John Curl's Blowtorch preamplifier part III

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Why do you think that discrete part is not doing much? It provide FB of 40dB up to 20kHz.

I meant in terms of current supplied and thermal issues an often used reason for going discrete. The circuit is fine the base current recapture in the mirror offers a tangible benefit (it has been used in IC's for several decades). I'm just saying this function discrete vs. integrated has little difference.
 
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Maybe that could be the “loudness switch” of the future; to have the option toggling between a balanced harmonics type of sound and a technically accurate sound.
Someone probably already has it.

Bob Katz already does. His effects box "Blender" was discussed in this forum 10 months ago: May 2018. After publication on the website InnerFidelity.
 
There is no H2 H3 blend. It just happens when you control the amount of GLOBAL NEGATIVE FEEDBACK that most amps will give some H2 and some H3 as a residual. First: H3 is the MINIMUM that you can have, IF you have any minimum distortion in most designs. H2 is just what you get because complementary devices are not really perfectly matched, even with a Class A output.
 
There is no H2 H3 blend. It just happens when you control the amount of GLOBAL NEGATIVE FEEDBACK that most amps will give some H2 and some H3 as a residual.

First: H3 is the MINIMUM that you can have, IF you have any minimum distortion in most designs.

H2 is just what you get because complementary devices are not really perfectly matched, even with a Class A output.


In any case, there can be NO H2 H3 ratio except at one output level. It will ALWAYS change with different amplitude.

This is because H2 follows a linear increase law, and H3 follows a square law in their relative increase with level.
Hi John.

What levels and ratios of H2/H3 do you find are good enough/useful ?.
Do you design for subjectively optimal/acceptable H2/H3 ratio at particular operating levels away from max power rating ?.
What is your take on the subjective 'damage' or 'excitement' caused by each of H2 and H3 nonlinearities.



Dan.
 
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What is the best way to make an VFA ic opamp have OLG reduced? THx-RNMarsh

If you're looking to reduce OLG by tinkering with external components only, Sergio Franco's book (link to inexpensive paperback edition) presents an excellent circuit approach, in Figure 8.24 (p.375) of the Third Edition. To find it in other editions, go to the chapter on "Stability" (ch.8) and find the section on "External Frequency Compensation" (sec. 8.4). There it is.

BTW I doubt that this is truly "the best" way. I'm sure there are company proprietary trade secrets that cannot be mentioned here, which are even more bester.
 
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