John Curl's Blowtorch preamplifier

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Scott, you haven't addressed my ORIGINAL question. Do you hold to 0.1uF as the optimum single bypass capacitor for your AD797?

Secondly, I attempt to design the RIAA as accurately as I can. I use 1% caps and then segregate them into groups, by actual measurement, if I have enough, and use 0.5% Holco resistors with them. I calibrate it with the Jung-Lipshitz inverse RIAA network, once offered by 'The Audio Amateur'. I am normally within 0.1dB and I am very proud of it.
I do not know who this hi end dealer is, but this person has nothing to do with me and knows nothing about my design. I resent your assertion that I would DELIBERATELY modify my designs away from the ideal frequency response.
 
syn08 said:


As I have said before: in this view, a low pass filter has distortions. Which, to me, doesn't make any sense.


It isn't that important. It's just a definition. Some people got together and said: if the amp has a non-flat freq response, let's call that linear distortion. All agreed, and that was that. As long as we all understand that, what's the problem?

Jan Didden.
 
john curl said:
Scott, you haven't addressed my ORIGINAL question. Do you hold to 0.1uF as the optimum single bypass capacitor for your AD797?

Secondly, I attempt to design the RIAA as accurately as I can. I use 1% caps and then segregate them into groups, by actual measurement, if I have enough, and use 0.5% Holco resistors with them. I calibrate it with the Jung-Lipshitz inverse RIAA network, once offered by 'The Audio Amateur'. I am normally within 0.1dB and I am very proud of it.
I do not know who this hi end dealer is, but this person has nothing to do with me and knows nothing about my design. I resent your assertion that I would DELIBERATELY modify my designs away from the ideal frequency response.


It depends, we have discussed it and have reached no conclusion. If we put 1000uF||1uF||.1uF on the data sheet what do you think the customers would say?

I was only repeating what someone said to me, I thought you already explained that you had a mistake in a very early Levinson preamp that was corrected.
 
Scott, that was 35 years ago, BEFORE we had an accurate measurement equalizer for RIAA. That was copied from Dick Burwen's RIAA network for the LMP-2 phono stage, which I presumed was accurate, because Dick Burwen is usually very accurate. I found out later, to my dismay, that it was slightly inaccurate, and I fixed it with a Levinson JC-2 upgrade. It was a matter of engineering pride, NOT sonic improvement, for all intents and purposes.
 
I prefer to use some tone controls...

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