[Tyson]

Last week, I had the good fortune to meet and visit with anotherl audiophile here in Denver.  He has a very nice, very high end system consisting of an Accuphase DP-65 CD player directly driving his Spectron Musician amp (via balanced outputs/inputs), which in turns drives a pair of magnificent Selah Audio Excelarray speakers.  The Accuphase is designed to be able to drive an amp directly, having a built in volume control, and what appears to be a pretty stout analogue output stage.  

I brought along my AVA T7 preamp, we inserted it after about an hour of listening without it.  I expected a loss of transparency, with possible gains in bass output, but what we heard was a very, very similar sound to having no preamp at all.  Transparency seemed to not be affected at all, and if anything dynamics were better, with a slightly warmer, more pleasing sound, but that was not a huge difference, just a touch more organic sounding.  Like I've stated elsewhere, I know the T7 is a very good pre, compared to some other good pre's I've had through my system, but this is the first time I got to compare it to NO preamp at all.  Needless to say I'm impressed as hell with the T7's transparency and general "straight wire with gain" type of capabilities.  Kudos and bravo!

[avahifi]

Glad to hear about your results with the T7 SL preamp.  It is likely that the differences you did hear were a function the the T7 doing removal of ultrasonic digital switching harmonics from the CD player output before it got to the amplifier and speakers.  Out of band garbage does great harm to the sound, causing slew rate limiting in the amplifier circuits and saturation of tweeter voice coils.  The T7 preamp was simply doing one of its jobs as it was designed to.

By the way, a preamp's duties are as follows:

1.  Provide a pure resistive 47 Kohm load for the sources so they have an easy load to drive.
2.  Provide a low impedance and high current, high current slew rate output to drive any possible interconnet cable and amplifier input impedance load.
3.  Remove high frequency trash from sources so that garbage does not get to the amplifier and speakers.
4.  Provide all the switching and control functions you need.
5.  Not screw up the music.

Two observations:

1.  A passive preamp fails most of these job duties.

2.  I wonder how many designers can actually express these job duties (have you ever heard them listed before?) and if not, how can they design a preamp that actually works well?

By the way, get that T7 back to us for the transformer upgrade at your earliest convenience, you have not heard nothing yet.

Frank Van Alstine

[Tyson]

Frank,
I PM'd you. . .