Posted this in a couple other threads but I think some tube geniuses here might have some thoughts.
@Chucky Stiletti you listening?
I have two pairs of vintage Mullard 12AX7’s, I got these from TC Tubes (Great folks to work with). They show readings on the boxes which I have no idea what they mean:
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I posed the following questions to Chelsea (the “C” in “TC Tubes”) and she did her best to answer, but I’d like to hear what others think. It may not matter all that much, but if there’s an ideal choice for one pair in one amp, I’d like to start there. And, I think, I usually lean toward clean bass tone, clear headroom with not a lot of grit. Clean volume with no speaker distortion. At least I think that’s what I’m hearing when I like my tone… Here’s what I asked:
“Is there a simple explanation for the “readings” you have on the boxes?
In my application(s), one pair will be in the preamp of a 200w tube amp and the other pair will be in the preamp of a 500W class D amp.
Is there one pair more suited to the 200w tube amp and one pair more suited to the 500w class D amp?
Both are Orange bass amps and Orange claims the preamp sections of both amps are identical.
For instance, the ones in yellow/green boxes show higher readings over the ones in the white boxes. Does that equate to a slightly higher output, or….?”
Chelsea’s response was:
“Spec for 12AX7 is 1600 Gm. So the 10M Mullards test at 100% of spec, and the high gain Amperex-labeled Mullards test at 125% of spec. This will likely translate into higher output, though it may not be an audible difference. It might also be a cleaner tone.”
Based on that answer I’d think I’d put the higher output Aperex labeled Mullards in the AD200B 200w tube amp and the others in the TB500 500w class D amp since there’s more wattage available.
And it may just be splitting hairs…
