Look forward to your results - Lynn Olson - Tube DIY Asylum

Tube DIY Asylum

Do It Yourself (DIY) paradise for tube and SET project builders.

Look forward to your results

In Reply to: WinAudioMLS? posted by twystd on October 13, 2006 at 14:28:05:

John Atwood (over on the ClariSonus blog) has done some preliminary research, and found a mild degree of load sensitivity for the Harmonic Equalizer (or Harmonic Balancer) circuit - there's also some tuning required for the distortion profile of the tube. The tuning wasn't very critical, though - the lowest distortion tubes (DHT's) were at one end of the adjustment, and triode-connected pentodes and IDHT's were towards the middle.
The circuit does strongly reduce not only 3rd-harmonic, but all odd harmonics, out to the 9th and greater. Interestingly, in an obscure publication in the 1935 American Projectionist magazine, Bell Labs/WE mentions that feedback is most suitable for high-distortion amplifiers - referring to their own 91A SET amplifier, which does use feedback - but the Harmonic Equalizer was reserved for lower-distortion amplifiers, such as their 86 and 92 amplifiers. This is the opposite of the conventional wisdom we have today of non-feedback SET's and feedback PP amplifiers.
John and Mark Kelly came up with an interesting model, equating the balanced amplifier to a balanced modulator, with the WE circuit controlling the common-mode return current between plate and cathode. John also found the relevant patent: 1,970,325, filed by by John G. Kreer, assigned to Bell Labs, and granted in August 14, 1934.
If I wasn't working on getting ready for the RMAF, I'd have posted this already on the blog.

ClariSonus Blog (Open in New Window)

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Follow Ups Full Thread

Topic - WinAudioMLS? - twystd 14:28:05 10/13/06 (5)

Look forward to your results - Lynn Olson 19:16:02 10/15/06 (4)

BTW, nice blog, but I don't seem to be able to find the John Atwood WEHE info. (nt) - twystd 15:06:21 10/16/06 (0)

Thanks Lynn! (long) - twystd 14:55:32 10/16/06 (2)

I would avoid CCS on the cathodes - Lynn Olson 17:05:36 10/16/06 (1)

Thanks again Lynn, looking forward to Clarisonus blog info when you guys get time. Have fun at RMAF (nt) - twystd 17:52:34 10/16/06 (0)

Follow Ups

Look forward to your results - Lynn Olson 19:16:02 10/15/06 (4)

BTW, nice blog, but I don't seem to be able to find the John Atwood WEHE info. (nt) - twystd 15:06:21 10/16/06 (0)

Thanks Lynn! (long) - twystd 14:55:32 10/16/06 (2)

I would avoid CCS on the cathodes - Lynn Olson 17:05:36 10/16/06 (1)

Thanks again Lynn, looking forward to Clarisonus blog info when you guys get time. Have fun at RMAF (nt) - twystd 17:52:34 10/16/06 (0)

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