortcomings were by omission and not commission. They are characterized by things such as less detail, less response in various parts of the spectrum and the like. They did exhibit some sibilants and edgy sounding behavior on various selections, but were mostly listenable. I felt that the level of listening involvement suffered from the omissions. I would not recommend them for use in systems above the rather modest level. It must be noted that the two are diy kit based and low cost and would not be expected to compete in the same arena as the top performers. For entry level systems they might be a reasonable option. The K303 has two gain options and the recommended setting (less gain) resulted in an output significantly below all the other preamps. I changed the setting to the higher level and the output them was approximately equal to the other preamps.

(click to enlarge)

Equipment For The Bench Testing

HP 331A distortion analyzer
Velleman PCSD 1000 PC based digital storage oscilloscope
Tenma digital storage oscilloscope
Tenma precision signal generator
Circuit Specialists MS8040 true RMS multi-meter
B&K 290 electronic analog multi-meter
APC H10 AC line power conditioner

Bench Testing

All six phonograph preamps were bench checked with my typical set up of equipment. My results may or may not agree with results by other individuals, but are consistent among themselves. A long standing issue in my workshop is a relatively high level of electronic noise. All my equipment is fitted into a fairly small area and a lot of it generates noise. The noise floor in the shop is typically -91 to -95 dBv. This necessarily limits my ability to test really quiet equipment. This was the case with two of the preamps. On the day of the tests the noise floor was -91 dBv. The Moon LP3 measured -91 dBv and the Groove at - 89.9. All those results can tell me is that both units are very quiet. The specification for the Moon is -106 dBv and the Groove has been previously measured consistently right at the noise floor (-90 to -91). The remaining 4 preamps did measure within the capability of my equipment. They ranged from as low as -81 dBv to a high of -84 dBv (more negative is better).

The gain of the preamps ranged from a low of 34 dBv (DH101) to 44.2 dBv (Groove). The remaining 4 units were all clustered around 40 dBv. Initially the K303 was about 2 dB lower than all the others (at an estimated 32 dB) and I made the kit indicated modification for additional gain. In my opinion the original gain would be insufficient for many systems especially those using passive preamps.

For signal to noise level I used a combination of the noise floor and the gain. It might be better called effective difference between the level of output and the noise floor for a given input signal. That way it would provide an indication of how quiet a preamp would seem in any particular system. The more output you have from a preamp the less follow on gain you will need to use for a comfortable listening level. Then turning down of the system gain will apparently lower the noise floor of the entire system. The opposite is equally valid. An apparently excellent noise floor could be offset by low gain with the result being an apparent higher overall noise level in the final sound level from the system. The results here favored the Groove with its higher gain; however the Moon would probably be better if the actual noise level could have been measured. Both are extremely quiet in use. The remaining units were within a 5 dB span with the DH101 with the lowest apparent signal to noise ratio. None however exhibited sufficient noise to detract from the listening experience.

Distortion levels were measured at 1000 Hertz at the 1 volt RMS level into a 10k-ohms resistive load. Capacitance was minimal at approximately 100pF due primarily to the short cables used in the test set up. Deviating from my usual procedures, I used a battery powered signal generator. This eliminated a number of possible noise sources that would be considered by my distortion analyzer as distortion. For it anything that is not the fundamental is considered distortion. The penalty in doing this is that the residual distortion in the generator was 0.44%. However, since all preamps were tested the same the results while not definitive do provide a comparison. It should be noted that doing a complete test of the distortion levels and subsequent matching to the RIAA standard is a very time consuming process and was not the focus of this comparison. The actual distortion levels ranged from 0.65% for the Moon to 2.3% for the Jaycar. As noted in the listening tests there were no specific instances of audible distortion, but rather some less than stellar performances. Of particular note were issues with the TC750. In testing it was discovered that it had a very low output capability. It was unable to deliver over 1.75 volts RMS at low to mid frequencies and above approximately 10 kHz it could not deliver over 0.5 volts RMS without visible distortion of the wave form. All other preamps were able to deliver over 5 volts output at any frequency easily.

To determine basic compliance with the RIAA standard, I used 5 separate frequencies. All preamps were tested at the one volt output level except the TC750 that was unable to deliver that level and it was tested at the 0.5 volt level. The chosen frequencies were picked as they are the ones where the worst performance could be expected. This is at the upper and lower extremes of the audio band in comparison to the 1000 Hertz reference. My experience has been that nearly any phono preamp can come reasonably close to the standard between the limits of 100 Hertz and 10,000 Hertz. There is some disparity in what various manufacturers do at frequencies below 50 Hertz and above 15,000 Hertz. Some either flatten the curves there or in some cases actually intentionally reduce response there. The thinking behind this is most likely that there is little musical content there and there are possible benefits to the signal to noise and cancellation of rumble and low frequency resonances. In my opinion, the preamplifier should reproduce whatever signal it is fed and problems with noise should be handled at the source. As noted in earlier paragraphs, the measurements I made might or might not be the same as someone else would get, but all units were tested the same and the results allow for some comparisons. There really was no perfect fit. However the Groove, Jaycar and (surprise) TC750 were closest. The Moon was excellent on the high end, but for some reason demonstrated a reduction at 50 Hertz (only a dB) and a rapid reduction in response at 20 Hertz (3 dB). The K303 was significantly off at 50 and 20 Hertz and I can speculate it was because of its high sensitivity to the load. This was evident when a quick check of each preamp was done with a 5 k-ohm load in place of the standard 10k one. The only preamp that demonstrated a significant drop in output was the K303. The reduction was approximately 3 dB at mid band. This factor may limit its application to only systems with relatively high input impedance (the test system was approximately 50 k-ohms).


Electrical Test Data (click to enlarge)

Summary and Conclusions

Since the comparison was largely subjective with some bench testing used to verify or at least establish some relationships between the preamps, the conclusions necessarily are also subjective. None of the three “budget” preamps should be considered anything but entry level devices. The TC750 is at best a marginal one even in that group. The K303 and Jaycar are fairly well matched, but have slightly different sonic signatures. In modest and undemanding systems they would probably be adequate. I would not use the K303 without the modification for higher gain. The notation in its instructions that the extra gain would allow it to be used with low output moving coil cartridges is suspect. With the extra gain it was right in the middle of the group for moving magnet / moving iron cartridges. I would also not use it systems in which the following equipment had an impedance lower than 10K ohms and preferably with ones above 50K. The DH101 was a surprisingly good performer considering it was included primarily as a comparison of older technology, granted one with some exceptional design features. It would have fared better with more gain, but since it is actually part of a complete preamplifier it is entirely likely that the shortage in gain was compensated for in later stages. The remaining two preamps are both excellent and quite different in many respects. Both are extremely quiet. They have low distortion and with the exception of the curious bass reduction in the Moon, match the RIAA curves well. They both sound excellent, but different. The Moon is articulate and the Groove robust. Each is a product of its technology. The Moon is all solid state IC based. The Groove is an all valve design. The end choice is likely to be whether you prefer solid state sound or valve sound. I will not argue for either case as both are valid at the personal level. My personal preference is for the sound of the Groove, but I could, and have listened happily to the Moon for nearly a year while designing and perfecting the Groove.

