zipper noise was: digital control

[harrybissell at prodigy.net]

I should add that the "zipperless" feature was on their own encoder, not the incomming midi. So they could have a very high-res encoder.  But compared to their "minimoog" clone (sorry I dont know model numbers but its the one with "all the knobs").. its great. Their mini-clone doesn't work much better than the Pro V at zipper noise.

(I like to twiddle knobs... and I like them analog !!!)
:^) Harry


 ---- On Jan 12 "Grant Richter" <grichter at execpc.com> wrote: 
> You use a DAC with a very large number of bits,
> taking the incoming 0-127 controller levels you
> predict a series of higher resolution line segments
> based on the spacing of the controller messages.
> 
> That is to say the microprocessor is continuously
> trying to predict a line segment that will arrive at
> the next controller point in time with the message.
> 
> ----------
> > From: harrybissell at prodigy.net
> > To: DCMagnuson at aol.com
> > Cc: synth-diy at mailhost.bpa.nl
> > Subject: Re: zipper noise was: digital control
> > Date: Wednesday, January 12, 2000 9:47 AM
> > 
> > Yes... you can put a "glide circuit" or lowpass filter on the DAC output.
> The trouble is... what rate to filter at. If you do a very slow (manual)
> filter sweep... you need a very long time constant. If you "whip" the dial
> quickly... the long sweep will fight you.
> > 
> > You could detect how fast the dial is moving and filter slow or fast
> (either digital of analog) or have so many bits and clock so fast that
> no-one can hear it.
> > 
> > The Studio Electronics AT1 (???) the "tone chamelion" model with the
> single "Alpha Dial" is the only hybrid synth I have ever heard that does
> not have zipper noise... Even at high resonance settings it is dead smooth.
> I'd consider buying it just for that reason. I wonder how they did it ???
> > :^) Harry
> > 
> > 
> >  ---- On Jan 11 DCMagnuson at aol.com wrote: 
> > > In a message dated 1/11/00 9:36:41 PM Eastern Standard Time, 
> > > harrybissell at prodigy.net writes:
> > > 
> > > > The other problem is "zipper" or step noise... when you move a value 
> > > through 
> > > > a
> > > >  linear range (especially an oscillator or filter sweep) you hear
> jumps in 
> > > > the
> > > >  audio (like a zipper...)
> > > >  Really good programming chops can cover most of this up...
> > > >  
> > > 
> > > Here's a question... I haven't ever built a glide circuit, so I haven't
> been 
> > > able to try this yet, but if you put a glide circuit on your DAC
> output, 
> > > would it cover up the zipper noise?  I was figuring this would work
> well in 
> > > non-critical situations (like a filter sweep)
> > > 
> > > Dave Magnuson
> > > Independent Music Site
> > > http://www.indiemusicsite.com
> > 
> >