Search found 6 matches

by stoeffle
Wed Nov 09, 2011 4:30 am
Forum: Pro Audio Design
Topic: Let's Discuss Servos (Previously OPA188 Thread)
Replies: 46
Views: 94885

Re: Let's Discuss Servos (Previously OPA188 Thread)

ricardo wrote:Are these special phase equalisers minimum phase?
can't tell, as this correction network was a cut&try work done in simulation...

stoeffle.++++
by stoeffle
Tue Nov 08, 2011 9:26 am
Forum: Pro Audio Design
Topic: Let's Discuss Servos (Previously OPA188 Thread)
Replies: 46
Views: 94885

Re: Let's Discuss Servos (Previously OPA188 Thread)

@ Ricardo Are these non-minimum phase circuits? eg All-pass networks? Hi Ricardo, no, not really. Allpass networks produce a constant phase delay keeping the amplitude rather untouched. Here we produce a kind of phase equalization in context with the amplifier being corrected, so as to get a truly f...
by stoeffle
Tue Nov 08, 2011 3:36 am
Forum: Pro Audio Design
Topic: Let's Discuss Servos (Previously OPA188 Thread)
Replies: 46
Views: 94885

Re: Let's Discuss Servos (Previously OPA188 Thread)

@JR: The concept of a servo is to use an opamp so you can get away from large caps, or are your 1UF caps film? If they are they will probably be physically large. All caps are film caps (metallized foil), WIMA MKS2 series. The footprint of the latgest one, 1µF/63Vdc & 40VAC is WxLxH in mm: 5 x 7...
by stoeffle
Mon Nov 07, 2011 5:17 pm
Forum: Pro Audio Design
Topic: Let's Discuss Servos (Previously OPA188 Thread)
Replies: 46
Views: 94885

Re: Let's Discuss Servos (Previously OPA188 Thread)

@ Wayne: hope the pic upload worked... The amp's output runs through a Sallen&Key 3rd order Bessel LPF with a 1 Hz corner freq. Its output passes a lead-lag network before entering the servo integrator itself. The overall group delay performance including the power amp itself results in a comple...
by stoeffle
Mon Nov 07, 2011 4:46 pm
Forum: Pro Audio Design
Topic: Let's Discuss Servos (Previously OPA188 Thread)
Replies: 46
Views: 94885

Re: Let's Discuss Servos (Previously OPA188 Thread)

@ Wayne: .. show us?...

I am trying to extract the part of the schematic...have to do this on the other PC, sorry.

stoeffle.++++
by stoeffle
Sun Nov 06, 2011 4:21 pm
Forum: Pro Audio Design
Topic: Let's Discuss Servos (Previously OPA188 Thread)
Replies: 46
Views: 94885

Re: Let's Discuss Servos (Previously OPA188 Thread)

Hi all, may I throw in an aspect which seems to go by unnoticed in all the posts posted ahead? Fact: An audio circuit with a DC-servo to squeeze out that DC offset is, by all means, a HPF. It is the matter of group delay distortion. I have been dealing a lot with this subject, as some musicians gave...