well, a few months later and i'm back on the crusade to make my Steiner work.
situation: the filter works, but it has kinda low output level and
it's noisy. turning up the resonance makes the signal *quieter* until
it's completely silent at max. CV control of cutoff works fine in all
3 modes.
i have a working original rev Steiner here for reference and i put
the scope on both of them to try and track this down. i'm seeing that
the LP signal on the broken one is noticeably fuzzier after the first
cap in the chain (the 1uf). by the time the signal gets to the 2907
it's way fuzzier.
given that the 2907 tranny is involved in the main out, the feedback
path, and connects to the LP input (my understanding of this circuit
is limited!) i reckoned that swapping that out couldn't hurt, but it
made no difference. swapping out the 2222 before it made no
difference either. also swapped out the TL071 with no effect.
i was concerned that the to-92 trannies i have had different pinouts
than the metal cans, but i verified this -- and most likely CV
control etc wouldn't work without those being sorted.
not much to go wrong here, i'm scratching my head. any ideas appreciated!
situation: the filter works, but it has kinda low output level and
it's noisy. turning up the resonance makes the signal *quieter* until
it's completely silent at max. CV control of cutoff works fine in all
3 modes.
i have a working original rev Steiner here for reference and i put
the scope on both of them to try and track this down. i'm seeing that
the LP signal on the broken one is noticeably fuzzier after the first
cap in the chain (the 1uf). by the time the signal gets to the 2907
it's way fuzzier.
given that the 2907 tranny is involved in the main out, the feedback
path, and connects to the LP input (my understanding of this circuit
is limited!) i reckoned that swapping that out couldn't hurt, but it
made no difference. swapping out the 2222 before it made no
difference either. also swapped out the TL071 with no effect.
i was concerned that the to-92 trannies i have had different pinouts
than the metal cans, but i verified this -- and most likely CV
control etc wouldn't work without those being sorted.
not much to go wrong here, i'm scratching my head. any ideas appreciated!