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Old 20th January 2012, 11:26 PM   #1191
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Quote:
Originally Posted by ThorstenL View Post
John,


For example something like an AD815 has many features that would seem to recommend it for audio use, yet it's input current modulation limits our use, especially with Pots like the Alps conductive plastic ones, which have a quite strong non-linearity in the wiper/track interface (basically terminate them into as high an impedance as possible), as do carbon types.

Ciao T
To be fair that was not the intended application. Walt Jung's AD823/AD815 line amp has been well liked by many folks, Walt personally demoed me his prototype and it sounded fine to me but I can't get past how different people's preference in speakers just overwhelms the whole listening comparison experience.
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Old 20th January 2012, 11:40 PM   #1192
wahab is offline wahab  Algeria
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Indeed , the 0.01% to 0.00001% of THD due to amps or other
op amps seems for some people to have much more audibility than the
sometimes double digits of THD produced by the sum of two extremities of a chain
comprising a turntable on one side and the speakers on the other one....
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Old 20th January 2012, 11:57 PM   #1193
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Indeed, , the 0.01% to 0.00001% of THD does not matter. But 0.01% of 2'nd only error vs 0.01% of the wide spectrum feels like one 100 KG speed bump VS 100 KG of nails on the same road for car tires.
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Old 21st January 2012, 12:00 AM   #1194
tvrgeek is offline tvrgeek  United States
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Originally Posted by john curl View Post
Unfortunately, to make WORLD CLASS audio components, we have to provide expensive cases, as well as good electronics. That seriously raises the cost of production. If we do not, we lose at least 1/2 our market. Japan won't touch it, for example.
So a Levinson 27 would be dead meat! Guess Acrus would not have gone over very well. What a world we live in. I am waiting for the nostalgia stage; like the old Marantz of the 70's. Spinning that big heavy dial made you think you had something. Or Bakelite in tan or pink. Yea, that's the ticket. Art nuvo amps.
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Old 21st January 2012, 12:13 AM   #1195
a.wayne is offline a.wayne  United States
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Levinson stuff sells very well in asia, well in the past , not sure about now.....
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Old 21st January 2012, 12:40 AM   #1197
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Good article. It is what I was doing in my last Tower amps, bootstrapping output source followers. However, power consumption such a way is enormous, but it sounds very nice.
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Old 21st January 2012, 01:34 AM   #1198
jcx is offline jcx  United States
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in Dimitri's circuit the input op amp supplies are bootstrapped to give a composite op amp follower with ultra low distortion - tested with 1 MegOhm input series R, 5 Vrms, > 20 dB attenutation of 5th, 7th harmonics "input nonlinearity distortion"

Last edited by jcx; 21st January 2012 at 01:45 AM.
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Old 21st January 2012, 02:34 AM   #1199
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Default Sfdr

Quote:
Originally Posted by Wavebourn View Post
Indeed, , the 0.01% to 0.00001% of THD does not matter. But 0.01% of 2'nd only error vs 0.01% of the wide spectrum feels like one 100 KG speed bump VS 100 KG of nails on the same road for car tires.
Interesting point .01 % is a spur free dynamic range of only 40 dB; that is well above the noise floor and missing higher order harmonics. Can you actually hear a 40dB 2nd harmonic? I know I found ~.6 % clearly audible from 500 hz to 4khz.

FYI I have a designed and fabricated ~130dB SFDR splayed directional couplers for 40Gb optical transmission The triangle waves are quite precise (hopefully see attached) Bet the curvature in the triangle wave response would be clearly visible
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File Type: jpg 130SFDR.jpg (112.8 KB, 127 views)
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Old 21st January 2012, 02:40 AM   #1200
SY is offline SY  United States
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Quote:
Originally Posted by vanderpol4 View Post
Interesting point .01 % is a spur free dynamic range of only 40 dB
Really? I would have thought 80dB. Could you explain to a dummy how you got that number?
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