Korg Poly800/EX800 Users

Two great questions with long winded answers.

First, I think the MSM5232 might be able to do some primitive
frequency slides. I'm just not certain how fine grained the slide
would be.

In my searching on the Internet, all I could find on the MSM5232 TG
was emulation C code written by a guy called Jarek Burczynski for the
MAME project. The MAME project is a freeware Arcade game emulator.
Jared wrote the emulation for the MSM5232 chip because so many of the
old arcade games used this chip for sound generation. His code is not
commented nearly well enough for me to determine just exactly what the
chip can or cannot do. And to make matters worse, trying to work out
what a chip does from emulation code is kind of backward. I've called
numerous arcade repairers looking for the datasheet. I've tried OKI
themselves, who were helpful but ultimately failed to provide a
datasheet. And I've called a couple of other old chip distributors.
All attempts so far have failed.

I still have some inquiries out there. So hopefully, I will still get
my hands on the datasheet. In the end though, if I have to reverse
engineer the thing from scratch then so be it.

Second, in my opinion mono node will operate in both unison and non
unison modes. And mono mode will be designed to operate closely with
the arpeggiator and the portmento functions. If you enable unison then
the arpeggiator and portmento functions (if also enabled) operate on
all 8 voices simultaneously. If you enable mono mode without unison
then arpeggiator would be activated per individual voice and
portamento would slide each voice independently as well.

Right?

Mike.

so you mean the non-unison mono mode would still trigger separate voices succesively? so, for instance, vca release would take effect and would result in

Nah, if there's a way to set each voice's pitch separately then you
can detune them. It all depends on how that tone generator chip was
designed.


--- In korgpolyex@yahoogroups.com, "jure zitnik" <kokoon@...> wrote:
>
> so you mean the non-unison mono mode would still trigger separate voices
> succesively? so, for instance, vca release would take effect and would
> result in polyphonic effect? personally i wouldn't like that and would
> prefer mono to behave as a single-osc mono synth... unison wouldn't make
> much sense cause the oscillator is a dco and all of them would be
constantly

> hard-synced (you'd notice nothing but increase in loudness?)
> 
> cheers,
> jure
> 
> On 10/16/06, patrioticduo < patrioticduo@...> wrote:
> >
> >   Two great questions with long winded answers.
> >
> > First, I think the MSM5232 might be able to do some primitive
> > frequency slides. I'm just not certain how fine grained the slide
> > would be.
> >
> > In my searching on the Internet, all I could find on the MSM5232 TG
> > was emulation C code written by a guy called Jarek Burczynski for the
> > MAME project. The MAME project is a freeware Arcade game emulator.
> > Jared wrote the emulation for the MSM5232 chip because so many of the
> > old arcade games used this chip for sound generation. His code is not
> > commented nearly well enough for me to determine just exactly what the
> > chip can or cannot do. And to make matters worse, trying to work out
> > what a chip does from emulation code is kind of backward. I've called
> > numerous arcade repairers looking for the datasheet. I've tried OKI
> > themselves, who were helpful but ultimately failed to provide a
> > datasheet. And I've called a couple of other old chip distributors.
> > All attempts so far have failed.
> >
> > I still have some inquiries out there. So hopefully, I will still get
> > my hands on the datasheet. In the end though, if I have to reverse
> > engineer the thing from scratch then so be it.
> >
> > Second, in my opinion mono node will operate in both unison and non
> > unison modes. And mono mode will be designed to operate closely with
> > the arpeggiator and the portmento functions. If you enable unison then
> > the arpeggiator and portmento functions (if also enabled) operate on
> > all 8 voices simultaneously. If you enable mono mode without unison
> > then arpeggiator would be activated per individual voice and
> > portamento would slide each voice independently as well.
> >
> > Right?
> >
> > Mike.
> >
> >  
> >
>

I think you're right.

The first bank of four voices runs off of a master clock and the
second bank of four voices is detuned from the master.

So unison mono should be able to be either Single (a single voice) or
Double mode (two voices detuned from each other). Any more than that
is redundant (unless we add a second filter - OK now we're getting a
bit out of hand).

Portamento is either mono (one voice only) or double (two voices per
note) with up to four sliding notes. Or Poly (up to eight
simultaneously sliding notes).

And wouldn't it be nice to be able to slide notes from high side and
low side into one note - simultaneously. Or apply LFO to either, one
inverted to the other.

