Class ABCD ?

[RGA]

Before I do I want to ask you if you are saying that there is no such thing as a no-feedback amplifier?

[theaudiohobby]

Ho..hum.. I take it that there is no thread that refutes that article then.

[RGA]

No feedback means no global feedback which was the word I was trying to locate. It is the industry standard meaning of no feedback. Sorry TAH but I don;t save every thread on my hard drive for years just int he off chance get morons arguing semantic points of real engineers which it is clearly obvious you are not by the totally incompetant ways you read the Elac graph and it's frequency response.

" the article actually says that its possible to consider a triode as a pentode with feedback. Its just a mathematical construct. Doesn't mean anything one way or the other."

http://www.audioasylum.com/forums/se...ges/39794.html

[theaudiohobby]

No feedback means no global feedback which was the word I was trying to locate. It is the industry standard meaning of no feedback. Sorry TAH but I don;t save every thread on my hard drive for years just int he off chance get morons arguing semantic points of real engineers which it is clearly obvious you are not by the totally incompetant ways you read the Elac graph and it's frequency response.

" the article actually says that its possible to consider a triode as a pentode with feedback. Its just a mathematical construct. Doesn't mean anything one way or the other."

http://www.audioasylum.com/forums/se...ges/39794.html

, Big Laugh! I see that you were so embarrassed on the ELAC thread, confronted with three curves, you managed to pick the wrong one and in case you missed it, the adjusted curves are also mathematical constructs, duh . I hope you realise that other amplifying devices can be designed to avoid global feedback, however they still require some form of feedback to maintain linearity and in the case of the triode it is inherent to the device, so whichever you cut it, your original post or more correctly ad-copy amounts to erroneous marketing froth.

[RGA]

Triodes have degeneration, not feedback. They ain;t the same --- sorry but you have no clue.

No I read all the graphs on the the Elac correctly -- it is their measurements -- which is suspect as it is and even then they look bad -- all reports from listeners I know and the credible reviews think it's pretty unlistenable. Given the other speakers you like I'm hardly surprised.

[theaudiohobby]

Triodes have degeneration, not feedback. They ain;t the same --- sorry but you have no clue.

Ho Hum ...from the same thread

theaudiohobby presented me with this 1953 article and says that sets all have feedback and there is no such thing as a no-feedback amp

There is I believe indeed no..no feedback amp..that is no news..but there is such a thing a local feedback and global loop feedback

.

I offer no real rebuttal other than to say that those that understand tube circuits consider this info old, self-evident news. If someone wishes to model a triode as a pentode with "built-in" feedback that is their business and it may work for their needs within that model's limitations. Many such models are used. Some may model a pair of triodes in cascode as a pentode for example.

The triode has certain inherent features. Among them is that if the anode voltage is lowered the anode current lowers, because there is less tension between cathode and anode and thus less electrons are attracted by the anode from the cathode.

Now we may call this a feedback mechanism or not.

Now for the clincher..

The method is of particular interest for control circuits and output stages utilizing low-µ triodes, since the back action from the anode on the emission-controlling field at the cathode is then appreciable. Fundamentally, this electric field action is a form of negative feedback

correlated to the transistor behaviour

Simple transistor amplifiers use emitter degeneration to achieve negative feedback, which gives a relatively predictable gain compared to the gain of the transistor itself, which varies widely.

Degeneration is fundamentally used to achieve negative feedback in analog circuits, it is as simple as that. If it looks like a duck and quacks like a duck, it is a duck. Another popped bubble.

PS: You might as well give up now....Neither your english degree nor PQ marketing blurbs have equipped you for a technical discussion. Maybe I should post your blunders for the world to see that you do not know how to read FR graphs. Worse than that, you proceeded to do some character assasination in your referenced SET thread, shame on you .

[RGA]

.Neither your english degree nor PQ marketing blurbs have equipped you for a technical discussion. Maybe I should post your blunders for the world to see that you do not know how to read FR graphs. Worse than that, you proceeded to do some character assasination in your referenced SET thread, shame on you .

Too chicken to go on the AA thread yourself and battle with the engineers.

Sorry I can read graphs with the economics and math courses I have taken. you have little character to attack.

[theaudiohobby]

Triodes have degeneration, not feedback. They ain;t the same --- sorry but you have no clue.

I will be remiss if I do not post these comments made by the poster that you originally quoted, in one of his responses to me, he said this

No-one is disputing that cathode degeneration is NFB.

So back to the original question, Do triodes (including triode amplifiers) have negative feedback? Yes Indeed, they do.

[RGA]

And your point was 1. The original supposition was that a grounded cathode triode amplifier is fully equivalent to a pentode with NFB due to the inherent NFB action of the plate resistance. This is false.

BTW from the exact same poster you quote "Triodes have degeneration, not feedback.
Yes there is a difference." Feedback involves feeding back some of the output signal to the input, which means that the signal presented to the input is different from the open loop case.

Degeneration means that the output affects the field within the triode in such a way that the output is different from the "open loop" case with the same input."

BTW since you obviously only posted this to attack Audio Note -- just so you know they don;t claim all their amps are no negative feedback. Mine for example uses some negative feedback as does the Soro. The Meishu is zero negative feedback.

To prove you are right to me -- take them to court for false advertising. Yeah thought so!