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Polysix Overdrive Mod

Polysix Overdrive Mod

2015-11-30 by chipaudette@yahoo.com

Hi All,


After my Polysix be velocity sensitive, I was really grooving on additional responsivness in the electric piano (EP)  and clav sounds from my Polysix.  But those EP and clav sounds weren't quite right...they were too clean.  I needed a little more compression and more grit.  So, I started to look into modifying the Polysix to give me some overdrive or distortion.


My first try was diode-based distortion.  If you're interested, you can check out my write-up and audio demos here:


http://synthhacker.blogspot.com/2015/11/polysix-drive-diode-distortion.html


In the end, I decided that I didn't like the diode distortion.  Oh well.  I'll have to try something else.  I think that my next attempt will be to add an overdrive capability to one of the LM13600 OTAs.  We'll see if that sounds any better.


Does any of you use an overdrive or distortion for certain sounds with your Polysix?


Chip



Re: [PolySix] Polysix Overdrive Mod

2015-11-30 by eidorian@aladan.net

This isn't specific to the PolySix, but here are some guitar FX electronics sites that you might get some ideas from:

http://www.electrosmash.com/
http://www.moosapotamus.net/
http://hammer.ampage.org/
http://www.muzique.com/
http://www.geofex.com/

One very simple thing to try is to reduce one of the supply voltages (or add a DC offset to the input, which should be very nearly equivalent) on the voice summing op-amp stage, to give you (voltage-controllable) asymmetrical clipping, similar to the Moog CP3 module (which is quite a nice, musical effect in small amounts).  Then again, it still probably isn't quite what you're looking for.

Alternatively you could grab a cheap guitar pedal from craiglist :)  I have a box of them that I love trying out on my synths!

Cheers,
A.

 

On 2015-12-01 08:10, chipaudette@yahoo.com [PolySix] wrote:

 

 

Hi All,

 

After my Polysix be velocity sensitive, I was really grooving on additional responsivness in the electric piano (EP)  and clav sounds from my Polysix.  But those EP and clav sounds weren't quite right...they were too clean.  I needed a little more compression and more grit.  So, I started to look into modifying the Polysix to give me some overdrive or distortion.

 

My first try was diode-based distortion.  If you're interested, you can check out my write-up and audio demos here:

 

http://synthhacker.blogspot.com/2015/11/polysix-drive-diode-distortion.html

 

In the end, I decided that I didn't like the diode distortion.  Oh well.  I'll have to try something else.  I think that my next attempt will be to add an overdrive capability to one of the LM13600 OTAs.  We'll see if that sounds any better.

 

Does any of you use an overdrive or distortion for certain sounds with your Polysix?

 

Chip

 

 

 

Re: [PolySix] Polysix Overdrive Mod [1 Attachment]

2015-11-30 by eidorian@aladan.net

Fantastic work on the velocity mod, by the way!  That's very impressive.

Cheers,
A.

 

On 2015-12-01 09:08, eidorian@aladan.net [PolySix] wrote:

 
This isn't specific to the PolySix, but here are some guitar FX electronics sites that you might get some ideas from:

http://www.electrosmash.com/
http://www.moosapotamus.net/
http://hammer.ampage.org/
http://www.muzique.com/
http://www.geofex.com/

One very simple thing to try is to reduce one of the supply voltages (or add a DC offset to the input, which should be very nearly equivalent) on the voice summing op-amp stage, to give you (voltage-controllable) asymmetrical clipping, similar to the Moog CP3 module (which is quite a nice, musical effect in small amounts).  Then again, it still probably isn't quite what you're looking for.

Alternatively you could grab a cheap guitar pedal from craiglist :)  I have a box of them that I love trying out on my synths!

Cheers,
A.

 

On 2015-12-01 08:10, chipaudette@yahoo.com [PolySix] wrote:

 

 

Hi All,

 

After my Polysix be velocity sensitive, I was really grooving on additional responsivness in the electric piano (EP)  and clav sounds from my Polysix.  But those EP and clav sounds weren't quite right...they were too clean.  I needed a little more compression and more grit.  So, I started to look into modifying the Polysix to give me some overdrive or distortion.

 

My first try was diode-based distortion.  If you're interested, you can check out my write-up and audio demos here:

 

http://synthhacker.blogspot.com/2015/11/polysix-drive-diode-distortion.html

 

In the end, I decided that I didn't like the diode distortion.  Oh well.  I'll have to try something else.  I think that my next attempt will be to add an overdrive capability to one of the LM13600 OTAs.  We'll see if that sounds any better.

 

Does any of you use an overdrive or distortion for certain sounds with your Polysix?

 

Chip

 

 

 
 
 

Re: [PolySix] Polysix Overdrive Mod

2015-12-01 by Florian Anwander

Hello Chip

I think that for a paraphonic effect an external stomp box will be
always more useful.

But distortion per voice after the VCF or even after the VCA would be
very interesting. A sound with low cutoff frequency, but a good amount
of resonance, can sound like hardsync if sent through a fuzz box.

