Category Archives: Amplifiers

Tubes Tubes Tubes


When it comes to guitar amplifiers, it all starts with the tubes. And the speakers. And the Circuit. And the guitar. And the guitarist. You get the idea, there’s a lot of things that affect your tone, and you should never overlook the tubes you’re using in your amplifier.

I recently had a lot of issues with tube reliability using JJ EL84 tubes. They sound good, but a large percentage of them came to me with a defect: the light-bulb effect shown here: Some people say it’s okay, others say it’s very dangerous and can eventually/potentially destroy transformers. I’m not interested in taking the risk either way.

To compare the tubes, I took a good pair (no flash defect) of JJ tubes, and put them up against the TAD EL84-STR and the Tung Sol (reissue) EL84-TS. The test amp is a JMP Guitars 18 Watt EF86 “TNB” (not to be confused with TMB).

Check out the EL84 output tube comparison video hero:

Check out the EF86 preamp tube comparison video hero:

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Tube Amplifier Comparison

JMP Guitars - TNB Series Amps

A while ago I did a video of a wah wah pedal from the JoshuWah Series named “The Beast.” In music products there’s a lot of hype about different components, and there was so much crap about capacitors and inductors it lead to build The Beast. The Beast has 12 Sweep Capacitors built in, along with two Inductors and a few other options. The demo videos go through all sorts of options and do so in a controlled manner to give a true to life comparison and demonstration of this different components from different brands.

This topic of conversation comes up quite a bit in the amplifier world as well. So, I recently built three 18 Watt EF86 based preamp guitar tube amplifiers. All three amps were built the same way, with all of the same parts, except for the capacitors.

The recording was done with a Jensen C12N 16 Ohm speaker, and a Shure SM58 microphone. A Weber Mini Mass 50 Watt attenuator was used, set at 3 (a 70% drop in output level) to drop the volume for recording. While it still sounds great, it theoretically can drop some of the dynamics and treble of the amp. This is not an issue for the purpose of this video as the attenuation was consistent for all amps and settings. So there’s your controlled environment, take a look at the video and decide for yourself.