Nelson Pass also has his own paper on negative feedback - appreciate you probably know that Andy just mentioning for others.
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Orb
Preference vs. audibility - please keep them separate.
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Nelson Pass also has his own paper on negative feedback - appreciate you probably know that Andy just mentioning for others.
Cheers
Orb
Hah Bruno now has the Master Class presentations on their site (no idea when added).
I can strongly recommend for most not interested in the maths this presentation as it is better to look at regarding negative feedback as it shows the effect in terms of charts and easier to follow with quick summary conclusions.
Start from Page 8 with summary on page 13 : http://www.hypex.nl/docs/papers/AES123BP.pdf
Opamp negative feedback basic considerations for those interested is from page 26.
Cheers
Orb
I can strongly recommend for most not interested in the maths this presentation as it is better to look at regarding negative feedback as it shows the effect in terms of charts and easier to follow with quick summary conclusions.
Start from Page 8 with summary on page 13 : http://www.hypex.nl/docs/papers/AES123BP.pdf
Opamp negative feedback basic considerations for those interested is from page 26.
Cheers
Orb
Tim,
I warned you in post #200 that it would not be simple ... And considering your aggressive way of referring to the high-end I doubt that you can really find any one wanting to explain it, unless you are just looking for a confirmation that they all sound the same.
Edit: I have just read post #222 - it says it all in the last sentence.
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Orb,
The excellent presentation you suggest is a very good work table for some one knowing electronics, but I doubt that anyone that does not know the basics of transistors and operational amplifiers can get anything from it, specially as it misses the talk! Unless people really understand things such as the basic difference between frequency response and slew rate - and IMHO it is not easy to explain it without considering the amplifier topology - you can not debate the effects of bandwidth. Surely YMMV.
I'm sorry, I should have put an address on that post. I already got an answer on the feedback quesion. On audibility, I know "it's complicated" is your favorite answer, but I often find with high-end audio that the more complicated it is, the less substantial it is. We have many incredibly complex solutions to inaudible problems in this hobby, so I thought it was worth asking...of someone who might actually know, and give me a straight answer. JJ perhaps...
Tim
Yes it is part of an engineering presentation-class I agree but it is easier to follow (I thought so anyway) than that paper with all the maths (takes a long time thinking that one through for me doh), especially if one just focuses on the pages I mention; pages 8 to 13.
That is all required for the debate in this thread IMO as it sort of is digressing as you mention.
Edit:
Could be worse, we could bring in some Walt Jung papers/book publications to follow
Thinking though this, the Nelson Pass paper is probably the best to follow on here if someone is interested (thats you Tim) in negative feedback (may be on his site).
Cheers
Orb
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I'm not an expert.
Feedback is like an EQ tool. The more you use some the more you EQ the sound. ...The less....
Low negative feedback; sounds about right, closer to the aspired truth of none at all. ...I think.
Feedback is like an EQ tool. The more you use some the more you EQ the sound. ...The less....
Low negative feedback; sounds about right, closer to the aspired truth of none at all. ...I think.
Andy thanks for the link, interesting his view on applying small amounts of feedback as this goes against what Bruno suggests (agree he does recommend to use large amounts but makes the case also for as little as possible) and Nelson Pass, but maybe I am looking at the context wrong in the interview.
Thanks again for the link.
Orb
"It's complicated" most often than not translates to "It depends". You'll find that James said just that.
My favorite answer it is not "it's complicated" - this is your interpretation. But yes, most of the time my view is that the subject is complex and needs some basic knowledge to be debated, and oversimplification does not lead to any valid conclusion, although it can fuel endless debates. Some people consider that ignorance is a blessing, sorry I am not one of them.
FETS are very different. Power FET's make it actually harder to get a good crossover between sides of a push-pull amplifier than bipolar transistors, but also offer some speed, and a voltage to current gain vs. a current to current gain for bipolar devices.
The tradeoffs are not simple, and one can go either way.
With Power FET's you're likely to wind up with more low-order distortion. Of course all depends on design, compensation, and circuit topology, and someone can always get it wrong.
Err - no. Just no.
Bear in mind a cathode follower tube amp has enormous negative feedback, it's just local feedback.
Thanks j_j and other commenters for your answers to my innocent questions regarding amps. But I'm still none the wiser! (Because I realise "it depends"). I suppose it prompts the question: why all these different types of amps? After all these years couldn't we have come up with a topology that just 'does the job'? The literature for Quad's current dumping amps seems to make quite a compelling case for their being something like the perfect amp, but outside a small band of enthusiasts they don't seem to have taken the audio world by storm. On the other hand, can we separate the true merits of the amps from pre-conceived notions about Quad, or the fact Peter Walker was despised by the High End fraternity for his straight talking?
Like Tim (I think), I'd like to separate the High End excesses from what is a good workmanlike, scaleable amplifier that does no more and no less than what is required to faithfully reproduce the source. Rather than labelling it "What's Good Enough", I think that such an amplifier would, in fact, be "The Best", but just not "The Fastest", "The Most Expensive" etc.
(I'm also interested in what can be done with Class D and direct digital amps, but happy with class AB, B etc. until they're perfected).
Like Tim (I think), I'd like to separate the High End excesses from what is a good workmanlike, scaleable amplifier that does no more and no less than what is required to faithfully reproduce the source. Rather than labelling it "What's Good Enough", I think that such an amplifier would, in fact, be "The Best", but just not "The Fastest", "The Most Expensive" etc.
(I'm also interested in what can be done with Class D and direct digital amps, but happy with class AB, B etc. until they're perfected).
Thanks j_j and other commenters for your answers to my innocent questions regarding amps. But I'm still none the wiser! (Because I realise "it depends"). I suppose it prompts the question: why all these different types of amps? After all these years couldn't we have come up with a topology that just 'does the job'? The literature for Quad's current dumping amps seems to make quite a compelling case for their being something like the perfect amp, but outside a small band of enthusiasts they don't seem to have taken the audio world by storm. On the other hand, can we separate the true merits of the amps from pre-conceived notions about Quad, or the fact Peter Walker was despised by the High End fraternity for his straight talking?
Like Tim (I think), I'd like to separate the High End excesses from what is a good workmanlike, scaleable amplifier that does no more and no less than what is required to faithfully reproduce the source. Rather than labelling it "What's Good Enough", I think that such an amplifier would, in fact, be "The Best", but just not "The Fastest", "The Most Expensive" etc.
(I'm also interested in what can be done with Class D and direct digital amps, but happy with class AB, B etc. until they're perfected).
If this is the kind of straight talk you're talking about:
...no, I doubt you'll ever be able to have a conversation about Quad that isn't tainted by prejudice.
Tim
Tim,
the counter argument to that then is; why did Quad then bother to engineer-develop the current-dumping amplifier design
After all it should not even needed to be developed going by that quote.
Devialet are the ones who really perfected that design, but without original Quad theory-design I am not sure it would had been done.
Cheers
Orb
the counter argument to that then is; why did Quad then bother to engineer-develop the current-dumping amplifier design
After all it should not even needed to be developed going by that quote.
Devialet are the ones who really perfected that design, but without original Quad theory-design I am not sure it would had been done.
Cheers
Orb
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