Can Somebody Explain EL34, EL84, and KT66?


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I've always had Fender style amps, 6V6s and 6L6s. This last year, I've gotten heavily into Les Pauls. I would like to explore some non-Fender style amps. Can anyone explain the differences in the tubes and perhaps provide some well-known examples? Thanks.


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As far as I know, KT66s pretty much came and went with the JTM45/Bluesbreaker era at Marshall. That'd make the recorded example Eric Clapton in the 60s. More midrange and sweeter breakup than a 6L6 perhaps.

The EL34 is the tube that Marshall has used ever since, and that clang and crunch is what I most associate with them. Depending on the circuit they can be as clean as 6L6s (Traynor used them in some Twin copies) but tend to break up a bit smoother and sooner.

The EL84 can act as a mini-EL34 in Marshall style circuits (think the 18w Marshall reissue), or as the chime and crunch of an AC30 (much of the early Beatles, Tom Petty etc), or even a glassy clean like the Traynor Guitarmate or the Maz 38. Of all the tubes, it's probably been in the widest variety of amp types and sounds great in all of them...


There's a bit of a difference between the 2XEL84's and 4XEL84s tonally.
2XEL84's will get you anything from 15-20 watts on average with tones
generally in the Vox AC15 Marshall 18 watt and even Trainwreck, Matchless
low wattage characteristics.

4 XEL84's are generally considered the Vox AC30 power core with numerous

EL34's for classic Marshall and Hiwatt tones.

KT66 and KT88 for a slightly different flavor in the Marshalls and Hiwatts.

The KT 66 powered Reeves Custom 30 has been said to be 2/3 Hiwatt 1/3
JTM 45.

These are very general descriptions and the pre amp section, transformers and other components can make a considerable difference in tone.


My Koch Twintone can switch between KT77's and EL 34's. I have run both of them back and forth to find the one I like more and the KT's won. The KT's are louder and fuller sounding. No real difference in the tone. There's an old thread that compared these two tubes. General agreement seemed to be the KT's are the EL's bigger brother.


Another amp using KT66 is the Dr Z Rt 66. A great amp in the JTM vein, but with a bit of it's own flavor.

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