Wow! This could take a while.

Mike.


--- In korgpolyex@yahoogroups.com, "jure zitnik" <kokoon@...> wrote:
>
> so you mean the non-unison mono mode would still trigger separate voices
> succesively? so, for instance, vca release would take effect and would
> result in polyphonic effect? personally i wouldn't like that and would
> prefer mono to behave as a single-osc mono synth... unison wouldn't make
> much sense cause the oscillator is a dco and all of them would be
constantly

> hard-synced (you'd notice nothing but increase in loudness?)
> 
> cheers,
> jure
> 
> On 10/16/06, patrioticduo < patrioticduo@...> wrote:
> >
> >   Two great questions with long winded answers.
> >
> > First, I think the MSM5232 might be able to do some primitive
> > frequency slides. I'm just not certain how fine grained the slide
> > would be.
> >
> > In my searching on the Internet, all I could find on the MSM5232 TG
> > was emulation C code written by a guy called Jarek Burczynski for the
> > MAME project. The MAME project is a freeware Arcade game emulator.
> > Jared wrote the emulation for the MSM5232 chip because so many of the
> > old arcade games used this chip for sound generation. His code is not
> > commented nearly well enough for me to determine just exactly what the
> > chip can or cannot do. And to make matters worse, trying to work out
> > what a chip does from emulation code is kind of backward. I've called
> > numerous arcade repairers looking for the datasheet. I've tried OKI
> > themselves, who were helpful but ultimately failed to provide a
> > datasheet. And I've called a couple of other old chip distributors.
> > All attempts so far have failed.
> >
> > I still have some inquiries out there. So hopefully, I will still get
> > my hands on the datasheet. In the end though, if I have to reverse
> > engineer the thing from scratch then so be it.
> >
> > Second, in my opinion mono node will operate in both unison and non
> > unison modes. And mono mode will be designed to operate closely with
> > the arpeggiator and the portmento functions. If you enable unison then
> > the arpeggiator and portmento functions (if also enabled) operate on
> > all 8 voices simultaneously. If you enable mono mode without unison
> > then arpeggiator would be activated per individual voice and
> > portamento would slide each voice independently as well.
> >
> > Right?
> >
> > Mike.
> >
> >  
> >
>

Mike, just bite the bullet and set it up with an Oberheim-style
modulation matrix ;) (just kidding!)

If the first bank of four is synced to the master clock any slides you
do to that are going to affect the second bank as well. I don't think
this is the case though. From the sound of the oscillators they've got
separate clocks. In double osc mode with the detune parameter set to
00 you can occasionally get changes in timbre where the two oscs are
the same frequency but out of phase.

--- In korgpolyex@yahoogroups.com, "korgpolyex800" <korgpolyex800@...>
wrote:
>
> I think you're right.
> 
> The first bank of four voices runs off of a master clock and the
> second bank of four voices is detuned from the master.
> 
> So unison mono should be able to be either Single (a single voice) or
> Double mode (two voices detuned from each other). Any more than that
> is redundant (unless we add a second filter - OK now we're getting a
> bit out of hand).
> 
> Portamento is either mono (one voice only) or double (two voices per
> note) with up to four sliding notes. Or Poly (up to eight
> simultaneously sliding notes).
> 
> And wouldn't it be nice to be able to slide notes from high side and
> low side into one note - simultaneously. Or apply LFO to either, one
> inverted to the other.
> 
> Wow! This could take a while.
> 
> Mike.
> 
> 
> --- In korgpolyex@yahoogroups.com, "jure zitnik" <kokoon@> wrote:
> >
> > so you mean the non-unison mono mode would still trigger separate
voices
> > succesively? so, for instance, vca release would take effect and would
> > result in polyphonic effect? personally i wouldn't like that and would
> > prefer mono to behave as a single-osc mono synth... unison
wouldn't make
> > much sense cause the oscillator is a dco and all of them would be
> constantly
> > hard-synced (you'd notice nothing but increase in loudness?)
> > 
> > cheers,
> > jure
> > 
> > On 10/16/06, patrioticduo < patrioticduo@> wrote:
> > >
> > >   Two great questions with long winded answers.
> > >
> > > First, I think the MSM5232 might be able to do some primitive
> > > frequency slides. I'm just not certain how fine grained the slide
> > > would be.
> > >
> > > In my searching on the Internet, all I could find on the MSM5232 TG
> > > was emulation C code written by a guy called Jarek Burczynski
for the
> > > MAME project. The MAME project is a freeware Arcade game emulator.
> > > Jared wrote the emulation for the MSM5232 chip because so many
of the
> > > old arcade games used this chip for sound generation. His code
is not
> > > commented nearly well enough for me to determine just exactly
what the
> > > chip can or cannot do. And to make matters worse, trying to work out
> > > what a chip does from emulation code is kind of backward. I've
called
> > > numerous arcade repairers looking for the datasheet. I've tried OKI
> > > themselves, who were helpful but ultimately failed to provide a
> > > datasheet. And I've called a couple of other old chip distributors.
> > > All attempts so far have failed.
> > >
> > > I still have some inquiries out there. So hopefully, I will
still get
> > > my hands on the datasheet. In the end though, if I have to reverse
> > > engineer the thing from scratch then so be it.
> > >
> > > Second, in my opinion mono node will operate in both unison and non
> > > unison modes. And mono mode will be designed to operate closely with
> > > the arpeggiator and the portmento functions. If you enable
unison then

