[robinje]

Hello.  I've read about the general sound characteristics of the T8 and Ultra preamps.  Do the phono sections' sound characteristics follow those of the line stage in these preamps?  That is... from what I've read, the T8 line stage (being all tube) has a bit of tube "magic" and may be a little softer than the Ultra, which is supposedly outragously dynamic and totally transparent with no "tube sound" to speak of.  Do the phono sections follow these generalizations also? 

On another note, apparently the phono section input impedance is 47kohm for AVA preamps.  I like to dabble with tube rolling in an external headphone amp that I connect to the unbuffered tape outs on my existing pre.  If I buy an AVA preamp with unbuffered tape outs and have my external headphone amp hooked up, would the input impedance on my headphone amp (100kohm) affect the AVA phono section input impedance (as well as all the other inputs), or would it remain at 47kohm?  That is, would the incoming phono signal see the 47kohm phono section input impedance in parallel with the device hooked up to the tape outs?  This would result in about 32kohm if my calculations are correct, certainly a non-standard value for MM cartridges.  If so, perhaps the buffered tape out option would be the best solution.  I am leery of having a buffer in the signal path, though, as I like to feed sources to my headphone amp with as pure and unaltered signal as possible. 

Thanks!

[BrianM]

I used to have a T8 with phono and would say yes, the same characteristics applied.  I don't see why the same wouldn't apply for the Ultra, too (mine does not have the phono stage).

[avahifi]

The input impedance of your external headphone amplifier will not affect the input impedance of any of our RIAA phono sections.  A very low input impedance of an external headphone amplifier might possibly affect the linearity of the RIAA feedback loop of the tube only T8 preamplifier, but not the Ultra or Insight series.

We urge the use of our Buffered Tape Output option for connecting strange loads to the preamp's tape outputs.  It has a bandwidth in the megahertz range, less than .0005 percent THD and a slew rate approaching 2000 V/uS.  Guaranteed to not affect the musical performance at all and drive any silly load you care to connect.

Regards,

Frank Van Alstine

[robinje]

Thanks for you explanation. 

So, what would be considered to be a "strange load"? 

Also, if the tape buffer option is installed, obviously the preamp would need to be powered up for the buffer to be activated and, therefore, for a signal to appear at the tape outs.  If the buffer option is not installed, does the preamp not need to be turned on?  I assume that the input source selector knob would simply route whatever source signal that is selected right through to the tape ouput jacks.  This would be nice because I could listen to my external headphone amp without having to power up the preamp, but simply using the preamp (without turning the power on) to select the desired source.  Can you answer this one, too?

Sorry for all the questions, but I want to make sure I understand this thoroughly.  Thanks again...

[avahifi]

One other observation, the built in headphone amplifier in any of our new preamplifiers is most likely lots better than your separate headphone amp.

Regards,

Frank

[robinje]

One other observation, the built in headphone amplifier in any of our new preamplifiers is most likely lots better than your separate headphone amp.

Regards,

Frank

I surely didn't mean to imply that my external headphone amp would be superior in any way to the ones built in to the AVA preamps.  I'm not a tweaker for the most part, but I do rather enjoy futzing around with tube rolling in my tube headphone amp and observing the changes in sound quality brought about by incorporating the various compatible tube types.  If I buy an AVA preamp, I'll still be able to enjoy this tweaky pursuit while also obtaining a very fine headphone amp built right into the preamp.  Although, it may be redundant to have two quality headphone amps around.  If I find that I don't listen to my external amp any more or need to free up some funds, I can always sell it.