Good listening,

Bruce Heran

Knock-Down Birch Speaker Cabinets

2011-11-12T16:01:00.001-06:00

Speaker building is a lot of fun and there are many who would love to try it out but can't due to some common woodworking hurdles. You may not have the space, tools or skills necessary to build a good loudspeaker enclosure. For others sawdust or climate (winter) could be the problem. Fortunately there are some great solutions that can eliminate much of the woodworking necessary to build a speaker box. For a number of years Dayton Audio has been producing pre-made speaker enclosures like the Dayton pre-made curved speaker cabinets which make it real simple to put together a great looking finished speaker. Perhaps the only downside to the great looking ready-made cabinets is that they eliminate too much DIY and they are bulky to ship.

Enter these great Knock-Down Birch Cabinets from Parts Express. The cabinets are CNC-cut and made from seven-ply, 1/2" birch panels. The cabinets have dadoed top, bottom, sides and braces to maximize the gluing surface. The knock-down speaker cabinets are unfinished leaving you with many different finishing options.

Knock-Down Birch Speaker Cabinets

Shown in the photo above is the Knock-Down Birch 5.1 Home Theater Cabinet Package and a Knock-Down Birch 0.60 cu ft Monitor Cabinet. The YouTube video below shows just how simple it is to put together the knock-down birch speaker cabinets.

With the CNC birch knock-down cabinets it is easy even for the beginner to end up with amazing finished results without the need for expensive tools or access to a woodshop. There are a number of cabinet sizes to choose from. See the Knock-Down Birch Cabinets for a full selection.

More DIY speaker kits and cabinets

Groovewatt Tube RIAA Phono Preamp

2011-11-02T22:12:00.001-05:00

The latest project from Bruce's workbench is the Groovewatt, a tube based RIAA phono preamplifier. The Groovewatt is the result of over one year of work and several build iterations. Bruce set some pretty high performance requirements for the tube preamp and he is very pleased with the results.

Second Groovewatt Build

The Groovewatt uses a symmetrical SRPP (12AX7) input stage which feeds a passive RIAA equalization network. The second gain stage is nearly identical to the input stage and is direct coupled to the third stage which is a cathode follower (12AT7). Bruce used Gold Pin JJ ECC83S for the SRPP stages and half of a ECC81 for each side of the cathode follower. The power supply is solid state and DC is used for the tube heaters. Total gain of the RIAA phono preamp is about 45 dB which should be sufficient for use with a high output MC cartridge.

Inside View - Third Groovewatt Build

Third Groovewatt Build

The measured performance of the Grovewatt is excellent and noted in the project page. Bruce reports excellent results with the Groovewatt in place in his system. For the full details of the Groovewatt, see the DIY Vacuum Tube (Valve) RIAA Phono Preamp project page.

More Hi-Fi Vacuum Tube Projects by Bruce

BK-12m Folded Horn Kit - Fostex FE126En

2011-09-11T22:54:00.000-05:00

There is a new high-sensitivity folded horn speaker kit being offered by Madisound. The new BK-12m is a single-driver folded horn speaker kit that follows in the lineage of the BK-16 and BK-20 designs. The BK-12m uses the Fostex FE126En full-range speaker driver in a custom folded horn enclosure while the driver is run full range with no filters whatsoever. The Fostex FE126En driver is 4.7" (120 mm) in diameter with a rated sensitivity of 93dB/W(m). This high-sensitivity means that the BK-12m speakers will be suitable for use with low powered amplifiers.

BK-12m Folded Horn Kit - Fostex FE126En

The enclosure panels are made using high quality 5/8" (16 mm) thick Baltic Birch multiplex cut using a CNC machine and bundled as a flat pack. Once completed the speaker cabinets have overall dimensions of 31-5/8" x 7-1/4” x 14-1/2" (800 x 185 x 370 mm). The Birch plywood is unfinished so you can finish the speakers how you like.

The BK-12m speaker kit includes:

2 x Fostex FE126En 4.5" Full Range Drivers;
2 x Unassembled, unfinished Baltic Birch Cabinets;
3 oz. Acousta-Stuff internal damping material;
5 ft Supra Classic 1.6 15 AWG speaker wire;
4 x QC187 Quick Connects (2 red, 2 black);
8 x 8X1 Socket Head Wood Screws (8x Philips Head wood screws also included);
Assembly Instructions.

To put the kit together you will need just a screwdriver, wood glue, sand paper, bar clamps and binding posts. An inside view of the folded horn speaker enclosure is shown in the photo below.

Inside - BK-12m Horn Speaker Kit - Fostex FE126En

The BK-12m kit is available from Madisound for $315US + shipping. For full details about the BK-12m speaker kit see the product page at Madisound.

More single-driver speaker kits and projects:

DIY 2-Way Tower Speakers - Ion

2011-09-05T12:01:00.000-05:00

Adam has put together a fantastic looking pair of tower loudspeakers and he has shared his design with us. The speaker design uses a Tang Band 25-1372SC 1" inverted titanium dome tweeter combined with a pair of Audax HM170CO 6" woven carbon fiber mid-woofers and used in a TMM configuration.

The loudspeaker enclosures are constructed using 1.5" thick MDF with solid oak side panels. The overall dimensions of the tower speakers are 37.5" x 8.5" x 11.5" with each weighing about 60 pounds. The MDF is painted with a textured graphite spray and the side oak panels are stained.

Speaker Box Assembly with Straps

Test Fitting the Drivers

A 2-Way passive crossover dividing network consisting of a 3rd order Butterworth filter at 4000 Hz is used along with an impedance correction network. The nominal impedance of the speakers is noted at 4 ohms and the loudspeaker covers a frequency range of about 60 Hz to 20 kHz. In-room you will get some additional bass extension (shown on the in-room measurements). The total cost for the pair of tower loudspeakers was about $900 US.

Adam reports that the Ion speaker build is his favorite so far. "The Audax HM170CO woofers produce very warm natural tones up through the upper midrange. With the TangBand 25-1372SC tweeter the highs are crystal clear, detailed but far from harsh. The Ion speaker is a very challenging build but it comes with a huge payoff! These have quickly become my favorite loudspeakers." Great work Adam and thanks for sharing your work.

For the full details of Adam's speaker project see the Ion - DIY 2-Way TMM Tower Loudspeaker Project page.

More DIY Speaker Projects by Adam

Boozhound Labs JFET RIAA Phono Preamp Kit Review

2011-07-11T12:29:00.003-05:00

After building a few diy versions of the Boozhound Labs / Le Pacific JFET RIAA phono preamps, Mark decided to try the actual $79US Boozhound Laboratories (BHL) JFET RIAA phono preamplifier kit. In Mark's diy versions of the phono preamp he used polypropylene capacitors.

DIY JFET Phono Preamp on Stripboard

On the other hand, the BHL phono preamp kit comes with fabulous looking vintage new old stock (NOS) Russian military paper-in-oil (PIO) capacitors. PIO capacitors made in this fashion are quite respected and sought after for their sonic qualities. The BHL phono preamp kit comes with a PCB, the circuit parts and detailed building instructions. The kit builder will need to supply a 24VDC power supply (linear, regulated or battery will work), a chassis to house the preamp and various miscellaneous hardware items like connectors and switches.

Finished JFET Phono Preamplifier Kit PCB with PIO Capacitors

For his kit build, Mark used AA cell batteries for a noise free power supply and he housed the preamplifier circuit and battery power supply in the 19-inch 1U chassis shown below.

Inside View - JFET Phono Preamp

Mark reports that this is his best phono preamplifier build so far. For full details about this project, see Mark's review of the Boozhound Laboratories JFET RIAA phono preamplifier kit.

