RIAA update?

DrM · « **on:** 19 Apr 2003, 01:51 pm »

Hi John,
Any update on the RIAA?

Dan

John Chapman · « **Reply #1 on:** 19 Apr 2003, 02:59 pm »

Hello!

Thanks for the reminder as it's about time I checked on this. The 10K unit was due at about the end of this month - I'll check this week and report back here with an updated ETA - maybe it's early

Thanks!

John Chapman
www.bentaudio.com

Marbles · « **Reply #2 on:** 19 Apr 2003, 03:39 pm »

John,

Can you post more on this, as there is no info on your website.

Is this just the step up transformers (103?), or is this a phono pre?

Thx

John Chapman · « **Reply #3 on:** 19 Apr 2003, 03:59 pm »

Hello!

The RIAA module is one part of a phono pre-amp and is in no way related the TX103 MC stepup - other than the fact both are used for 'phono stuff'. The RIAA module is for DIY constructors who are designing their own phono stages. It is kind of a RIAA 'curve in a can'. In time I'm sure there will be a few circuits using the modules floating around as well. For info on the RIAA modules have a look here:

http://www.stevens-billington.co.uk/riaapage.htm

Thanks!

John

John Chapman · « **Reply #4 on:** 19 Apr 2003, 06:04 pm »

DrM,

I don't think I ever did get an answer to the RIAA thread where you asked about external components. I had spoken to S&B and there would be no problem with getting an inductors only version - Jonathan will provide schematics showing component values and hook-up.

Thansk!

John

DrM · « **Reply #5 on:** 20 Apr 2003, 01:44 am »

Oops, the reply didn't seem to take, try again.

Thanks let us know the details, and approx pricing if you can.

Are the 600 ohm versions available yet?

Dan

John Chapman · « **Reply #6 on:** 20 Apr 2003, 02:00 am »

Hello!

I'll try for an update next week. The pricing will be the same as a pair of TX102's - $380.00 per pair. A bit less for inductors only I'd guess.

The 600 Ohm version is shipping now.

Thanks!

John Chapman
www.bentaudio.com

JoshK · « **Reply #7 on:** 27 May 2003, 08:58 pm »

John,

Are these RIAA curve in a can units passive re-eq'ing or is a lot more needed to make a phono pre?

John Chapman · « **Reply #8 on:** 27 May 2003, 09:37 pm »

Hello!

Good to hear from you and I hope all is well. They require more circuitry - modest to advanced level diy stuff. You need an input circuit and an output circuit on either side of the S&B RIAA unit. It's just not possible to get the small signal from a cartridge 'stepped up' and EQ'd without some active circuits for gain and buffering.

Thanks for posting as I am overdue on getting an update on the 10K version. I have been shipping some of the 600 ohm version but I don't think any projects are done yet. I'll post an update as soon as I can.

Thanks!

John

Prospect · « **Reply #9 on:** 21 Aug 2003, 10:29 pm »

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&B phono eq and the following gain stage?

John Chapman · « **Reply #10 on:** 22 Aug 2003, 06:00 pm »

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