> > > the arpeggiator and portmento functions (if also enabled) operate on
> > > all 8 voices simultaneously. If you enable mono mode without unison
> > > then arpeggiator would be activated per individual voice and
> > > portamento would slide each voice independently as well.
> > >
> > > Right?
> > >
> > > Mike.
> > >
> > >  
> > >
> >
>

Jure,

Looking at the schematics.

The joystick and modulation (from the LFO) are fed into the master
oscillator. The master OSC is fed to the first four voices and the
detuned oscillator goes into the second four voices. The detuning is
not an oscillator but rather is a divider/multiplier that takes the
master OSC as its input. The detune is just fine tuning around the
master OSC.

The LFO and Joystick do the major sliding. In the EX800, you can send
pitch wheel (to replace the joystick). So there is a D to A converter
in there that provides the feed into the master OSC.

So portamento could be done with a slide from one octave to the next
whereupon the TG would switch octaves while the analog OSC control
would reset back to zero and start the slide again on to the next octave.

Thinking about this though, since all of the voices ultimately take
their OSC from the master and since there is only one voltage control
input to the OSC. We are only going to be able to do single note
portamento.

Oh well. 

Mike.

--- In korgpolyex@yahoogroups.com, "Alexander" <arf_hotdogdeity@...>
wrote:
>
> Mike, just bite the bullet and set it up with an Oberheim-style
> modulation matrix ;) (just kidding!)
> 
> If the first bank of four is synced to the master clock any slides you
> do to that are going to affect the second bank as well. I don't think
> this is the case though. From the sound of the oscillators they've got
> separate clocks. In double osc mode with the detune parameter set to
> 00 you can occasionally get changes in timbre where the two oscs are
> the same frequency but out of phase.
> 
> --- In korgpolyex@yahoogroups.com, "korgpolyex800" <korgpolyex800@>
> wrote:
> >
> > I think you're right.
> > 
> > The first bank of four voices runs off of a master clock and the
> > second bank of four voices is detuned from the master.
> > 
> > So unison mono should be able to be either Single (a single voice) or
> > Double mode (two voices detuned from each other). Any more than that
> > is redundant (unless we add a second filter - OK now we're getting a
> > bit out of hand).
> > 
> > Portamento is either mono (one voice only) or double (two voices per
> > note) with up to four sliding notes. Or Poly (up to eight
> > simultaneously sliding notes).
> > 
> > And wouldn't it be nice to be able to slide notes from high side and
> > low side into one note - simultaneously. Or apply LFO to either, one
> > inverted to the other.
> > 
> > Wow! This could take a while.
> > 
> > Mike.
> > 
> > 
> > --- In korgpolyex@yahoogroups.com, "jure zitnik" <kokoon@> wrote:
> > >
> > > so you mean the non-unison mono mode would still trigger separate
> voices
> > > succesively? so, for instance, vca release would take effect and
would
> > > result in polyphonic effect? personally i wouldn't like that and
would
> > > prefer mono to behave as a single-osc mono synth... unison
> wouldn't make
> > > much sense cause the oscillator is a dco and all of them would be
> > constantly
> > > hard-synced (you'd notice nothing but increase in loudness?)
> > > 
> > > cheers,
> > > jure
> > > 
> > > On 10/16/06, patrioticduo < patrioticduo@> wrote:
> > > >
> > > >   Two great questions with long winded answers.
> > > >
> > > > First, I think the MSM5232 might be able to do some primitive
> > > > frequency slides. I'm just not certain how fine grained the slide
> > > > would be.
> > > >
> > > > In my searching on the Internet, all I could find on the
MSM5232 TG
> > > > was emulation C code written by a guy called Jarek Burczynski
> for the
> > > > MAME project. The MAME project is a freeware Arcade game emulator.
> > > > Jared wrote the emulation for the MSM5232 chip because so many
> of the
> > > > old arcade games used this chip for sound generation. His code
> is not
> > > > commented nearly well enough for me to determine just exactly
> what the
> > > > chip can or cannot do. And to make matters worse, trying to
work out
> > > > what a chip does from emulation code is kind of backward. I've
> called
> > > > numerous arcade repairers looking for the datasheet. I've
tried OKI
> > > > themselves, who were helpful but ultimately failed to provide a
> > > > datasheet. And I've called a couple of other old chip
distributors.
> > > > All attempts so far have failed.
> > > >
> > > > I still have some inquiries out there. So hopefully, I will
> still get
> > > > my hands on the datasheet. In the end though, if I have to reverse
> > > > engineer the thing from scratch then so be it.
> > > >
> > > > Second, in my opinion mono node will operate in both unison
and non
> > > > unison modes. And mono mode will be designed to operate
closely with
> > > > the arpeggiator and the portmento functions. If you enable
> unison then
> > > > the arpeggiator and portmento functions (if also enabled)
operate on
> > > > all 8 voices simultaneously. If you enable mono mode without
unison

