[sdiy] Seeking for help...

[rkmoore at memphis.edu]

Hi Rouslan,
The waveform that you drew looks to me like a filtered sawtooth wave 
(mostly just first and second harmonics in your picture).  A sawtooth 
oscillator and a vcf will achieve such a waveform easily.  PAiA makes 
a good monosynth kit suitable for bass with two sawtooth oscillators 
and a vcf.  I built one a few years ago and still use it regularly.  
Here's the link below:

http://www.paia.com/fatman.htm

Richard Moore

----- Original Message -----
From: "Rouslan Placella" <r.placella at tiscali.it>
Date: Wednesday, February 2, 2005 12:08 pm
Subject: Re: [sdiy] Seeking for help...

> Hi Harry,
> Sorry bothering you, as you can see I'm just a novice.....
> What do you mean by filtering the unwanted harmonics. Using a VCF? 
> Some kind
> of waveshaper? Or something else?
> 
> Thanks again, Rouslan.
> 
> 
> >-- Messaggio Originale --
> >Date: Wed, 2 Feb 2005 07:00:45 -0800 (PST)
> >From: Harry Bissell Jr <harrybissell at prodigy.net>
> >Subject: Re: [sdiy] Seeking for help...
> >To: Rouslan Placella <r.placella at tiscali.it>, synth-
> diy at dropmix.xs4all.nl>
> >
> >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.
> >
> 
> 
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