[quote author="Samuel Groner"]Do you mind posting a link to the schamtic you are referring to? I don't have the whole net in my mind... :wink:
Anyway, I suggest that you don't match the input transistors. For almost all audio applications 1 mV offset is not required, and trimming offset current is pointless because we don't have equal DC resistances at both terminals.
Matching does not influence the sound of an opamp, just it's DC precision.
Get a free sunday morning instead.
Samuel[/quote]
Hmm, would life indeed be
that easy ? The DC-specs are indeed less interesting for audio, but I've always lived in the assumption that a mismatched input-pair would in principle give a different distortion-signature.
and trimming offset current is pointless because we don't have equal DC resistances at both terminals.
Could be made to, but indeed it can't always be done. But then it's handy to have high beta devices for the diffpair. And also for noise.
Can't imagine the various 'DOA's' use that expensive LM394 only for fun.
Get a free sunday morning instead.
Fully agreed, we shouldn't overdo things. Maybe we could spend the time saved on what started it all, misic :wink: But I feel
some selection for the discretes for the DOA-input-pair would still be required. (Although I haven't compared a 'selected' versus a 'just throw it in'-version)
Note this is not meant as criticism, but I'm joining the discussion for a better understanding of the topic of how relevant those matching efforts are.
Bye,
Peter