I don't see NP critising feedback particularly, just stating his philosophy. All commercial amplifier designers have a philosophy.
And you said violin sounded scratchy live, which is doesn't when played properly.
I have plenty of sax recordings that sound like a live sax and plenty of vocal recordings that sound like a person singing, and go to enough concerts to keep some form of reference. With multitrack pop music all bets are of course off as to fidelity to source, as the raw source is not what they wanted to provide.
I have plenty of sax recordings that sound like a live sax and plenty of vocal recordings that sound like a person singing, and go to enough concerts to keep some form of reference. With multitrack pop music all bets are of course off as to fidelity to source, as the raw source is not what they wanted to provide.
My comment wasn't aimed at Mr. Pass but rather at those who parrot the evils of feedback by citing the poor sound of the high feedback, low distortion amps of the 80's.
Wrong, You heard sax and singing raw without mic. I repeatedly said without going though mic, read the post. I listened to Paul Something that played Love is Blue in the late 60s in concert, even their violin was scratchy.
Do you play music? I did, for 10+ years, performing in concerts, I first hand playing with people that played violin and sax.
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Things are way difficult for me to understand. But can anyone in simple language explain if negative feedback increases higher order harmonic distortion, can anything be done about it ? If we have wide band amplifier can they be pushed even higher out of audible range ? I presume at lower sound levels it would not be that much a problem. A Single ended amp with high sensitivity speaker would be one good option, isn't it ? I also presume with band limited sub-woofer the moderate amount of feed back will not be a problem as we already cut off mid and high frequency range.
Thanks and regards.
Thanks and regards.
As we are not able to even measure wire in a meaningful way, what are the chances we could measure something with lots of wires plus other, even stranger stuff?
Mike, maybe we are not moving because we are already there?
Observe: one guy swears by a coloring SET amp, another mortgages his house for a vintage super duper very high NFB Krell; yet another doesn't want anything else than a 12W class A.
And ALL strongly maintain that THEIR amp is the very best ever made, and if you disagree it is because you are deaf and/or never listen to music.
So, if I am an aspiring audio amp designer, where do you want me to move to??
(I know where I want to go; just interested in your view on it).
Jan
Your point of view seems overly cynical to me, Jan. Surely a good-sounding amplifier will sell itself to come extent - it can't all be down to marketing and reviewer's moods etc. Especially these days when only real enthusiasts spend money on good audio gear. Yes there is always taste to account for, but if you were an aspiring amp designer, wouldn't you just try and create a design that sounds good to you and then give it to some experienced listeners to compare it with other designs and go from there? You'd soon figure out your niche.
Why can't we (well those of us willing to listen anyway) discuss what effect using more or less or no global feedback has on the overall sound of an amplifier, or compare using more local feedback vs more global etc? In my limited experience with "blameless" type Lin topology amps, I much preferred the sound when I increased the local feedback by heavier input pair degeneration, thereby reducing global feedback, for example.
Why can't we (well those of us willing to listen anyway) discuss what effect using more or less or no global feedback has on the overall sound of an amplifier, or compare using more local feedback vs more global etc? In my limited experience with "blameless" type Lin topology amps, I much preferred the sound when I increased the local feedback by heavier input pair degeneration, thereby reducing global feedback, for example.
OK, what you said was
Which I interpret as 'violins sound scratchy live'. I go to concerts and they don't. I learned music as a kid, but no aptitude, although still have a piano in the house for my kids to learn on.
I am still confused as to the point, but best possibly let it drop as this sounds like one of those 6 pint converstations to get to a consensus.
Cynical? No, not at all. But I hate turning around in circles and getting nowhere for my efforts. I can understand that you are somewhat disappointed, but am I wrong when I say:
"Observe: one guy swears by a coloring SET amp, another mortgages his house for a vintage super duper very high NFB Krell; yet another doesn't want anything else than a 12W class A. And ALL strongly maintain that THEIR amp is the very best ever made, and if you disagree it is because you are deaf and/or never listen to music."
That's a fact. You yourself illustrate it by saying hat for YOU the blameless with increased local and less global feedback 'sounds best'. I can easily find people with opposing views on what amplifier sounds best to them.
Why should I feel obliged to fool myself?
Jan
Could it be that any criticisms of global feedback comes back to the error circuit; the extraction of the error is fraught with non-linearities, and so the feedback cannot be exploited correctly........
The transfer function of a long tail pair is S shaped, like a BL magnetic curve.
The transfer function of a long tail pair is S shaped, like a BL magnetic curve.
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Jan: you shouldn't feel obliged. You're not wrong, but why is it a problem? I thought we were here to discuss what we think sounds best, so what's wrong with having an opinion on that and discussing it like adults? This is a DIY forum isn't it? Aren't we all here 'cause we enjoy building stuff and listening to it? What's the point if we aren't allowed to have our own opinions about what sounds best? I've never claimed my opinion is the only correct one or anyone else's is wrong.
If this is a purely technical argument as to whether global feedback improves conventional measured performance there is nothing much to discuss surely?
If this is a purely technical argument as to whether global feedback improves conventional measured performance there is nothing much to discuss surely?
If THD is so useless, why do the true believers keep mentioning it? Would it not be better to just ignore it and wait for the 'engineers' to mention it? The snag with this is that the 'engineers' only mention THD on those occasions when it says something useful, so the believers would be left with little to criticise. You seem to be erecting a false dichotomy between 'THD' or 'subjective'; are they the only two choices we have?AKSA said:
Competent 'engineers' have known this for some decades. Nice to see others now beginning to catch up.
But that is one of the few types of music where a genuine acoustic performance is available, so that 'hi-fi' has some real meaning and this discussion has any purpose. Small ensemble folk or (unmiked) solo singers are perhaps other examples. Rock/pop etc. never really existed as a sound so there is nothing to reproduce, except what the producer heard in the control room - so perhaps we should strive to replicate whatever characteristics (good or bad) the studio system had?Alan0354 said:
My post was a reaction to a post saying: I see why we don't move, it's only numbers' or something like that.
Jan
Yes. I want to add that with an open loop gain of say 80 dB, the differential input voltage for the LTP is 0.1mV per V output. Even at 100W/8ohms the Vin between the + and - LTP input is only 2.8mV RMS. That is smack in the middle of the most linear part of the S-shape.
an
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