Other Phono Preamplifier Projects by Mark

Fundamental Amplifier Techniques with Electron Tubes: Book Review

2011-06-14T21:34:00.002-05:00

Late last year Elektor released their most recent publication on the increasingly popular subject of hi-fi tube audio, Fundamental Amplifier Techniques with Electron Tubes by Rudolf Moers. The new book is actually the English translation of "Fundamentele versterkertechniek met elektronenbuizen" (ISBN 978-90-5381-226-6) authored earlier in Dutch by Rudolf Moers. The thick hard bound book is 834 pages and seemingly covers what appears to be just about every topic on the subject of audio amplifier design with vacuum tubes. I recently had an opportunity to read the book and here is my overview of the new electron tube book.

Fundamental Amplifier Techniques with Electron Tubes - Rudolf Moers

The thick book is divided into ten chapters. At just a few pages each, the first two chapters, (1) Introduction and (2) Principles of Electron Emission are very small relative to the remaining chapters and book. These very short introductory chapters provide only a very brief overview and assume that the reader has a reasonable background in electronics. The meat of the book begins with chapters 3, 4, 5 and 6 which each respectively go on to cover the basic electron tube types: diode, triode, tetrode and pentode. For each of the basic tube types the chapters generally include information on tube construction techniques, the tube characteristics, all the typical tube applications and several design examples. The chapter subsections are quite detailed and will for example get into the formulas and calculations of AC ripple that can be expected in a C-L-C pi-filter and calculating gain of as common cathode amplifier. Over 200 pages are dedicated towards the pentode and over 250 pages are spent on the tridode. The book also contains many technical questions which the reader can work through, much like the questions that would be found in a science text book. A detailed solution accompanies each of the questions and this makes the book a very good learning tool for those interested in audio theory and design. Frequency Dependent Behavior is covered in the 88 page Chapter 7. The chapter goes into details regarding linear distortions for the various components that make up an amplifier. Non-Linear Distortions and Noise are discussed in Chapter 8 and the various types of Negative Feedback is the topic for Chapter 9. The final chapter (10) pertains to the construction of electron tube amplifiers. As a builder of amplifiers I found interest in this chapter as it contained good practical information on electronics components, various construction techniques, crosstalk, heat / cooling issues, grounding, shielding and safety. Also included in Chapter 10 are additional details of Rudolf's parallel push-pull 300B monoblock tube amplifiers among other of his amplifier builds.

The full table of contents for Fundamental Amplifier Techniques with Electron Tubes is available from Elektor's website [PDF - 163kB].

The book which is written in a technical format with plenty of theory, math and graphs will be primary suited towards advanced hobbyists with a strong understanding of analogue electronics and towards students and professionals involved electrical engineering and audio design. Those without a good background in electrical science may not find the text and formulas all that easy to follow. The carefully written book is a significant undertaking and provides plenty of accurate and valuable theoretical information on numerous subjects related to understanding and designing electron tube amplifiers. Congratulations to Mr. Moers and his colleagues for the excellent learning tool and resource that they have compiled. I will continue to find value in this book as a reference resource in my workshop.

The book Fundamental Amplifier Techniques with Electron Tubes, by Rudolf Moers (ISBN 978-0-905705-93-4) is available for $104.90US (plus shipping) from Elektor.

More DIY Audio Books

SuperCables CookBook - Book Review
DIY Audio Books and Manuals - book suggestions

How to Solder - Comic Book Guide

2011-04-12T21:45:00.001-05:00

There are a number of great soldering tutorials already available via the internet in the form of videos and webpages and today I came across another great soldering guide - this one packaged in a comic book format (see below for PDF download link).

The great new seven page comic book guide about how to solder has been put together by Mitch Altman (Cornfield Electronics) , Andie Nordgren and Jeff Keyzer (Mighty Ohm). The comic book guide is based on the popular one-page soldering guide below that Andie and Mitch made last year. (Click image to enlarge)

The Soldering Is Easy comic book guide is easy to follow and informative. The guide is published under a Creative Commons License and the link to the PDF version of the soldering guide is below.

Soldering Is Easy - Here's How To Do It

Soldering Is Easy - Comic Book Guide [PDF - 812kB]

Feastrex NF-5 and NF-5ex Drivers at SSI 2011

2011-04-07T22:16:00.003-05:00

We are big fans of single full-range driver loud speakers so we were excited to check out the Feastrex drivers. Michael Tang of Mike Tang Audio is importing the Japanese Feastrex NF-5 and NF-5EX drivers into Canada and had them on display at the show.

The 5" Feastrex NF-5 ($2000CDN, shown above) uses a large Alnico magnet. The handmade cones are made from Japanese Washi paper (a higher density fibrous paper) which is impressed in a spiral pattern with embossed ridges. The drivers surround is made from lamb skin.

The 5" Feastrex NF-5ex ($3000CDN, shown above) uses the same Washi paper cone and a lambskin surround, but with a motor that uses a field-coil magnet (electromagnet). The field-coil magnet can be operated between 10 and 17V dc. Changing the voltage allows you to change the damping of the driver. Michael uses a 12V car battery for the field-coil magnet. 16 ohms, 95 dB, 35 to 25,000 Hz (+/- 3dB).

A Mastersound Compact 845 SET powered the 5" Feastrex NF-5 drivers which were housed in a bass reflex enclosure (enclosure plans from Feastrex, shown below), no passive filters were used. The speakers sounded excellent, wide soundstage and impressive depth. The single drivers delivered superb clarity with vocals to die for.

Michael indicated that he is working on a transmission line enclosure design for use with the Feastrex NF-5 and NF-5ex drivers which he plans to have ready for the TAVES (Toronto Audio and Video Entertainment Show) this fall.

More Salon Son & Image 2011 Coverage

Voxativ Ampeggio Horn Speakers at SSI 2011

2011-04-07T15:57:00.004-05:00

There were a number of ultra high-end Hi-Fi systems at the Montreal show and like last year, my favorite Hi-Fi systems at the show was once again a low powered single-ended tube amp matched with high sensitivity fullrange drivers. My favorite this year were the new German made Voxativ Ampeggio single-driver rear-loaded horn speakers. The hand built rear-loaded horn enclosures are built in a collaboration between Voxativ and the famous German piano factory Schimmel Pianos. The cabinet surface is finished with a minimum of 13 applications of hand polished lacquer covered in real piano lacquer. The finish on the loudspeakers was simply amazing.

The product literature lists the following specifications for the Ampeggio:

Frequency Response: 38 - 20,000 Hz
Sensitivity: 101 dB / 1w / 1m
Impedance: 10 ohms
Dimensions (W x H x D): 16" x 43" x 14" (40 x 110 x 35 cm)
Weight: 121 lbs (55 kg)
Cost: $29,750US

The lone transducer used in the Ampeggio is the Voxativ AC-3X, which is their largest neodymium driver and unavailable for purchase. The drivers suspension is made from goat leather. The loudspeaker systems does not use any crossover components.

A Don Garber Fi WE421A ($3275) single-ended triode amplifier (a single dual triode), putting out just 5 watts per channel was used to drive the Ampeggio speakers. With a sensitivity of 101dB it was plenty loud. The high sensitivity and easy 10 ohm loads means these speakers will mate very well with low power SET amplifiers. The Ampeggio speakers sounded every bit as wonderful as they looked. Open, dynamic, excellent clarity and plenty of detail.

