2. amps-preamps
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TVC Gain effects

A lot of TVCs, like my AudioZone, can produce gain, usually 6dB. The AZ does this with a switch (I think the Bent just engages gain automatically once you're above unity.)

Does anyone know what the effects, if any, on output Z and frequencey response are of engaging gain?

I tend to prefer the unit with the +6dB setting engaged, even at lower volumes.
paulfolbrecht
ngjockey
1,042 posts
 
The additional 6 dB of gain affects impedance issues for the worse. For the S&B, the input impedance would be 2500 and the output impedance increases. Obviously, that isn't a problem or you prefer the frequency extremes slightly rolled off.
paulfolbrecht OP
586 posts
 
Thanks! I did find this information on the S&B page as well.

I guess it is better to use a volume setting closer to unity gain (-8 or -12dB usually) with the 6dB switch off then to keep it on with a lower setting.

With a source Zout of around 30 and amp Zin of 100K, you might say I have "impedance differential" to spare, but still..

Some say that they prefer the trannies with the extra gain, which is probably a little strange.
sutts
668 posts
 
The Audiozone Pre-T1 TVC preamp tends to sound a bit better with the additional 6db of gain- don't ask me why...
paulfolbrecht OP
586 posts
 
Would that go for any S&B tranny implementation, then? Hard to see why it wouldn't.

Does anyone have any guesses as to what could cause such an improvement with gain? Other than that the induced response variations end up correcting for some other problem in the chain?!
gregm
3,021 posts
 
Does anyone have any guesses as to what could cause such an improvement with gain
You have current to spare -- but are lacking in voltage. I.e. yr source outputs a lot of energy -- but lower voltage than you like, or than the amp likes -- the latter admittedly, being strange as most amps reach their spec'd limit @~1,5V. (Upping the voltage on the tranny, you halve the current -- all other things being equal.)
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