THD claims of audio signal generators

No, he's simply thrashing about in defence of a lost argument - as usual.

Hell, you are very unlikely to find peaks more than 10dB above average on most disks these days.

MrT.

You fry the speaker.

Get real!

Its even pretty hard to find 36 dB peaks in live performances.

Every once in a while someone drops, or unplugs, or heavily bumps a mic at one of the preformances I record. This is *always* the biggest peak in the recording. IOW, the whole recording chain has enough dynamic range to handle

And, in the case of his little 20 watt tube amplifier, even if there was that much energy in the power supply and the plate resistance were damned near 0, the output transformers would have long since saturated.

He can't: his argument falls apart, and he can't have that, can he?

I believe the tubie argument is that between being able to put out say 80 watt peaks and the euphonic nature of tube clipping, the 20 watt amp could be asked to deliver 2000 watt peaks every few milliseconds, and the listeners would be pleased.

I think that "Bret Ludwig" is just another alias for a Luddite troll that's been around here for years. So, not even the poster is real.

Yes, as far as the signal is concerned, but if the cartridge crosses a scratch or some dirt, there can be a large transient. Some phono preamps take quite a while to recover from one of these transient events.

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I think any discussion of tubes transistors and distortion should be tempered with an appreciation of the historic shift in design techniques.

For example, undergraduate 1950's and 1960's tube designers didn't have Root Locus in their tool bag. They used feedback gingerly and empirically. The transistor guys were fresh out of school, had Root Locus, and would pour on the feedback. The little detail about SID was mostly overlooked till about 1980.

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Only the very poorly designed ones. But I'm uncertain why you are worried about the amplifier distortion levels caused by a "scratch or some dirt". The whole transient itself is distortion. One reason why I always hated vinyl.

MrT.

If the preamp bumbles for a while, the event lasts longer than it needs to.

In some respects you can have a similar situation with CD players. A relatively minor (from a data recovery or error concealment point of view) bald spot on the disc can cause the transport to bumble around so long while attempting to reacquire the track that it runs out of data and the audio must mute. Had the transport been able to coast through the bald spot, there would have been no audible problem.

My point being that a design shortcoming causes more audible damage than necessary.

I agree that tic, pop, wow, and tracing distortion are a bummer.

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I learned root locus stability analysis in the mid-60s.

This page references a text from that time:

Coughanowr's book came out in 1965. Coughanowr received his PhD in 1956, so any precident-setting paper was probably published in the preceeding 15 or so years.

I think that it was Bode and crew at Bell Labs during the 1940's that developed the ground work. I can remember a Knight Kit tube amplifier of about 1960 that was advertised as being unconditionally stable. Then, it was a unique product. A few years later I learned exactly what that meant, but at the time I did appreciate that I did not need to fuss about accidentally unloading the output.

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