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Old 1st April 2007, 03:29 AM   #1
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Default Published/DIY ultra-low THD designs?

I know that THD doesn't carry much weight in this forum, and those designs which feature low THD using large NFB and such are not too popular, however if you would be kind as to point such designs out and save me some tedious searching, that would be appreciated.
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Old 1st April 2007, 03:35 AM   #2
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Default Re: Published/DIY ultra-low THD designs?

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Originally posted by leadbelly
I know that THD doesn't carry much weight in this forum, and those designs which feature low THD using large NFB and such are not too popular, however if you would be kind as to point such designs out and save me some tedious searching, that would be appreciated.
Try Googling for the Williamson amp. That was a high gNFB, low THD design.
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Old 1st April 2007, 06:38 PM   #3
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Default Re: Re: Published/DIY ultra-low THD designs?

Thanks.

Any SE designs?
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Old 1st April 2007, 07:52 PM   #4
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Default Re: Re: Re: Published/DIY ultra-low THD designs?

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Originally posted by leadbelly
Thanks.

Any SE designs?
Higher THD, terrible transciens?
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Old 1st April 2007, 08:16 PM   #5
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Default Re: Published/DIY ultra-low THD designs?

Quote:
Originally posted by leadbelly
I know that THD doesn't carry much weight in this forum, and those designs which feature low THD using large NFB and such are not too popular, however if you would be kind as to point such designs out and save me some tedious searching, that would be appreciated.


Bob Cordell's desing is both - www.cordellaudio.com , http://www.cordellaudio.com/papers/MOSFET_Power_Amp.pdf .


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Old 1st April 2007, 08:29 PM   #6
Jeb-D. is offline Jeb-D.  United States
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If you want low THD in a Single Ended amp, screw the feedback loops and go cathode follower. It's a more natural form of feedback, opposed to loops which arn't quite phase correct. Especially in transformer coupled amplifiers.

Just my .02, as I'm sure some will disagree.
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Old 1st April 2007, 10:03 PM   #7
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Quote:
Originally posted by Jeb-D.
If you want low THD in a Single Ended amp, screw the feedback loops and go cathode follower. It's a more natural form of feedback, opposed to loops which arn't quite phase correct. Especially in transformer coupled amplifiers.

Just my .02, as I'm sure some will disagree.
I agree.
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Old 1st April 2007, 10:30 PM   #8
phn is offline phn  Sweden
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What do you mean by low THD?

Ken Shindo promises the following for his 300B SET:

Total Harmonic Distortion: 0.1%.
Signal to Noise Ratio: 110dB.
Intermodulation Distortion: 0.09%

But the question makes little sense.

All of the old Leak amps have a THD of around 0.1 pct. Everybody who has heard them say the TL/12 and TL/25A are the best-sounding Leak amps. Anyone can make a poor sounding amp, be it tubes or whatever.

And there's no tube amp without NFB. A triode has internal NFB, which is the reason it operates different from pentodes and all other components.

Edit: Fixed weird characters thanks to ultra slow, instable, bug infested piece of junk IE7.
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Old 1st April 2007, 10:48 PM   #9
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Quote:
Originally posted by phn
ultra slow, instable, bug infested piece of junk IE7.
use firefox.
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Old 1st April 2007, 10:52 PM   #10
phn is offline phn  Sweden
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Quote:
Originally posted by sorenj07

use firefox.
And lose the privilege of bitching and moaning? Where's the fun in that?
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