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pat allen 24th January 2005 01:52 PM

PREAMP suggestion for my IRAUDAMP.
Hi, as some of you knows now, i have done a prototype of the IRAUDAMP. It sounds marvelously good.
I would like to build a simple preamp for it, that will at least, match its performances.

Preamp have to be: max 600 ohm ouput res. capable of 5vrms output.
Preferably non inverting, no op amp please.
Possibility if a baxandal circuit (who likes flat flat sound anyway)

Ive been looking at some of the Pass projects. Id like to get a simple one, but not that much ;)

any suggestions ??
schematics please !!


SDF 19th March 2005 11:04 AM

You can try to do one with the PGA2311 (or2310) I kanow it's a AOP but it sounds good.

If you don't need gain, a passive preamp can be used.

I made one with an IR controller and motorized pot.

It's the first part of this page:

...more, congrats for your project about IRaudamp, I'm really interested by.

ohenry 19th March 2005 12:18 PM

I'm not sure if this meets your criteria, but you may want to check out the Stereophile archives for the BUF03 preamp. A friend of mine made one and it's good and simple.:D

pat allen 21st March 2005 12:42 AM

Hi, thank you for the suggestions.

Main problem is the low input inpedence of my iraudamp, and then a passive preamp is not enough ( i did try it). A small gain is needed to get full potential of the amp.

Anyway, in my latest version, i have added an opa2134 to do a balanced input mode, mainly for bridging capabilities, and it have something like 47kohm of input load, while the output got like 100ohm impedence, so it will get no difficulties to drive the amp. I havent assembled the final board, but initial test shows quite good performance, the opa is a very good opamp, and seems at home on this design.

Then maybe a passive preamp will work ok, i didnt try it on this final design. My Luxman tube CD player got a motorized potentiometer at one of its output, it is my passive preamp :D


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