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Discussion in 'Glowing Bottle Tube Amp Forum' started by Joe M, Oct 1, 2020.
Never heard of these guys. How do they compare, sound-wise, to 6V6's, 6L6's, EL84, etc.?
Tough question to answer. Ime, the circuit is the first determining factor of the Sonics. Since the 7591 has a different pinout than do the 6L6,6V6,6550,EL34 tubes; it is hard to compare the tubes.
old post if I recall on it
My Fisher stereo amp uses 7591 tubes. They sound tubey.
In Ampegs---they sound great. Not as robust or scooped as a 6L6 type, but more output and fidelity than a 6V6.
I don’t own one but I would think that if Dr. Z likes them there must be something in them.
M. Zaite said he built the Jetta after hearing an early version of an a Ampeg Jet. The Jetta uses 2x12AX7. It has to have a simple preamp using one of those while one is used as a phase inverter.
In comparison, the Gibson GA35RVT also uses 7591 power tubes. However, it’s circuit is not as simple as the Ampeg Jet or the Z Jetta modelEd after the Ampeg. Therefore, despite having the same power tubes, I will guarantee that the Gibson sounds nothing like these other two amps. The choice of a power tube is important, but imho and ime the choice of the circuit is a much more influential variable when it comes to what one hears coming out of the speaker. If this were not so, the Gibson GA35RVT/Epiphone EA1a6RVT Amps would be much more desirable in the marketplace. And Keith Richards might have used one of those Gibson amps instead of an Ampeg Jet back in the day for some of his recording.
I have a Sano 250R that uses 2 cathode biased 7591 tubes along with a Ampeg Gemini II which uses them in fixed bias. They all have their own sound, but very un-Fender sounding.
good examples of how the circuit determines what goes on. That Gemini II preamp has two gain stages followed by a Baxandall tone stack, so there is no way any Fender could sound like it, ime. Fwiw, I had an Alamo Fury that used 7868 power tubes and probably could sound like that Gemini II.
The Sano 250....it has a ?Baxandall? Tone stack in between the first two gain stages. Very different from any Fender and different from the Ampeg, also.
circits, circuits, circuits. Jim Marshall’s first amp used the 5881 power tube that was used in the 5F6A. He changed OT the KT66 and then the EL34 for availability and expense. You can run EL34s in a Fender BF circuit with a minor change at the tube socket. It will not sound like a JTM 45 Marshall. And...the first Reissues of that early Marshall ran 6L6 type tubes. It did not sound like a BF Fender. the Marshalls that were sold during the ‘70s in the USA ran 6550s, but those amps do not sound like say an SVT or the Premier Super 88 I have...and those two amps run 6550s.
in order to hear what different a certain tube makes in a circuit, one must run that tube in a circuit and compare it to another type of tube in the same circuit, ime.