More Salon Son & Image 2011 Coverage

The AuDIYo.com room at SSI 2011

2011-04-05T22:26:00.003-05:00

Like last year, the AuDIYo.com room was displaying a number of high-end audio accessories, cables, audio connectors, tweaks and DIY parts from Furutech, Mundorf, DACT, TentLabs, 1877Phono and others.

The AuDIYo show setup was focused around the recently introduced Furutech GT40 USB DAC with phono stage - $495. The Furutech GT40 USB DAC with phono stage was previously used with a computer to make vinyl rips into 24bits/96kHz lossless digital files. The digital files were then played back through the DAC which fed a vintage Dynaco ST-70 tube amplifier, which in turn drove a pair of Klaro speakers. The quality of the vinyl rips was excellent and if you were not paying attention you would think that you are listening to a record as the recording preserved all the surface noise, pops and clicks one would expect from vinyl. The Furutech GT40 USB DAC also features a very good headphone amplifier and a pair of Sennheiser HD598 headphones were on hand to audition the head amp section.

The vintage Dynaco ST-70 tube amplifier on had been upgraded with Mundorf high voltage filter capacitors and M-Caps were used upgrade the signal and coupling caps. Simon Au of AuDIYo indicated that they are working on printed circuit boards and customizable kits that can be used to upgrade ST70 amplifiers. We will post an update when we get word that the upgrade kits are available.

More Salon Son & Image 2011 Coverage

Solen.ca DIY Speaker Kit - SSI 2011

2011-04-04T18:13:00.004-05:00

On display on the Solen.ca room was a new DIY bookshelf speaker kit that is currently being developed and should be available soon.

The DIY speaker kit will use a pre-finished curved Dayton Audio 0.38 ft^3 speaker enclosure. The drivers are from Airborne, a 120 mm wood cone driver with a 25 mm voice coil (HR124B8-10L) and the high-end is covered by a Air Motion Ribbon Tweeter (RT-20021). The kit will use a 2-way passive crossover which has yet to be finalized. No word on when exactly the DIY speaker kit will be available but Solen indicated that that the price of the kit will be about $550. As more details come available about the kit we will post an update.

Also on display were a number of drivers, amplifiers, connectors and feet for you DIY speakr projects.

More Salon Son & Image 2011 Coverage

Little Horn Speakers - SSI 2011

2011-04-02T17:39:00.006-05:00

The unique looking "Little Horn Speakers" caught my eye and I was particularly excited to see they use a familiar transducer, the Fostex FE108E Sigma. While their size is far from what most would describe as a little speaker, they are little for a horn. [Click on the images to enlarge]

The custom handcrafted speakers are produced by Specimen Products from Chicago. The enclosure (base) is made using Baltic birch plywood and this acts as the compression chamber. The horn is cast using a heavy-duty resin and both the base and horn are finished with lacquer.

The overall height is 36" (915 mm) and the bell of the horn is 14" (355 mm) across. The base is an 8" (200 mm) cube. The impedance is noted as 8 ohms with a sensitivity of 90 dB. The frequency response is listed as 77Hz to 23kHz. The speakers are well suited for use with low power tube amplifiers.

The Little Horn Speakers delivered a surprising large soundstage and you get the single-driver finesse and detail that FE108E Sigma is known to deliver. The speakers retail for $2400 / pair are available in a number of colors. More information and photographs are available from Specimen Products website.

More Salon Son & Image 2011 Coverage

Orangutan O/96 High Sensitivity Speakers - SSI 2011

2011-04-01T18:03:00.008-05:00

We have arrived at the Salon Son & Image 2011 show and have taken a quick look at the various exhibits. Since we cannot cover the entire show, we have decided that our coverage will be focused primarily around our favorite topics, DIY audio, high sensitivity speaker systems, headphones and vacuum tube gear. To get the show coverage started, here are the Orangutan O/96 Oscar loudspeakers (click image to enlarge).

The DeVore Fidelity Orangutan O/96 is a 2-way design that uses a custom SEAS 10" (254 mm) paper cone woofer with a phase plug. The tweeter is a 1" (25 mm) silk-dome tweeter that uses a double-magnet motor system and is gently loaded by a waveguide. The speakers are individually hand built in New York City and are listed at about $12,000US.

The sensitivity is noted at 96 dB and the nominal impedance is 9 ohms. The in-room representative indicated that the impedance does not drop below 7.8 ohms - so these speakers will be an easy load to drive. The frequency bandwidth is noted as 30 Hz to 31 kHz. The overall dimensions are 12" d x 18" w x 28.5" h (305 x 457 x 723 mm).

The speakers had a very nice coherent sound with holographic imaging. With the high sensitivity and easy to drive load, this speaker mates well with lower powered single-ended tube amplifiers.

More Salon Son & Image 2011 Coverage

Salon Son & Image 2011 - Show Coverage

2011-03-30T23:32:00.007-05:00

The Salon Son & Image 2011 show, known to audiophiles as the Montreal Hi-Fi is just several hours away from kicking off and once again diyAudioProjects.com will be in attendance providing show reports.

If you have any suggestions for what you would like to see with regards to show coverage - post a note in the Salon Son & Image 2011 - diyAudioProjects.com Show Coverage thread and let us know.

Show reports will be posted right here on the DIY Audio Projects Blog.

Here is the SSI 2011 Press Release:

The most anticipated Home Entertainment event arrives in Montreal!

Feel the sound of rhythm and image

Montreal, March 16th — The 24th edition of Salon Son & Image settles at the Hilton Bonaventure in Montreal from March 31st to April 3rd . Our spokesman François Charron is pleased to invite the general public, music lovers and audiophiles to come see and hear more than 300 brands of high-end gear, including wireless multi-zone systems, USB readers, on-wall speakers, 3D projectors, custom earbuds, the iPad2 and so much more.

Don’t miss the amazing audio and home theater demonstrations presented throughout the weekend. Free seminars are offered everyday to teach you how to select, connect, optimize and use all types of devices.

We're proud to introduce, for the first time at the show, home automation technology in all its forms. It will be displayed in an area of over 6,000 square feet. You can witness how to control lighting, temperature, audio distribution and much more. Home automation is accessible to all ... come and discover.

SSI partners with the Fondation Dédé Fortin:

This year, the president and director of SSI are partnering with the Fondation Dédé Fortin. Michel Plante and Sarah Tremblay have focused on suicide prevention by presenting the vibrant live performance "Passe-moé la puck Dédé". This benefit concert will be presented Friday, April 1st at 9pm at the Montreal Hilton Bonaventure. Featuring 20 artists, including Pierre Flynn, Bori, Charles Dubé, Gaële, Bon Débarras, the dance troupe Bourask and many other surprises. It’s not necessary to mention that the sound will be awesome! All funds raised will be donated to the Fondation Dédé Fortin.

More details: www.fondationdedefortin.com

About Salon Son & Image

SSI has been hosted in Montreal since 1984. Its reputation has long since crossed the border and has become, over time, the largest high-end show open to the general public in North America.

Its mission is to educate consumers to help them make informed choices in their future purchases, present the latest technology in high-end home entertainment, and highlight the best brands in the field and network of dealers.

More details: www.salonsonimage.com

Schedule:

*Thursday: 11am – 6pm *Thursday is reserved for media and industry professionals.

