[sdiy] Synthesizers...

[David G. Dixon]

HA!  I was just trolling the Oakley Sound website for tips on wiring panel
components to PCBs, and just happened to go to the VCO page, and what did I
see?

A switch for selecting "centred" or "edge" PWM type!

David G. Dixon
Professor
Department of Materials Engineering
University of British Columbia
309-6350 Stores Road
Vancouver, B.C. V6T 1Z4
Canada
 
Tel 1-604-822-3679
Fax 1-604-822-3619
 
"PERFECTA FINGAMUS SERVIAT NATURA"
 
The information in this email and in any attachments is confidential and
intended solely for the attention and use of the named addressee(s).  It
must not be disclosed to any person without the writer's authority.  If you
are not the intended recipient, or a person responsible for delivering it to
the intended recipient, you are not authorized to and must not disclose,
copy, distribute, or retain this message or any part of it.
> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-
> bounces at dropmix.xs4all.nl] On Behalf Of David G. Dixon
> Sent: Wednesday, February 18, 2009 2:55 PM
> To: 'Scott Nordlund'; synth-diy at dropmix.xs4all.nl
> Subject: RE: [sdiy] Synthesizers...
> 
> Scott,
> 
> Thanks for that.  It makes me feel even more inclined to leave it in the
> circuit.  Not a bad little addition for $1.25!
> 
> David G. Dixon
> Professor
> Department of Materials Engineering
> University of British Columbia
> 309-6350 Stores Road
> Vancouver, B.C. V6T 1Z4
> Canada
> 
> Tel 1-604-822-3679
> Fax 1-604-822-3619
> 
> "PERFECTA FINGAMUS SERVIAT NATURA"
> 
> The information in this email and in any attachments is confidential and
> intended solely for the attention and use of the named addressee(s).  It
> must not be disclosed to any person without the writer's authority.  If
> you
> are not the intended recipient, or a person responsible for delivering it
> to
> the intended recipient, you are not authorized to and must not disclose,
> copy, distribute, or retain this message or any part of it.
> > -----Original Message-----
> > From: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-
> > bounces at dropmix.xs4all.nl] On Behalf Of Scott Nordlund
> > Sent: Wednesday, February 18, 2009 11:19 AM
> > To: synth-diy at dropmix.xs4all.nl
> > Subject: RE: [sdiy] Synthesizers...
> >
> >
> > I've never seen any synth-related reference to this (guess it would be
> > in electronotes if it's anywhere), but saw-derived PWM and tri-derived
> > PWM do have different spectra.  PWM from a sawtooth wave results in an
> > upward (or downward) sideband shift proportional to the modulation
> > frequency, while PWM from a triangle wave results in a simultaneous
> > upward and downward sideband shift.  This is why saw-derived PWM can
> > sound "out of tune", especially at low frequencies.  Using a triangle
> > wave should sound much better.  Unfortunately synths usually use the
> > saw wave for PWM, even when a triangle is available.
> >
> > One of my professors in college had written a paper on it...
> >
> > ----------------------------------------
> > > Date: Tue, 17 Feb 2009 23:48:06 -0800
> > > From: dixon at interchange.ubc.ca
> > > Subject: RE: [sdiy] Synthesizers...
> > > To: tom at electricdruid.net; synth-diy at dropmix.xs4all.nl
> > > CC:
> > >
> > > I thought of one little innovation today which is very simple: I put
> in
> > a
> > > switch to select between the triangle and the ramp for the input to
> the
> > > pulse wave comparator. When the resulting pulses are mixed with the
> > sines
> > > or triangles from the same VCO, they morph them in different ways. I'm
> > not
> > > sure if the results really sound very different, but it is a very
> simple
> > > thing to do, so I'll probably keep it. Has anyone else tried this?
> >
> > _________________________________________________________________
> > Get more out of the Web. Learn 10 hidden secrets of Windows Live.
> > http://windowslive.com/connect/post/jamiethomson.spaces.live.com-Blog-
> > cns!550F681DAD532637!5295.entry?ocid=TXT_TAGLM_WL_domore_092008
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at dropmix.xs4all.nl
> > http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy