[sdiy] Configurable Phase Shift Project

[scottnoanh at peoplepc.com]

I might add the Vactrol elements each have 1.5 MOhm in parallel with them.

Cheers,
Scott

----- Original Message -----
From: <scottnoanh at peoplepc.com>
To: "JH." <jhaible at debitel.net>
Cc: "Synth-Diy at Dropmix. Xs4all. Nl" <synth-diy at dropmix.xs4all.nl>
Sent: Wednesday, February 22, 2006 6:24 PM
Subject: Re: [sdiy] Configurable Phase Shift Project


> Hi JH,
>
> Thanks!  You don't know how many times I've refrained from bugging you
with
> questions the last couple of days =-D.
>
> I'm using the VTL5C3/2 dual element phase shifter and TL074's.  The timing
> cap is 560 pF.  I started out with the template I'd used long ago when
> working with VTL5C2's, which used 2n7 caps (and this was still a bit
> fiddly), but I just couldn't get a decent sweep out of that value with the
> 5C3/2's.  The sweep seemed to be bunched up around the lower frequencies.
I
> then tried 1n caps, which was an improvement, and then I went down to 560
pF
> (the only other value I had a fair quantity of).  This seemed to really
> improve the sweep tremendously, as small as that value is.  I'm not sure
if
> it's the optimal value, but it's working for me right now.  As an aside,
um,
> the caps are disk caps (yuck), but I had a bunch of them.  The last four
> stages I threw on today were some polystyrene that I found while looking
for
> my germanium diodes (can you see where this is leading?).  Anyway, just
> testing the four stages of polystyrene certainly demonstrated the value of
> using them (next order from Mouser).
>
> I really want to try the Quadra compandor method that you used in the,
well,
> Quadra phase shifter as well as the Storm Tide flanger.  With this phaser,
> my ears don't notice much amplitude variation with added regen, but it
sure
> makes getting a decent recording level without compression tricky.  I'd
like
> to get the amplitude a bit more uniform, and the effect of a balanced
> signal/regen signal you describe certainly sounds attractive.
>
> I tried it just a bit with an NE570 yesterday, but my results were
abysmal.
> It was sort of a cursory check, and I think I'll try the 4007 based
> circuitry of the Quadra and Storm Tide.  I'm not sure if this is correct,
> but it looks like controlling the expander with the rectified control
> voltage of the compressor will certainly help.  As an aside, I notice Dr.
> Moog used the 4007 at least for compression in the Moog Stage Phaser.
>
> All of those extra peaks and notches, when modulated very slowly, sound
> really good through the Dim C, so I can imagine they'd really sound great
> through the Dimension D clone.
>
> Take care,
> Scott
>
> ----- Original Message -----
> From: "JH." <jhaible at debitel.net>
> To: <scottnoanh at peoplepc.com>; <synth-diy at dropmix.xs4all.nl>
> Sent: Wednesday, February 22, 2006 5:35 PM
> Subject: Re: [sdiy] Configurable Phase Shift Project
>
>
> > Sounds beautiful.
> >
> > Are these all equal stages? VTL5C3? what capacitor value?
> >
> > JH.
> >
> >
> > ----- Original Message -----
> > From: <scottnoanh at peoplepc.com>
> > To: <synth-diy at dropmix.xs4all.nl>
> > Sent: Wednesday, February 22, 2006 10:34 PM
> > Subject: [sdiy] Configurable Phase Shift Project
> >
> >
> > > I've returned to a project I started last summer, a multi-stage phase
> > > shifter I call, surprisingly, the MultiPhase.
> > >
> > > The intended product is a phase shifter with two independently
> controlled
> > 12
> > > stage chains that can be operated in series or parallel.  Like the
Moog
> > > Stage Phaser, the resonance and output taps will be selectable for
each
> > > section.  Having two 12 stage chains will allow up to 24 stages in
> series,
> > > with the ability to configure the structure to emulate the phase shift
> > > structures (but obviously not the sounds exactly) of many different
> phase
> > > shifters.
> > >
> > > One thing I've played with, for example, is the structure of the
Schulte
> > > Compact A - eight phase shift stages with the resonance, inverted and
> low
> > > pass filtered, between the first two stages.  I have no idea if it
> sounds
> > > anything like a Compact A, but it still renders a very nice sound.
> > >
> > > The new page is here:
> > >
> > > http://mypeoplepc.com/members/scottnoanh/birthofasynth/id18.html
> > >
> > > Not much there yet, but a couple of samples - the big one has a
section
> > > using the 'Compact A' structure, plus 16 stage phase shift with no
> > resonance
> > > and 16 stage with resonance.
> > >
> > > There's a short white noise sample of 20 stages.
> > >
> > > I'll add more to it as time goes by.....
> > >
> > > What?  Oh, Vactrols.
> > >
> > > Cheerio,
> > > Scott
> > >
> > >
> >
>