[KTpG]

Is it possible to use a multiloop topology for the SDS amp? I really wanted to use a better opamp for the input (OPA2132 is great, and what I am using now, but it is because I am using ti now that I want better). I have OPA627 and OPA637. Last time I breadboarded, I A/B'ed the 627 and 637, and the 637 was a LOT smoother, with nice highs and great bass, whereas the 627 had shrill highs. Maybe this was just the config, but it was a standard META. 627 is unity stable, so it would work without multiloop, but 637 wouldn't unless I threw a gain of 300 on it, but then my ears would bleed.

SO, is this a safe route to get to use my 637? Overall gain=about 10... inner loop around 250, outer loop 19, for 10 total. (figured on the fly in my head... could be wrong)


EDIT: If I did multiloop, wouldn't I have to remove the cap going from opamp output to inverting input so the resistor could be there?

 

[guzzler]

theres not a whole lot of point as the real deciding factor in the sound of the SDS amp comes from the MOSFET output section, the OPA just providing a gain stage...

strange you've brought this up now as i asked the same question only a week ago or so, but the answer was the same...

i've designed a PCB for it as well, different from the original but based around it, made it double sided to cut down on twists and turns and reduce trace length...

h

 

[300_baud]

I've tried this a while back, and I tried to build 3 jung multiloop amps, and I could never get it stable.. no matter what i had DC offset at output, ranging from 30mv to 200mv. I tried adjusting the inner loop gain to no avail. No matter if i increased it or decreased it, i just never could get it stable.