Synth-DIY Yahoo! Groups Archives

External Audio in Mod.

2011-07-17 by 7yash

Hi all,

Considering that the Osc section of the Poly-800 uses an additive form synthesis with Square waves, I thought that the next nice mod for mine would be to build an External Audio Input module.

This would help beef up the Osc section with either additional Osc modules or help treat external audio through the excellent NJM2609 VCF.

Looking at the schematics, I think I should use Pin 19. It looks like I could also use Pins 20 & 21. I though I saw a way to switch between the Noise generator and external audio.

Is this the way to go and should I use resistors or capacitors to wire in the Audio Input?

If there is a way to wire more than one input by mixing signals, that would be even better.

Re: [korgpolyex] External Audio in Mod.

2011-07-17 by billmeirelles@uol.com.br

I'm not sure how I did it, I found the descripton at the forum but
can't remember where, anyways I believe I took out the negative
leg of the cap prior to pin 19, connect the negative leg to the center
of a 2 pos switch, at one side of the switch you connect your external
audio source and at the other side you reconnect it to the board so
you can choose between external in and noise. The thing is, the EG
used to modulate this VCA input is the same used to to modulate
the VFC so you and up with a one EG only synth if not using the
internal oscilators. Check this page for a good disciption the
NJM2609 chip http://tnt23.livejournal.com/789722.html

Cheers,
Bill Meirelles

Em 17/07/2011 12:22, 7yash < josh.nursing@... > escreveu:

Hi all,

Considering that the Osc section of the Poly-800 uses an additive form synthesis with Square waves, I thought that the next nice mod for mine would be to build an External Audio Input module.

This would help beef up the Osc section with either additional Osc modules or help treat external audio through the excellent NJM2609 VCF.

Looking at the schematics, I think I should use Pin 19. It looks like I could also use Pins 20 & 21. I though I saw a way to switch between the Noise generator and external audio.

Is this the way to go and should I use resistors or capacitors to wire in the Audio Input?

If there is a way to wire more than one input by mixing signals, that would be even better.

DCO2 detune

2011-07-18 by korgpolyex800

I am looking for some help from some of you electronics engineer types that i know are on this forum.

I want to create a new detune circuit to include in the AtomaHawk kit.

The current detune is awful in my opinion. Korg made it that way because it was very cheap.

What I want to do is create a detune so that we can create really good phasing and a truly independent DCO2. The current detune is not actually independent clocking.

Can anyone suggest a way that I could produce a slightly offset oscillation based on a master clock source? And that slight offset could be adjusted using digital or analog signal voltage technique?

Mike

Re: External Audio in Mod.

2011-07-18 by 7yash

Hi Bill,

Looks like wiring through a cap is the way to go.

I found this existing thread. It is not easy to make full sense of it as it is:
http://launch.groups.yahoo.com/group/korgpolyex/messages/311?threaded=1&m=e&var=1&tidx=1

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-18 by billmeirelles@uol.com.br

Yes, I'm sure it is, I bet it is just before pin 19, if you follow
the tracks you will find it, connect the tip of your audio signal
to the negative leg of the cap and the sleeve to ground, using
the switch method you can select between noise and external
audio, I just can't remember the cap number, it's a shame I don't
have notes on these mods as I do mods for clients and I'll have
one Poly 800 from a client comming in my direction soon, anyways
I'll have to open up mine to swap a connector and I could check
it out for you, but I'm not sure when I'll have time for this.
You can also send it to me for a complete modification service,
I'll do all the mods for you for 299 USD plus shipping and VAT,
the thing is I'm in Brazil so shipping rates are a bit higher than
usual, also one will never know if there will be taxes when it get
in here or not, unless you ship it as a gift. Anyways check the
ph otos of my mods in here:

http://groups.yahoo.com/group/korgpolyex/photos/album/28347805/pic/list

As you can see they look good, work very well and will take any Poly 800 to
another level. The mods are:

1 - CUTOFF and RES pots
2 - NOISE LEVEL pot
3 - FM pot (OSC1 to VCF)
4 - VCF EXT CV input pot
5 - VCF EXT CV input connector (1/4 TS or 3.5mm jack)
6 - VCF EXT CV input switch (ON/OFF)
7 - VCF EXT AUDIO input pot
8 - VCF EXT AUDIO input connector (1/4 TS or 3.5mm jack)
9 - VCF EXT AUDIO input switch to select between EXTERNAL AUDIO and NOISE
10 - VCF SLOPE switch to select between 12dB and 24 dB operation modes

I'm working on printed labels covered with transparent plastic wich
will put a name in every newly added pots, switches and connectors,
these are included in the 299 USD price and I assure you they will
look fantastic.

Cheers,
Bill Meirelles

Em 18/07/2011 04:04, 7yash < josh.nursing@... > escreveu:

Hi Bill,

Looks like wiring through a cap is the way to go.

I found this existing thread. It is not easy to make full sense of it as it is:
http://launch.groups.yahoo.com/group/korgpolyex/messages/311?threaded=1&m=e&var=1&tidx=1

Re: External Audio in Mod.

2011-07-18 by 7yash

It looks like C24 is the one: it the one just below the 4 yellow components on the right of the NJM2609 chip.

Re: [korgpolyex] DCO2 detune

2011-07-18 by Gordon JC Pearce

On Mon, 18 Jul 2011 00:55:06 -0000
"korgpolyex800" <korgpolyex800@...> wrote:

> Can anyone suggest a way that I could produce a slightly offset oscillation based on a master clock source? And that slight offset could be adjusted using digital or analog signal voltage technique?

Not easily, but you could use a crystal oscillator with a varicap diode to pull it a few kHz. I don't know if that would get you the range you're looking for. Some radios use a transistor and a capacitor to shift the CPU clock a bit. That way, if a harmonic of the clock oscillator will cause interference to a particular channel you can move it out of the way. I'll see if I can scan in the relevant page of a manual that shows this - I know the Motorol MC Micro has this, so if you find a PDF you can maybe do something with that.