Florian




On 30.11.15 22:40 , chipaudette@yahoo.com [PolySix] wrote:
> Hi All,
>
>
> After my Polysix be velocity sensitive, I was really grooving on
> additional responsivness in the electric piano (EP) and clav sounds from
> my Polysix. But those EP and clav sounds weren't quite right...they were
> too clean. I needed a little more compression and more grit. So, I
> started to look into modifying the Polysix to give me some overdrive or
> distortion.
>
>
> My first try was diode-based distortion. If you're interested, you can
> check out my write-up and audio demos here:
>
>
> http://synthhacker.blogspot.com/2015/11/polysix-drive-diode-distortion.html
>
>
> In the end, I decided that I didn't like the diode distortion. Oh well.
> I'll have to try something else. I think that my next attempt will be to
> add an overdrive capabi lity to one of the LM13600 OTAs. We'll see if
> that sounds any better.
>
>
> Does any of you use an overdrive or distortion for certain sounds with
> your Polysix?
>
>
> Chip
>

Re: Polysix Overdrive Mod

2015-12-10 by chipaudette@yahoo.com

After deciding that the diode distortion sounded bad, I poked around the Polysix schematic and found a bunch of LM13600 in there that were just begging to be overdriven.  Perhaps that's the compression and grit that I'm looking for?

So, I gave it a try.  You can see a demo of the results here:

I think that it's a pretty interesting sound.  I don't want it active all of the time, but I think that it's a cool effect.  Now I just need to figure out how to make it usable without requiring that clip leads hanging out of my synth!

Chip

Re: Polysix Overdrive Mod

2015-12-23 by chipaudette@yahoo.com

Continuing my work on adding OTA overdrive to my Polysix...

Last time, I showed demos where I simply clipped in different resistors to give me the amount of overdrive that I want.  Now, I've started working out how to add a variable resistor (so, a potentiometer) to control the overdrive, yet do it in a way that the overdrive setting will get saved and recalled with the Polysix's patch memory (so, not a potentiometer).

I ended up re-using the approach of an Arduino-controlled digital potentiometer.  I control the amount of overdrive by listening to the Polysix's "Attenuator" knob setting.  Since I never use the lower half of the knob's values, I sense those settings and start turning up the overdrive.  Works pretty well!

Here's a write-up on what I've assembed so far:

http://synthhacker.blogspot.com/2015/12/arduino-controlled-ota-overdrive.html

 

The next steps are to fix one little remaining issue and then to package it nicely for installation in the synth.


Chip




Re: Polysix Overdrive Mod

2015-12-28 by chipaudette@yahoo.com

In my hacking together of my Arduino-controlled OTA Overdrive mod, you may have noticed how messy it was.  Tons of wires everywhere!  I'm thinking that, to finalize this mod, I'll need to make my own little PCB.  I then though, hey, if I'm going to make a custom PCB, why not build the Arduino right into the board!?!  I don't know how to do that, but I figured that I'd give it a try.  

One important motivation for me was that, I learn how to build in my own microcontroller (Arduino or otherwise), I could then use that skill to design all sorts of fun new modifications for the Polysix...like making a more flexible LFO, or like adding a set of six wavetable oscillators (one for each voice) to expand the synth's tonal palette.  Oh, the fun that could be had!

So, I started by figuring out how to build an Arduino on a breadboard.  It's been done many times before by others, but it's the first time that I've ever done it.  I was surprised at how simple it was.  If you're interested, you can check it out here:


Chip

Re: [PolySix] Re: Polysix Overdrive Mod

2015-12-29 by simon

Remember, the Arduino is not the board, but the IDE and libraries behind
it. There are a ton of chips you can use as a Arduino, from a Attiny45
up to a Atmega1280 and even a esp8266 wifi module. and with the latest
Arduino IDE'sthere is a system to add "cores" for other processor
architecture like ARM or intel.

as a bare minimum, you need a chip like the atiny45. not even a
oscillator or pull up resistors are needed. but then of course you need
a programmer to get the code onto your chip, like the avrispmkII or
similar. those can aslo be used from within the IDE by pressing shift
while clicking upload. and a bootloader (if needed) can also be put on
the chip with the programmer. then serial uploading works.

On 28-12-15 15:55, chipaudette@yahoo.com [PolySix] wrote:
> In my hacking together of my Arduino-controlled OTA Overdrive mod, you may have noticed how messy it was. Tons of wires everywhere! I'm thinking that, to finalize this mod, I'll need to make my own little PCB. I then though, hey, if I'm going to make a custom PCB, why not build the Arduino right into the board!?! I don't know how to do that, but I figured that I'd give it a try.
>
> One important motivation for me was that, I learn how to build in my own microcontroller (Arduino or otherwise), I could then use that skill to design all sorts of fun new modifications for the Polysix...like making a more flexible LFO, or like adding a set of six wavetable oscillators (one for each voice) to expand the synth's tonal palette. Oh, the fun that could be had!
>
>
> So, I started by figuring out how to build an Arduino on a breadboard. It's been done many times before by others, but it's the first time that I've ever done it. I was surprised at how simple it was. If you're interested, you can check it out here:
>
>
> http://synthhacker.blogspot.com/2015/12/making-breadboard-arduino.html http://synthhacker.blogspot.com/2015/12/making-breadboard-arduino.html
>
>
>
> Chip
>
>

--
Met vriendelijke Groet,

Simon Claessen
drukknop.nl

Re: Polysix Overdrive Mod

2015-12-30 by tlule@gmx.de

Hi Chip,


Great stuff to add this overdrive possibility.


In the mean time I have advanced on cloning the entire KLM-368 board.

I am now cleaning up design rule violations on the board traces.


Since your overdrive is entirely acting on the KLM-368,

I was thinking of embedding your mod into my schema.


What you do is to control the input attenuation through an analogue voltage on P-Vol.

From my analogue eye, this may be possible in a more direct way through a couple of active elements, like transistors resistors, or maybe an LED-LDR combination? Will think about it.


Cheers,


Haitar