Modifications

I use a number of Doepfer and Analogue Systems modules for sound design and live performance. Here are a few very simple modular synth modifications that I have carried out recently. Of course, you will void your warranty with these mods and I offer no guarantee that they will work (well I have to say that), but these really aren't rocket science and there's nothing clever going on here, just some obvious but useful stuff.

Thanks to Tim Stinchcombe for the excellent info on his site, and the Doepfer A-150 VCS mod and everyone at the Doepfer Yahoo group, especially Dieter himself. Also a big thank you is due to Graham Hinton who has a wealth of information about the EMS synths on his site too: Hinton Instruments - EMS mods

Switched Multiple and old fashioned passive Ring Mod...

Another really simple one... pics and details coming soon....

Analogue Systems RS40 Noise/Sample & Hold

The problem: no internal connections means that you need several patch cords just to get the most basic functionality from this otherwise excellent module.
The solution: i. internally patch the noise output to the S&H signal input, allowing the path to be broken by a physical input.
ii. internally patch the internal clock to the external clock input with the same provision as above.
What you need: two short bits of wire.

1. Solder short wires to points marked A.
2. Ensure that the solder bridges at these points marked B are allowed to separate as in the photo. (From the factory the two blobs of solder at B are just one large blob connecting the two pins). Solder the other end of the new leads as marked. You are soldering these connections to the normalled side of the input jack.

3. Future mod: I need to get the drill out and put in an extra output for the S&H out and the Noise out as I ALWAYS seem to need multiples of these and there is plenty of space.

******** I decided to remove the one-shot button and use the hole for a multiple of the S&H output after all.
******** Much better!

Doepfer A-141 VCADSR

The problem: envelope rate is a bit slow.
The solution: replace C2 for a lower value or better still, add a switch and another capacitor to switch the overall speed.
What you need: a 10nF capacitor, a two way switch and some wire.

1. Drill a hole for the new switch wherever is convenient.
2. Remove capacitor C2.
3. Solder two wires in its place. Connect one wire to the middle of a 2 position switch: A (although I've covered the connection with heatshrink here so it's not easy to see).
4. Connect one leg of capacitor C2 (0.1µF) to one side of the switch: B.
5. Connect one leg of the new 10nF capacitor to the other side of the switch: C.
6. Connect one leg of capacitor C2 (0.1µF) to one leg of the new 10nF capacitor and connect this to the remaining long wire soldered in place of C2: D.

Personally I don't need voltage control of longer envelopes so with this mod in place I can now get Voltage Control of really fast Sequential Circuits Pro-1 style envelopes and this makes me happy.
If you want longer envelopes too, just put in a 3 position switch and an additional 100µF capacitor.
Thanks to Dieter for the capacitor values.

Doepfer A-148 Sample & Hold

This mod is for the old version marked 1996 on the circuit board. It may well work with the newer version but I'm not sure.
The problem: I want to trigger the S&H from the System Bus.
The solution: cut some tracks and solder in some wire.
What you need: some wire.

1. Cut the tracks at the two positions marked as A.
2. Solder a wire between B and C.
3. Solder another wire between D and either of the top two connectors from the ribbon connector as shown in the larger picture.

This mod connects the gate signal from the bus to the trigger input of the Sample & Hold unless a signal is input via a lead plugged into the trigger input socket, in which case the gate bus is disconnected. If you don't cut the tracks as shown you may well bugger up either the bus system, other modules or perhaps your whole synth, so use a logic probe and make sure the tracks are cut properly!

Note also that this only mods the top S&H unit. If you want them both running from the bus then I'm sure you can work out how to do the other one.

Contact

To send a message please use myfirstname at mydomain.