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Jen SX1000 (Synthetone)
MODS - Jen Keyboard Mods

| Synth Index | Jen SX1000 | Jen Kbd Mods | Jen Rack Plan | Jen Rack Mods |

| IEC Main Socket | Sub-Osc | Ext Audio In | Amplitude Boost | Better Filter |
| Saw Multiplier | Kenton CV & Synhouse MidiJack |

Most of the mods i've done are combinations of mods from
Bluebear, Håkan Eriksson and Neil Johnson's sites.

IEC Mains Socket & Power LED
The Jen came with flying lead.... 1st to do is of course cutting that and add an IEC Mains Socket

To make the IEC Mains Inlet hole, I use a screwing hand tool, which is an M10 Radius Hand Hole Cutter, 28x21mm (
RS Cat.#543-614 or or 541-501), with matching 10A Snap In PCB Mount IEC 320 Plug Socket (311-8031 or 488-191).

Power LED

i also did the LED mod as suggested on Neil Johnson's site, although i did keep the Rocker Switch at the back.



The Sub-Osc is from Neil Johnson's site. The most simplest mod ever - using a 4024 IC.
I only did up to -4 octaves.
The Stripboard:

(Click to Enlarge)

I dun do custom made PCBs, so I convert everything into stripboard. It's nice, and everyone without PCB making equipment could do it.


Drilled a small hole on an empty area on the PCB and mounted the small stripboard there. Connectors are used to link the output to the new Noise Selector Rotary Switch.
External Audio Input to VCF
Even more simple. Since the noise output goes to the just a jack socket going to the OFF position of the Noise Selector Rotary Switch - so OFF position becomes the Audio Input.
Since i had to replace the Noise Selector Rotary Switch, i used a 1 pole 12 way rotary switch set to 8 positions (ie doing 8 ways).

The selector will now take care of the 4 sub-osc, the original white and pink noises and also the external audio input (plus i left the OFF position there too).


Noise & Waveform Amplitude Boost
Similar to what Neil Johnson's site suggested, but rather than replacing the resistors, i did them all in parallel and added switches to act as Bypass or Boost.

The Jen SX Noise PCB

I drilled 4 small holes at an empty area on the PCB, and used a connector to solder the necessary wires tapped to the resistors. The connector then connects to the switch that has new resistors wired in. The same was done to the Waveform (Saw/Square).

Better Filter
Håkan Eriksson's site suggested removing the 1uF capacitor at the VCF input and Neil Johnson's site has confirmed this.

Well, again, i did this with a switch so to switch between original and the new Lesser High Pass. The difference is very subtle tho....

I originally put a switch here for another mod (to switch between non-inverted and inverted envelope for the filter) but it didn't work out well (as I need another Pot). So the hole became spare and the VCF Cap Bypass switch was mounted here.
Sawtooth Multiplier
This is totally from Neil Johnson's site.. but i found some extras (maybe I've messed up, but it's fun).
The Stripboard...
Jen SX1000 Saw Multiplier Stripboard
(Click to Enlarge)

This is actually quite kool, it changes the soundz the most (OK, i dunno, it might be i have messed up, but what i get is quite nice).

I did the additional feeding the PWM to the multiplier, and also i added a DPDT switch for turning this whole multiplier mod on/off.

Reason being, somehow, the 2 pots affected the PWM as well (which is also quite nice) but if i want the original PWM sound, i needed the switch there.


Kenton CV Sockets/Sub-board & Synhouse Midi Jack

Basically that's all the mods i have done on the 1st Jen Keyboard.

Well, I have added the Kenton CV sockets (with the sub-board) and also the Synhouse Midi Jack (which doesn't do pitchbend nor portamento).

Only 1 drawback of the Kenton board - it doesn't do Glide/Portamento.... so for external CV, the Glide pot would have no effect :(

The Kenton Sub-board

Midi Jack mounting

Midi Jack cal/config and also the Kenton Switch selecting internal keyboard or external CV or midi.

So now the rear sockets have Audio Output, Audio Input to VCF, a Midi Jack Footswitch input, the 3 Kenton CV/Gate/Filter Inputs and the Midi In.




Well, after all was done, time to put everything back together.... hmmmm, not as bad as the 800DV wire jungle tho!!

There are other mods, like Inverted Filter Env, new LFO, better White Noise... (all from Neil Johnson's site) but i am planning to add these to my 2nd Jen which would become the dreaded Jen Rack!!




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