5v333
Well-known member
hi!
im back with my makeup/output pushpull amp for my NYDeq now that summers live gigs are over and i have repaired my tektronix tm503 mainframe unit containing my funktion generator and freq counter.
ive been re drawn the amps stages many times from doing versions of the loadlines and calculating the 2nd and 3d harmonic distortions on paper.
almost everytime ive seem to come up with improvments, sometimes just a fraktion sometimes x2 or x4 lower harmonics.
figures on paper and real life figures might not be the same i guess but the only distortion analyser ive got for the moment is my ears so getting good stuff on paper first seems like a good goose to follow.
initialy doing 2-4 different graphs get me in the ballpark, then 2-5 versions more will finetune the amp to very low figures.
however, what is low here?
for now i have, on paper, a transformer coupled pushpull line output stage with about Hd2 = 2.5% and Hd3 0.13% (even harmonics cancels out)
and a symetric 12ay7 pre stage with Hd2 -0.68% and Hd3 -0.45%.
theres also a couple db global feedback here.
so what is to much, tolerable, good and really good?
im back with my makeup/output pushpull amp for my NYDeq now that summers live gigs are over and i have repaired my tektronix tm503 mainframe unit containing my funktion generator and freq counter.
ive been re drawn the amps stages many times from doing versions of the loadlines and calculating the 2nd and 3d harmonic distortions on paper.
almost everytime ive seem to come up with improvments, sometimes just a fraktion sometimes x2 or x4 lower harmonics.
figures on paper and real life figures might not be the same i guess but the only distortion analyser ive got for the moment is my ears so getting good stuff on paper first seems like a good goose to follow.
initialy doing 2-4 different graphs get me in the ballpark, then 2-5 versions more will finetune the amp to very low figures.
however, what is low here?
for now i have, on paper, a transformer coupled pushpull line output stage with about Hd2 = 2.5% and Hd3 0.13% (even harmonics cancels out)
and a symetric 12ay7 pre stage with Hd2 -0.68% and Hd3 -0.45%.
theres also a couple db global feedback here.
so what is to much, tolerable, good and really good?