> > > > then arpeggiator would be activated per individual voice and
> > > > portamento would slide each voice independently as well.
> > > >
> > > > Right?
> > > >
> > > > Mike.
> > > >
> > > >  
> > > >
> > >
> >
>

yeah but i m okay with that. i mean - if you want to turn the poly-800 into a monosynth... you don t need to add any functionalities, just take the polyphony

The MSM5232 produces the voices. The 8 voices are grouped into two
groups and the 16', 8', 4' and 2' outputs are provided for the two
groups of voices.

The Poly then has two sets of resister ladders that convert the
outputs into either sqaure wave (where each foot output is mixed
equally) or into a saw tooth (where the 16' is mixed twice as loud as
the 8' is mixed twice as loud as the 4' etc).

Ofcourse, the foot outputs for each group of four voices can be turned
on or off. But not per voice.

The two banks of four voices do have a separate clock input on the
chip. So it is conceivable that you could build a second master clock
and feed it to the second input. But that is too much work and too
expensive. And all you get is two portamento notes instead of one.

We have to keep in mind that this whole reengineering thing is not
designed to make a Poly 800 into a Matrix-12. LOL

However, I am looking to see if I can obtain additional NJM-2069's and
MSM5232's. Because it is not inconceivable that we could build
retrofit boards to provide dual or quad filters and dual or quad OSC's.

Right now though, I just wish I could get my hands on the datasheet
for the MSM5232.

Mike.

