Anyone technical have any thoughts on this?
Is it a first as he says?
If it varies the gain why is there also a volume knob? My impression was that it would only vary the gain and work differently to a usual pre.
It does make sense to have just enough gain so you’re not burning it all away with the pot. You’d still need the pot for fine adjustments, I would have thought.
The issue with some pre-amps that vary the gain is that the sound may not be exactly the same at all volume levels. I know that Guy measured TVCs and found this to be a problem; obviously this is totally different tech but it could still be an issue.
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Makes sense. I find it interesting anyway.
Variable mu valve in a line stage? Ta but no.
Yeah I like that this kind of thing is tried
Quite. This is not particularly new, remote cut-off tubes were developed for automatic gain control circuits, back in the day. It works, but the penalty is high distortion.
The innovation here is in marketing/being daft enough to use them for a preamp rather than an effects box.
My audible illusions pre has two knobs on the front to adjust the gain, plus a volume control. It sounds great. I find the adjustable gain really useful to adjust / improve the sound.
Is that using a transformer?
It’s not a passive preamp, if that’s what you mean. Mine uses 2 Russian valve 6922 equivalents. It’s also zero feedback.
I think I can improve the sound quality by using different gain settings. It sounds better when adjusted. I try and use less gain and more volume. That’s a rough rule that varies according to the source and even perhaps the recording.
It was once a Class A Stereophile rated component.
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You remember correctly It was a brilliant thing -I should have kept it.