If you really wanted to go nuts with it, you could use a DDS chip.

Gordon MM0YEQ

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-18 by billmeirelles@uol.com.br

Yes, I believe C24 is the one, it's located right after the trasistors of the noise
generator but it input at pin 7 not 19, you should desolder the negative leg
and connect the ext audio source to the leg, solder a wire to the pcb where the
negative leg used to be, reconnect the wire to the negative leg using a switch to have
the noise signal back. You will end up with 2 wires coming from pcb at the C24 area,
a nice tip is to use a plastic strap to hold the wires together just after the cap, this
way you make it harder to the solder to get broken, just make sure you have the
terminals properlly insulated. Using a 2 pos switch you can connect the negative
leg to the middle point of the switch and use the sides for the signals as described
before.

Em 18/07/2011 10:25, 7yash < josh.nursing@... > escreveu:

It looks like C24 is the one: it the one just below the 4 yellow components on the right of the NJM2609 chip.

Re: External Audio in Mod.

2011-07-18 by 7yash

Thanks Bill, I am ready to try that and also the 12/24 Db Filter mod. Then, I'll also do the Moog Slayer and FM-800 mods. Much Fun.

How would one wire the Noise Level Mod? Is that a simple trim pot replacement too?

Also, what if instead of toggling the noise vs External input, one would like to mix the noise with the External Input?

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-18 by billmeirelles@uol.com.br

The noise level is VR3, you have to swap the wiring from left to right
or the pot will reverse the noise level, 0 pos = 100 and 100 pos = 0.
I've never tried to mix the noise gen with external audio but I do
believe it will be a better choice if you send another noise source
mixed with the audio before it hits the synth, if you want the exact
noise source from the poly just record it and play it back together with
any other audio material. If you wire both signals at the same time you
can run into problems like signal loss, distortion or even fry the transistors
of the noise generator. Remeber that making mods do take trial and error
to have it fine tuned to your taste so take care and try not to do anything
that can't be undone, also take it easy with resonance when you get the
moog slayer mod done, it can easily fry your speakers or blow your ears.

Em 18/07/2011 18:32, 7yash < josh.nursing@... > escreveu:

Thanks Bill, I am ready to try that and also the 12/24 Db Filter mod. Then, I'll also do the Moog Slayer and FM-800 mods. Much Fun.

How would one wire the Noise Level Mod? Is that a simple trim pot replacement too?

Also, what if instead of toggling the noise vs External input, one would like to mix the noise with the External Input?

Re: External Audio in Mod.

2011-07-18 by 7yash

Thanks for the additional info, Bill.

It does makes more sense to mix another Noise source prior to using the External Audio In rather than Mix it with the existing Noise generator: this way one could use other types of Noise too.

Yes, I did hear of tales of either equipment or ear damage with the Moog Slayer mod. More like Ear Slayer or Monitor Slayer to me! ;)

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-18 by billmeirelles@uol.com.br

Ur welcome ;-)

Take care,
Bill Meirelles

Em 18/07/2011 19:35, 7yash < josh.nursing@... > escreveu:

Thanks for the additional info, Bill.

It does makes more sense to mix another Noise source prior to using the External Audio In rather than Mix it with the existing Noise generator: this way one could use other types of Noise too.

Yes, I did hear of tales of either equipment or ear damage with the Moog Slayer mod. More like Ear Slayer or Monitor Slayer to me! ;)

Re: External Audio in Mod.

2011-07-19 by 7yash

Tried the Moog Slayer pot mod with pots I had in hand. If I use a smaller pot resistance value, it's normal that I get a low range, right?

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-19 by billmeirelles@uol.com.br

Only if the pot value is too small, than the ground will leak and you will
loose signal power, if you are using a 50k or bigger it should be ok, I do
prefere B 50k linear pots instead of log audio taper, the response is
much smoother. Also I do put a general porpouse diode bettween the
cutoff pot's positive out (middle terminal) and the pcb to prevent short
circuit and signal loss. The diode could be an 1N4148, very easy to find.

Em 18/07/2011 21:37, 7yash < josh.nursing@... > escreveu:

Tried the Moog Slayer pot mod with pots I had in hand. If I use a smaller pot resistance value, it's normal that I get a low range, right?

Re: External Audio in Mod.

2011-07-19 by 7yash

Nice. Can't wait to get the proper parts for these mods.

On circuitbenders.co.uk, they have a switchable source for the FM modulation: DCO1 or DCO2 or Noise or External Audio. That should be interesting to implement as well.

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-19 by billmeirelles@uol.com.br

Select between DCO1 or DCO2 will give you the same response as both
DCOs are exactly the same, no diference between them, as for noise
or external audio it can be done by converting the audio signal to DC,
check the expert sleepers AC enconder page for a simple circuit design
of a rectifier for converting AC audio to DC for CV control of the VCF.
Check it out: http://www.muffwiggler.com/forum/viewtopic.php?t=14328&highlight=voltage+doubler

Em 18/07/2011 22:15, 7yash < josh.nursing@... > escreveu:

Nice. Can't wait to get the proper parts for these mods.

On circuitbenders.co.uk, they have a switchable source for the FM modulation: DCO1 or DCO2 or Noise or External Audio. That should be interesting to implement as well.

Re: External Audio in Mod.

2011-07-19 by 7yash

I will definitely look into Expert Sleepers at one time. I think you mentioned getting extra LFOs and other controls like this, so this will be handy.

As for switching between DCOs: although they ultimately sound the same, they can each be configured differently, so switching between two differently set DCOs as FM input can be useful too.

