Last Updated:
KORG 800DV (Maxi-Korg)
MODS - Filter CV Inputs / Audio Inputs & Routings

| Synth Index | Korg 800DV | 800DV Mods1 | 800DV Mods2 |

| Aux CV to VCF | Audio Inputs | Routings | To Do's |

Aux CV Inputs to the 2 Travelers
Well, 2 VCF travelers, HPF and LPF on each, how can we not have CV controls for these ?!

From the schematics, the traveler pass thru a 22k resistor to the Korg/Keio Filter IC...

Click to Enlarge

External Aux CVs each goes thru a 22k resistor and patched to the other sides of the 22k resistors near Pad 52 and Pad 57 on the SBC-050 filter PCBs.

There are 2 SBC-050 boards, one for Upper and one for lower. The both have the same Pads numbering.


Solder a wire with a 22k resistor to the long leg of the vertically mounted 22k left to Pad 57 and another wire with 22k resistor to the long leg of the vertically mounted 22k left of Pad 52. Repeat for the other upper or lower voice vcf pcb.
Again, like the CV In's, I got the Filter Sockets Linked, so that upper is linked to lower if no jacks are plugged into lower inputs.

Also, I have a switch on both of them, not to switch between internal/external, but to actually just turn the external sockets on or off.


External Audio Inputs

Well, actually, i think the factory "FROM ACCESSORIES" sockets actually routes to the traveler VCF.

From the manual:

So "TO ACCESSORIES" socket is actually "VCO OUTPUT" and  "FROM ACCESSORIES"  is "VCF AUDIO IN" !

Simple, eh?
Actually, since I have already pre-planned and drilled holes for sockets, I have 2 extra sockets. I thought, the "FROM ACCESSORIES" inputs goes straight to VCF (traveler)... how about i use the remaining 2 sockets and route them to the VCO selectors...
There are some mods documented on the The Old Korg Owner's Club mod page, i didn't actually tried them as I found them a little too rough plus I have had enuf trouble with the 800DV anyway. There was this 1 mod i was interested and thought might be easy to do - routing the one of the VCO back to the other's mixer selector, so to create further thicker sounds.
My 800DV came with some dirty rotary selectors in the VCO section, all of these old wafer rotaries have got such bad contacts that certain positions they're not conducting.

So... since I have to replace them and rewire them anyway, I thought, I could change them from 1-pole 6-ways to say 1-pole 7-ways or 8-ways. So i got these 1-pole 12 ways rotaries ...

(Picture below was not using 1-pole 12 ways, it was taken while i started changing the rotaries, before i thought about this - hence the 4-pole 3-ways...)

The 800DV VCO section contains:



- an Extra Sawtooth Mixer and

- a Extra Sawtooth Blender Selector which includes Ring Modulation...

A 1-pole/12-way rotary was used to replace the OCTAVE selector, set to 7 positions. The extra position was wired to one of the external audio input sockets.
For the Extra Saw Selector, I used a 1-pole/8-way to add 2 more options:
One is again from the Audio input, and the other is from the opposite VCO waveform selector output (before the mixer). Roughly like this:

So there could be many options.
Could even go further and make all these selections as modular VCO output sockets !



Future Plans (To Do List...)
Well, this is what I've done so far on my 800DV, as of mid December, 2003.
Future plans include:
- adding MIDI
I don't want to add a Synhouse Midi-Jack II, because it doesn't support Pitchbend or Portamento plus also it doesn't support extra AUX CV's, and the Hz/V has very limited range.
The Doepfer Midi-to-CV's wouldn't do as the Hz/V aren't up to spec...
A Kenton Pro-2 would be ideal if it supports 2 channel Hz/V. Maybe building an Anti-log amp (V/Oct to Hz/V converter) and totally mount a Pro-2 inside the 800DV would be ideal....
Or maybe I'll have to build a dual Paia Midi2CV8 with Hz/V options....

- Rackmounting or Removing Keyboard
This has been on my mind from Day1, but it's so difficult - to modulefy it includes cutting the metal casing which is very difficult, or else i'd have to get a new case custom made, but the measurements is very specific/difficult.
Rackmounting is an option, but involves re-wring the whole wire jungle of 300 - 400+ wires......hell.....

So i might just keep it as is for the time being....

The Wire Jungle!!



Home Synths

Korg 800DV 800DV Mods1 800DV Mods2