Jen SX-1000 Sub-Oscillator

Categorized | Tutorials

Posted on 31 July 2007 by Luca Capozzi

This is a simple tutorial for add a Sub-Oscillator to a Jen SX-1000, a little monophonic synth of late ’70s.
by Carlo Castellano.

MODIFICATION AND SOLDERING

For this modification we need a single integrated circuit, a 4013, and a soldering iron, solder and wires. As for every integrated circuit we count pins counterclockwise positioning the little “U” shape, on the IC surface, on top. We can plug the 4013 directly on a perfboard or using a piece of carton to keep it, let pins out.

Let’s soldering some 4013 pins in this way:

pin 7 to pin 8 and pin 10
pin 9 to pin 12

Next we will connect separate and enough long wires to pins 8, 11, 12 and 14. We will name these 4 wires as pin numbers.

Jen SX-1000 Mod

Open the lid of the Jen SX-1000 and flip up the panel.

Now we will connect the 4 wires in this way:

wire 8 on left pin of Pulse Width pot (2nd from left, centre row)
wire 11 on pin 9 of IC 4013 inside the Jen (you can find it between Octave switch and Vibrato potentiometer, last row)
wire 12 to right pin on Noise switch (2nd from left, first row)
wire 14 to right pin on PW pot (same pot we solder the wire

Now place our 4013 on the Jen SX-1000 bottom using screws or glue to lock it down.

In order to activate the Sub-Oscillator we have to turn Noise switch to OFF and gently raise the Noise Level pot. You’d hear a square wave, one octave below, over the original sound. Don’t raise the level too much or the original sound will be totally covered by the Sub-Oscillator sound.

Unfortunately you can’t use Noise while using Sub-Osc, but in this way you can switch back using Noise as usual.