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-19 by billmeirelles@uol.com.br

Yes, Silent Way is great, you get synced LFOs with lots of wave shapes,
o Step LFO and lots of other stuff. You made your point about the DCO
selector, I haven't going that far in studing the project to find where to
take the DCO2 output, I just implemented the mod that you can find
in here: http://www.synthmod.net/korg/fm800/

Em 18/07/2011 22:47, 7yash < josh.nursing@... > escreveu:

I will definitely look into Expert Sleepers at one time. I think you mentioned getting extra LFOs and other controls like this, so this will be handy.

As for switching between DCOs: although they ultimately sound the same, they can each be configured differently, so switching between two differently set DCOs as FM input can be useful too.

Re: External Audio in Mod.

2011-07-19 by 7yash

Yes, I was looking at that DCO1 FM-800 mod today in the schematics too. Basically, they're tapping into IC 4 and Pin7, with the nearby R 74.

If you trace that back to the Tone generation, you can see that it's taking Pins 28-31 from the MSM5232, marked as 1-2' to 1-16'.

So, basically, I'd say one could do the same with DCO2 by taking Pin 1 of IC 5, with R 75.

We'd need a multi-way switch for all the possibilities here.

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-19 by billmeirelles@uol.com.br

No, I believe you should connect it to pin 7 of IC5 where it leads to R76. The other
side can still be connected to R22, seems to work.

Em 18/07/2011 23:12, 7yash < josh.nursing@... > escreveu:

Yes, I was looking at that DCO1 FM-800 mod today in the schematics too. Basically, they're tapping into IC 4 and Pin7, with the nearby R 74.

If you trace that back to the Tone generation, you can see that it's taking Pins 28-31 from the MSM5232, marked as 1-2' to 1-16'.

So, basically, I'd say one could do the same with DCO2 by taking Pin 1 of IC 5, with R 75.

We'd need a multi-way switch for all the possibilities here.

Re: External Audio in Mod.

2011-07-20 by 7yash

Yes, looks more like it. Interesting stuff, what does that Pin 1 do then?

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-20 by billmeirelles@uol.com.br

I'm not sure, but looks like they are the clock dividers for the octave switches.

Em 19/07/2011 21:57, 7yash < josh.nursing@... > escreveu:

Yes, looks more like it. Interesting stuff, what does that Pin 1 do then?

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-20 by Michael Hawkins

I don't think so. The octave selection is done inside the MSM5232 tone generator.

Which chip are you talking about?

Mike

From: "billmeirelles@..." <billmeirelles@...>
To: korgpolyex@yahoogroups.com
Sent: Tue, July 19, 2011 9:53:19 PM
Subject: Re: [korgpolyex] Re: External Audio in Mod.

I'm not sure, but looks like they are the clock dividers for the octave switches.

Em 19/07/2011 21:57, 7yash < josh.nursing@... > escreveu:

Yes, looks more like it. Interesting stuff, what does that Pin 1 do then?

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-20 by Josh Nursing

They are the IC4 and IC5 chips respectively.

On Wed, Jul 20, 2011 at 6:48 PM, Michael Hawkins <korgpolyex800@...> wrote:

I don't think so. The octave selection is done inside the MSM5232 tone generator.

Which chip are you talking about?

Mike

From: "billmeirelles@..." <billmeirelles@...>
To: korgpolyex@yahoogroups.com
Sent: Tue, July 19, 2011 9:53:19 PM
Subject: Re: [korgpolyex] Re: External Audio in Mod.

I'm not sure, but looks like they are the clock dividers for the octave switches.

Em 19/07/2011 21:57, 7yash < josh.nursing@... > escreveu:

Yes, looks more like it. Interesting stuff, what does that Pin 1 do then?

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Re: [korgpolyex] Re: External Audio in Mod.

2011-07-20 by billmeirelles@uol.com.br

IC4 and IC5 they come right before the MSM5232 chip and inputs at
the MSM5232 are marked as 16", 8", 4" and 2", looks like they are the
clock dividers.

Em 20/07/2011 19:48, Michael Hawkins < korgpolyex800@... > escreveu:

I don't think so. The octave selection is done inside the MSM5232 tone generator.

Which chip are you talking about?

Mike

From: "billmeirelles@..."
To: korgpolyex@yahoogroups.com
Sent: Tue, July 19, 2011 9:53:19 PM
Subject: Re: [korgpolyex] Re: External Audio in Mod.

I'm not sure, but looks like they are the clock dividers for the octave switches.

Em 19/07/2011 21:57, 7yash < josh.nursing@... > escreveu:

Yes, looks more like it. Interesting stuff, what does that Pin 1 do then?

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-21 by Michael Hawkins

Those two chips come after the tone generator.

They take the square wave outputs of the TG (16,8,4,2) and buffer them and also provide the quasi triangle wave (by attenuating the higher foots more).

This gives four outputs. Two for each DCO. One is square the other triangle for each DCO.

Mike

From: "billmeirelles@..." <billmeirelles@...>
To: korgpolyex@yahoogroups.com
Sent: Wed, July 20, 2011 6:58:29 PM
Subject: Re: [korgpolyex] Re: External Audio in Mod.

IC4 and IC5 they come right before the MSM5232 chip and inputs at
the MSM5232 are marked as 16", 8", 4" and 2", looks like they are the
clock dividers.

Em 20/07/2011 19:48, Michael Hawkins < korgpolyex800@... > escreveu:

I don't think so. The octave selection is done inside the MSM5232 tone generator.

Which chip are you talking about?

Mike

From: "billmeirelles@..."
To: korgpolyex@yahoogroups.com
Sent: Tue, July 19, 2011 9:53:19 PM
Subject: Re: [korgpolyex] Re: External Audio in Mod.

I'm not sure, but looks like they are the clock dividers for the octave switches.

Em 19/07/2011 21:57, 7yash < josh.nursing@... > escreveu:

Yes, looks more like it. Interesting stuff, what does that Pin 1 do then?

Re: External Audio in Mod.

2011-07-21 by 7yash

Hmmm, interesting. Do you think they are mixable with the original DCOx signal without detriment?

--- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@...> wrote:
>
> Those two chips come after the tone generator.
>
> They take the square wave outputs of the TG (16,8,4,2) and buffer them and also
> provide the quasi triangle wave (by attenuating the higher foots more).
>
> This gives four outputs. Two for each DCO. One is square the other triangle for
> each DCO.

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-21 by Michael Hawkins

Yes, you could mix them but it wouldn't do anything much at all. Let me explain...

The biggest drawback of the Poly-800 design was the tone generator. The MSM5232 was produced to be used in arcade games and it was used in many, many of them too!

So Korg took the MSM5232 and put it into the Poly-800 because they were trying to build a low cost synth. They certainly achieved that but in doing so, they left the Poly-800 with a very primitive oscillator source. The MSM5232 produces pure square wave output. IC4 and IC5 section provides a way to produce a slightly, kind of, sort of triangle wave shape by attenuating the four octave sources.

Mixing them is not going to achieve anything in my opinion. I hate to disappoint you but the MSM5232 waveform generation is THAT primitive.

That's why my focus now (and it's a rather fuzzy focus given my other commitments) is on altering the DCO2 clock so that it is far more independent of DCO1 (giving us far better phasing). And, I am also thinking about providing a kit to completely replace the original TG with a new one so that all eight DCO's are fully independent of each other and so that they can produce a far wider variety of wave forms (perhaps using a waveform ROM like the DW-8000). But that is all just a bit of a wish list right now.

It's actually interesting how a global economic slow down has real effects on projects like these (which I consider to be "cultural"). So as economic considerations become major to individuals (including me), time on "cultural" projects, hobbies etc is pressured or crimped.

But hopefully, I will be able to get the HAWK arpeggiator done this year!

Mike

From: 7yash <josh.nursing@...>
To: korgpolyex@yahoogroups.com
Sent: Wed, July 20, 2011 8:58:53 PM
Subject: [korgpolyex] Re: External Audio in Mod.

Hmmm, interesting. Do you think they are mixable with the original DCOx signal without detriment?

--- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@...> wrote:
>
> Those two chips come after the tone generator.
>
> They take the square wave outputs of the TG (16,8,4,2) and buffer them and also
> provide the quasi triangle wave (by attenuating the higher foots more).
>
> This gives four outputs. Two for each DCO. One is square the other triangle for
> each DCO.

Re: External Audio in Mod.

2011-07-21 by 7yash

Thanks for the info, Mike. You sure know your way around it.

I totally agree about the Osc section limitations, and this is why any way where we could improve it is valuable.

What if we dabble with the wave-shaping section after the MSM5232? That was my line of thought.

However, I think that I would be able to do much more and in a simpler way by mixing into the VCF any external Audio. For instance, I could mix a set of oscillators from the Kurzweil K2500 into the External Audio In, and treat those with the Korg VCF. By connecting the Kurz to the Korg through Midi too, then the Korg's Oscs + the Kurz's Oscs would be mixed and transposed simultaneously.

In addition, the External Audio in would laso allow me to mix in any new DIY Oscs too.

Ideally a new Osc module would be installed within the synth itself.

--- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@...> wrote:
>
> Yes, you could mix them but it wouldn't do anything much at all. Let me
> explain...
>
> The biggest drawback of the Poly-800 design was the tone generator. The MSM5232
> was produced to be used in arcade games and it was used in many, many of them
> too!
>
> So Korg took the MSM5232 and put it into the Poly-800 because they were trying
> to build a low cost synth. They certainly achieved that but in doing so, they
> left the Poly-800 with a very primitive oscillator source. The MSM5232 produces
> pure square wave output. IC4 and IC5 section provides a way to produce a
> slightly, kind of, sort of triangle wave shape by attenuating the four octave
> sources.
>
> Mixing them is not going to achieve anything in my opinion. I hate to disappoint
> you but the MSM5232 waveform generation is THAT primitive.
>
> That's why my focus now (and it's a rather fuzzy focus given my other
> commitments) is on altering the DCO2 clock so that it is far more independent of
> DCO1 (giving us far better phasing). And, I am also thinking about providing a
> kit to completely replace the original TG with a new one so that all eight DCO's
> are fully independent of each other and so that they can produce a far wider
> variety of wave forms (perhaps using a waveform ROM like the DW-8000). But that
> is all just a bit of a wish list right now.
>
> It's actually interesting how a global economic slow down has real effects on
> projects like these (which I consider to be "cultural"). So as economic
> considerations become major to individuals (including me), time on "cultural"
> projects, hobbies etc is pressured or crimped.
>
> But hopefully, I will be able to get the HAWK arpeggiator done this year!
>
> Mike
>
>
>
>
>
> ________________________________
> From: 7yash <josh.nursing@...>
> To: korgpolyex@yahoogroups.com
> Sent: Wed, July 20, 2011 8:58:53 PM
> Subject: [korgpolyex] Re: External Audio in Mod.
>
>
> Hmmm, interesting. Do you think they are mixable with the original DCOx signal
> without detriment?
>
> --- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@> wrote:
> >
> > Those two chips come after the tone generator.
> >
> > They take the square wave outputs of the TG (16,8,4,2) and buffer them and also
> >
> > provide the quasi triangle wave (by attenuating the higher foots more).
> >
> > This gives four outputs. Two for each DCO. One is square the other triangle for
> >
> > each DCO.
>

Re: [korgpolyex] DCO2 detune

2011-07-22 by Michael Hawkins

Gordon,

I want to be able to digitally control the oscillator variation of DCO2. Digital control also might mean using a D2A or use an analog control. Or even a digital pot.

But the goal here is to be able to vary the frequency of DCO2 which gets its "master" rate from the master clock. The master clock will continue to be sent direct to DCO1. And the MG and joystick bend will also continue to vary the master clock rate (thus giving both DCO1 and DCO2 the same MG and joystick bend.