Friday: 11am – 9pm

Saturday: 10am – 6pm

Sunday: 10am – 5pm

Admission (for the week-end, including Passe-moé la Puck concert)

Regular: $15

Senior: $10

Student: $10

Free under 12 years old

Exhibition site:

Hôtel Hilton Bonaventure

900 de la Gauchetière West

Montreal, Qc, Canada

More Salon Son & Image 2011 Coverage

DIY Audio, Hi-Fi and Music Roundup #2

2011-01-10T21:37:00.002-06:00

Happy New Year folks and welcome to our second installment of the DIY Audio, Hi-Fi and Music Roundup.

PARTS AND KITS

Oatley Electronics K295 Stereo Tube Sound Line Buffer Amplifier Kit

The latest kit offering from Oatley Electronics is the K295 Stereo Tube Sound Line Buffer Amplifier Kit which retails for $36AU. The low cost, simple to construct, stereo tube buffer, lets you experience "tube sound". The kit is based around JAN 6418 sub-miniature vacuum tubes and designed for 100-120 or 200-240V 50/60Hz AC operation. These inexpensive tube kits can sound quite good, see Mark's review of the K272 Headphone Amplifier Kit and the recent review in audioXpress. Via - Mark [K295 stereo JAN6418 tube buffer / preamp kit].

Oatley Electronics K295 Stereo Tube Sound Line Buffer Amplifier Kit

Decware FRX Full Range Driver

Decware has released the 8" Decware FRX Full Range Driver for open baffle loudspeakers. The unique driver is hand built and offers an extended ultra flat response made possible by it's electromotive coupling technology and powerful neodymium magnet. The exotic drivers retail for $595US each.

SPECIFICATIONS	TS	PARAMETERS
95 dB with 1 watt at 1 meter Response is 38Hz ~ 25kHz 8 ohm nominal impedance 17 watts RMS Dimensions: A: 8.7", B: 7.2", C: 4.0" D: 9.8" 1 inch voice coil machined copper phase guide 5 way machined gold plated binding posts on rear Shipping weight 15 lbs ea.	Re Fs Qe Qm Qt Le Vas Xmax Ef Zmin Zmax	7.36 ohms 70 Hz 0.83 8.45 0.76 1.88 2.04 4.22 mm 95dB 1w/1m 7.4 ohms 72 ohms

The FRX represents an obsessive effort on my part to perfect the full-range point-source driver for Open Baffle speakers at a sane cost. While the build quality of this driver will compete with with other brands costing many times the price, I don't believe any of them will hold up sonically because of the side effects of high flux low mass designs. Side effects like the occasional shouty mid-range and forward presentation or ringing that comes with the tipped up response that is characteristic of these types of drivers. The FRX overcomes these side effects with a unique motor assembly that uses electromotive coupling between the amplifier and the voice coil. There is no other single driver in the world with this technology.

I personally hand build these drivers to order. Build time on a pair of these fine drivers is 6 to 8 weeks.

-Steve Deckert

PROJECTS

Solo 103 Build with Fostex FE103En

Kris at HIFI ZINE has tried out the Solo 103 enclosure with the new Fostex FE103En driver. The Solo 103 enclosure was originally meant for the Fostex FE103 (a.k.a. ACR FE103) and there have been many positive reports with the more recent Fostex FE103E. For full impression of the Solo 103 speaker with the new Fostex FE103En drivers see A Solo 103 Build.

Solo 103 Build with Fostex FE103En

ECC802S Tube SRPP Preamplifier
Bruce of OddWatt Audio has shared with us his ECC802S tube SRPP preamplifier design. The preamplifier uses a solid state power supply and DC is used for the heaters. The gain of the preamp can be set at 7 or 11. 12AU7 and ECC82 tubes can also be used. For more information about this project, see the DIY ECC802S (12AU7 / ECC82) Vacuum Tube SRPP Preamplifier.

ECC802S Tube SRPP Preamplifier

NEWS

There is a new annual audio and video show in Toronto, Canada. The Toronto Audio Video Entertainment Shows (TAVES) will be holding it first annual consumer audio, video and electronics show in Toronto in 2011. The show is scheduled for September 30 to October 2, 2011 at the King Edward Le Meridien. For more information, see the TAVES website.

MUSIC

HDtracks Offers Select Titles with 24-Bit/192kHz Resolution

HDtracks is now offering select titles in full 24-bit/192kHz resolution. The currently available titles are Jen Chapin - reVisions: Songs of Stevie Wonder and The Jazz Side Of The Moon by musical artists Seamus Blake, Ari Hoenig, Mike Moreno, and Sam Yahel. Both titles are from the Chesky Recrods label and are priced at $26.98.

FUN

DIY Chocolate Records

Meet a man who makes sweet sweet music... A video showing the creation of a chocolate record that actually plays yummy music.

Giveaway #5 - Fundamental Amplifier Techniques with Electron Tubes

2010-12-29T19:32:00.000-06:00

The good folks at Elektor have provided us with a copy of Rudolf Moers' new book, Fundamental Amplifier Techniques with Electron Tubes for this giveaway. Fundamental Amplifier Techniques with Electron Tubes is the English translation of Fundamentele versterkertechniek met elektronenbuizen (ISBN 978-90-5381-226-6) and has been available since last month. The 834 page hard bound book covers the fundamentals of vacuum tubes and shows how to apply that information towards audio amplifier design.

We will be giving away one copy of the book. The giveaway winner will be selected at random from the giveaway list on 10 January 2011. You can get on the giveaway list twice. Once by signing up for our RSS Feed through Email (you don't need to sign up again if you are already subscribed), and you can earn an second entry on the list by participating in the Giveaway #5 thread on the forum. Note that the verification emails often ends up in the spam folder so be sure to check there after you have signed up to verify your subscription. The randomly selected winner will be contacted through email for their shipping details.

Good luck!

The Fine Wire Audio Cable Shoot-Out

2010-12-07T21:15:00.003-06:00

After finishing the SuperCables CookBook by Allen Wright I decided to make some audio cables. One of the concepts that Allen pushes in the book is very thin wires. Originally I had no intentions of making any cables from the book but after reading through the book I got the urge. According to Allen thin is in. I chose to try a couple of the designs that use wire wrap wire (WWW). Details of the cables that were built using WWW are noted in Part 2 of the SuperCables CookBook review.

The HiFi Test Set-up

The test set-up used to evaluate the cables consisted of an upgraded Oppo 980H, a diy build of the Nelson Pass B1 buffer preamp, a diy 6AS7 SET power amplifier and Fostex FE206En drivers in a back loaded horn enclosure. I selected a number of test tracks which I thought had enough variation to exhibit any great cable sonics. To make sure I was not biased I enlisted the aid of a golden eared friend, Ron from the Melbourne Audio Club. He also brought along his test tracks.

Oppo 980H, Pass B1 Buffer, 6AS7 SET, FE206En Rear Horn

Cable Shoot-Out

We played through about half a dozen test tracks using both short and long runs of #1, Air-spaced Finewire RCA cables and set of #6, Air-spaced Finewire speaker cables which were 2 m in length. My SET amp produces only 3W so fine wire speaker cables will work with this amp. But will it be the best sound we can get?

What we found was in just three test tracks we could listen for:

The shimmer in cymbals
The breathiness in flute and its balance against a harp
The rich tone of a fully fleshed violin

Of course this in no way covers every tone or nuance of every sonic effect listenable on any recording but I feel it was enough to highlight the main differences in the cables.