--- In korgpolyex@yahoogroups.com, "jure zitnik" <kokoon@...> wrote:
>
> yeah but i'm okay with that. i mean - if you want to turn the
poly-800 into
> a monosynth... you don't need to add any functionalities, just take the
> polyphony away. portamento is an added bonus but if we're talking
monophonic
> then portamento on the master OSC is perfectly okay.
> 
> if we could detune each voice separately or to add envelopes so each
voice
> would have its own would be an awesome thing but i guess it's not
possible
> (judging from what you said)
> 
> what about alternative waveform options? the way it is now tells me that
> there *are* some possibilities... does anyone know how the thing really
> works?
> 
> jure
> 
> On 10/18/06, korgpolyex800 <korgpolyex800@...> wrote:
> >
> >   Jure,
> >
> > Looking at the schematics.
> >
> > The joystick and modulation (from the LFO) are fed into the master
> > oscillator. The master OSC is fed to the first four voices and the
> > detuned oscillator goes into the second four voices. The detuning is
> > not an oscillator but rather is a divider/multiplier that takes the
> > master OSC as its input. The detune is just fine tuning around the
> > master OSC.
> >
> > The LFO and Joystick do the major sliding. In the EX800, you can send
> > pitch wheel (to replace the joystick). So there is a D to A converter
> > in there that provides the feed into the master OSC.
> >
> > So portamento could be done with a slide from one octave to the next
> > whereupon the TG would switch octaves while the analog OSC control
> > would reset back to zero and start the slide again on to the next
octave.
> >
> > Thinking about this though, since all of the voices ultimately take
> > their OSC from the master and since there is only one voltage control
> > input to the OSC. We are only going to be able to do single note
> > portamento.
> >
> > Oh well.
> >
> > Mike.
> >
> > --- In korgpolyex@yahoogroups.com <korgpolyex%40yahoogroups.com>,
> > "Alexander" <arf_hotdogdeity@>
> >
> > wrote:
> > >
> > > Mike, just bite the bullet and set it up with an Oberheim-style
> > > modulation matrix ;) (just kidding!)
> > >
> > > If the first bank of four is synced to the master clock any
slides you
> > > do to that are going to affect the second bank as well. I don't
think
> > > this is the case though. From the sound of the oscillators
they've got
> > > separate clocks. In double osc mode with the detune parameter set to
> > > 00 you can occasionally get changes in timbre where the two oscs are
> > > the same frequency but out of phase.
> > >
> > > --- In korgpolyex@yahoogroups.com <korgpolyex%40yahoogroups.com>,
> > "korgpolyex800" <korgpolyex800@>
> > > wrote:
> > > >
> > > > I think you're right.
> > > >
> > > > The first bank of four voices runs off of a master clock and the
> > > > second bank of four voices is detuned from the master.
> > > >
> > > > So unison mono should be able to be either Single (a single
voice) or
> > > > Double mode (two voices detuned from each other). Any more
than that
> > > > is redundant (unless we add a second filter - OK now we're
getting a
> > > > bit out of hand).
> > > >
> > > > Portamento is either mono (one voice only) or double (two
voices per
> > > > note) with up to four sliding notes. Or Poly (up to eight
> > > > simultaneously sliding notes).
> > > >
> > > > And wouldn't it be nice to be able to slide notes from high
side and
> > > > low side into one note - simultaneously. Or apply LFO to
either, one
> > > > inverted to the other.
> > > >
> > > > Wow! This could take a while.
> > > >
> > > > Mike.
> > > >
> > > >
> > > > --- In korgpolyex@yahoogroups.com <korgpolyex%40yahoogroups.com>,
> > "jure zitnik" <kokoon@> wrote:
> > > > >
> > > > > so you mean the non-unison mono mode would still trigger
separate
> > > voices
> > > > > succesively? so, for instance, vca release would take effect and
> > would
> > > > > result in polyphonic effect? personally i wouldn't like that and
> > would
> > > > > prefer mono to behave as a single-osc mono synth... unison
> > > wouldn't make
> > > > > much sense cause the oscillator is a dco and all of them
would be
> > > > constantly
> > > > > hard-synced (you'd notice nothing but increase in loudness?)
> > > > >
> > > > > cheers,
> > > > > jure
> > > > >
> > > > > On 10/16/06, patrioticduo < patrioticduo@> wrote:
> > > > > >
> > > > > > Two great questions with long winded answers.
> > > > > >
> > > > > > First, I think the MSM5232 might be able to do some primitive
> > > > > > frequency slides. I'm just not certain how fine grained
the slide
> > > > > > would be.
> > > > > >
> > > > > > In my searching on the Internet, all I could find on the
> > MSM5232 TG
> > > > > > was emulation C code written by a guy called Jarek Burczynski
> > > for the
> > > > > > MAME project. The MAME project is a freeware Arcade game
emulator.
> > > > > > Jared wrote the emulation for the MSM5232 chip because so many
> > > of the
> > > > > > old arcade games used this chip for sound generation. His code
> > > is not
> > > > > > commented nearly well enough for me to determine just exactly
> > > what the
> > > > > > chip can or cannot do. And to make matters worse, trying to
> > work out
> > > > > > what a chip does from emulation code is kind of backward. I've
> > > called
> > > > > > numerous arcade repairers looking for the datasheet. I've
> > tried OKI
> > > > > > themselves, who were helpful but ultimately failed to
provide a
> > > > > > datasheet. And I've called a couple of other old chip
> > distributors.
> > > > > > All attempts so far have failed.
> > > > > >
> > > > > > I still have some inquiries out there. So hopefully, I will
> > > still get
> > > > > > my hands on the datasheet. In the end though, if I have to
reverse

