SV: SV: [sdiy] Sine VCO

[Michael Zacherl]

Hi Michael,
I'm going to start with four VCO's (or four 
operators in Yamaha-language).
I think I will start with some of the schematics 
Tim Ressel posted and see
how I can make one of them to fit into my project. 
But I don't have much
time for this project before the summer... Right 
now I'm just gathering
information.

The whole idea with this project is to start with 
a sine wave (the
fundamental) and to build up interesting sounds 
using another VCO and to
modulate the first with the second one. My thought 
is: when you change the
pitch of the second VCO you change the timbre of 
the output of the first
VCO, and if you change the volume of the output of 
the second VCO you also
change the timbre of the first VCO since 
modulation decreases/increases in
intensity. Therefore I need to make some strange 
connections...

The next part I have to figure out is how to get a 
smart routing system.
Every module will consist of one VCO, one (or 
more) EG and one VCA. I want
to have every module fully patchable, but all 
internal connections should
be made with switches instead of cables. So every 
module could be connected
in different ways:
CV IN -> EG -> VCO -> VCA - In this way the EG 
controls the pitch
CV IN -> VCO -> EG -> VCA - In this way the EG 
controls the output volume
(of course...)
CV IN -> VCO -> VCA
CV IN -> EG -> VCO -> EG -> VCA - If I make two 
EG's per module...
Maybe I can solve the routing with some logic 
switches?

Every module has at least two audio outputs and 
two FM inputs, there is
also a CV input (and I'm planning to have a CV IN 
bus for three CV's, which
are selectable with a switch on every module) and 
a gate input (and
probably a gate bus too).

There is a "master VCA" with four (at least) 
inputs to summon up the sound
from the VCO's I want to use directly and an EG to 
control it.

This will end up in a kind of four-operator 
analogue FM-synth, or in a
synth with four sine VCO's, or four synths with 
one VCO, or...

Hopefully you understand my clumsy English...

What do you think, is it possible?

Regards

Niklas


-----Ursprungligt meddelande-----
Från: Michael Zacherl [mailto:sdiy-mz01 at arsprototo.at]
Skickat: den 30 mars 2003 23:30
Till: Rönnberg, Niklas
Kopia: synth-diy at dropmix.xs4all.nl
Ämne: Re: SV: [sdiy] Sine VCO


Hi Niklas,

Rönnberg, Niklas wrote:

> I want linear FM, but oct/v or v/Hz is not that crucial. The cleaner sine
> the better... I'm planning to make a small additive synth, so if I can
> start from almost nothing, just the fundamental frequency, then I think I
> can make more different sound from a pure sine to quite complex sounds.
> 
> So if you have any good ideas, I will gladly discuss these with you!

after browsing through the numerous answers
regarding your subject I've come to the
conclusion, that for my purpose (gaining control
of individual harmonics of the output waveform)
I'd better go for an .. uhm ... digital approach.
:-(
Before, I was thinking of a "master circuit"
containig CV preprocessing, exponentiator etc.
followed by a rather large number of "slave
oscillators" each generating a rather pure
sinewave with a succeeding VCA.
But since I'd need at least 20 to 30 of such
slaves for a _single_ output wave.
This is a "rather" feeble-minded idea.
So I'm going to discard it.

As far as I understood your needs, I'd go for the
"Buchla"-approach in order to get a pretty good
triangle and to shape it to a sine afterwards.

How many of this VCOs would you like to have in
your system? Maybe the number of parts you'd need
isn't that bad at all using a more conventional
approach?


cheerio,
    Michael.