John Curl's Blowtorch preamplifier part II

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Sounds like Kosher salt to me is needed on some of this stuff.

I can't seem to get a straight answer to my straight question. What do you say Scott, is there really any reason at this point in time that an IC based preamp or power amp would be inferior to a discrete circuit using what is presently manufactured and available today, and not some NOS devices that are not available to the masses?
 
The audio game is very straightforward, if one works at it a step at a time. If you do something, the the sound will subjectively change, or not, depending upon everything. If it does change then there is a physical reason for it - not the fact that you consumed the wrong amount of alcohol - and the smartest thing to do is to then track down the reason for the change. Your system will benefit, and you will have learnt something ...

Frank
 
Well, Frank. Perhaps you can recommend to me what IC's I should use to replace my discrete designs. I certainly need something for the masses. '-)
It's not so much the particular device used, it's how it's fed and nurtured. I would be paranoid about getting the FB right, in terms of the components and the precise physical layout, being super fussy about the quality of the power supply feed right at the pins of the chip, and getting the grounding scheme right. This to me is where the real work has to be done, to make the opamp work as well as it theoretically can ...

Frank
 
Frank, read my article in Volume 2 of Linear Audio where I did precisely that experiment.
SY, thanks for that. I don't have the mag, so cheated by looking up other's comments. NwAvGuy says the transparency limit was 6 in series, of "cheap" opamps, by your subjective testing, so did you then resort to any objective testing to try and determine any causal link? Could it have been that the 7th was a "weak" unit, substandard, damaging the chain in itself?

Frank
 
Too late, we already did.

Did Widlar have a Bentley?

I think he was into small fast cars. It's surprising these days how few $$$ wheels I see in the lot. There's one Merc SLK and (now gone) a bright red Lotus. There's a salesman that drives a Shelby Cobra but he's not ours just here once and a while. One of the bosses in Ireland drove a Bentley. It's Jaguars for the bosses here, but they are in Norwood.

Someone like Bob just could not exist today.

Out In Paris With Bob Widlar, Charlie Sporck and Peter Sprague - Mannerisms
 
Well it seems JC has gotten another bar fight started.

As I mentioned a bit back around here we have been playing with microphone preamps. One of the IC based transformer manufacturer's reference designs had been found not to work well as shown. After getting it to work, it had much lower noise and distortion than the "B" design. However it was decided it was unacceptable for our use.

As many microphone preamps do, it would clip under some conditions. The clipping behavior really had a standout signature. Now it is possible to change this.

The preamps that use discrete devices were not as limited by voltage rails. So there is a behavior differences in the designs. Now it certainly is possible to use ICs in a preamp design supported by other components to achieve excellent results.
 
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I have never seen a IC-spec that would give information about the change of properties over a broad range of output level. Certainly a class B output can have a real nasty distortionspectrum at some lower levels than published. I know that at least tube PP class B amps can have inferior properties at certain lower levels. Could it be possible that IC manufacturers nowdays "trim" theyr datasheets so they only show data that looks the most favourable? I have seen old datasheets where the manufacturer was not afraid to show also pretty ugly and unfavourable data.
 
Well, Frank. Perhaps you can recommend to me what IC's I should use to replace my discrete designs. I certainly need something for the masses. '-)
You asked severall time this question and get responses. One of them was to try fast Current feedback devices. Did-you tried one of them ? NO, of course. In fact, you are only interested in everything witch can add argues to your hype hate for ICs.
 
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