> > > > > > engineer the thing from scratch then so be it.
> > > > > >
> > > > > > Second, in my opinion mono node will operate in both unison
> > and non
> > > > > > unison modes. And mono mode will be designed to operate
> > closely with
> > > > > > the arpeggiator and the portmento functions. If you enable
> > > unison then
> > > > > > the arpeggiator and portmento functions (if also enabled)
> > operate on
> > > > > > all 8 voices simultaneously. If you enable mono mode without
> > unison
> > > > > > then arpeggiator would be activated per individual voice and
> > > > > > portamento would slide each voice independently as well.
> > > > > >
> > > > > > Right?
> > > > > >
> > > > > > Mike.
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
> >  
> >
>

--- In korgpolyex@yahoogroups.com, "jure zitnik" <kokoon@...> wrote:
>
> what about alternative waveform options? the way it is now tells me that


How about throwing in some XORs?

Jure,

The foot outputs from the MSM5232 go straight into two sets of
resistor ladders that are individually selected such that you get to
choose between square or sawtooth (as per DCO1 and DCO2 parameter
settings).

It would be conceivable to add further waveforms by adding additional
networks of resistor and capacitor ladder filters. However, to do this
would require yet another drop in retrofit board. It would have to
drop in where the NJM2069 and MSM5232 chips are. We would need some
additional chip select logic (quite doable). And then some additional
programming - of course.

Although, you could probably achieve alternative waveforms with just
the drop in board and a couple of toggle switches to select the
alternative waveforms. I'll put a little thought into that over the
next couple of weeks.

Very interesting but I have to tell you - you give someone an inch and
they take a mile. LOL's.

Mike.


--- In korgpolyex@yahoogroups.com, "austeritygirlone" <ziggystar@...>
wrote:
>
> --- In korgpolyex@yahoogroups.com, "jure zitnik" <kokoon@> wrote:
> >
> > what about alternative waveform options? the way it is now tells
me that

> 
> 
> How about throwing in some XORs?
>

... output something else apart from a set of square waves. maybe PWM? jure

No, it's just square. That's why they're called DCO's.



--- In korgpolyex@yahoogroups.com, "jure zitnik" <kokoon@...> wrote:
>
> :D don't bother. what i meant was if it was possible for the MSM5232 to
> output something else apart from a set of square waves. maybe PWM?
> 
> jure
> 
> On 10/19/06, korgpolyex800 <korgpolyex800@...> wrote:
> >
> >   Jure,
> >
> > The foot outputs from the MSM5232 go straight into two sets of
> > resistor ladders that are individually selected such that you get to
> > choose between square or sawtooth (as per DCO1 and DCO2 parameter
> > settings).
> >
> > It would be conceivable to add further waveforms by adding additional
> > networks of resistor and capacitor ladder filters. However, to do this
> > would require yet another drop in retrofit board. It would have to
> > drop in where the NJM2069 and MSM5232 chips are. We would need some
> > additional chip select logic (quite doable). And then some additional
> > programming - of course.
> >
> > Although, you could probably achieve alternative waveforms with just
> > the drop in board and a couple of toggle switches to select the
> > alternative waveforms. I'll put a little thought into that over the
> > next couple of weeks.
> >
> > Very interesting but I have to tell you - you give someone an inch and
> > they take a mile. LOL's.
> >
> > Mike.
> >
> > --- In korgpolyex@yahoogroups.com <korgpolyex%40yahoogroups.com>,
> > "austeritygirlone" <ziggystar@>
> > wrote:
> > >
> > > --- In korgpolyex@yahoogroups.com
<korgpolyex%40yahoogroups.com>, "jure

> > zitnik" <kokoon@> wrote:
> > > >
> > > > what about alternative waveform options? the way it is now tells
> > me that
> > >
> > >
> > > How about throwing in some XORs?
> > >
> >
> >  
> >
>

If we place an XOR between Voice 1 and Voice 2 in dual mode we'll get
some kind of cross-modulation/pwm effect I think. All we need would be
one IC with 4 XORs and maybe a 4 way switch to select beween normal
OSC and cross-modulated output.