Looking for nice OPA134 preamp to build

[robmil]

Hi

I would like to build a small preamp based around the OPA134 or AD797 with a 4 transistor follower discrete buffer. I've hunted around but can't find anything.
Can anyone point me in the right direction please. The voltage rails are +/- 15v but I can go higher on the output buffer as I have an extra winding on the transformer I have (+/- 24vac with a center tap).
I would like a Class-A discrete zero-feedback buffer as I have seen one somewhere.....but where?

thanks for the help

Rob

 

[AndrewT]

Walt Jung details combining opamp with buffer.

 

[richie00boy]

You probably haven't found anything because there is little point in adding a discrete buffer to an op-amp stage to driver power amps. The op-amp is more than capable enough on its own.

Maybe what you really want is just a simple discrete pre-amp. I've got a design ready if you want to try?

 

[robmil]

Hi

Thanks for the options and replies. I pretty convinced that I do not want to go the chip opamp way (by itself) as a friend played me the difference between chip with and without a buffer on his DIY preamp and yes although sound came out of the chip opamp and was able to drive the power amp, adding the buffer sounded so much better, fuller, better soundstage and more 'real'.


I've looked at the Millett diamond buffer but it's too much. Something like the Sijosae class-A but that will work at +/- 15v

R

 

[Voegelchen]

Walt Jung is worth looking for... and see here....
http://www.ac-vogel.de/TransBuffer_Artikel/TransBuffer_APN_1.html

I've build a CLASS-A Buffer and measured THD/THD+N.......

Andreas

 

[Albrerta]

how about this one

Current boosted diamond buffer preamplifier stereo kit on eBay.ca (item 320538649111 end time 22-Sep-10 23:38:36 EDT)

 

[robmil]

Albrerta...how did you find that? That is just what I was looking for..infact that is pretty much it.
Thank you

regards

R