6L6 vs. EL-34 ~ FEEL the power ~ of your amp's power section
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.
Mesa 6L6s on a matching tray
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 or 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.
A tray of EL-34 Power tubes waiting to be packed
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.