> Date: Thu, 11 Mar 2004 19:36:30 -0500
> From: Richard Brewster <pugix@...>
> Subject: Re: CGS Synthacon VCF Stooge panel
>
>
> ixqy@... wrote:
>
>> Do you mean each of the three existing inputs on the PCB (LP/BP/HP) would
>> need an opamp mixer in order to sum the All Pass to each of the three said
>> inputs?
>>
> Yes.
>
>> Is this because a passive mixer would load the inputs? Sorry for the
>> technician part of me showing. ;-)
>>
>>
> Basically, yes. The Synthacon VCF inputs presume a single low-impedance
> signal coming in. Injecting two signals at any of these inputs really
> calls for a proper mixing circuit.
>
> What's the opinion about the All pass feature? I know Cynthia Webster's
> version of the Synthacon has it, but there is not a separate attenuator
> for the All input.
>
> -Richard Brewster
Howdy!
The ALL PASS input on the Cynthia Synthacon Filter does not have it's
own attenuator because the signal is buffered to all three of the other
input channel pots! this way, the ALL PASS input can be mixed a certain
percentage to each of the bands from the single ALL PASS input jack.
(you can have a little of it going into the high pass if you like,
and a little more into the Low pass, and if you like none of it going into
the bandpass input for example, (or anything in-between).
For phasing effects simply run all three pots wide open, however no
phasing will be experienced, unless the ear can ~compare~ it to the original
unaltered signal, so adding a mixer for this to your custom modules would be
very handy!
Another simple but groovy mod is to add a WET/DRY balance pot
I did this mod for someone passively (no active electronics) simply by
adding a 50K pot with one terminal attached to the input jack, and the other
attached to the OUTPUT of the pc board, and the wiper going to the OUTPUT
jack on the front panel. So simple! (although I felt this additional pot
sort of spoiled the certain "look" I was going for in the panel layout so it
was only a one-off. Nothing that could not be done with a simple mixer)
See the beauty of this arrangement is that you can mix the various degrees
of the ALL PASS input ~along with~ the individual band inputs for true
spectral mixing. (I know of no other module by any manufacturer that is
capable of such an elegant solution for this).
The idea of using Peter's Gizmotron circuit is a good one,
and here is why... (Unlike most filters, the Synthacon affects it's
incoming signal ~asymmetrically~ meaning for example that you will hear a
different result from an inverted sawtooth input... than you will from a
positive sawtooth input, and ~that~ Henrietta is part of the Synthacon's
sonic secrets!)
Happy Bleeping!
Cynthia
wwww.cyndustries.com
BTW, I don not advertise this, but anyone wanting to buy assembled Cynthia
boards without pots, switches, and panels should contact me privately.
Not everyone has the time or inclination to to add their own Voltage
Controlled Resonance or Spectral Mixing sections to their Synthacons, etc
(of course that is half the fun) and some may want to add Sawtooth Animator
boards to their Buchlas (or even their Casios for that matter!) LOL!
(Wow, can you imagine someone ordering some Low Pass Gate Boards from me
to add to their Buchla rigs? Wouldn't that be freeky!) LOL!