[sdiy] More Questions...

[Ray Wilson]

Hi Jesse

The reason there are several CV outputs on a keyboard controller is so you 
can control several voltage controlled modules with the keyboard voltage. As 
you begin to get several oscillators and filters going for a patch (a 
particular setting of the synthesizer) you may wish you had more. That is 
where a control voltage distributor (essentially a circuit to give you even 
more CV outputs) comes in handy. A typical patch might include controlling 
two oscillators with Kbd CV, a voltage controlled filter with the same Kbd 
CV and a third oscillator (controlled with the same Kbd CV) which is being 
used to ring modulate one of the other oscillators.

As far as gates and triggers go you also want more than one so you can 
trigger, gate (or both) more than one envelope generator from the keyboard 
at the same time.

Oscillators typically have several CV inputs so that you can control them 
with several sources of voltage simultaneously. Example Kbd voltage for 
pitch into one of the CV inputs. Sequencer CV voltage into another of the CV 
inputs for arpeggiation, and perhaps a third CV for low frequency modulation 
(vibrato).

Feeding the square wave of one oscillator into the other oscillator's sync 
input causes the sync'd oscillator's integrator to reset on the edges of the 
first oscillator's square waves and results in interesting timbres in the 
second oscillator when either its pitch is modulated or the first 
(oscillator providing the square waves) pitch is modulated. Once you get a 
couple of oscillators built experiment a bit. The difference between linear 
and logarithmic CV inputs is that the log inputs are for 1V/octave tracking 
(e.g. 0V = 10Hz, 1V=20Hz, 2V=40Hz, 3V=80Hz, 4V=160Hz, 5V=320Hz, etc.) The 
linear input responds linearly (e.g. 0V=10HZ, 1V=20Hz, 2V=30Hz, 3V=40Hz, 
4V=50Hz, 5V=60Hz, etc.).

As far as books go you can still get these if you look hard enough (Ebay, 
Amazon) although they may be out of print.
Barry Klein In 1982 Barry wrote a book entitled Electronic Music Circuits 
(EMC) that presents schematics and techniques to build your own modular 
analog music synthesizer. Out of print since the mid-80's, due to increased 
interest he now self-publishes it in an enlarged 8 1/2" x 11" formatted size 
with corrected schematics and updated parts sources. He has also put 
together a collection of SSM and Curtis electronic music IC data sheets and 
app. notes into what he has entitled The Electronic Music IC Databook . 
Check this site out for info on each and how to order: Get Barry's 
"Electronic Music Circuits" you will love it!!!

Many ideas for the VCO, VCF, and Analog Keyboard Controller circuits came 
from Hal Chamberlin's seminal work (affectionately acronymed MAM): 
Chamberlin, Hal. Musical Applications of Microprocessors, 2nd ed. Rochelle 
Park NJ: Hayden Book Co., 1985. which is unfortunately out of print but I 
understand that copies can be obtained here: PAIA Authors Page

Hang in there. You'll tame the analog monster yet and then you'll wish you 
had more gate and trigger outputs and CV inputs before it's all over.

Ray





----- Original Message ----- 
From: "Jesse Yoder" <jojomanee at gmail.com>
To: "Synth-DIY List" <synth-diy at dropmix.xs4all.nl>
Sent: Saturday, May 28, 2005 1:30 AM
Subject: [sdiy] More Questions...


> OK, I just have more questions.  Thanks for all the help given so far.
> This is the most ambitious electronics project I've attempted and it
> helps to be able to ask questions.  I am really excited about it
> though as I have never gotten a chance to play around with an analogue
> synth before.
>
> So, 1st question is if there is a book which might explain simply the
> concepts and connections, etc. of analogue synths, e.g. answer
> questions similar to those I pose today.
>
> In reference to this schematic:
> (http://www.musicfromouterspace.com/analogsynth/keybrdcontroller.html)
> there are (2) gate out jacks, (2) trigger out jacks, and (4) CV out
> jacks.  This may be a silly question, but why exactly do I need so
> many?  Do I need more than one out to connect to these ins on a
> module?  Is it just to give me more sonic options? (plugging into
> multiple modules at once?)  Just curious about that.  In this
> schematic for a VCO:
> (http://www.musicfromouterspace.com/analogsynth/August2003VCO.html) we
> have (3) inputs for 1V/Oct CV, (1) input for linear CV in, and (1)
> osc. sync input, as well as outputs for square, saw, triangle, and
> sine wave oscillations.  Just wondering about the specifics of how
> everything fits together.
>
> Thanks!
> ~~Ponyboy
>