Mesa Boogie Unlimited

2011-04-18T14:00:00.001-07:00

6L6 vs EL-34

2010-09-13T14:48:00.000-07:00

On the subject of tube amplification, you’ll often find discussions of one tube type being better than another. Guitar players are quick to defend the how-and-why of their preferences and the type of tube used is a common jumping-off point for what makes an amp great.

While there is certainly some truth to the idea that different tubes offer different flavors of tone, in Mesa’s humble opinion, the power tubes are largely ‘in service’ to the preamp circuit design; the circuit is essentially the cake and the output tubes are the icing. Like most things, there’s a long and short story, and the audible differences between the tubes oddly ends up being the short story. The long story may well provide you with some new insights as to how to approach tube tone and regardless of your tube preference, you may find yourself appreciating both for their inherent specialties.

It’s ironic that MESA has long been thought of as a company specializing in preamp sounds (not accidentally – since the all-tube, cascading high-gain preamp originated here). But it has always been our view that an amplifier’s magic comes from the perfect harmony between preamp and the power section. The many patents we hold covering all aspects of the power amp – from Channel Assignable Wattage, Switchable Rectifiers, Switchable Classes of Operation and even Wiring Styles hints at our inclusion of the power amp as a huge part of the tonal greater good. The power tubes’ type and role is indeed an important one, but it’s only part of a larger picture.

These days, the subtleties of power-tube distortion and clip are often overshadowed by the greatly expanded range of preamp gain available in modern amp designs. Most modern distortion circuits and sounds are usually generated by massive preamp gain being amplified through very clean power sections that are operating below their power rating (threshold of clip). This translates into less potential for power section/tube qualities to be a major part of the sonic style – even with Master and Output levels turned way up. Extremes of distortion and harmonic layering from the preamp are amplified with articulate detail through this cleaner power section. For Rectifier high gain sounds (and Roadking & Roadster), especially when using the amp for its original intended purpose (massive gain sounds in Orange and Red channels), switching between 6L6s and EL-34s may produce only slight differences, if any. Power tube influence can be masked at lower playing volumes with high preamp GAIN settings.

How about those differences?

While 6L6 and EL-34 power tubes are more likely to surprise you with their similarities in an A/B situation, you’re actually more likely to FEEL the differences between them. Audible differences do exist though and for those of you looking for the quick answer to the title of the post, these next two paragraphs are for you.

Sonically speaking, 6L6s are well-known for being versatile and balanced across their entire range of low, mid and high frequencies. They are often loosely referred to as being ‘fat and round’ with a musically blooming bass response but they are also well regarded for being brilliant, detailed, sparkling and ‘open’ in high-end and presence frequency ranges. With the 6L6 being so well balanced yet bass-full and high-end brilliant, you might be thinking to yourself that the 6L6 has everything anyone could ever want from a tube… and Mesa’s history tends to agree. The 6L6 is easily the most versatile tube for any styles from pristine clean for jazz to mind-numbing metal and anything in between. The same headroom that delivers full range clean tones simultaneously offers the same clarity to support huge but accurate low-end with modern high gain applications. Versatility being one of the cornerstones of Mesa products, the vast majority of Mesa amps have either been designed specifically with 6L6s only, or, those amps with the Switchable Bias are originally shipped with 6L6s from the factory. Beyond its expansive sonic signature, 6L6 tubes are consistent, reliable and a mainstay for tube guitar amplifiers since the inception of guitar amplification.

While Mesa admittedly has a bias toward the 6L6 as the go-to, big bottle tube, there are characteristics of EL-34s that are undeniably rooted in rock ‘n’ roll that make the skinnier bottle ‘34 well worthy of it’s position in rock history. In bass frequencies, EL-34s tend to offer less bass in low frequency ranges (in the sub-low regions) compared to 6L6s, BUT – the higher bass this tube DOES generate is more focused, tight and extremely punchy. The frequency of this punch is similar to the kick drum punch range – closer to the beaters’ attack frequency than the sub-air that comes out of a kick drum’s front head. Another key signature of EL-34 character is its considerable peak in upper midrange and low treble regions in addition to an overall brighter disposition. It’s this upper-mid/low-treble peak that is the true signature of the EL-34 gain and it’s also the range where harmonic layering in distortion sounds begins to stack up in earnest. It’s also this frequency range that has the potential to produce what many refer to as “icepick” frequencies – unpleasant brightness that stings your ears. Careful settings of middle, treble and presence controls is crucial to avoid exposing you, your bandmates and your audience to these “icepick” settings. When tastefully set, there is an unmistakable and musical edge, cut and bite from EL-34s which lends itself well to medium preamp gain settings, heavy handed attack, and power tubes pushed into overdrive as amp Masters get cranked. This is where the EL-34 shines!