After listening with the cable combination above we swapped the #1, Air-spaced Finewire RCA cables for a cheap $2 store bought RCA cable. Some areas of the test music actually improved. The sound stage appeared to widen or was it just smeared between the speakers. The violin appeared to fatten-up or was the detail just lost. Ron and I then, cable by cable, started putting back both sets of #1, Air-spaced Finewire RCA cables and the other various cables that we had on hand.

We started with the short #1, Air-spaced Finewire RCA cables which lead from the CD player to the preamplifier. We also introduced my twisted version of the WWW interconnect cables and also my braided Silver Highway RCA cables. I have built many sets of these high-purity silver wire RCA cables and everyone who has used them claims they are excellent. At each stage we re-listened to the three test tracks.

What We Found

Without boring the pants off you with every detailed cable swap this is what we found.

The #1, Air-spaced Finewire interconnect cables work best between the CD player and the preamp (short cable, 150 mm long)
My diy Silver Highway RCA cables (900 mm) worked best between the preamplifier and power amplifier. They worked better than my twisted WWW cable, but only slightly better.
Multi-stand heavy OFC speaker leads (3 m long) with heavy brass banana plugs only just outperformed the #6, Air-spaced Finewire speaker cables (2 m long).

Cable Measurements

Ron brought his dedicated capacitance and inductance meter and here are the cable measurements:

RCA Cables

#1, Air-spaced Finewire (short): 30 pF, 8 uH, 0.4 ohm

#1, Air-spaced Finewire (long): 30 pF, 13 uH, 1.5 ohm

Twisted cables (destination end): 13 pF, 8 uH, 0.4 ohm

Twisted cables (source end): 138 pF, 10 uH, 0.4 ohm

Silver Highways (900 mm): 71 pF, 2 uH, 0.3 ohm

$2 Generic RCA (1000 mm): 370 pF, 0.1 uH, 0.1 ohm

Speaker Cables

#6, Air-spaced Finewire (2 m): 25 pF, 17 uH, 1.5 ohm

Multi-stand heavy OFC (3 m): 210pF, 1uH, 0.1 ohm

Note: The twisted cables comprise of three wire wrap wires, only two of which are terminated at the destination end. I believe the 30 pF of capacitance for some of #1, Air-spaced Finewire cables is due to the cheap RCA plug that was used. The twisted cables had only 13 pF for the destination end which only has two wires connected. Also the RCA used on the twisted cable were heavy weight high-end types and I believe low capacitance types.

Just a Cable Suggestion

It is worth while trying different cables, weather you make your own or buy them off the shelf. If possible, try borrowing some friend’s cables before outlaying hundreds of dollars on expensive ones. Different combinations of cables can work better than just one cable type used throughout your system. If nothing else, cable swapping and comparison will fill in an afternoon and you may enjoy the music along the way.

Mark Houston - retro-thermionic.

This concludes Mark’s three part series of the SuperCables CookBook. For the full story, refer to the SuperCables CookBook (Part 1) which reviews the book and Part 2 of the SuperCables CookBook review which takes a look at a couple of the cable recipes.

Update (11 December 2010): I've updated the terminations for both the #1, Air-spaced Finewire RCA interconnect cables and the #6, Air-spaced Finewire Speaker Cables. See the Skinny is in! - Thin wire audio cables thread for more information and further discussion.

DIY Cable Projects

SuperCables CookBook - Review (2/2)

2010-12-05T20:05:00.005-06:00

A couple of days ago I posted a partial review of the SuperCables CookBook by Allen Wright. Of course there is not much use in working your way through a audio cable design book and then not building at least one of the cable designs. In this second part of the SuperCables CookBook review I will share my experience with a couple of the book designs and also try a simple design of my own using some of the design concepts outlined in the book.

Over the past few years I have built a number of diy twisted RCA interconnect cables using high purity silver wire. Some of the cable design concepts outlined in the SuperCables CookBook agree with my past construction methods. So, can I use the new concepts to build a better interconnect cable? There are several cable designs in the book and I chose to build the wire wrap wire (WWW) interconnect and the WWW speaker cables. Wire wrap wire is typically 30AWG silver plated copper wire often insulated with Teflon. It is cautioned in the book that the WWW speaker cables can be no longer than 2m and that they should be used for low power amps only. My axe-of-choice when it comes to power amps is a 3W 6AS7 based SET (Single-Ended Triode) amp. Perfect. The book also cautioned that if you use these light weight speaker cables, you must remove all heavy connectors.

#1 Air-spaced Finewire RCA Interconnect Cables

Constructing DIY Audio Cables

For my HiFi setup I needed to construct at least two sets of RCA interconnect cables and one set of speaker cables. For RCA interconnect cables I built three sets in total of two different designs. Following the book design for #1, Air-spaced Finewire, I built two sets of wire, one very short set and one about 900 mm in length. The third RCA cable set was built by applying some of the concepts I picked up from the book. For the speaker cables I followed recipe #6, Air-spaced Finewire. All the audio cables were made using 30AWG wire warp wire.

For the Air-spaced Finewire speaker and RCA interconnect cables I followed the directions outlined in the book. I even used $2 light weight plastic RCA plugs with insulated ears, as per the book. But with the third pair of interconnects I mixed some of the concepts from the with other cable ideas I had used in the past.

In my Silver Highway RCA interconnect cables a three-wire braid using insulated pure silver 0.7mm (~ 22AWG) wires. The extra earth wire is not terminated at the destination end. The braided wires are encased in heat shrink and a ferrite choke is used at the destination end. I used heavy RCA plugs and the connections are made using 5% silver solder. The idea of the second earth wire is that it gathers electrical noise and drains it back to the source. I think this cable sounds good and have built many sets for friends over the years.

To reduce the chance of picking up unwanted noise on these RCA cables which will be 900mm in length I lightly twisted the three wires using a variable speed drill. The second earth wire was cut away at the destination end and fitted with a small choke. High-end heavy Pro Co plated premium RCA plugs were fitted and silver solder used. The #1, Air-space fine wire RCA cables may look cheap in comparison, but we are not here to win a beauty prize.

My three wire twisted RCA cable

Where the book concepts have been applied in my three wire twisted RCA cables are:

Lightly twisted conductors;
Very thin conductors;
Silver solder;
Three wire construction;
Not terminating one earth;
Heat shrink to strengthen connection and hold twist in place;
No additional outer case;
Minimum length required;
Insulating wire strain ears.

Where the book concepts may not agree with my approach:

Heavy plated RCA plugs;
Ferrite choke;
Marking the cable directional;
Using this cable where the simpler two wire Air-space may work.

DIY Audio Cables made with Wire Wrap Wire

HiFi Listening Setup

I wanted to test out all these WWW cables I had made and followed the books suggestion to remove all heavy cables from my system. The gear consisted of:

Custom Analogue modified Oppo 980H DVD/CD player;
DIY build of a Nelson Pass B1 Buffer (battery powered, WWW internal wiring);
3W 6AS7 SET power amplifier;
Fostex FE206En back-loaded horn speakers;
Two pairs of #1 Air-space WWW interconnects;
2M #6 WWW speaker leads.

HiFi Listening System

Air-spaced FineWire Cables Listening Notes

Usually when auditioning some new equipment you drop it into your existing system, pick your favorite test tracks and work your way through them. You listen for bass extension and weight, mid-range clarity and texture, treble extension, soundstage depth and width etc. After a few tracks you will start to recognize that the new gear has made an improvement in some areas and a reduction in others. If you are riding a winner that day it will be win, win all the way.

