Chris,
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?
Grey
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?
Grey
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.
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.
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 ?.
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 ?.
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.
If Nelson is listening in, maybe he could provide some insight or influence. These two collaborated on the A-75 some years back.
Chris,
Metaxas Audio has the schematic for a passive RIAA phono stage on their website. There's no reason you couldn't substitute the Burr Brown chips for the gain stages they're using. Or, you could go discrete. They've got schematics for a regulated power supply to go with it, too.
http://www.metaxas.com/pages/technology/diy.html
Grey
Metaxas Audio has the schematic for a passive RIAA phono stage on their website. There's no reason you couldn't substitute the Burr Brown chips for the gain stages they're using. Or, you could go discrete. They've got schematics for a regulated power supply to go with it, too.
http://www.metaxas.com/pages/technology/diy.html
Grey
Perhaps you can find what you are looking for here?
http://www.epanorama.net/audiocircuits.html
/Freddie
http://www.epanorama.net/audiocircuits.html
/Freddie
Thanks to everybody for giving me and others usefull information and new ideas !!! I agree with Paul B. and Hoffmeyer that sending around newly published material is bad net etiquette and will give this forum some bad karma.
I`m still not shure what I`m going to designvise.
Opamps or discrete ?
Having read Mr Nelson Pass diy opamps makes me wonder if two discrete opamps (jefet or mosfet) with a passive riaafilter between them is the way to go ?
Have any of you DIY`ers tried this in similar disigns? (Headphone amps, analouge stages in dac`s etc.)
Chris
I`m still not shure what I`m going to designvise.
Opamps or discrete ?
Having read Mr Nelson Pass diy opamps makes me wonder if two discrete opamps (jefet or mosfet) with a passive riaafilter between them is the way to go ?
Have any of you DIY`ers tried this in similar disigns? (Headphone amps, analouge stages in dac`s etc.)
Chris
One thing I remember about Thagard's design is that it was based on a discrete op-amp implementation of the design in a National app note:
http://www.national.com/an/AN/AN-346.pdf
I think Thagard said that it was very difficult to get performance from discretes as good as that available from ICs.
http://www.national.com/an/AN/AN-346.pdf
I think Thagard said that it was very difficult to get performance from discretes as good as that available from ICs.
RIAA Phono Preamps
For anyone who may be looking to build some very good low noise moving coil phono pre-amps. Take a look at the one I layed out a number of years back on my web site:
The Link is:
http://www.audioamps.com/diyparts/pcb/pcb.htm
Pictures for the Printed circuit boards are shown and blank circuit boards are available. Each channel is on its own board. Also posted on the site are handy graphs for the RIAA curves. Prehaps these can help fill a requirement that you may have.
Best Regards,
John Fassotte
Alaskan Audio
Changed the link on 10/27/2001
[Edited by alaskanaudio on 10-27-2001 at 12:43 PM]
For anyone who may be looking to build some very good low noise moving coil phono pre-amps. Take a look at the one I layed out a number of years back on my web site:
The Link is:
http://www.audioamps.com/diyparts/pcb/pcb.htm
Pictures for the Printed circuit boards are shown and blank circuit boards are available. Each channel is on its own board. Also posted on the site are handy graphs for the RIAA curves. Prehaps these can help fill a requirement that you may have.
Best Regards,
John Fassotte
Alaskan Audio
Changed the link on 10/27/2001
[Edited by alaskanaudio on 10-27-2001 at 12:43 PM]
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