[sdiy] Seeking for help...

[Harry Bissell Jr]

Hi Rouslan

the technique you are describing is a form of additive
synthesis. You can make any waveshape that way but if
you use analog VCOs it is very hard.

The more common way is subtractive synthesis, start
with an easily generated wave (sawtooth, square, etc)
then filter the wave to remove the unwanted harmonics.

Because the high frequency energy usually decreases
over time, you can lower the filter frequency to
simulate that as well.

If you are trying to simulate bass guitar... the
harmonics are not perfect multiples of the fundamental
frequency. They will be progressively sharp as you
increase in frequency.  In that case you might want to
use multiple oscillators...but with some circuit that
starts them all in phase.

H^) harry



--- Rouslan Placella <r.placella at tiscali.it> wrote:

> Hi lads,
> I deeply apologise for the horrible drawing of the
> waves of yesterday, I've
> attached a picture of what I actully meant.
> 
> (hope can attach files to the e-mail, (I'm new to
> mailing lists))
> 
> Thanks to everybody!!!
> 
> <I'm trying to build a bass synth. And I found out
> that to generate a suitable
> <
> < wave for this I need 3 VCO. The first one should
> do a regular sin wave,
> but
> <the other two should do something like the figure
> B(at twice the frequency).
> <
> <I still didn't come up with anything...
> <Can anybody help me out?
> <
> <Thanks to everyone in advance, Rouslan.