John Loffink wrote:
Late 70's- early 80's.
<<t does not create a stairstep in the intermediate position as you would
get by crossfading square and pulse waveforms. ..
I can't post the schematic. But from the one I have, it sure looks like a
crossfader to me. Put it this way...the waveshape circuit has four inputs.
Sine, pulse, saw, tri - those come from the non-variable outs of each of the
four. All four are gated through 3080's to a summed output which becomes
the variable out. The four 3080's are controlled (pin 5) by a single source
(pot or VC input) through a series of op amps (this part of my explanation
is simplified). Each of the four op amps have a different ref voltage -
hence, they fade on at different voltage thresholds from a single source.
Now who knows if this schematic is correct. I didn't have to repair this
function of the NTO and did not 'test' this part of the diagram - but I did
use it to repair another section of the VCO and it proved accurate.
In any event, there is no apparent waveshaping going on here. This has
already occurred by the time these four signals go into this crossfader.
If you're not seeing what you expect as far as the morphed waveshapes, keep
in mind the four are not in phase relation to one another. if you take that
shift into account, possibly it will prove this theory?
- Peter
> It does not create a stairstep in the intermediateFirst gen I would assume - it was in the system Darrel made for himself.
> position as you would get by crossfading square and pulse waveforms.
>
> What was the vintage of the NTO you repaired?
Late 70's- early 80's.
<<t does not create a stairstep in the intermediate position as you would
get by crossfading square and pulse waveforms. ..
I can't post the schematic. But from the one I have, it sure looks like a
crossfader to me. Put it this way...the waveshape circuit has four inputs.
Sine, pulse, saw, tri - those come from the non-variable outs of each of the
four. All four are gated through 3080's to a summed output which becomes
the variable out. The four 3080's are controlled (pin 5) by a single source
(pot or VC input) through a series of op amps (this part of my explanation
is simplified). Each of the four op amps have a different ref voltage -
hence, they fade on at different voltage thresholds from a single source.
Now who knows if this schematic is correct. I didn't have to repair this
function of the NTO and did not 'test' this part of the diagram - but I did
use it to repair another section of the VCO and it proved accurate.
In any event, there is no apparent waveshaping going on here. This has
already occurred by the time these four signals go into this crossfader.
If you're not seeing what you expect as far as the morphed waveshapes, keep
in mind the four are not in phase relation to one another. if you take that
shift into account, possibly it will prove this theory?
- Peter