Korg Poly800/EX800 Users

I've been looking for this information myself for a while now. I'm tempted
say it simply does not exist at this point in time.

Only one way to find out: are you feeling lucky?

Hey,
Anyone got the datasheet for this? This chip has the 3 VCA's and a 4-
pole VCF onboard. Even just a pin description would be good.

I'm trying to determine which pins of the NJM2069 are used as Log CV 
inputs for each of the three VCA's. The schematic leaves this detail 
out (Ie. is Pin 2 & 3 Linear or Log).

I'm just tossing around the idea of using the onboard LFO to tremelo 
the three noise sources individually, as Pin 5 of IC8 is the log CV 
output of the LFO, this wouldn't be to hard.

Anyways,

Any help appreciated

P9

Yeah, well, if said pins actually controlled the volume for the first and
second oscillators, each voice would be sharing the same VCA. I honestly
don't see how that would work very well... one filter, after the VCA's, one
per oscillator, is how I always thought the Poly was laid out. I could be
wrong, however.

I would expect these two pins to control the master Level for the oscillators,
that is, parameters 17 and 27. But I could be wrong.

--- In korgpolyex@y..., trip@b... wrote:
> 
> I've been looking for this information myself for a while now. I'm 
tempted
> say it simply does not exist at this point in time.
> 
> Only one way to find out: are you feeling lucky?


Well, maybe if the info for the NJM2069 is included in the full 
service manual, I've just been workin' off the schematics in the 
files section.

I'm tempted to think that the pins labled "Level 1 & Level 2" (Pins 2 
& 3) are the Log CV's for Osc1 & Osc2 VCA's respectivley. 

I imagine "Pin9" (VCA LIN), is the Linear CV for the Noise Source, 
maybe the Level + EG3 CV's are summed together into this Pin.

Pin 6 (VCA Log),is tied to ground. This at least, is the Log CV for 
either the OSc1/Osc2 or Noise. So, thats one down at least.

Anyways,

Any thoughts

P9

Here's the pinout:

KORG NJM2069

Pin#	Function

1	Audio In GND (GND)
2	Mixer Signal 1 Level CV In
3	Mixer Signal 2 Level CV In
4	VCF Resonance CV In
5	VCF 12dB/oct Audio Out
6	VCF 24dB/oct Audio Out
7	VCA Signal In
8	VCA Level CV Log In
9	VCA Level CV Lin In
10	VCA Signal Out
11	Vss (GND)
12	-Vee
13	VCF Cutoff CV Lin In
14	VCF Cutoff CV Log In
15	VCF cap C4
16	VCF cap C3
17	VCF cap C2
18	VCF cap C1
19	VCF Ext Audio In
20	Mixer Signal 2 In
21	Mixer Signal 1 In
22	+Vcc


Chip has separate
*VCA with in,out and lin&log CV ins, 
*VC Mixer with two audio inputs, two CV ins for each input level
control, it's output is
 hardwired to vcf audio in (no ext pin here), separate gnd for input
signal
*VCF with separate ext audio input (in addition to hardwired input from
vc mixer),
output, lin&log cv ins, four pins for integrating capacitors, vc
resonance with
pin for res cv

This is almost half of synt-chip type just like old CEM chips, but
sounds much
fatter IMHO. Short look at pins 5/6 reveals easy mod for poly800 to get
2/4 pole
filter... Poly800 misuses it's vca for adding 3rd vc audio channel to
the mix
as 'real' vca control is performed digitally inside osc chip driven by
soft
envelopes. 




--- 



marjan


me    : Marjan Urekar
e-mail: urekar.m@...
s-diy : http://surf.to/marjansystems
music : http://go.to/forcemajeure

> Yeah, well, if said pins actually controlled the volume for the first and
> second oscillators, each voice would be sharing the same VCA. I honestly
> don't see how that would work very well... one filter, after the VCA's, one
> per oscillator, is how I always thought the Poly was laid out. I could be
> wrong, however.
> 

You are wrong. There's no analog VCA for the oscillators. Software
envelopes
control the oscillator chips internally, so in a way vca for each osc is
_before_ the filter chip, where two sources are just mixed in VC mixer
and 
passed to the vcf. Onboard VCA that wasn't needed for usual task was
misused
to give sorta 3rd VC mixer input by adding it's out to the ext audio
in in the vcf.

