tl;dr: Have I missed any methods to to address bias current indeterminacy in Push-Pull VAS/Transimp. Stage using Current Mirrors? Has anyone actually built/tested these or any other methods and been successful?
Hello,
I’ve spent the weekend going through all the DIYA threads on the Topic Title. I have read Mr. Cordell and Mr. Self’s (6th Ed.) writings on the title topic in their excellent books and have read Mr. Groner’s writings (both his comments on Mr. Self’s book and his great paper on an improved Transimpedance Stage) as well.
I’m pulling together some blind A/B listening tests of a collection of mass produceable Class A headphone amplifiers circuits. For one variant in the collection, I would very much like to include a Push-Pull IPS and VAS/Transimpedance Stage. (I should note here that I recognize this may be considered by some as unnecessary and overkill, but nonetheless I would like to hear the difference in blind listening tests to prove it. Please be gracious with me.)
I understand there are these techniques to address the aforementioned indeterminate quiescent current in the 2nd stage:
1. Groner’s Bias Servo featured in his Comments on Self’s book.
2. Groner’s new transimpedance stage (as appearing in Mr. Jan Didden’s publication and later on EDN.)
3. Cordell’s “Helper Transistor” method featured in his book
So, with all of that said, here are my questions:
1. Have I missed any options/methods to address this issue?
2. Is anyone aware of examples of any of these options (or others) being used in end-products (headphone amps or otherwise)?
3. Even if not mass-produced, has anyone built up any of the above mentioned options and found them to be suitable and stable? Could you share your experience?
Once finished, I’ll happily post my approach/results for community critique.
-Warmest Regards
Hello,
I’ve spent the weekend going through all the DIYA threads on the Topic Title. I have read Mr. Cordell and Mr. Self’s (6th Ed.) writings on the title topic in their excellent books and have read Mr. Groner’s writings (both his comments on Mr. Self’s book and his great paper on an improved Transimpedance Stage) as well.
I’m pulling together some blind A/B listening tests of a collection of mass produceable Class A headphone amplifiers circuits. For one variant in the collection, I would very much like to include a Push-Pull IPS and VAS/Transimpedance Stage. (I should note here that I recognize this may be considered by some as unnecessary and overkill, but nonetheless I would like to hear the difference in blind listening tests to prove it. Please be gracious with me.)
I understand there are these techniques to address the aforementioned indeterminate quiescent current in the 2nd stage:
1. Groner’s Bias Servo featured in his Comments on Self’s book.
2. Groner’s new transimpedance stage (as appearing in Mr. Jan Didden’s publication and later on EDN.)
3. Cordell’s “Helper Transistor” method featured in his book
So, with all of that said, here are my questions:
1. Have I missed any options/methods to address this issue?
2. Is anyone aware of examples of any of these options (or others) being used in end-products (headphone amps or otherwise)?
3. Even if not mass-produced, has anyone built up any of the above mentioned options and found them to be suitable and stable? Could you share your experience?
Once finished, I’ll happily post my approach/results for community critique.
-Warmest Regards
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