So I want to continue to use the original Poly master clock but want to insert a new DCO2 "detune" that has far more frequency variation and far more granular control than the current detune.

I seem to remember from my electronic engineering classes (that would be 15 years ago now) that a phase locked loop (4066?) might be the way to do this. Does anyone have experience with PLL's for generating frequencies that are slightly varied from the input master clock?

Mike

From: Gordon JC Pearce <gordon@...>
To: korgpolyex@yahoogroups.com
Sent: Mon, July 18, 2011 2:17:47 PM
Subject: Re: [korgpolyex] DCO2 detune

On Mon, 18 Jul 2011 00:55:06 -0000
"korgpolyex800" <korgpolyex800@...> wrote:

> Can anyone suggest a way that I could produce a slightly offset oscillation based on a master clock source? And that slight offset could be adjusted using digital or analog signal voltage technique?

Not easily, but you could use a crystal oscillator with a varicap diode to pull it a few kHz. I don't know if that would get you the range you're looking for. Some radios use a transistor and a capacitor to shift the CPU clock a bit. That way, if a harmonic of the clock oscillator will cause interference to a particular channel you can move it out of the way. I'll see if I can scan in the relevant page of a manual that shows this - I know the Motorol MC Micro has this, so if you find a PDF you can maybe do something with that.

If you really wanted to go nuts with it, you could use a DDS chip.

Gordon MM0YEQ

Re: DCO2 detune PWM?

2011-07-22 by k9k9dog

if this is being discussed, any plans to add pulse width?
(to original DCO)
eg: if the square is produced by a comparator, varying the
input compared to will vary the pulse width. maybe
simething similar is possible here?

--- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@...> wrote:
>
> Gordon,
>
> I want to be able to digitally control the oscillator variation of DCO2. Digital
> control also might mean using a D2A or use an analog control. Or even a digital
> pot.
>
> But the goal here is to be able to vary the frequency of DCO2 which gets its
> "master" rate from the master clock. The master clock will continue to be sent
> direct to DCO1. And the MG and joystick bend will also continue to vary the
> master clock rate (thus giving both DCO1 and DCO2 the same MG and joystick bend.
>
> So I want to continue to use the original Poly master clock but want to insert a
> new DCO2 "detune" that has far more frequency variation and far more granular
> control than the current detune.
>
> I seem to remember from my electronic engineering classes (that would be 15
> years ago now) that a phase locked loop (4066?) might be the way to do this.
> Does anyone have experience with PLL's for generating frequencies that are
> slightly varied from the input master clock?
>
> Mike
>
>
>
>
> ________________________________
> From: Gordon JC Pearce <gordon@...>
> To: korgpolyex@yahoogroups.com
> Sent: Mon, July 18, 2011 2:17:47 PM
> Subject: Re: [korgpolyex] DCO2 detune
>
>
> On Mon, 18 Jul 2011 00:55:06 -0000
> "korgpolyex800" <korgpolyex800@...> wrote:
>
> > Can anyone suggest a way that I could produce a slightly offset oscillation
> >based on a master clock source? And that slight offset could be adjusted using
> >digital or analog signal voltage technique?
>
> Not easily, but you could use a crystal oscillator with a varicap diode to pull
> it a few kHz. I don't know if that would get you the range you're looking for.
> Some radios use a transistor and a capacitor to shift the CPU clock a bit. That
> way, if a harmonic of the clock oscillator will cause interference to a
> particular channel you can move it out of the way. I'll see if I can scan in
> the relevant page of a manual that shows this - I know the Motorol MC Micro has
> this, so if you find a PDF you can maybe do something with that.
>
> If you really wanted to go nuts with it, you could use a DDS chip.
>
> Gordon MM0YEQ
>

Re: DCO2 detune PWM?

2011-07-22 by 7yash

I second the idea, although it can also be done from the external audio in mod.

--- In korgpolyex@yahoogroups.com, "k9k9dog" <domgoold@...> wrote:
>
> if this is being discussed, any plans to add pulse width?
> (to original DCO)
> eg: if the square is produced by a comparator, varying the
> input compared to will vary the pulse width. maybe
> simething similar is possible here?

Re: [korgpolyex] Re: DCO2 detune PWM?

2011-07-22 by billmeirelles@uol.com.br

Put the output of you Poly 800 into a scope and you will
see that your Poly will never output a square wave, looks
more like a fuzzy saw wave, anyways, finding a way to
modulate the wave shape will be of great value, sure thing.

Em 22/07/2011 07:40, k9k9dog < domgoold@... > escreveu:

if this is being discussed, any plans to add pulse width?
(to original DCO)
eg: if the square is produced by a comparator, varying the
input compared to will vary the pulse width. maybe
simething similar is possible here?

--- In korgpolyex@yahoogroups.com, Michael Hawkins wrote:
>
> Gordon,
>
> I want to be able to digitally control the oscillator variation of DCO2. Digital
> control also might mean using a D2A or use an analog control. Or even a digital
> pot.
>
> But the goal here is to be able to vary the frequency of DCO2 which gets its
> "master" rate from the master clock. The master clock will continue to be sent
> direct to DCO1. And the MG and joystick bend will also continue to vary the
> master clock rate (thus giving both DCO1 and DCO2 the same MG and joystick bend.
>
> So I want to continue to use the original Poly master clock but want to insert a
> new DCO2 "detune" that has far more frequency variation and far more granular
> control than the current detune.
>
> I seem to remember from my electronic engineering classes (that would be 15
> years ago now) that a phase locked loop (4066?) might be the way to do this.
> Does anyone have experience with PLL's for generating frequencies that are
> slightly varied from the input master clock?
>
> Mike
>
>
>
>
> ________________________________
> From: Gordon JC Pearce
> To: korgpolyex@yahoogroups.com
> Sent: Mon, July 18, 2011 2:17:47 PM
> Subject: Re: [korgpolyex] DCO2 detune
>
>
& gt; On Mon, 18 Jul 2011 00:55:06 -0000
> "korgpolyex800" wrote:
>
> > Can anyone suggest a way that I could produce a slightly offset oscillation
> >based on a master clock source? And that slight offset could be adjusted using
> >digital or analog signal voltage technique?
>
> Not easily, but you could use a crystal oscillator with a varicap diode to pull
> it a few kHz. I don't know if that would get you the range you're looking for.
> Some radios use a transistor and a capacitor to shift the CPU clock a bit. That
> way, if a harmonic of the clock oscillator will cause interference to a
> particular channel you can move it out of the way. I'll see if I can scan in
> the relevant page of a manual that shows this - I know the Motorol MC Micro has
> this, so if you find a PDF you can maybe do something with that.
>
> I f you really wanted to go nuts with it, you could use a DDS chip.
>
> Gordon MM0YEQ
>

