Let’s Talk About Power Tubes! The Differences Between 6L6, E34, EL84 and 6V6 Guitar Amp Tubes

Let’s talk power tubes for a minute. You know, those weird light-bulb lookin’-things inside your guitar amplifier? While the job of every type of power tube is to increase the power of the signal created by your guitar and the amplifier’s preamp section, each type will sound different while they do just that. In this guide, we’ll touch on some of the most common types of power tubes and the tonal qualities associated with each one. Hopefully, being armed with this information will help you match up the sound in your head with the right amplifier.

6L6

The 6L6 power tube is the most popular currently used in guitar amplifiers. Another commonly used name for this tube is 5881. These are the tubes that are most commonly found in American amplifier designs, from the early days of rock to the present. The tonal qualities of the 6L6 emphasize lows and highs with a somewhat relaxed (some will call it scooped) midrange, and is equally at home pushing out sparkling and chiming cleans, swampy surf sounds, or high-gain dropped-D chugging. The versatility of the 6L6 has led many amplifiers to use these tubes as the backbone of their channel-switching amp designs, as they tend to sound great when being fed varying amounts of gain from clean, to crunch, to CRUSH. The headroom capabilities of the 6L6 are great for high-power clean setups, or to keep the low end robust in high-gain rhythm guitar scenarios.

For those of you unfamiliar with the “H-Word,” headroom refers to how hard a player can push the power section on an amp before the power section starts to compress and distort on its own, independent of the pre-amp or speakers. Many amps will stay clean with the volume knobs set low, and will start to distort as the knob is pushed into the upper regions of the dial. If your amp stays clean almost all the way up to “10,” you have a lot of headroom available.

EL34

The EL34 power tube is most commonly associated with high powered British “Stack” designs of the 70′s. Tonally the EL34 will emphasize the midrange, and the distortion characteristic will tend to be a little less smooth with a “bark” or a “roar” to it. One way that the difference between EL34 types and 6L6 types has been explained to me is that when vocally imitating a guitar sound, the EL34 tubes will make an “AHHH” type of vowel sound as opposed to an “OOOH” or “UHHH” type sound that a 6L6 will make. (I enjoy explaining it this way because singing guitar riffs really loudly is a lot of fun!) The lows on EL34 tubes are often present, but “tight” which will help the player avoid a “muddy” sound, while a bigger push in the mid-range makes it easier to to stand out in the mix while using less volume. The latter is especially helpful when trying to cut through a crowded band mix where you have to compete with another guitarist or a cape-wearing synth enthusiast with a four-tiered keyboard stand.

The EL34 still has a fair amount of clean headroom, but will break up just a little sooner than a 6L6 in many amplifier designs.

EL84 and 6V6

As you might be able to infer from their names, the EL84 and 6V6 are similar to the two tubes I discussed earlier, however they are lower output tubes and are most commonly found in “Class A” designs. While a pair of 6L6s or EL34s might generate anywhere from 40 to 65 watts in most amp designs, a pair of EL84s or 6V6s will put out anywhere from 15 to 25 watts. This means that in addition to reduced output, amps using tubes of these types will also have much lower headroom. Common applications for these tubes are in low-powered combo amps popular in recording studios, or for smaller gigs and styles of music that do not require a “wall of sound.” Blues players and classic rock types LOVE low-powered EL84 and 6V6 combos, while modern rock players are more likely to feel at home with a 6L6 or EL34-based amp.

Tonally, the EL84 has the same mid-range push as the EL34 but with slightly less low end, and enhanced highs. EL84 amps are most popular with guitarists who prefer single-coil pickups and tend to gravitate towards the “Liverpool” sound. The 6V6 was used by many of the same manufacturers that also used 6L6 types. Because of this, in some applications, a 6V6 power section will sound remarkably similar to that of a 6L6 with just a tiny hint of an EL34′s midrange.

Can I switch power tubes in my amp?

Sometimes! It all depends on what amplifier you’re using, and it is best to defer to your amplifier’s owners’ manual and/or a competent amp tech. Some amps (Such as the BUGERA 6260 or 6262, for example) can be switched from 6L6 to EL34 and back with a push of a button, while on others you run the very-real risk of frying components on the amp’s circuit board. Some amps will need to be modified to accept a different type of power tube, but in most cases my personal opinion is that most amps sound the best using the tubes they were designed around. BUGERA will soon be offering the INFINIUM series of amplifiers that will let the player select any of several power tubes with an octal base: EL34, 6L6, KT88, KT77, KT66, 6550 and more! We will be previewing the INFINIUM series of amps on this blog in the near future.

If you have any questions regarding the many different kinds of power tubes used in guitar amplifiers, please ask in the comments below!