-- 



marjan


me    : Marjan Urekar
e-mail: urekar.m@...
s-diy : http://surf.to/marjansystems
music : http://go.to/forcemajeure

> Onboard VCA that wasn't needed for usual task was
> misused
> to give sorta 3rd VC mixer input by adding it's out to the ext audio
> in in the vcf.

Could you explain this futher, I don't understand at all.  Is the VCA 
used for the noise generator or what?

Jon

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).

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? So aren't the VC mixers on 
the NJM2069 just VCA's who's outputs are internally routed into 
the VCF? 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 ?(buffered LFO CV 
output comes from Pin 14 of  "IC7").

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!

P9 (Who'd get a kick out of a patchable Poly 800)

--- In korgpolyex@y..., "phdinfunk" <phdinfunk@h...> wrote:
> > Onboard VCA that wasn't needed for usual task was
> > misused
> > to give sorta 3rd VC mixer input by adding it's out to the ext 
audio
> > in in the vcf.
> 
> Could you explain this futher, I don't understand at all.  Is the 
VCA 

> used for the noise generator or what?
> 
> Jon

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: urekar.m@...
s-diy : http://surf.to/marjansystems
music : http://go.to/forcemajeure

phdinfunk wrote:
> 
> > Onboard VCA that wasn't needed for usual task was
> > misused
> > to give sorta 3rd VC mixer input by adding it's out to the ext audio
> > in in the vcf.
> 
> Could you explain this futher, I don't understand at all.  Is the VCA
> used for the noise generator or what?

Yes. VC Mixer is nothing more than two VCAs with their outputs
summed into an opamp. I suppose they have only log CV inpits
(called Level CV here). Main VCA, which was intended to be used
as normal final VCA (like in a classic monosynth), wasn't needed
so it was fed with white noise and that to the second audio
input of vcf (first is fed with vc mixer's output).

Real polysynth would need 8 such chips, two inputs for each osc
of a voice, to vcf and to vca, and so 8 times for each voice.
Alas, poly800 was unfortunate mix of designs so it ended with
string machine configuration - all poly voices summed and then
routed to the single VCF.

-- 



marjan


me    : Marjan Urekar
e-mail: urekar.m@...
s-diy : http://surf.to/marjansystems
music : http://go.to/forcemajeure

So to get external audio in, you put the signal into pin 2 or 3 and
ground at pin 1?

And to change from 24dB to 12dB you put a switch on pin 5 and 6?


--- In korgpolyex@yahoogroups.com, ">>>marjan<<<" <urekar.m@...> wrote:

>
> 
> Here's the pinout:
> 
> KORG NJM2069
> 
> Pin#	Function
> 
> 1	Audio In GND (GND)
> 2	Mixer Signal 1 Level CV In
> 3	Mixer Signal 2 Level CV In
> 4	VCF Resonance CV In
> 5	VCF 12dB/oct Audio Out
> 6	VCF 24dB/oct Audio Out
> 7	VCA Signal In
> 8	VCA Level CV Log In
> 9	VCA Level CV Lin In
> 10	VCA Signal Out
> 11	Vss (GND)
> 12	-Vee
> 13	VCF Cutoff CV Lin In
> 14	VCF Cutoff CV Log In
> 15	VCF cap C4
> 16	VCF cap C3
> 17	VCF cap C2
> 18	VCF cap C1
> 19	VCF Ext Audio In
> 20	Mixer Signal 2 In
> 21	Mixer Signal 1 In
> 22	+Vcc
> 
> 
> Chip has separate
> *VCA with in,out and lin&log CV ins, 
> *VC Mixer with two audio inputs, two CV ins for each input level
> control, it's output is
>  hardwired to vcf audio in (no ext pin here), separate gnd for input
> signal
> *VCF with separate ext audio input (in addition to hardwired input from
> vc mixer),
> output, lin&log cv ins, four pins for integrating capacitors, vc
> resonance with
> pin for res cv
> 
> This is almost half of synt-chip type just like old CEM chips, but
> sounds much
> fatter IMHO. Short look at pins 5/6 reveals easy mod for poly800 to get
> 2/4 pole
> filter... Poly800 misuses it's vca for adding 3rd vc audio channel to
> the mix
> as 'real' vca control is performed digitally inside osc chip driven by
> soft
> envelopes. 
> 
> 
> 
> 
> --- 
> 
> 
> 
> marjan
> 
> 
> me    : Marjan Urekar
> e-mail: urekar.m@...
> s-diy : http://surf.to/marjansystems
> music : http://go.to/forcemajeure
>

For audio in mod You should use C24 capacitor