No global negative feedback

Stereo Mic said:
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.
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You know perfectly well that no such test exists.

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?
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I fail to follow you.
 
SM,

Well you know the saying : Never argue with an idiot, they simply drag you down to their level and beat you with experience :D

Stereo Mic said:
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..
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Markus Sauer said:
You know perfectly well that no such test exists.
.
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Then how can we say that NFB has a negative impact on perceived sound quality Markus?

On the other point I was merely highlighting that in this case Antonio seems happy to utilise graphs to demonstrate a measurable impact whereas he is loathe to accept same said forms of measurement when they show no change whatsoever (ie. cables, supports, CD players wtc).
 
Stereo Mic said:
On the other point I was merely highlighting that in this case Antonio seems happy to utilise graphs to demonstrate a measurable impact whereas he is loathe to accept same said forms of measurement when they show no change whatsoever (ie. cables, supports, CD players wtc).
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When did I say that... :confused:
 
I'm buying an amp tomorrow with lashings of NFB. In fact it has so much NFB that I'm surprised it doesn't play backwards ;)

I'll let you all know just how nasty and distorted it sounds asap.
 
Markus Sauer said:
My guess - a chip amp or some Deltecs.
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Heard a superb Deltec pre/power driving H2s at Martin Clark's a few weeks ago. Could happily live with those but I lack Martin's ability or inclination to repair them when they explode, as it seems many do :)
Also, too many boxes.

Novel use of feedback though so very much on subject.
 
Markus Sauer said:
Ah. Cambridge.
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Spot on Markus.

840A:

303307-1.jpg
 
Hi,

melorib said:
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... :confused:
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Yes, remove the Sucker. Also, you can try other input valves with less gain, for example the 12AU7 (ECC81) would likely work okay and would lower the gain.

Another thing to try, you can replace C2/4/5 with Mundorf M-Cap Zn or Audyn KP-SN (both are tinfoil types). And re-try triode mode for the output stage.

Ciao T
 
3DSonics said:
Hi,

Yes, remove the Sucker. Also, you can try other input valves with less gain, for example the 12AU7 (ECC81) would likely work okay and would lower the gain.

Another thing to try, you can replace C2/4/5 with Mundorf M-Cap Zn or Audyn KP-SN (both are tinfoil types). And re-try triode mode for the output stage.

Ciao T
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Thanks Thorsten,

To remove the sucker I have to remove the PCB, quite dangerous, because of whatever connections underneath, C3 I had to cut... :rolleyes:

What is the problem with higher gain, I already use SIEMENS E81CC triple mica... :confused:

C2/4/5 are WIMAs, I know they are nothing special, but they are not too bad either, so I am told...

I have been using it in triode mode since I tried it again, after removing NFB, as I said then, now it improves the sound without softening bass, particularly significant more body...

Already took many risks, I will wait for a good audio engineer to visit Riga and do those more "complicated" changes, arent you coming to Riga, nice place... ;)
 
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