Re: External Audio in Mod.

2011-07-22 by 7yash

All right so I'm starting to grasp the importance of the Muffwiggler rectifier so that we can get an Audio signal to send CV as well. Looks like if I want have all the flexibility I envision, I will have to go through this route anyway.

If I do this circuitry, then with the same single Stereo Input Jack, I would be able to route the External Audio into the DCO1 signal mix and also send the CV to whichever CV Input?

That would be fairly awesome.

Re: [korgpolyex] Re: DCO2 detune PWM?

2011-07-23 by Michael Hawkins

not possible because the master clock is many times the actual tonal output which is created within the MSM5232.

From: k9k9dog <domgoold@...>
To: korgpolyex@yahoogroups.com
Sent: Fri, July 22, 2011 6:40:25 AM
Subject: [korgpolyex] Re: DCO2 detune PWM?

if this is being discussed, any plans to add pulse width?
(to original DCO)
eg: if the square is produced by a comparator, varying the
input compared to will vary the pulse width. maybe
simething similar is possible here?

--- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@...> wrote:
>
> Gordon,
>
> I want to be able to digitally control the oscillator variation of DCO2. Digital
> control also might mean using a D2A or use an analog control. Or even a digital
> pot.
>
> But the goal here is to be able to vary the frequency of DCO2 which gets its
> "master" rate from the master clock. The master clock will continue to be sent
> direct to DCO1. And the MG and joystick bend will also continue to vary the
> master clock rate (thus giving both DCO1 and DCO2 the same MG and joystick bend.
>
> So I want to continue to use the original Poly master clock but want to insert a
> new DCO2 "detune" that has far more frequency variation and far more granular
> control than the current detune.
>
> I seem to remember from my electronic engineering classes (that would be 15
> years ago now) that a phase locked loop (4066?) might be the way to do this.
> Does anyone have experience with PLL's for generating frequencies that are
> slightly varied from the input master clock?
>
> Mike
>
>
>
>
> ________________________________
> From: Gordon JC Pearce <gordon@...>
> To: korgpolyex@yahoogroups.com
> Sent: Mon, July 18, 2011 2:17:47 PM
> Subject: Re: [korgpolyex] DCO2 detune
>
>
> On Mon, 18 Jul 2011 00:55:06 -0000
> "korgpolyex800" <korgpolyex800@...> wrote:
>
> > Can anyone suggest a way that I could produce a slightly offset oscillation
> >based on a master clock source? And that slight offset could be adjusted using
> >digital or analog signal voltage technique?
>
> Not easily, but you could use a crystal oscillator with a varicap diode to pull
> it a few kHz. I don't know if that would get you the range you're looking for.
> Some radios use a transistor and a capacitor to shift the CPU clock a bit. That
> way, if a harmonic of the clock oscillator will cause interference to a
> particular channel you can move it out of the way. I'll see if I can scan in
> the relevant page of a manual that shows this - I know the Motorol MC Micro has
> this, so if you find a PDF you can maybe do something with that.
>
> If you really wanted to go nuts with it, you could use a DDS chip.
>
> Gordon MM0YEQ
>

Re: [korgpolyex] Re: DCO2 detune PWM?

2011-07-23 by Michael Hawkins

I am not talking about the output of the synth.

I am speaking about the master clock that the TG uses to produce the various note frequencies.

Those note frequencies are indeed square wave before they enter into IC4/5. Check it out for yourself.

Mike

From: "billmeirelles@..." <billmeirelles@...>
To: korgpolyex@yahoogroups.com
Sent: Fri, July 22, 2011 9:17:43 AM
Subject: Re: [korgpolyex] Re: DCO2 detune PWM?

Put the output of you Poly 800 into a scope and you will
see that your Poly will never output a square wave, looks
more like a fuzzy saw wave, anyways, finding a way to
modulate the wave shape will be of great value, sure thing.

Em 22/07/2011 07:40, k9k9dog < domgoold@... > escreveu:

if this is being discussed, any plans to add pulse width?
(to original DCO)
eg: if the square is produced by a comparator, varying the
input compared to will vary the pulse width. maybe
simething similar is possible here?