One of the important and likely more noticeable differences players will experience when properly comparing 6L6s and EL-34s is threshold of clip and distortion. This living, breathing aspect of tube tone might not be as obvious to players new to tube amplification and/or those who haven’t been able play their amp very loud or at gig levels yet. So… let’s start by defining some of the concepts in the title above.

“Threshold of distortion” – as it relates power amp sections – is the point where the Output and/or Master settings of the amp, with settings dialed for clean sounds in the preamp, is being turned up loud enough to begin saturating the power section and power tubes, generating distortion. Clip is a term that describes the subtle initial onset of this distortion and the transition from clean sound to distorted sound. Overdrive is a term generally used to describe distortion sounds beyond this soft clip – but before full gain saturation and layering we all call distortion. Overdrive is often the term used to describe distortion that is smoother and warmer and better for single-note solo tones or purring rhythm sounds. Hopefully these descriptions shed light on some of the more obscure details behind great distortion tones. Now, let’s compare our two tube competitors in the arena of feel.

Technically speaking, EL-34s are served higher voltages and utilize more current than their 6L6 counterparts. Non-technically, they run hotter! This hotter/higher current operation is one of the reasons why EL-34 tubes (and the amps that use them) offer such a wide range of overdrive and crunch sounds from their power sections. The allure of EL-34s, particularly for gain sounds, stems from the tube’s earlier threshold to clip and distort when pushed. As you increase the amp’s overall volume, the potential and usable range for EL-34 power tubes to break up musically increases in a big way. This is the land where great, gut-punch gain sounds are born (think early AC/DC or vintage Van Halen). These fabled early rock distortion sounds were generated by power sections of amps being cranked up, since all-tube cascading preamp gain as we know it today was JUST being born by Mesa’s designer and high-gain preamp pioneer and innovator, Randall Smith.

6L6s offer a noticeably different range of distortion threshold and clip potential once you know ‘where’ to listen. The rich, full range of bass frequencies highlighted in 6L6s can generate a wide sonic footprint when pushed, but too much power section clip with a 6L6 can cause bass “bloom” that expands beyond a desirable sound. With smoother mids and low-treble frequencies compared to the EL-34, 6L6s also produce less obvious saturation when pushed. Power tube distortion and overdrive with 6L6s tends to be warmer, smoother and sweeter overall and is more commonly used in traditional blues and roots styles or wherever low to medium gain clip or pushed clean sounds are what the music calls for. For those looking to exploit the 6L6 clip threshold, single notes and solos can take on almost unlimited personalities. Solo tones from the likes of Andy Timmons, Robben Ford, or classic Steely Dan solos are great examples of the wide array of clipped and pushed clean sounds available from 6L6s while high gain sounds from the likes of John Petrucci and Dream Theater, Lamb Of God and Metallica are just a few excellent examples of 6L6s in action on the heavy rock front.

Mesa/Boogie Express 5:50 1x12 Combo

2010-09-02T20:11:00.000-07:00

Mesa/Boogie Express 5:50

1E501BBCO Express 5:50 1x12 Combo

AMP SHOPPING can be a lot like buying a new car. If you’re on a limited budget, you usually have to settle for an underpowered American- or Asian-made model that’s low on frills and thrills. If you want a high-performance model packed with luxurious features, expect to spend a
small fortune.

Mesa/Boogie Express Series amplifiers and combos are the music industry equivalent of a Mini Cooper. Though extremely compact, they deliver plenty of hair-raising power as well as a full selection of useful high performance
features not typically found on products in their price class.
Priced just beyond the “budget” or “entry-level” range, Mesa/Boogie Express Series amps offer an affordable
alternative for gigging pros or anyone else who needs a versatile amp that can hold its own with the big boys.

