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Nice mods.

Nice mods.

2014-03-05 by <josh.nursing@gmail.com>

I did some recent mods and I am looking for any cool mods which are not too intrusive. I did: Effects VCF bypass (Treble + Attack Mod) and Enhanced bass response mod. Very worthwhile (thanks to Chip and Tony). Those SSM2056 have punch!: https://soundcloud.com/yashn/korg-polysix-bass-mod-attack

This was before tonight where I improve calibration and tuning, and also disconnected D1 so that I can now mix SAW + PW before going into the VCF. This, together with the attack mod and better frequency response is very good too as the Pulse provides for more impact on attack for those bass/percussive sounds.

What other simple mods should I consider?

Johannes's Noise input to VCF? Has anyone done it?

This would be great with an envelope to the noise, and together with a fast pitch envelope would help make great drum sounds or effects.

Yash

RE: Nice mods.

2014-03-05 by <chipaudette@yahoo.com>

You could modify the LFO circuit to make it go to higher frequencies.  Then, you could further mod the LFO circuit so that its frequency is deflected by the pitch CV that is commanding one of the voices (say, the first voice).  If you magically do both mods, and you put the synth in Unison mod (or Chord Mem with only the first voice), you could get some cool FM effects.

Chip

RE: Nice mods.

2014-03-05 by <josh.nursing@gmail.com>

Chip, that's a cool idea.

Actually, I was thinking of the LFO too yesterday, but in a slightly different way: I would like to increase its rate for sure, but then would also like to have either a second LFO route to its frequency or, perhaps even better, an envelope.

In some configurations, the Arp signal, the PWM Speed and the Effects Speed oscillators are lying unused, so I wonder if this can be tapped into.

I may do initial tests with on-board secondary (LF) oscillators driving the MG LFO and then wire in my own using the Arduino. I only have a UNO and not a Mega, so I'm a bit limited in the kind of performance and synthesis mods you effected (brilliant set of mods, by the way) for now.

Another way for more flexibility would be to do a CV-in for the LFO speed, which would let me wire in either the Arduino or Expert Sleepers' Silent Way. How feasible is this and what is required apart from a jack?

Coming back to the FM mod you suggested, this is very good and could also be used with the ones above. The question is: will we be able to get a good musical tracking in an easy way with the FM across the keyboard. Otherwise, we can still use the mod for FX sounds.

I can see Radek's mods around the Mod Wheel and LFO in the Photos section. Johannes's kit/mod file also describes some mods there, so that could be envisioned too.

Re: [PolySix] Nice mods.

2014-03-05 by Terje Winther

Good work and good sounds!

Terje


Den 5. mars. 2014 kl. 02.55 skrev <josh.nursing@gmail.com>:

 

I did some recent mods and I am looking for any cool mods which are not too intrusive. I did: Effects VCF bypass (Treble + Attack Mod) and Enhanced bass response mod. Very worthwhile (thanks to Chip and Tony). Those SSM2056 have punch!: https://soundcloud.com/yashn/korg-polysix-bass-mod-attack


This was before tonight where I improve calibration and tuning, and also disconnected D1 so that I can now mix SAW + PW before going into the VCF. This, together with the attack mod and better frequency response is very good too as the Pulse provides for more impact on attack for those bass/percussive sounds.

What other simple mods should I consider?

Johannes's Noise input to VCF? Has anyone done it?

This would be great with an envelope to the noise, and together with a fast pitch envelope would help make great drum sounds or effects.

Yash



Re: [PolySix] Nice mods.

2014-03-06 by Terje Winther

Hi,
I have been thinking about doing this mod, but a bit unsure if it will be any good. Now it seems like a good idea!

Terje


Den 6. mars. 2014 kl. 02.34 skrev <josh.nursing@gmail.com>:

 

Thanks Terje!


Wait till you hear this recording of a few patches I made today after the simultaneous Saw + PW mod (some slight clipping). We're not scared of Oberheim and Prophet filter sweeps:


Download the file for a high-resolution.

Yash



RE: Nice mods.

2014-03-06 by <chipaudette@yahoo.com>

Regarding the FM mod and its ability to track the pitch of the keyboard...

To have any chance of tracking, you need to get the CV for the voices.  You only have one LFO, so you'll only be able to track the pitch of one of the voices (hence my comment about putting the synth in unison mode, or in single-note chord mem mode).

The real trick is whether you want to get the pitch CV while it's in Volt/Oct scaling (ie, before the exponential circuit) or when it's in Volt/Hz scaling (ie, after the exponential circuit).  I'm not sure which gives better FM effects.

