plutoniq9 wrote:
>
> I'm slightly confused as well. The dedicated VCA (own input and
> output & cv control) on the NJM2069 is used for the white noise
> only. I assume that the EG3 (Depth determined by White Noise
> mixer level) is inputed into this VCA's CV input. The output of this
> VCA (Pin 10) then is externally routed into the NJM2069's VCF
> audio input (Pin 19).
>
That's right.
You can cut noise before VCA input and pump in any external
audio (thru cap) to process it thru VCF.
> Now what i am confused about is the terminolgy of a voltage
> controlled mixer VS. a VCA. Both control the Amplitude of an
> audio signal from a CV source, right?
Yep.
> So aren't the VC mixers on
> the NJM2069 just VCA's who's outputs are internally routed into
> the VCF?
They could be. Most of the VC Mixers are several VCAs mixed
into single point (opamp).
Only difference could be how good they are trimmed.
Final VCA should have minimal signal/CV feedthru - mixer
shouold also but it could be somewhat lower specd.
What may be going inside that they made 3 identical vcas inside
the chip, killed lin input on two of them and summed them,
leaving third free with all the i/o connections.
> Assuming that these are Log CV inputs (Pin 2&3),
> couldn't you amplitude mod Osc1 & 2 by rerouting the LOG CV
> output of the onboard LFO into these Pins ?
You sure can, but mind the polarity of the lfo signal.
CV input might dislike negative voltages, but maybe it
has internal protection diodes, maybe not. Check
lfo's DC component first.
Also, chorus lfo could be wired to vcf cutoff and res
inputs for more maynham. You can try to route it
to ref. HF oscillator, but that's more dangerous.
You should know what you're doing in there if you
wish to keep oscillators singing...
>(buffered LFO CV
> output comes from Pin 14 of "IC7").
>
That's unbuffered square out. But you don't need
buffer here. Pin 8 is unbuffered triangle. Pin 7
is buffered (and level shifted) triangle.
Add frequency control to lfo and it'll rock...
> Better yet, would be to mount patch points on the Poly 800 as CV
> inputs/outputs, another potential CV input would be for the
> resonance (which is Voltage Controlled), imagine the pleasure
> of modulating the resonance from EG3 or the onboard LFO or
> external CV generators....yummy!
>
That's easy, but watch the polarities.
--
marjan
me : Marjan Urekar
e-mail:
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