Synth-DIY Yahoo! Groups Archives

Thread

control voltage question

2003-08-19 by Einar Ekström

hi all,
i have a moog source with a control voltage input (CV), but i'm not
really familiar with what it does and how it works.
i understand you can feed a signal in to the CV input, and somehow
control the synth.

what kind of signal should be fed in to the CV-input(any audio
signal??), and which parameters(pitch only??) are controllable with
the signal?

thanks for any help!

/einar

Re: [oldsynths] control voltage question

2003-08-19 by Bonnie Goodwin

To put it simply, synthesizers work with a one volt per octabe change.Adjust accordingly, whether you are feeding a solid voltage, an audio voltage, or some kind of a ramp. The control voltage will change accordingly.

Bonnie *:>

Einar_Ekstr�m <einarekstrom@...> wrote:

hi all,
i have a moog source with a control voltage input (CV), but i'm not
really familiar with what it does and how it works.
i understand you can feed a signal in to the CV input, and somehow
control the synth.

what kind of signal should be fed in to the CV-input(any audio
signal??), and which parameters(pitch only??) are controllable with
the signal?

thanks for any help!

/einar

To unsubscribe from this group, send an email to:
oldsynths-unsubscribe@yahoogroups.com

Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

Do you Yahoo!?
Yahoo! SiteBuilder - Free, easy-to-use web site design software

RE: [oldsynths] control voltage question

2003-08-19 by Rory McDonald

To add to Bonnie's input:

The voltage is usually 0-5v or 0-10v depending on the system.

Most modulars have two types of signals being distributed- Audio signals and CV signals.

Sometimes it is a good idea to use two different colors of patch cables so you can quickly tell whats what.

Audio signals are obviously continuously variable and typically more complex.

CV signals can be variable or static voltage levels. The CV signal path may be altered in more than one place:

At the Keyboard, you generate a CV to the Oscillators. Then if you add an LFO you are applying CV to that signal.

The resultant CV is then moved on to perhaps a filter, then EG/VCA etc.

Depending on what you are trying to accomplish determines what kind of CV you put to the input.

For instance, if you want to add a vibrato to the pitch of an oscillator, you can apply a slow varying CV to the oscillator's CV input.

Usually you would apply it with the output CV of an LFO.

If you want to alter a VCA with CV you get a tremolo or varying amplitude effect.

You can apply CV to a filter module to sweep the frequency of the filter as well.

Get the idea?

I am not sure how the CV input on your Moog Source is set up- is it routable or is it applied to a particular place in the synth.

Surely someone on the list will know that one...

I recommend you find a tutorial on modular synthesis to really understand the applications of CV.

Anyone got a good link for that?

Rory McDonald

OldSynth Moderator

-----Original Message-----
From: Bonnie Goodwin [mailto:goodwinbonnie@...]
Sent: Tuesday, August 19, 2003 8:48 AM
To: oldsynths@yahoogroups.com
Subject: Re: [oldsynths] control voltage question

To put it simply, synthesizers work with a one volt per octabe change.Adjust accordingly, whether you are feeding a solid voltage, an audio voltage, or some kind of a ramp. The control voltage will change accordingly.

Bonnie *:>

Einar_Ekström <einarekstrom@...> wrote:

hi all,
i have a moog source with a control voltage input (CV), but i'm not
really familiar with what it does and how it works.
i understand you can feed a signal in to the CV input, and somehow
control the synth.

what kind of signal should be fed in to the CV-input(any audio
signal??), and which parameters(pitch only??) are controllable with
the signal?

thanks for any help!

/einar

To unsubscribe from this group, send an email to:
oldsynths-unsubscribe@yahoogroups.com

Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

Do you Yahoo!?
Yahoo! SiteBuilder - Free, easy-to-use web site design software

To unsubscribe from this group, send an email to:
oldsynths-unsubscribe@yahoogroups.com

Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

Re: control voltage question

2003-08-19 by Einar Ekström

Thanks for your replies, now I understand the CV thing a lot better,
even though there was a lot to digest. :-)

The reason I ask this question is I'm doing some home recordings
with my laptop, using Cool Edit Pro, and what I would like to
acomplish would be to control the synth with one of the drum tracks.

So, if I understood everything correctly: I could use the audio
signal from the snaredrum, for example, to control the pitch of the
synth. Because I'm using a drum machine, the amplitude of the single
drum track should be very consistent, therefore the resulting sounds
from the synth should be equally consistent.

I'm pretty sure the CV input is routed to pitch, since there's no
indication of what it does, nor is there any routing possibilities.