If you want the Volt/Oct scaling, you're gonna be in trouble because the Polysix keeps the pitch CV for all six voices multiplexed (in time) along with a bunch of other control signals on a single wire.  So, if you really want this pitch CV, you'll have to listen to the three clock signals and grab the pitch CV (with your Arduino) at just those times when the clock lines are set correctly.  This is feasible to do with an Arduino (I think) and I can help with what High/Low states you need to watch for the clock lines, but it will not be a super-easy thing to do.

Much easier would be to grab the pitch CV after the expo circuit when it is in Volt/Hz scaling.  These Volt/Hz pitch CVs are already demultiplexed and just sitting on a wire waiting to be grabbed whenever you feel like it...no special timing necessary.

Chip

Re: [PolySix] Nice mods.

2014-03-06 by <josh.nursing@gmail.com>

Hey Terje,

Actually, I'm surprised you *haven't* done this mod on your pimped out Polysix! 

I can see 11 Reasons to do it:

1. It's a mod suggested by Johannes. He made a lot of very clever mods, if you check out the Files section as well as the manual for his MIDI kit.

2. We have a subtractive synthesis engine and some consider the Polysix a single osc synth, so any additional harmonics before the filter section should be very valuable. With the mod, you can essentially have '3 simultaneous oscs' in a single voice before the filter stage: SAW + PW + Sub. On selecting SAW, PW is also mixed in. If you want to have just SAW like before, then set PW to 10.

3. It is 'programmable' in the sense that the setting will be stored and recalled in your patch.

4. There is no additional re-programming of the firmware to make the mod programmable. Once you've done the physical mod, there's nothing else to do, it will be stored and recall.

5. There is no additional circuit mod to make the mod programmable. Once you've done the simple physical mod, the existing circuit board will be enough.

6. There is no additional control to be wired in to be able to access the new feature: once the physical mod is done, the existing controls activate or deactivate the new feature.

7. Since the new feature can be deactivated with existing controls, there is no detrimental change to the synth's architecture nor 'vintage' status if you want to revert. (Sorry Murray, I don't agree with you here).

8. Since the new feature can be deactivated with existing controls, there is no need to add a switch to channel the mod on or off to 'revert to the original architecture'.

9. The physical mod is super easy: just remove D1 on KLM-366. You could also just cut one leg. I chose to lift one leg by heating a pad and that's it.

10. This is what it does, crazy osc/filter sweeps and brash, powerful pads, strings, leads and basses. It actually shakes the floor: https://soundcloud.com/yashn/korg-polysix-simultaneous-saw

11. You're a crazy modder :P

Do it!

Yash

RE: Nice mods.

2014-03-06 by <josh.nursing@gmail.com>

Thanks for the extra info, Chip. It does look like tapping the pitch CV after the expo circuit in V/Hz is the way to go. KLM-366 I31-13 for voice 0?

Re: [PolySix] Nice mods.

2014-03-06 by Terje Winther

Thanks - that helped!  :-)

Terje


Den 6. mars. 2014 kl. 13.52 skrev <josh.nursing@gmail.com>:

 

Hey Terje,


Actually, I'm surprised you *haven't* done this mod on your pimped out Polysix! 

I can see 11 Reasons to do it:

1. It's a mod suggested by Johannes. He made a lot of very clever mods, if you check out the Files section as well as the manual for his MIDI kit.

2. We have a subtractive synthesis engine and some consider the Polysix a single osc synth, so any additional harmonics before the filter section should be very valuable. With the mod, you can essentially have '3 simultaneous oscs' in a single voice before the filter stage: SAW + PW + Sub. On selecting SAW, PW is also mixed in. If you want to have just SAW like before, then set PW to 10.

3. It is 'programmable' in the sense that the setting will be stored and recalled in your patch.

4. There is no additional re-programming of the firmware to make the mod programmable. Once you've done the physical mod, there's nothing else to do, it will be stored and recall.

5. There is no additional circuit mod to make the mod programmable. Once you've done the simple physical mod, the existing circuit board will be enough.

6. There is no additional control to be wired in to be able to access the new feature: once the physical mod is done, the existing controls activate or deactivate the new feature.

7. Since the new feature can be deactivated with existing controls, there is no detrimental change to the synth's architecture nor 'vintage' status if you want to revert. (Sorry Murray, I don't agree with you here).

8. Since the new feature can be deactivated with existing controls, there is no need to add a switch to channel the mod on or off to 'revert to the original architecture'.