Mesa/Boogie offers two Express models: the 25-watt 5:25, which is powered by EL-84 tubes to provide “British” voicing, and the 50-watt 5:50, which uses 6L6 tubes to produce more distinctly “American” tones. The 5:25 is available as 1x10 or 1x12 combos while the 5:50 combos
offer a selection of single or dual 12-inch speaker options. Both models are also available in head-only configurations. I took a ride on the 5:50 Express 1x12 combo.

FEATURES
FORTY YEARS AGO, in 1969, Randall Smith invented the first Mesa/Boogie amp when he squeezed a tweed
Bassman circuit and a 12-inch speaker into a Fender Princeton combo cabinet. The Express 5:50 1x12 combo
remains true to the spirit of the original Boogie amp by providing the tone and versatility of a big amp in a surprisingly small package. Even better, the Express includes several of the most popular innovations that Smith and company have developed over the years, such as a high-gain cascading preamp, fully independent channel
switching and Duo-Class power.

Just about every GREAT Mesa / Boogie tone (and then some) lurks inside this compact powerhouse.

CLEAN/CRUNCH and BLUES/BURN modes proide everything from pristine clean to molten metal.

The CONTOUR controls duplicate the dramatic EQ curves of a graphic EQ without a mess of sliders.

The Express 5:50 features two fully independent and individually voiced channels, each featuring its own set of gain, treble, mid, bass, contour, reverb level and master
volume controls. Both channels have a mode switch that allows you to tailor the distortion and response characteristics to your preference, with Channel 1 providing a selection of Clean/Crunch tones and Channel 2 offering Blues/Burn choices.

Two 6L6 tubes provide 50 watts of power in Class A/B
mode, but the patented Duo-Class feature, accessible via a
rear panel switch, also offers the option of powering the
amp with just one tube to produce five watts of Class A single-ended power (which emphasizes the sweet
second harmonic, an octave above the note played). Five 12AX7 tubes are used for producing Mesa/Boogie’s
signature cascaded high-gain tones and for the reverb and effect loop circuits.

The Express 5:50 combo ships with a heavy-duty footswitch for controlling channel select, contour on/off and
reverb on/off functions. If you prefer to control these features with MIDI program change commands, four 1/4-inch jacks are provided for switching channels, reverb on/off, contour 1 on/ off and contour 2 on/off individually. Should you forget to bring your footswitch controller to the gig, you can still control contour on/off and channel select functions via switches on the front panel. The effect loop has mono send and return jacks and a nonvariable level designed for use with everything from stomp boxes to studio-quality rack processors.

PERFORMANCE
JUST ABOUT EVERY great Mesa/Boogie tone (and then
some) lurks inside this compact powerhouse. Channel 1’s Clean mode combined with the luscious Accutronics spring reverb produces one of the best clean tones I’ve heard from a Mesa, with a fat roundness and three-dimensional clarity that rivals a vintage Twin Reverb. Switch over to Crunch mode for tight, gnarly overdrive with plenty of punchy low end, throaty midrange and razor-sharp presence. Channel 2’s Blues mode is loose, raw and raunchy, but cranking up the mids can produce singing, violin-like overdrive comparable to the classic Boogie Mark I. Burn mode is where modern metal tones lurk, and you can dial in brutal scooped mid rhythm tones with the Contour control and disengage it to boost midrange definition for in-your-face solos with all the volume you need.

The tone controls interact significantly, and while that makes it tricky to dial in exactly the tone you have in mind, it ultimately provides a wider and more versatile range of tones. Although the 5:50 lacks a presence control, it’s really not necessary thanks to the expanded EQ range that the Contour control delivers. The ability to switch between the sweet, harmonically rich distortion of the five-watt Class A mode and the focused grit and growl of 50- watt Class A/B mode gives the 5:50 two very distinct tonal personalities.

The Celestion C90 12-inch speaker and the combo’s open-back cabinet design deliver excellent performance for almost any variety of tones, but some metal players may find that the bass response isn’t always tight enough. Fortunately, the 5:50 features individual eight- and four-ohm speaker outputs for using a variety of external speaker options. When connected to a Mesa 4x12 Rectifier cabinet, the bass response of the 5:50’s Crunch and Burn tones became as tight as PVC underpants.

THE BOTTOM LINE
IF YOU PLAY a variety of studio and performance gigs and need a compact amp that covers everything from pristine
clean to the dirtiest metal tones, the Express 5:50 is the way to go. Its price is as small as its size, but its sound and versatility are about as big as it gets.