Feedback clarification please

[SoundMods]

Hey I am just trying to learn here
I did not understand the quote so I asked the question
I think I have a better understanding now and I thank you guys for your answers,but I do not like being belittled for asking a question

You weren't belittled -- it's just that for the most part -- unless you are designing from scratch the issue doesn't come up and can be confusing. It's kind of a given -- like blue skies -- fluffy white clouds.

[SoundMods]

At first, it appeared to be Tom P., because he uses real purty words. But by the end it was obvious. It's Steve, isn't it?

If it is hollow state it would never be me. I gave that stuff up eons ago.

The same issues exist with solid-state unless you take the easy way out and use IC op-amps. Yet IC op-amps -- if you look at a typical schematic of one -- you'll find the same design criteria reduced to a tiny die.

[Pelliott321]

Stuart you are a gentleman
thanks

[dberning]

One interesting note is, let's say, you were to start with an amplifier that had loop feedback from the sec of the output transformer brought back to the input stage cathode. Now let's say the second stage had a cap-bypassed resistor to run that second stage at the highest gain. You would then have an amplifier with a certain amount of overall (global) feedback. Now let's remove that bypass cap in the second stage. This would reduce the open-loop gain and would reduce the global feedback but shift some feedback to local where there was none before (at least in the second stage). One thing that would happen is the output impedance would increase. Another would be likely increased stability, although not guaranteed if a bad design fundamentally. Both of these and possibly other effects such as overall bandwidth would likely change the sound, better to some listeners, worse to others.

Paul, to answer your question, the term degeneration is used to refer to degrading the gain of the tube by effectively reducing transconductance. Interestingly, when a tube's transfer characteristics are observed on a curve tracer, you get one set of curves. Now add a resistor in series with the cathode and those characteristics will look similar to those of a bad tube. On close inspection the spacing between the various curves will improve in linearity. But a certain amount of this will happen with a bad tube in a rather uncontrolled way, but superficially they appear very similar.

[Pelliott321]

Thanks, David for putting this bed.
It is certainly more understandable that amp design is not a walk in the park. These very subtle things is probably why some amps sound great and others not.

[SoundMods]

Thanks, David for putting this bed.
It is certainly more understandable that amp design is not a walk in the park. These very subtle things is probably why some amps sound great and others not.

BINGO!! Thanks to David!

And anyone that thinks designing audio equipment requires nothing more than having a working knowledge of electronics is sadly mistaken.

David has many well-reviewed products out there -- I had the chance to have one here to play in my system.

Those did not come easy as designing a product such as his is a horrible process that even after a prototype is finalized -- then comes the industrial engineering part -- coming up with a manufactured product for sale -- pricing it -- and marketing it.

And yet -- David has somehow maintained his sanity. BRAVO!!

Anyhow -- I was hoping he would jump in and provide us lay persons with solid information -- he did -- we're happy.

[FerdinandII]

I have actually seen this topic come up frequently, when people are discussing cathode followers and where degenerative feedback reduces gain to (effectively) unity.

Hey I am just trying to learn here
I did not understand the quote so I asked the question
I think I have a better understanding now and I thank you guys for your answers,but I do not like being belittled for asking a question

You weren't belittled -- it's just that for the most part -- unless you are designing from scratch the issue doesn't come up and can be confusing. It's kind of a given -- like blue skies -- fluffy white clouds.