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synthacon: which pots?

2005-05-14 by ps_minor

well i have my synthacon boards (thanks ken!) and i'm ready to get started. looks like all
the parts are available from mouser, excellent. i'm ordering plenty of transistors to try to
match a pair of each for this stereo unit. (thanks richard for the the info you posted on
this subject a while back!)

one question about pots though. i've been searching the archives and i can't find an
answer.. which pot goes where? does 100k
control freq or resonance?

also, i see many have added a pot to the LP/BP/HP inputs. what value pot should be used
here? and is it a simple matter of wiring the pot in series w the input jack?

one more q, what value pot will be needed to add a CV Amount pot to the freq cutoff
control , and should it be wired simply in series w the CV input jack?

thanks! -psm

Re: synthacon: which pots?

2005-05-14 by Adam Schabtach

I'm about to start on a Synthacon filter also, but only one of them.

Show quoted textHide quoted text

> one question about pots though. i've been searching the archives and i
> can't find an
> answer.. which pot goes where? does 100k
> control freq or resonance?

Peering at the schematic, it looks like the 100k pot is the frequency
control.

> one more q, what value pot will be needed to add a CV Amount pot to the
> freq cutoff
> control , and should it be wired simply in series w the CV input jack?

I've been pondering similar questions. What I'd like to end up with is one
CV input jack with no pot that makes the filter track at 1V/octave
(approximately--I'm not expecting high precision from this filter), and
another CV input jack with an attenuator. That way the filter can be set up
to follow a keyboard CV with a variable amount of envelope CV be added, both
independently of the nominal setting of the frequency control. Looking at
the schematic I think one could just add another input resistor at the base
of the transistor, but that might make the CV inputs prone to interaction so
adding a simple op-amp CV mixer before the transistor might be a better way
to go.

--Adam

Re: synthacon: which pots?

2005-05-14 by sasami@hotkey.net.au

>one question about pots though. i've been searching the archives and i

can't find an

>answer.. which pot goes where? does 100k
>control freq or resonance?

As mentioned, see the circuit diagram - it's there for a reason!

>also, i see many have added a pot to the LP/BP/HP inputs. what value pot

should be used

>here? and is it a simple matter of wiring the pot in series w the input jack?

100k Wire them the same as the 100k Freqency pot, except instead of
connecting the Clockwise end to positive, use it as your input.

>one more q, what value pot will be needed to add a CV Amount pot to the

freq cutoff

>control , and should it be wired simply in series w the CV input jack?

Same as above.

Ken
_______________________________________________________________________
Ken Stone sasami@... or sasami@...
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

Re: synthacon: which pots?

2005-05-14 by ps_minor

> As mentioned, see the circuit diagram - it's there for a reason!

yes, of course. sorry! i've stared at that diagram so many times i can't believe i didn't
notice that part.

> 100k Wire them the same as the 100k Freqency pot, except instead of
> connecting the Clockwise end to positive, use it as your input.
>

ken and adam, thanks so much for the quick help w my novice question. cheers, -psm

Cgs synth

synthacon: which pots?

synthacon: which pots?

Re: synthacon: which pots?

Re: synthacon: which pots?

Re: synthacon: which pots?

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