[chrismercurio]

split this off and moved it here... seems I also accidentially deleted you chris... sorry... dave

[quote="DowdyLama"]Guys:

I don't know off the top of my head exactly what a Hammond 715 is, but I'm guessing that you're exceeding the 83's voltage ratings.
Is a mu of 8 (or 5.6 with the 46) adequate? Buzz, don't tell me you're falling for Jeffrey's "we don't need no stinking gain" mantra

Jim[/quote]

I was going to send Jeffery a PM but figured I would just post it here. I went to a buddy's house this morning to listen to his system and he has an Air Tight 300b amplifier with an Air Tight ATC1 preamplifier. The gain on the front of the amp was wide open and as such, the volume knob had to be turned very little to achieve a very high spl through his Altecs. The sound was thin and tinny at best. As an experiment, I turned the gain down on the amplifier to almost nothing so that the pot was nearly wide open on the preamp to set a comfortable listening level. The sonic difference was night and day with the experiment being wholly better than what we started with in every way. I thought to do this because I use a source buffer (impedance converter) or preamp with no gain at home. It can turn things down but not really up.

Can someone say why it was so much better with minimal gain from the amp and max or near max from the preamp? In the first scenario with the gain at full on the amps is the source voltage (the music?) getting choked off at the preamp?

Best regards to all,

Chris

[JeffreyJ]

hey chris..

as you can guess form the lack of reples, this one is tough to dignos without knowledge of teh circuit...

teh difference is in teh preamp.. the amplifier is getting teh same voltage to the first tube in both cases... well, the source impedance seen by the first tube changes, but that usually affects the HF roll-off, and I bet it is designed competently...

in case one, vol down on teh preamp, it is seeing a signal that may well be down in the noise floor... when you crank this up, scenario two, the components may like seeing that higher AC level... that is my best guess... as you are on a magnetic guy's forum, let's call it Barkhausen...

not sure I helped.. but that is best guess... I'd just be glad you found the sweet spot... :^)

Peace,
Me