But on occasions from the first few seconds of the first track you will be shaken to your very foundations. You never expect it to happen but occasionally it does. You go from 0 to 100 in 10 seconds. The test set-up above caught my attention within the first few seconds of Stan Getz live. My mind struggled for the first second or two to track what I was hearing and place it in some logical place in conscience land.

The cymbals rang clean and clear like nothing I had ever heard. All instruments were crisp, defined, real and raw. It felt like I had thrown all my old gear out and just set-up all new gear from scratch. Stunning. And forget trying to find your speakers with your eyes closed. They were gone, vanished never to come back. What remained was a fat sound stage projecting from the back wall. The sound stage could have been deeper but it was detailed and etched.

I could go on for pages but let’s just say that these gossamer like ultra low-cost diy cables breathed new life into components, whose sound I knew very well. They appeared to strip away so much vagueness in the presentation and laziness in the projecting of the over-all sound it was hard to comprehend.

I spent six hours in a single listening session in front of the HiFi system above. Not all recordings shook me as much as others but all seem to benefit. Some recording far more than others and I’m not sure why.

Summary - Air-spaced FineWire Audio Cables

Ok, so you may have noticed there are no comments about how the air-spaced RCA cables tested or compared against my twisted set. I’ll save those listening notes for a cable shoot-out and listening session report which will follow in a few days. Just a comment about the #6 Air-spaced Finewire speaker cables. Because I used no terminating connection they were clamped in the power amp and speaker binding posts. As you can imagine, in time the thin wire will eventually break. It is my intention to parallel a few inches of 1 mm thick pure silver wire to the ends of the speaker cables. This should provide a light weight binding connection that will last for a while.

That’s it – now go and build some cables!

Mark Houston - retro-thermionic.

For more details about the book, see Part 1, The SuperCables CookBook review. In the third part of the SuperCables CookBook series Mark and Ron have a cable shoot-out with the new fine wire audio cables. See The Fine Wire Audio Cable Shoot-Out story for the full details.

DIY Cable Projects

SuperCables CookBook - Review (1/2)

2010-11-30T22:58:00.008-06:00

Recently I got a chance to read the "SuperCables Cook Book" (3rd edition) by Allen Wright of Vacuum State Electronics and I thought I would share my findings. As the title implies, this is an instructional book on how to make various cables. The book covers balanced and unbalanced line level (interconnect) cables, speaker cables, mains (power) cables, digital cables and even video cables. The book is just shy of 200 pages and retails for 40 Euro and that price includes worldwide postage.

I thought of writing a book review only with no chat about the technical gems held within. That was until I finished reading the book through. I found not only some cable designs I would like to build but some confronting mathematical and theoretical proof that thin wires rule over thick wires.

SuperCables CookBook Review

The book is spiral bound, with a clear plastic front cover, black card-stock back cover and the paper quality is low. For about the same money one can purchase beautifully bound, hard cover manuals full of color photos, but let's not judge a book by it's cover. One plus about the spiral binding is the book will lay flat which makes it easy when working from a particular page. Unfortunately the image quality is poor and boring – the images look like black and white copies of color photos. You don’t find yourself looking at a picture of a good looking cable and think “I want to build that”, but don't let that discourage you. Some of the images are of such poor quality that it is hard to work out what point is being displayed.

Apart from the usual trademarks, disclaimers, copyright warnings etc. The book opens with Contents, About the Author, Introduction and A Brief History. It then works you through the theory and concepts of electricity traveling through a conductor. The book then works it way into speaker cable constructions, interconnect cables, mains cables etc. Toward the back of the book more varied cable types can be found, balanced, digital and even video cables. The list of cable types is very comprehensive. I must congratulate the author on covering such a huge range of cables.

Reading the Book
There are three ways you can go about reading the book.

You can read the book cover to cover;
You could skip the preface, author, intro, theory and concepts and jump right to a cable recipe. For many you can follow a recipe, construct the cable and enjoy while never looking back;
But here is my suggestion after reading the book. Read from the front cover to the theory. Jump the theory but read the concepts. Then find your first cable to build and you will likely not stop at one.

Working through the theory and maths, no matter which famous mathematician developed them, will not make you a better cable builder. However, understanding and the concepts for better cable construction and applying those concepts will. If you read nothing else prior to your mystical journey into strange cables, read the concepts section from pages 42 to 52. Other portions of the book that are must reads, Connector Basics and any of the other “Basic” sections in the book. This may be “basic” information, but it is good information that is often overlooked or forgotten.

Cable Construction Pages
There are 35 projects in the book and the project page layout is excellent. Across the top of the page is the cable project you about to start, “#7 Intimate Silver Foils” which makes it obvious what this cable is made of. The other guides on this page are: Sonics, Difficulty, Pro’s, Con’s. Some have a numerical rating other a verbal description. The next section outlines the Materials required supported by some more images. The Materials are numbered. From here we go to Method, once again numbered. At the end of the method, which is really a step-by-step list of how to put the cable together, you may find some other notes. For example, “if using Lemo’s (a brand/type of connector) and “if using RCA’s”. This layout makes it simple to follow and construct. The author also makes comments about what you may experience when listening to the cables in an attempt to rate and compared the many cable recipes in the book.

Lessons Learned
Here’s what I discovered and do agree with:

Thin (even ultra fine) wire is better than thick wire;
Thin foil is better than thin wire;
Cheap light weight plugs are better sounding than extra heavy ones;
All dielectric is bad, some not as bad as others;
The best plug is no plug;
Separated wires sound better than clumped;
Solid core wire is better than stranded,
Solder with a few percent silver or copper is good;
The shorter the wire length the better (I think we all can agree here);
Skin effect does occur at audio frequencies;
Plumbers Teflon tape has more than one use;

Summary - SuperCables CookBook Review
As I stated earlier the book is very comprehensive on the subject of cables. It also highlights tricks and traps when making cables and safety issues when dealing with mains power cables. The book is well thought out, hand-holding and thought provoking. The SuperCables CookBook challenges preconceived ideas about materials used in cables, cable construction, plugs and even how a cable should look.

At around $AU60 the book is not cheap. Do I recommend the book? Yes I do. If you want a good read, buy a novel. If you are a DIY Hi-Fi nut, this book will ease your cravings. Expert or novice the book guides you through each build with the goal of producing a better sound from your system at very little cost. Just don’t tell your friends you replaced your expensive speaker cable with a few strands of 30 AWG silver plated copper wire wrap. They may have you certified.

Mark Houston - retro-thermionic.

Part 2 of the SuperCables CookBook review covers how a couple of the cable recipes from the book perform in my system. In the 3rd installment of the series Mark and Ron give the 30AWG wire wrap cables a good listen. See The Fine Wire Audio Cable Shoot-Out for the story.

DIY Cable Projects

Fundamental Amplifier Techniques with Electron Tubes

2010-11-15T19:39:00.005-06:00

About 6 weeks ago Rudolf Moers shared with us the details around his parallel push-pull 300B monoblock tube amplifiers. We noted that the design of the parallel push-pull 300B tube amplifiers is explained in his new book Fundamentele versterkertechniek met elektronenbuizen, ISBN 978-90-5381-226-6 which was at the time only available in Dutch. Good news! The English translation of Rudolf's new book is now available - Fundamental Amplifier Techniques with Electron Tubes.