--- In korgpolyex@yahoogroups.com, Michael Hawkins wrote:
>
> Gordon,
>
> I want to be able to digitally control the oscillator variation of DCO2. Digital
> control also might mean using a D2A or use an analog control. Or even a digital
> pot.
>
> But the goal here is to be able to vary the frequency of DCO2 which gets its
> "master" rate from the master clock. The master clock will continue to be sent
> direct to DCO1. And the MG and joystick bend will also continue to vary the
> master clock rate (thus giving both DCO1 and DCO2 the same MG and joystick bend.
>
> So I want to continue to use the original Poly master clock but want to insert a
> new DCO2 "detune" that has far more frequency variation and far more granular
> control than the current detune.
>
> I seem to remember from my electronic engineering classes (that would be 15
> years ago now) that a phase locked loop (4066?) might be the way to do this.
> Does anyone have experience with PLL's for generating frequencies that are
> slightly varied from the input master clock?
>
> Mike
>
>
>
>
> ________________________________
> From: Gordon JC Pearce
> To: korgpolyex@yahoogroups.com
> Sent: Mon, July 18, 2011 2:17:47 PM
> Subject: Re: [korgpolyex] DCO2 detune
>
>
gt; On Mon, 18 Jul 2011 00:55:06 -0000
> "korgpolyex800" wrote:
>
> > Can anyone suggest a way that I could produce a slightly offset oscillation
> >based on a master clock source? And that slight offset could be adjusted using
> >digital or analog signal voltage technique?
>
> Not easily, but you could use a crystal oscillator with a varicap diode to pull
> it a few kHz. I don't know if that would get you the range you're looking for.
> Some radios use a transistor and a capacitor to shift the CPU clock a bit. That
> way, if a harmonic of the clock oscillator will cause interference to a
> particular channel you can move it out of the way. I'll see if I can scan in
> the relevant page of a manual that shows this - I know the Motorol MC Micro has
> this, so if you find a PDF you can maybe do something with that.
>
> I f you really wanted to go nuts with it, you could use a DDS chip.
>
> Gordon MM0YEQ
>

Re: [korgpolyex] Re: DCO2 detune PWM?

2011-07-23 by billmeirelles@uol.com.br

Yep, I got it, it's just that I was talking about the actual output of the synth,
as you certainly know it's not possible to have a square wave at the output
of a Poly 800, that was all...

Em 22/07/2011 22:09, Michael Hawkins < korgpolyex800@... > escreveu:

I am not talking about the output of the synth.

I am speaking about the master clock that the TG uses to produce the various note frequencies.

Those note frequencies are indeed square wave before they enter into IC4/5. Check it out for yourself.

Mike

From: "billmeirelles@..."
To: korgpolyex@yahoogroups.com
Sent: Fri, July 22, 2011 9:17:43 AM
Subject: Re: [korgpolyex] Re: DCO2 detune PWM?

Put the output of you Poly 800 into a scope and you will
see that your Poly will never output a square wave, looks
more like a fuzzy saw wave, anyways, finding a way to
modulate the wave shape will be of great value, sure thing.

Em 22/07/2011 07:40, k9k9dog < domgoold@... > escreveu:

if this is being discussed, any plans to add pulse width?
(to original DCO)
eg: if the square is produced by a comparator, varying the
input compared to will vary the pulse width. maybe
simething similar is possible here?

--- In korgpolyex@yahoogroups.com, Michael Hawkins wrote:
>
> Gordon,
>
> I want to be able to digitally control the oscillator variation of DCO2. Digital
> control also might mean using a D2A or use an analog control. Or even a digital
> pot.
>
> But the goal here is to be able to vary the frequency of DCO2 which gets its
> "master" rate from the master clock. The master clock will continue to be sent
> direct to DCO1. And the MG and joystick bend will also continue to vary the
> master clock rate (thus giving both DCO1 and DCO2 the same MG and joystick bend.
> < br /> > So I want to continue to use the original Poly master clock but want to insert a
> new DCO2 "detune" that has far more frequency variation and far more granular
> control than the current detune.
>
> I seem to remember from my electronic engineering classes (that would be 15
> years ago now) that a phase locked loop (4066?) might be the way to do this.
> Does anyone have experience with PLL's for generating frequencies that are
> slightly varied from the input master clock?
>
> Mike
>
>
>
>
> ________________________________
> From: Gordon JC Pearce
> To: korgpolyex@yahoogroups.com
> Sent: Mon, July 18, 2011 2:17:47 PM
> Subject: Re: [korgpolyex] DCO2 detune
>
>
gt; On Mon, 18 Jul 2011 00:55:06 -0000
> "korgpolyex800" wrote:
>
> > Can anyone suggest a way that I could produce a slightly offset oscillation
> >based on a master clock source? And that slight offset could be adjusted using
> >digital or analog signal voltage technique?
>
> Not easily, but you could use a crystal oscillator with a varicap diode to pull
> it a few kHz. I don't know if that would get you the range you're looking for.
> Some radios use a transistor and a capacitor to shift the CPU clock a bit. That
> way, if a harmonic of the clock oscillator will cause interference to a
> particular channel you can move it out of the way. I'll see if I can scan in
> the relevant page of a manual that shows this - I know the Motorol MC Micro has
> this, so if you find a PDF you can maybe do something with that.
>
> I f you really wanted to go nuts with it, you could use a DDS chip.

>
> Gordon MM0YEQ
>

Re: DCO2 detune

2011-07-26 by 7yash

Mike, see if Page 2 here helps - there seems to be a filter and a comparator:

https://docs.google.com/viewer?a=v&q=cache:zW7k4kBsO6MJ:www.national.com/an/AN/AN-335.pdf+PLL+digital+synthesis&hl=en&pid=bl&srcid=ADGEESigG-vt_-x_Yugyin2LsF9407YCMaxLSlWXMxpksYPyByfCHTG3DhRFRg-Ni2lwlTPLqRDs9O0-U6yFheqcv-3ymUXKerNC2jXMOAMcI_qDyPhAy11N7WpSJpIeYoJmswrTtMgd&sig=AHIEtbRD5S1yHyW2rEaUi0VxjTPf7Gblzw&pli=1

--- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@...> wrote:

> I seem to remember from my electronic engineering classes (that would be 15
> years ago now) that a phase locked loop (4066?) might be the way to do this.
> Does anyone have experience with PLL's for generating frequencies that are
> slightly varied from the input master clock?
>
> Mike

Re: External Audio in Mod.

2011-07-27 by 7yash

Success!

I opted for mixing into the DCO1 & DCO2 Pins on the NJM2069 rather than switching from the Noise Input for now as it was easier. When you do this, you should set the DCO level to max, go into Hold mode and press a key, then turn each harmonic of the DCO to 0 for it to work.

