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Chris 9th September 2001 02:04 PM

For some time now I have been searching the net, for a good
diy phono preamp. One design I have found is the TNT solidphono. I wondered if some of you have built this design or a similar design using a passive RIIA network ?
(or other design sulotions).

Thanks in advance !!!!

GRollins 9th September 2001 03:29 PM

I worked my fingers to nubbins in a similar search. Unfortunately, many of the designs I saw were flawed in one way or another; there weren't many left by the time I separated the wheat from the chaff. Eventually, I decided to do my own from scratch.
Are you looking for tube designs, solid state, or either?


Chris 9th September 2001 03:41 PM

My current idea is to use two Burr Brown 606 op-amps with a passive riaa network between them for one channel. Not unlike what is used in the TNT solidphono diy project.
Initially I wanted to build the riaa descretly with MOSFETS or JFETS, but I havent
found any designs like that.

paulb 9th September 2001 03:47 PM

Thagard phono preamp
There is a 2-part article in AudioXpress January and February 2001 (apparently also printed in Electronics World in April). This is an excellent article because it goes into detail on the design decisions. Unless you insist on tubes, this appears to be a state-of-the-art design.
The circuit is entirely discrete components except for the servo feedback circuit; it uses JFETs in the signal path. A PCB pattern is included.

Chris 9th September 2001 03:53 PM

Thanks !!!

Is this design available on the net ?

Chris 9th September 2001 05:29 PM


I have searched the net for a while, and did not find the articles you mention. Do you know any sites where I might find these? I live in Norway so I do not think my local magazine vendor have these.

arnach 9th September 2001 06:16 PM

Aleph ONO

I don't like ICs in audio circuits.. have a look at the Pass Aleph Ono service manual.. There is also an ongoing thread by me about my progress with it, etc., since I am building it.

-- Aaron Finley

Hoffmeyer 9th September 2001 06:42 PM

Hi Chris.
I have the articles, and I can scan them, and mail them to you.
How about that?
Just mail me your e-mail address.

Chris 9th September 2001 07:38 PM

Hi Aaron

The Aleph Ono was the first design I looked at when I started my quest for a RIAA. Unfortunatly i haven`t found
anybody who sells the 2sk389 dual jfets. Using only the MM part of the circuit sounds like a good idea. What other Jfets do you think (if properly matched) could replace the 2sk389 ?.

paulb 10th September 2001 03:32 AM

I don't think Norman Thagard has a website but I could be wrong. I'd be a bit uncomfortable scanning and emailing the articles since they are fairly new and published in AudioXpress. Perhaps he could be persuaded to publish them on the net somewhere, if his agreement with AudioXpress allowed it (obviously Nelson Pass's does).
If Nelson is listening in, maybe he could provide some insight or influence. These two collaborated on the A-75 some years back.

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