9. The physical mod is super easy: just remove D1 on KLM-366. You could also just cut one leg. I chose to lift one leg by heating a pad and that's it.

10. This is what it does, crazy osc/filter sweeps and brash, powerful pads, strings, leads and basses. It actually shakes the floor: https://soundcloud.com/yashn/korg-polysix-simultaneous-saw

11. You're a crazy modder :P

Do it!

Yash



Re: Nice mods.

2014-03-25 by <josh.nursing@gmail.com>

Since I repaired the oscillating part of the MG/LFO I gave the KLM-367 a little mod for increasing the LFO speed. I wanted to increase it by an order of magnitude, so according to the series capacitor equation, I can do that by putting a new cap of say 0.033uF in series.

I actually soldered a 103K one (cap code) to get around 0.01 uF.

Results: as expected, my LFO now goes to audio rate or so. I get all types of sounds like vowels or formants to noise at extreme values of Frequency and Level. Very cool.

Side-effects: when my MG Frequency is a 0 and Level is >0, the MG is still there.

Now, what I would like to do is connect the Envelope to the MG Level. The question is: how?

Re: Nice mods.

2014-03-25 by <chipaudette@yahoo.com>

Regarding ENV->LFO, you have to decide whether you want one ENV to affect your one LFO (which is then applied universally to all voices), or if you somehow want the ENV to affect how the LFO is applied to each individual voice independently based on that voice's ENV.  

If you want it to affect each voice inidividually, that will be much harder.  I think that you'd need to introduce a VCA to control the LFO amplitude going to each voice, or you'd have to implement a single VCA that would be in-sync with the CV multiplexing that is going on within the Polysix.  Both sound too hard.

If you don't mind your ENV->LFO mode being applied to all voices, then you can think of it as a mod that is mostly useful in unison mode.  In unison mode, all the envelopes trigger at the same time.  So, you only need to tap into one of the ENV signals.  Pick any of Pin X0-X5 on IC24 on KLM-366.

Then run it to a pot or something so that you can attenuate it.

The hard part is injecting your signal into the LFO (MG) generation circuit on the bottom right of KLM-367.  The existing MG AMT control voltage is mislabled on the schematic.  It's the one that comes off Pin X5 off IC19.  Ideally, there would already be a summing point somewhere in that pathway to which you could add your ENV-based CV.  Unfortunately, there is not.  So you might have to add an op-amp that is configured as a summing amp, pull the existing CV off KLM-367 (I'd break into the path by snipping out R78...take the signal from the upstream leg of R78), and sum it with your new CV from the ENV circuit.

From the output of your summing amp, you'll have to add some resistance to replace the impedance of VR2 and the R78.  After adding that resistance, drop your signal back into the path on KLM-367 (drop it into the downstream leg of what was R78).

Assuming that the DC levels of the two circuit paths are compatible...this should rock!

Chip

Re: Nice mods.

2014-03-27 by <josh.nursing@gmail.com>

Hi Chip,

Thanks for the detailed response, it helps a lot to discuss the architecture and the possibilities as they can directly impact the feasibility of the mods.

I think it will also help if I describe more of what I had in mind, knowing that the single LFO is a bit of a limitation.

As it is, the higher LFO speed is quite useful already - it has made me spend a little more time within the synthesis engine thanks to the new sounds possible. Now, the sounds would be even better if we could make the high-speed LFO effect be strong at attack time and less at sustain time. As an alternative to different sounds, we can also envision sounds which start with low LFO Level and the latter rises up with the sustain portion of the sound.

This means that the ideal implementation of this mod necessitates a re-trigger for each note. Now, we do have an envelope for each note and the Tubbutec mod taps into this. If my understanding is good, the Envelope output has to be buffered to be useful.

Additionally, in your personal setup, you have extra flexibility since you can intercept note triggers: you could do a soft LFO on the Arduino Mega, triggered on each note on, and program it to decrease with time or a soft envelope as well, provided you allow switching that new LFO in in place of the old one in the Polysix. Terje has done something similar so let's see if he can help us understand the electronic implications.

As a peripheral useful mod, I was reading about your detection of a square signal at I16-7. That can come in very useful as well. I am wondering if instead of swapping it in before the next opamp at I16-3, the signal is injected at J on the schematics. There could be a useful combination of the square and triangle signals as well.

I was trying to understand from the schematics how to make the Mod Wheel act upon the VCA and VCF in addition to the usual VCO, but that part stumped me a little. I can see where the signal is switched for MG. For VCO, the schematics are proving hard to decipher for me.