No global negative feedback

http://www.nutshellhifi.com/library/FindingCG.html

 

?

Do people really buy an amplifier because of it's specs?

 

Another excert from the above link:

Stereo Mic, maybe you can understand this...

 

will you two guys stop bickering?!

 

Cables dont work, but...

 

No need to admit it Antonio. Just keep posting.

I fully understand your posts and those of Thorsten. What I have asked for is a real world example of an amplifier that displays audible levels of higher harmonic distortion because of it's NFB loop.

Sadly despite all of the theorising and bluster, I'm still waiting.

Good to see you posting scientific findings though. Next you'll be convinced all CD players sound the same and cables only vary in their LCR charateristics

 

You want to bet, before that you will start listening to equipment, besides reading the specs...

 

Antonio, can you think of a product that displays the problems I have asked about? Genuinely rather than just having a childish tit for tat. The question remains as to whether there are audible panalties for employing NFB. Until I see otherwise, I will assume there isn't.

For your reference, I measure and listen as most do. That way I can understand why my system sounds good/bad and can make a mental note of what works. I find that rather more educational that simply blindly swopping or worse cables.

 

I did my education in different areas, this is only an hobby, but it doesnt take a genius to sujjest you to listen to your only amplifier with 12db feedback than with 3db, if you cannot disconnect it completely, then you will know the difference more or less feedback does... :bookworm:

I dont go around testing amplifiers, particularly since I am in Riga, so I cannot give you any examples, except for mine and Thorsten's, as he mentioned already... :SLEEP:

 

I've spent 6 pages trying ever so hard to explain that the only audible consequence of what you did would have been the increase in the amplifier's output impedence and the consequential frequency non linearities when driving your loudspeakers. I've also hypothesised that the critical damping of the bass unit could well be affected too.

And after all that effort you still write:

It's disappointing and glaring proof that some only read what they want to read.

 

Yet, never occurred to you that your explanations might be wrong, and Thorsten's + the other links posted might be right...

It's disappointing and glaring proof that some only read what they want to read.

 

Now I see what Ian meant!

Antonio. Of course I could be wrong. That's why I've repeatedly asked for someone to show me an example of a current amp with audible high order HD caused by the NFB.

I can happily show the effects of a high output impedence on FR so I know my position is secure. I am waiting for you or someone else to provide proof that your claims are also true. In the absence of that, I can only assume you are merely hypothesising.

 

Who is Ian ???

 

A friend.

Now shall we put this on hold until someone can give me an example as requested? There's not really much of interest until we see that..

 

More cientific data to help iluminate you:

http://www.melorib.com/data/cheever_thesis.pdf

 

Ah, so this is the source you are using

http://w3.mit.edu/cheever/www/main.htm

 

It does not follow that you'll increase the drive unit's non linearities (i.e., in certain cases you may tame them -- as in an over-damped driver...)

And you seem capable of seeing that:

I assume this can also lead you to determine an "optimum" range of damping for any particular drive unit?

Audible or not, there may be serious penalties if you don't use some f/back loop on a transistor amp. Otherwise, your assumption is, I imagine, perfectly fine in the context of this thread -- the original subject of which was about a small but satisfactory modification melorib performed on his amp Cheers

 

I was sent the pdf by a friend, didnt know about the page, thanks...

 

Not that illuminating I'm afraid Antonio. Cheever is, like Geddes, trying to put forward an alternative metric that has yet to be universally accepted.

I'm looking for a test where the feedback circuit was removed from an amplifier and higher order harmonics were reduced whilst there was objective agreement that there was a sonic improvement. All whilst keeping the output impedence constant.

That's the kind of evidence that will make me sit up and take notice. It would be worth bearing in mind though Antonio that the same kind of documents as you present, are often used to show that all CD players sound the same and that there is no magic in cables (although the latter does tend ot be based on accepted thinking rather than pure hypothesis). Accept one and you must surely accept the other?

 

Maybe without feedback cables stop making noticeable difference, hmmm...

Now back to topic...

So far I removed what is in the red boxes, selector, volume and NFB...

My friend wants me to also remove the "input capacitor" C1, he says the gain will go back to close to the original value, and increase input and output impedance, besides eliminating a "poor quality" electrolitic CAP...

What do you guys think, is it safe, can it improve my amplifier...