Vacuum Tubes – Favorite Power Tubes for Guitar Amps

Two 6V6 with a GZ-34 rectifier is a great recipe for clean to crunchy rock and roots music

Despite all the progress in digital modeling and analog circuit design, for some people a guitar amp isn’t a guitar amp without a few glowing glass bottles heating up the room. Technically obsolete but sonically beloved, tubes are still with us. And the crazy thing is they all sound different from type to type, and even brand to brand. Depending on your point of view this is a tweaker’s delight or nightmare.

Truth be told, there is some great sounding digital stuff, and if you are generally immersed in very high gain sounds or lots of effects, I’m not sure tubes are essential. There is just so much other signal processing going on that the subtle qualities of vacuum tubes can get lost. My friend’s Eleven Rack sounds pretty darn good pounding out raging “SLO” crunch, but as a semi-clean Fender Deluxe? Not so much. So if you are still chasing clean to slightly dirty tones, I think analog and vacuum tubes still hold the edge. Speaking of “The Edge:” By the time his guitar has run through fifty feet of effects and remote switching gear, does it matter that it’s plugged into a vintage Vox? No, especially not in a stadium. Sometimes it’s all about what you’re seen playing, which is why most of those stacks at a typical concert aren’t even plugged in (unless you are Yngwie).

If you are deciding to go the tube route, or are looking at a new tube amp, you also have to think about what types of power tubes. Preamp tubes are almost always the venerable 12AX7 — with an occasional EF-86 — so that choice is usually made for you. But with power tubes you have some decisions to make. Here are some comments and thoughts:

6V6 – The mainstay of the 30 watt and under Fender amplifiers, especially from the Tweed and Blackface era. Some of the newer small Fenders today like the Junior and Deville series use EL-84, so check under the hood. Sweet sounding with a high end that is complex and not overly bright, they are a great tube for small amplifiers. Maligned by some as not having strong bass response, that can be as much cabinet size and circuit design as the tube itself. A great tube for Strats and Teles. Less popular today than the EL-84, but a Dr. Z Remedy on half power is one of my all-time favorites. The ValveTrain Trenton is also another great recent 6V6 amp, and Rivera is also a proponent of this tube (they don’t make an EL-84 amplifier).

6L6 – The mainstay of the larger American amplifiers, the 6L6 can put out up to 25 watts per tube and is found in higher powered amps like Twin Reverbs, and many Mesa amplifiers. A little harder sounding and less complex than a 6V6, but it’s got a lot of low end. Great for chunky tones, sparkling loud cleans, and high gain.

5881 – A lower output alternative to the 6L6, the 5881 is often used interchangeably and is felt to have a little more delicate top end, and be a touch more musical. Amps with a 6L6 may be running at higher voltages not suitable for a 5881, so do your homework before you swap.

EL-84 – Developed by Philips, probably the most popular tube for amps under 30 watts, and the darling of boutique builders. Many of the small Fender amps today use this “European” tube rather than the 6V6. Personally not my favorite, especially not for gigging. They do have a lovely round “bouncy” tone that is really cool at low volumes, but these tubes tend to get shrill when cranked up, and have flubby, weak bass. YouTube is full of videos of people playing totally cranked small EL-84 amps through attenuators in their home studios. That may be fun, but not for your vocalist, or the crowd. This tube may be the “sound” of a Vox, but gimme a 6V6 any day.

EL-34 – This tube is the crunch of the big Marshall amplifiers: Punchy, with a strong upper midrange bite and lots of harmonic content. Most big Mesa 6L6 amps will also accept the EL-34, and it’s worth making the swap.  The problem is that any Class AB amp with these tubes is going to be pushing 50 watts or more. So they are fun but loud. There are some specialty Class A amps that will take a single EL-34, so you can have some fun without peeling the paint.

Wrap Up – Depending on the size range of amplifier you are shopping for, your choice of tube may be per-determined by the power rating. On the sub 40 watt end, my recommendation would be the 6V6. Not as ubiquitous as EL-84, but worth it for overall sound quality and flexibility. The 6V6 has a different pin arrangement than the EL-84, so they cannot be swapped unless you purchase adapters.

For larger amps, my pick is the EL-34, and a number of big rigs can flip a switch and accept an EL-34 or 6L6. For a 6L6 amp that cannot use an EL-34, check with the manufacturer and see if it is compatible with the 5881. This can be a nice tweak for a little less headroom and power output. A lower-voltage Fender Bassman running 5881’s is a delectable clean-to-mildly-crunchy tone machine.

For amp offerings at Upfront Guitars: