[John Chapman]

Hello!

The old thread seemed to burp when I tried to reply to the latest post by 'Prospect' so I thought I'd start a new one.  Could be that the computer has grown tired of the long wait for 10K RIAA's.....

Here is his post:
"
Curious about the following,

I currently use a phono stage that I designed after reading several Sound Practices articles and Morgan Jones' book on tube amps.

The signal that is produced by a phono cartridge is a naturally balanced signal (not single-ended). Given the low-noise advantages of running a balanced interconnect and staying balanced in the circuitry, I can't help but wonder if the Stevens and Billington phono eq can be used in a balanced mode.

Does anyone know?


If not, I suppose a balanced first gain stage could be used.....then converted to single-ended and run through the EQ.....then reconverted to balanced by using a transformer to split phase.....then fed into a balanced output gain stage of the phono-preamp......and finally passed through a line output transformer to the main preamp.

This is less elegant but would keep most of the path balanced. If this conversion path was used, is there a recommended transformer for the interface between the S phono eq and the following gain stage?
"

[John Chapman]

Now onto my reply:

"Hello!

First - the 10K RIAA should be done in Sept. I know, I know... You're all going to say "yes but what year.... ". I spoke with Jonathan at S&B and he is re-arranging his shop to have time to do some R&D stuff and the 10K RIAA is the first item on the list. He has it all worked out and just need time to proto and tweak.

Now, onto your question about Ballanced operation. To really run it ballanced (two separate paths) you'd need 2 RIAA's per channel.  You could convert to SE and back again as you suggest and S&B has some trannies that would do that (and do it very well) but it would be introducing 2 more trannies to the signal path and the 'min path guy' inside me says that would outweigh the advantage of going ballanced.

I have a pair of TX103's on the way now that have a center tap on the output that will be ideal for conecting to truely ballanced phono stages and I have an interest in running this part of the signal path ballanced as it does make good sense - but it is more expensive to implement.

Many Thanks!

John Chapman
www.bentaudio.com
"