Thanks,
Einar

Re: [oldsynths] control voltage question

2003-08-19 by Gur Milstein

Hi Einar and list .
I would add to Bonnies explanation .
vintage synthesizers (and most of the new analog ones) are having voltage
control inputs to able the user to control the parameters using external
devices , such devices can be analog sequencers , midi>cv converter ,
voltage quantizer or a CV keyboard .
some of this CV inputs are 1V/Oct and are used for controlling the
pitch/tune of the synthesizer as Bonnie had explain . usually you would want
to connect a controller that would generate this 1V/Oct format such as a
quantizer module or midi>cv .
other CV inputs that are not using the 1V/Oct format can be control by any
voltage source in order for example to control Frequency/cut-off of a VCF ,
PWM etc .
connecting audio in to the 1V/Oct would make an exponential FM of your VCOs
, nice sounds (-:

Hope that help .

Cheers
Gur Milstein
ANALOGIC Analog Control System
http://www.analogic-acs.com

----- Original Message -----
From: "Einar Ekström" <einarekstrom@...>
To: <oldsynths@yahoogroups.com>
Sent: ??? ????? 19 ?????? 2003 16:18
Subject: [oldsynths] control voltage question

> hi all,
> i have a moog source with a control voltage input (CV), but i'm not
> really familiar with what it does and how it works.
> i understand you can feed a signal in to the CV input, and somehow
> control the synth.
>
> what kind of signal should be fed in to the CV-input(any audio
> signal??), and which parameters(pitch only??) are controllable with
> the signal?
>
> thanks for any help!
>
> /einar
>
>
>
> To unsubscribe from this group, send an email to:
> oldsynths-unsubscribe@yahoogroups.com
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>

Re: control voltage question

2003-08-20 by Mike Walters

Okay, I've been wondering about bipolar CV... I built a joystick
controller for someone's Analogue Solutions modular, and I built it
to have -9v/+9v outputs. When I was building it, I'd heard they used
0-6v, then I heard 0-12v, and then -6/+6v. Not knowing for sure, I
contacted the manufacturer, and they said the modules were
controlled -10V/+10V, bipolar. From the hoarse's mouth......

I guess I didn't quite understand. I built the joystick to run off 2
9v batteries, and calibrated the center X/Y positions to 0v. Left = -
9v, Right = +9v, same with Up/Down. I sent each voltage to an
individual output. So there were 4 outputs total (-9, +9, -9, +9).

When I got done and sold it to him, only the + voltages worked. The -
voltages had no effect on any module.

But it worked great, so there was no issue. Just redundant outputs!

The only thing I could think was maybe the CV inputs had stereo
jacks? +/-/ground?? That seemed wrong though.

Can anyone explain bipolar CV?

Thanks,
-Mike Walters
www.mysterycircuits.com

Re: [oldsynths] Re: control voltage question

2003-08-20 by Oakley Sound

> Can anyone explain bipolar CV?

Bipolar CVs are used in most modular systems. But it maybe that the
module in question does not respond to negative (-ve) inputs. Most VCAs
tend to work only with +ve input voltages. However, a negative input
voltage is also a good thing if your VCA has a gain bias (or initial
gain) control. Turn this pot up to half way, and your bipolar input CV
will now open and close the VCA.

A VCF and VCO will happily run with both -ve and +ve inputs. -ve inputs
will control the module's parameter downwards, and +ve ones upwards. So
a VCF's cut-off frequency will move downwards with increasing -ve CV.
But you will of course have to have set the VCF's cut-off to a point
where it can move downwards. If its already at its minimum, it probably
can't go any lower.

But I am puzzled by the fact that your unit had four outputs. Normally
one would expect just two outputs, X and Y. Both outputs would usually
be allowed to go either +ve or -ve.

Regards,

Tony Allgood Penrith, Cumbria, England

Oakley Sound Systems www.oakleysound.co.uk
Modular Synthesisers www.oakleysound.co.uk/projects.htm

Re: control voltage question

2003-08-20 by Mike Walters

> But I am puzzled by the fact that your unit had four outputs.

Normally

> one would expect just two outputs, X and Y. Both outputs would

usually

> be allowed to go either +ve or -ve.

I can't remember... Looking now at the schematic, I originally
intended just 2 outputs. I had a few issues once I had it built. I
think when it just had 2 outputs, somehow it would combine to 0-18v.
Then, I tried to send the + to one lug, and the - to the other, but
then that caused problems grounding with the chassis. I think I may
have just run out of ideas by then, and seperating them worked. Now,
what's the simple solution? I know I'm going to kick myself...
-Mike Walters
www.mysterycircuits.com