Discrete Opamp Open Design

[gpapag]

Originally Posted by scott wurcer

You can use Excel and SoX to directly create .wav files at any resolution and sample rate supported.

SoX. Didn’t know about it. Impressive list of features.

SoX - Sound eXchange | Features

Thanks Scott

Originally Posted by Joachim Gerhard

The distortion isolation test :Distortion Isolation in the Time Domain

Joachim I read the description of the test. The method seems to me very powerful. Congratulations.

George

[Joachim Gerhard]

Thanks George.

[bear]

Question from high up in the nosebleed seats.

If one uses extraordinary quality regulation on the rails, does PSRR still matter? If so why?

_-_-bear

[gpapag]

Once you stop the nose bleeding…

If the very good (stiff and clean) psu is accompanied with some measures for rail isolation/RC filtering btn active stages (local post regulation is another option), PSRR requirements I think can be relaxed.
It remains the problem of rail coupling btn input & output on each stage (e.g. base-collector). RC filter there too.
What else left then to PSReject?

George

[bear]

yes, yes, from up here, the oxygen is very thin...

....also, everything is so far away it seems so little. Small, like ants. Small, like hundreds of tiny micro details. Hard to keep track of...

[jan.didden]

Originally Posted by bear

Question from high up in the nosebleed seats.

If one uses extraordinary quality regulation on the rails, does PSRR still matter? If so why?

_-_-bear

Bear, I'm not sure I get the question.
As I see it, PSRR always matter because it determines how much of the psu junk makes it to the signal output.
If you have a maximum 'bleed through' goal, like you don't want more than say 1uV of supply junk at the signal output, you need a certain combination of actual power supply junk and PSRR.
Improve your psu regulation and you can relax the PSRR requirement for your goal, but it always will matter.

Probably when you make your goal with a specific supply and PSRR you will want to try for an even lower goal...

jan

[gpapag]

yes, yes, from up here, the oxygen is very thin...

Dive bellow the 3000 feet

Hard to keep track of...

What’s the use? Let us ants go back and forth. Winter is coming.

Did you have anything special in your mind (PSRR wise )?


George

[bcarso]

Originally Posted by bear

Question from high up in the nosebleed seats.

If one uses extraordinary quality regulation on the rails, does PSRR still matter? If so why?

_-_-bear

Some of us like to also confine currents to loops as local to a given circuit section as possible. Walt Jung discusses this in his recent interview in audioXpress, and Bruno Putzeys mentions it somewhere (possibly on the Grimm Audio site?).

When I designed the electronics for the photodiode array spectrometer in the mid-late 70's, I grappled with circuits that needed to be both fast and precise. There was often some relatively local regulation, but the main power supplies were separate from the primary instrument, and although well-regulated, low noise, and fast response, if the circuitry had substantial variation in currents in operation the system would not have worked well enough.

So in virtually every part, after local R-C decoupling, local shunt regulation acted to produce a system overall with invariant power supply currents. In some cases the shunt conduction was actually driven by the signals, not regulating after the fact. It worked very well indeed, and allowed the boards to share a heavy copper ground plane; each board was attached by a copper angle bracket to the plane and was itself constructed of two-sided copper-clad boards, all hand-wired point-to-point.

[bear]

hmmm... more tiny ants to herd.

_-_-

[john curl]

Interesting question, Bear. Of course, all else being equal, why NOT have high PSRR? However, many good circuits do NOT have really high PSRR, so what do we do with them? Avoid them? OR do we make extremely good power supplies. I do the latter.