[sdiy] Re: Saw phase shifter was: English lessons

[Magnus Danielson]

From: mark verbos <mverbos at earthlink.net>
Subject: Re: [sdiy] Re: Saw phase shifter was: English lessons
Date: Thu, 15 Sep 2005 18:33:15 -0400
Message-ID: <4329F6AB.4040700 at earthlink.net>

> oh. well then scratch that all from the record.

Sure!

> Incidentally, didn't Jörgen Bergfers add that to his LFO?

Yes he did. As I recall it he made it quadrant that way, so it has 90 degrees
phase-shift. Did wonders for PWM-modulation of the oscillators... Mmmm!!! ;O)

Don't trust my memory, check his pages instead!

BTW, Jörgen lives 2 km from me.

Cheers,
Magnus

> Mark
> 
> 
> 
> Harry Bissell Jr wrote:
> 
> >Yes you can sweep the phase with CV
> >
> >By dependant on power supply voltages, Magnus'
> >version relies on the clippling of the opamp to
> >get the shift. So if the opamp does not clip politely
> >or if the supply voltage changes, you will be out
> >of calibration.
> >
> >Likewise if the Sawtooth amplitude in changes, you
> >will be out of calibration as well.
> >
> >It would be possible to make a precision clipper to
> >get
> >around this problem.  If the sawtooth does not have
> >fast reset time, there will be a major glitch in the
> >wave. Trying to filter this without killing the normal
> >reset of the saw is difficult.
> >
> >I think that having individual harmonics able to be
> >phase shifted might be underwhelming. It could be done
> >but humans are not super sensitive to pahse of
> >harmonics (unless they are shifting) which would seem
> >to be the point here. 
> >
> >H^) harry
> >
> >--- mark verbos <mverbos at earthlink.net> wrote:
> >
> >
> >---------------------------------
> >    wait, you can sweep the phase 360 degrees with a
> >CV? That's what Imean. I thought you had to trim it in
> >and leave it. Didn't you say thatit was dependent on
> >power supply voltages?
> >
> >anyway, the Buchla thing (and he only made one like
> >this, so he learnedhis lesson) as far as I understand
> >it, has the root and the next 9harmonics in sine
> >waves. Those sine waves can be swept 360 degrees
> >andhave their volumes mixed. I think this is a big
> >difference from justhaving the sines all starting at
> >the same place, but maybe I'm kiddingmyself. 
> >
> >you're right it's not MORE important.  :(
> >
> >Mark
> >
> >
> >Harry Bissell Jr wrote:
> >  
> >MORE importantly... (what are you saying ?)The phase
> >voltage 'is' sweepable isn't it ?If you mean that
> >changing the voltage changes therelative phase shift
> >of the sawtooth.The neat thing would be to be able to
> >sweep overmultiple cycles.I'm using sawtooth phase
> >shift now.  It sounds good,but if you compare it with
> >the input sawtooth itsboring. The sound would be more
> >like a simple PWMwave.So what do you mean ???H^)
> >harry--- mark verbos <mverbos at earthlink.net> wrote:  
> >      
> >more importantly, how do you make the phase
> >voltagesweepable? You need to put the Buchla harmonic
> >generator in MillsCollege to shame.MarkMagnus
> >Danielson wrote:    
> >          
> >OK, now to get you back on track... remember my      
> >        
> >sawtooth phase-shifter? What do    
> >          
> >you guys think needs to be done to make it      
> >        
> >workable? Should a good op-amp be    
> >          
> >enought maybe?Cheers,Magnus       
> >        
> >  
> >
> >
> >
> >  
> >