Re: op-amps with wide open-loop bandwidth ?

Dave Moore wrote:

: And since, it is fairly obvious that you are not yet a circuit
: designer, you would probably get a more helpful response if you start
: over in sci.electronics.basics
:
: Good luck.

Well John, that's all fine and well in the world of pseudo-intellectual
EE-expertism, however in the real world of empirical eveidence,
it don't pan out. There are op-amps with specs far exceeding your
limited definition of what's necessary to 'dissappear the source of
sound coloration' that sound entirely different in the same circuit
and exhibit very different qualities of dynamics in the feel of a guitar
when you're playing it.

Then I suspect that the circuit is not well designed (is making demands on the opamp that do not allow the assumption of excess gain to apply). By the way, sorry if I underestimated your experience. The question just sounded like one from a newbie. I was sincerely trying to be helpful.

I started out designing guitar amps over 20 years ago and quickly
learned that the op-amps of the era couldn't compare with my discrete
designs. I only recently started to look at op-amps again as a viable
possibility due to recent advances in op-amp design.

Like any component, there is some art in getting the expected performance form them. No audio circuit, especially one in an instrument amplifier should ever let the opamp output saturate, even under severe signal overload conditions. That is when you hear the opamp, as it struggles to recover closed loop operation and can do all sorts of strange and prolonged things. The feedback should keep the loop closed for any signal it can reasonable be expected that someone will put through the amp.

I didn't ask for a lecture on tone. I asked for knowledge of any
op-amps that have a flat open-loop response beyond 20KHz
instead of the typical corner of 100Hz to 19Khz.
The open-loop gain in V/mv I don't give a rats ass about other
than that it's relatively flat to 20KHz or higher.

That is becoming clear.

I realize that I didn't do a very good job of communicating
my quest, but cut me some slack here. Ever since hurricane
Katrina waxed my estate, I've been averaging 5-7 hours sleep
per night sometimes even skipping sleep altogether in an effort to
complete a very important project for a rather important person
on schedule in spite of the hurricane induced setback.

You have my sympathy.

I can't tell you about the circuit it's going to go in because it's
not for any circuit in particular but rather for sonic evaluation
for exacly the reason that in the work I do, sonic evaluation is
the only thing that means diddly-poop.

I'm interested. What are the test conditions for this test? Will the opamp output saturate during this test?

I've heard the theories
of the "experts" on the subject of tone fall by the wayside over
the years and watched rather bemusedly as they scramble to
come up with new theories as to why the old theories didn't
account for fact that people can hear the difference in circuits
that so-called experts would logically conclude
(according to the theory du juor) should be sonically
indiscernable.

There are lots of poorly designed audio (especially instrument) amplifiers out there. The good ones sounds impressively similar.

IOW, the reason I want such an op-amp is to collect empircal
data rather than rely on the opinion of self-proclaimed experts
such as yourself that don't know near as much as they think
they do.

Now, you are the one presuming. If you don't like the advice, you are guaranteed double the purchase price refunded.

Now, if you want to rail on and hurl insults because I
misinterpreted your question and gave a seemingly non-sequitur
answer, do carry on.

I guessed wrong on your skill level and made what I hoped was a useful suggestion. People get lots of helpful hand holding on the basics group. The designers are more critical of each other, here, where they are more of a club.

Get over it, please.
.

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