When optimizing, go for Lowest 3rd harmonics .. not THD!! - Page 2 - diyAudio
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Old 13th December 2008, 11:06 AM   #11
roender is offline roender  Romania
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Quote:
Originally posted by AndrewT

Curl talks about eliminating the seventh...
There is only one way which could bring down the 7th, and this is the hard way ... dumping as much as possible bias current into the output stage, many transistors correctly biased in class B as per Douglas Self definition.
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Old 13th December 2008, 11:09 AM   #12
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Quote:
Originally posted by AndrewT
I like the idea being promoted by Lineup.
I wonder if there is a cheap way to actually perform the adjustment of minimising the third and the other odd harmonics?
Curl talks about eliminating the seventh. Could this be along similar lines?
Hi Andrew,

It is difficult to generate only certain orders of harmonics but I have found that one can push the even order harmonics to be higher than odd orders by a tiny little "feed-forward" from output to LPT emitter, values in the Mega Ohm should be used.
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Old 13th December 2008, 11:11 AM   #13
Mooly is offline Mooly  United Kingdom
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The problem with all of this is that it is subjective.
I am the first to accept that the perfect amp is the " the piece of wire with gain ". The problem comes when you have achieved that or at least come very close as some designs do, and you find that sonically/musically, call it what you will, you find that you are still not happy. You can not get into the music, it may be good "HiFi" but does it recreate that believable image, does it encourage you to explore the music -- to take up playing an instrument even ?
Designing the perfect power amp or whatever is more to do with instrumentation IMO. It appears to have no correlation to how well it reproduces music.
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Old 13th December 2008, 11:17 AM   #14
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Andrew,

I first saw John do this in patch work and only after modifying it a little I noticed this. I am not sure if John did this intentionally or whether it was a sort of bootstrap.

It does not lower other harmonics it but increases H2 by whatever amount you want.

Nico
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Old 13th December 2008, 11:26 AM   #15
Bonsai is offline Bonsai  Taiwan
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quote
"The problem with all of this is that it is subjective. "

so what?

there is no agreement on this forum and there never will be (excellent!)

do/buy/listen to what you think is best.

I think Nico is right on the button with his comments on this issue.
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Old 13th December 2008, 11:34 AM   #16
Mooly is offline Mooly  United Kingdom
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Hi Nico and Bonsai & Homemodder
I agree with a lot of what you say.
Homemodder, you say don't get tricked by the mind, compare to a real instrument played live in the same room !

Maybe like this
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Old 13th December 2008, 11:36 AM   #17
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Compare to a good old record player or a reel to reel recorder, and come to speak to me again. BTW the reel to reel the one Ive tested together with a family member and was used in studios and produced the well known album of yello, produced mostly H3 distortion. Digital sources have become much better as time has passed especially the high end ones, if one looks why youll see the use of tubes or discretes with the sound of tubes, again looking for H2 to disguise some shortcomings. We now have a more serious problem affecting cd, record producers are damaging the sound with their quest for sound levels. My 1991 bought CD of Dire Straits sounds 10x better than a recent copy I bought. The sound quality as we getting from DVD, now we getting somewhere close to vynhul. Wait till the producers lay their hands on these too and we back to square one.
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Old 13th December 2008, 11:38 AM   #18
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Quote:
Originally posted by Mooly
Hi Nico and Bonsai & Homemodder
I agree with a lot of what you say.
Homemodder, you say don't get tricked by the mind, compare to a real instrument played live in the same room !

Maybe like this
And the conclusion:

real instruments sound rubbish, hi-fi is much better!
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Old 13th December 2008, 11:40 AM   #19
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Yep, this thats the right way to evaluate a amp, I get my sister to play the violin and sax, while my brother in law is a pretty handy with drums and electric guitar.
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Old 13th December 2008, 11:40 AM   #20
Mooly is offline Mooly  United Kingdom
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Hi Nico,
Keep taking the tablets
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