Fundamental Amplifier Techniques with Electron Tubes by Rudolf Moers is the latest Elektor publication on the subject of vacuum tubes. The 800+ page hard bound book covers just about every topic you need to know about the fundamentals of vacuum tubes and how to apply that information towards audio amplifier design.

The aim of the Fundamental Amplifier Techniques with Electron Tubes book is to give the reader practical knowledge about vacuum tube technology and how to apply that knowledge in audio amplifiers. The practical applications include power supplies, audio design and DIY construction of tube based amplifiers. This new book is much more than just building a tube amplifier from a schematic, it walks you through the theory so you understand the design of circuits and the accompanying calculations. Then with a multimeter, signal generator and an oscilloscope, you can verify the actual circuit parameters to confirm the theory and practice are very close. The 834 page book Fundamental Amplifier Techniques with Electron Tubes, by Rudolf Moers is bound in a hard cover and sure to be a must-have reference source for all tube audio fans.

Fundamental Amplifier Techniques with Electron Tubes, by Rudolf Moers, ISBN 978-0-905705-93-4 is available for $104.90US (plus shipping) from Elektor. The table of contents is available from the publishers site and you can take a look at Rudolf's parallel push-pull 300B monoblock tube amplifiers to get a visual image of the book contents.

UPDATE (2011-06-14) - see our book review of Fundamental Amplifier Techniques with Electron Tubes.

More DIY Audio Books

Oatley K272A Head Amp audioXpress Review

2010-11-12T14:35:00.002-06:00

The December 2010 issue of audioXpress magazine includes a review of the $30AU Oatley Electronics K272A tube based Headphone Amplifier Kit. Mark Houston completed a review of the Oatley Electronics K272 Headphone Amplifier Kit in August 2009 and since then many hobbyists have enjoyed this inexpensive audio kit. The hybrid headphone amplifier kit uses 6418 sub-miniature vacuum tubes and a headphone driver integrated circuit (PT2308). Adding appeal to the tube based kit is battery operation.

Highlights from the audioXpress Reliable Review of the Oatley Electronics K272A Headphone Amp by Aren van Waarde.

"Oatley Electronics (www.oatleyelectronics.com), which sells electronic parts and used equipment in New South Wales (Australia), has launched a small range of audio kits based on tube technology. My interest was raised by glowing reviews written by Mark Houston, ..."

"My initial impression of the sound of the K272A: warm, pleasant, and detailed. Organ music sounded great."

"... the K272A/Grado combination produced excellent sound: a fne bass (powerful and deep but not overblown), detailed mid-range, sweet top-end. Tonal colors of string instruments and vocals of male and female soloists were naturally represented. Many small, previously unnoticed details of recordings were revealed."

"In direct A/B comparisons, the K272A sounded better than the G4OEP (3/08 aX, p. 36) and even slightly better than the Stor class A amplifier (6/03 aX, p. 30)."

"For the asking price of 30 Australian dollars, the K272A is an absolute bargain. And it does not involve any dangerous voltages."

The full review of the Oatley Electronics K272A Headphone Amp is available as a direct download from audioXpress [PDF- 737kB].

Additional Oatley Electronics Audio Kit Information:

Mark's review of the Oatley Electronics K272 Headphone Amplifier Kit.
Tube Matching circuit in the Oatley Electronics K282 RIAA Phono Preamplifier Kit review.
Forum thread: 6418 Tube / Opamp Headphone Amp (Oatley Electronics K272A Audio Kit).
Forum thread: Oatley Electronics K281 6418 Tube / LM1875 IC Amplifier Kit

What's Playing: Clannad - Macalla

Parallel Push-Pull 300B Tube Amplifiers

2010-09-29T15:52:00.005-05:00

Rudolf Moers from the Netherlands has kindly sent us details of his parallel push-pull 300B monoblock tube amplifiers to share with the DIY Audio community. It should be quite obvious from the photographs that the design and construction of a pair of amplifiers this size is by no means a small undertaking. Rudolf tells us that he spent about 14 months designing and constructing the pair of monoblock amplifiers. The total cost of each amplifiers was about 1300 Euro, or about $1760US as of 29 September 2010. Each monoblock weighs 25 kg (55 pounds) and the overall dimensions are 530 mm deep, 390 mm high, 400 mm wide.

Schematics - Parallel Push-Pull 300B Tube Amplifier

The few notes on the schematics are written in Dutch. You can use a free online language translation service like Google Translate to translate them into English.

Parallel push-pull 300B vacuum tube amplifier Schematic - [PDF - 270 kB]
Parallel push-pull 300B vacuum tube amplifier Block Diagram - [PDF - 43 kB]

Parallel Push-Pull 300B Tube Amplifier

The input stages consists of a preamplifier and cathode phase splitter using a ECC82 (12AU7), amplitude amplification (driver) using a ECC99 and cathode followers using a ECC82 (12AU7) tube. The output stage uses four 300B directly heated power triodes in a parallel push-pull configuration (Ia = 40mA and Vak = 356 VDC) with no negative feedback. The output power for each monoblock is about 25W.

When powered on the heater supply for the ECC[82,99,82] tubes goes from 1.5 to 6.3 VDC in 30 seconds. Likewise, the 300B heater supply goes from 1.5 to 5.0 VDC in 30 seconds. Polarity of 5.0 VDC heater supply can be reversed with a switch. All the heater voltages are separated using galvanic isolation.

The high voltage supply uses a mercury filled full-wave rectifier AX50 and is switched on when all heater voltage are at about 90% of their final value. The AX50 rectifier limits the maximum output power to 25W.

The enclosure is wooden and easily accessible with a hinged lid and there is plenty of interior space. The amplifier is constructed in a completely modular fashion with connectors. All the modules are built on prototyping boards.

Measurements Parallel Push-Pull 300B Tube Amplifier
Input power: 281 W(RMS) at 230V (50Hz/60Hz) mains voltage
Output power: 25 W(RMS) at 0 dB (775 mV) sine wave input signal
Efficiency: 8%

Bandwidth:
-0.1 dB at 20 Hz and 50 kHz at 25 W
-3.0 dB at 10 Hz and 100 kHz at 25 W

Distortion (THD) (distortion without hum suppression)
1.5% at 5 W and 10 Hz
4.0% at 23 W and 20 Hz
3.5% at 25 W and 50 Hz
3.5% at 25 W and 100 Hz
3.5% at 25 W and 200 Hz
3.4% at 25 W and 500 Hz
3.5% at 25 W and 1 kHz
3.5% at 25 W and 2 kHz
3.5% at 25 W and 5 kHz
3.5% at 25 W and 10 kHz
3.3% at 25 W and 20 kHz
2.7% at 25 W and 50 kHz
4.4% at 15 W and 100 kHz

THD < 1% at 2 W between 10 Hz and 20 kHz
THD < 2% at 10 W between 10 Hz and 20 kHz
THD < 3% at 15 W between 10 Hz and 20 kHz

Hum voltage over the loudspeaker is < -51 dB and inaudible with an ear against the loudspeaker.

Rudolf informs us that the design of this parallel push-pull 300B tube amplifier is explained in his new book "Fundamentele versterkertechniek met elektronenbuizen", ISBN 978-90-5381-226-6 which is currently only available in Dutch. However, an English translation "Fundamental Amplifier Techniques with Electron Tubes" is expected in November 2010. We will post an update when the English version is available.

UPDATE (2010-11-15) - the English translation Fundamental Amplifier Techniques with Electron Tubes is now available.

More 300B Tube Amplifiers