[sdiy] Seeking for help...

[Scott Gravenhorst]

<rkmoore at memphis.edu> wrote:
>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

And it's really easy to add that third oscillator.

http://home1.gte.net/res0658s/fatman/index.htm

I use one of my FatMan synths specifically for bass.

>
>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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>> 
>> 
>> 
>> 
>

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-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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