Korg Poly 800

[hellomynameis]

Hey guys,

I recently did the cut off and rez filters and also added the fm synthesis which is found on the moog slayer page. But however I cannot help but notice that there are way more mods.

I was just curious about the switch for the FM and the input from an external source, as well as the 12dB / 24dB switch.

Is there any info I can have about wiring these?

Thanks

[nochtanseenspecht]

hmm, i can't help you, but there must be more mods possible.. filter in would be nice.
i sold my poly 800 long time ago, but i remember that after i installed the FM mod, the filter seemed
weaker, it screamed less... did you notice that to ? o , i remember there was a back up battery mod
on the web as well that i can reccomment, at least if you have an early revision. and there are some trimpots
that you could exchange with a normal pot, like white noise, if i remember well..
nice synth, the poly800. still miss it sometimes... but i exchanged it for a casio vz1, wich i don't regret

[hellomynameis]

Yeah I added the battery because it was an early revision and didn't have one. That was the first mod I did and then I installed the FM synthesis mod and then finally sorted out my Cut Off and Rez today because it didn't work.

I just noticed the mods on the website and was curious about them really, it's quite a nice synth really but I havn't been able to use it because still waiting on a power supply 

Also was thinking about this mod: http://patrioticduo.tripod.com/hawk800/index.html

but I'm not sure if I am really up to ripping IC's out yet lol

[nochtanseenspecht]

Also was thinking about this mod: http://patrioticduo.tripod.com/hawk800/index.html

but I'm not sure if I am really up to ripping IC's out yet lol

interesting mod, but for the price you could buy a second poly800 also... anyway it would be worth if you could
tweak parameters with cc's, if that is possible.. it would live more... programming was a bit slow with the buttons, but ok.
maybe piggyback ic's ?  anyway, mod the thing as much as you can ! for it has a good sound and it is word to put some
energy to get out more.. and who cares about a few extra holes in the case, it is an ugly plastic box anyway

hey but be carefull with the reso.. you'll easily hurt something   the value you program with the buttons, will be the
upper limmit ... so if you set it to 13 or so, your always save.  i still blame the moog slayer mod (partly) for destruckting
my ears

[hellomynameis]

haha fair enough, I havn't had a chance to really mess around with the reso and cut off just yet but however I have found some even more useful info on some of the mods done on this website based around the NJM2069 VCF chip which has so much potential! From reading this I believe that you only have to short out two pins on the IC in order to get the 12/24dB filtering, but who knows!

Also says there are 3 sources for external input on the chip and you can control the VCF externally using CV's... mmm very interesting but I think I would simply like to put in the 12/24dB mod then add more control over the FM synthesis as well as an audio in. The 12/24dB mod shouldnt be too hard as well as the audio in. I imagine the FM synth expandability will be more difficult...

here is the link before I forget!

http://sounddoctorin.com/synthtec/korg/njm2069.htm

[Circuitbenders]

The 12/24db mod is easy but to be honest it doesn't make that much difference. If i recall correctly all you have to do is cut the track coming from pin 6 of the NJM2069 and wire a switch to select output from pin 5 or 6.

Off the top of my head, the  external audio can be wired into either pin 19,20 or 21.

[hellomynameis]

Yeah I figured the 12/24db switch won't be much use, but then again my FM 800 pot is too close to rez and cut off so I figured I could put a switch in there.

I found the yahoo group detailing lots of info with the switches for the 12/24db switch. All you have to do is cut one leg of a cap and solder to a middle lug of a switch and then either pin 5 or 6 on the njm chip.

The audio input also involves soldering to a cap as well, however I assume you can just put a pot in here? Or would it be wise not to? I'll crack it open tonight and have a look, also going to install the switch and move the fm 800 elsewhere on the board

[hellomynameis]

Ah did the switch today and also installed the audio filter in, havn't been able to test yet sadly due the requirement of a power supply!

Ended up removing the FM mod for now, I'm thinking of installing the selector switch sometime soon, although I could find no info on any hook up points. Also got to do level pot at some point but i'm currently lacking in pots! Pics to follow...