I used some stacked saws from the Kurzweil. These are multi-samples and DSP-based Oscs.

Video with the Kurz providing the Oscs and the arpeggiations:
http://www.youtube.com/watch?v=DHGhQdMpXDI

With a Kurzweil Solina program and with the Kurz filters turned off, I can get some very interesting Solina/Eminent-type sounds(!), especially when turning the Bucket-Brigade Chorus on, which is to be expected.

Next, as the DCO1 input got unsoldered again, I'll work on that and with a new cable, will try the Kurz sending to both inputs simultaneously.

After that, I will try to set up some judicious routing so that he raw Kurz Oscs go to the Korg Poly-800 for filtering, then the output of the Korg will go straight back into the Kurzweil for processing with the KDFX Digital multi-effects.

This is going to be amazing.

With the Noise Pin Audio In, I could also add another Osc input, giving me three different inputs into the Filter.

Re: [korgpolyex] DCO2 detune

2011-07-29 by Epiik Soul

Hi all.

If the signal were analog, you could use a lag processor to slow down the signal to DCO2.

Is there a digital equivalent?

On Jul 21, 2011, at 9:17 PM, Michael Hawkins <korgpolyex800@...> wrote:

Gordon,

I want to be able to digitally control the oscillator variation of DCO2. Digital control also might mean using a D2A or use an analog control. Or even a digital pot.

But the goal here is to be able to vary the frequency of DCO2 which gets its "master" rate from the master clock. The master clock will continue to be sent direct to DCO1. And the MG and joystick bend will also continue to vary the master clock rate (thus giving both DCO1 and DCO2 the same MG and joystick bend.

So I want to continue to use the original Poly master clock but want to insert a new DCO2 "detune" that has far more frequency variation and far more granular control than the current detune.

I seem to remember from my electronic engineering classes (that would be 15 years ago now) that a phase locked loop (4066?) might be the way to do this. Does anyone have experience with PLL's for generating frequencies that are slightly varied from the input master clock?

Mike

From: Gordon JC Pearce <gordon@...>
To: korgpolyex@yahoogroups.com
Sent: Mon, July 18, 2011 2:17:47 PM
Subject: Re: [korgpolyex] DCO2 detune

On Mon, 18 Jul 2011 00:55:06 -0000
"korgpolyex800" <korgpolyex800@...> wrote:

> Can anyone suggest a way that I could produce a slightly offset oscillation based on a master clock source? And that slight offset could be adjusted using digital or analog signal voltage technique?

Not easily, but you could use a crystal oscillator with a varicap diode to pull it a few kHz. I don't know if that would get you the range you're looking for. Some radios use a transistor and a capacitor to shift the CPU clock a bit. That way, if a harmonic of the clock oscillator will cause interference to a particular channel you can move it out of the way. I'll see if I can scan in the relevant page of a manual that shows this - I know the Motorol MC Micro has this, so if you find a PDF you can maybe do something with that.

If you really wanted to go nuts with it, you could use a DDS chip.

Gordon MM0YEQ

Re: [korgpolyex] Re: External Audio in Mod.

2011-07-29 by Epiik Soul

Your idea for using the DW8000 tone generator would be awesome.

I used to have a DW6000 and an 8000 and loved them both.

On Jul 21, 2011, at 9:34 AM, Michael Hawkins <korgpolyex800@...> wrote:

Yes, you could mix them but it wouldn't do anything much at all. Let me explain...

The biggest drawback of the Poly-800 design was the tone generator. The MSM5232 was produced to be used in arcade games and it was used in many, many of them too!

So Korg took the MSM5232 and put it into the Poly-800 because they were trying to build a low cost synth. They certainly achieved that but in doing so, they left the Poly-800 with a very primitive oscillator source. The MSM5232 produces pure square wave output. IC4 and IC5 section provides a way to produce a slightly, kind of, sort of triangle wave shape by attenuating the four octave sources.

Mixing them is not going to achieve anything in my opinion. I hate to disappoint you but the MSM5232 waveform generation is THAT primitive.

That's why my focus now (and it's a rather fuzzy focus given my other commitments) is on altering the DCO2 clock so that it is far more independent of DCO1 (giving us far better phasing). And, I am also thinking about providing a kit to completely replace the original TG with a new one so that all eight DCO's are fully independent of each other and so that they can produce a far wider variety of wave forms (perhaps using a waveform ROM like the DW-8000). But that is all just a bit of a wish list right now.

It's actually interesting how a global economic slow down has real effects on projects like these (which I consider to be "cultural"). So as economic considerations become major to individuals (including me), time on "cultural" projects, hobbies etc is pressured or crimped.

But hopefully, I will be able to get the HAWK arpeggiator done this year!

Mike

From: 7yash <josh.nursing@...>
To: korgpolyex@yahoogroups.com
Sent: Wed, July 20, 2011 8:58:53 PM
Subject: [korgpolyex] Re: External Audio in Mod.

Hmmm, interesting. Do you think they are mixable with the original DCOx signal without detriment?

--- In korgpolyex@yahoogroups.com, Michael Hawkins <korgpolyex800@...> wrote:
>
> Those two chips come after the tone generator.
>
> They take the square wave outputs of the TG (16,8,4,2) and buffer them and also
> provide the quasi triangle wave (by attenuating the higher foots more).
>
> This gives four outputs. Two for each DCO. One is square the other triangle for
> each DCO.

Re: External Audio in Mod.

2011-07-29 by 7yash

I just finalized some mods myself, including the two Audio Ins and I'm using the oscillators from my Kurzweil K2500 (which can be samples or DSP-based) and the setup sounds awesome.

I will upload a video or two soon.

--- In korgpolyex@yahoogroups.com, Epiik Soul <electrohead2000@...> wrote:
>
> Your idea for using the DW8000 tone generator would be awesome.
> I used to have a DW6000 and an 8000 and loved them both.