The Roland Drumatix TR606 is a well known and loved drum machine with, some people would argue, one major disadvantage. All the individual voices are internally mixed and output is through one ¼" jack socket. The voices have individual volume controls but what about eq? Sadly there is not much you can do about this with the standard machine. Obviously individual outputs would make the sounds a hell of a lot better, and to the dedicated Workbencher it is a matter of an hour or so of fiddling around with a drill and a soldering iron.

The Conversion

This little mod allows you to take one or more of the voices out of the mixed signal and do with them what you will. As you push in the plug to slave out a particular voice, the voice is removed from the mix signal and you get a full volume signal (ie unaffected by the mix volume control) to process. Any or all of the voices can be slaved out according to your needs. The five voices we can slave are bass drum, snare drum, low/high tom, cymbal and open/closed hi hat.

It's still not perfect in that the low/high tom can only be processed together, as can the open/closed hi hat, but it's a big improvement on what you started with.

Parts List

Five switched 2.5mm mono jack sockets
Five 2.5mm mono jack plugs
Five plugs to suit the input sockets of the signal processor (eg mixer)
Five lengths of coax cable
Thin, insulated stranded wire in three different colours
Sellotape

The tools you will require are:
Philips screwdriver
Sharp Knife, eg Stanley knife
Hand drill and drill bit to suit jack socket mounting bush (about ⅛")
Soldering Iron and solder
Sidecutters

Dismantling the Case

It is sensible to read through this before you start work!

1. Warm up the soldering iron — if by accident a battery lead becomes disconnected you will only have a couple of minutes to solder it back on before you lose all your drum patterns.

2. Pull off the four large rotary control knobs. Lay the TR606 face down on something soft e.g. carpet, towel etc.

3. Remove the five long screws and the two shorter recessed screws from the baseplate.

4. Holding the top and bottom of the case together turn it back over.

5. Gently lift away the top of the case revealing the baseplate, the four batteries and the red and black battery leads which join the top and bottom of the case. It is important notto strain these leads.

6. Use four strips of Sellotape to tape the batteries to the baseplate.

7. Remove the two screws securing the curved battery shield to the top plate and remove the shield.

8. Lift out the circuit board and lay alongside the baseplate.

Doing the Business

1. Drill five holes to fit the sockets, one hole beneath each of the voice volume controls, midway between the ridge and the bottom edge of the top plate. (See Figure one)

2. Fit the five sockets in place noting that there are three tags which you must identify: tag one connects to the barrel of the jack plug, tag two connects to the tip of the jack plug, tag three connects to a contact which touches the tip contact and is moved away from this as the plug is inserted.

As the layout of these sockets varies from manufacturer to manufacturer I can't provide a diagram to meet all needs but Figure two gives an idea of what I mean.

3. Solder wires to link all the Tag ones together and then solder a 3" length of, say, black wire to Tag one of the socket fitted under the Bass Drum control.

4. Solder a 3" length of wire (say red) to each of the socket Tag twos.

5. Solder a 3" length of wire (say yellow) to each of the socket Tag threes.

6. Turn the circuit board so that it is solder side up with the keyboard furthest from you. Along the near edge of the board are soldered the six independent volume control pots.

Ignore the Accent pot and look at the points where the Bass Drum pot is soldered. You should be able to identify the joints where the three pot terminals are soldered to the board. Also note that there are two larger joints, where the pot casing is soldered to the board, which are diagonally up to the right of the three terminal connections — Figure three shows what I mean.

The bit we're interested in is the small, ½" long, horizontal track running from the middle terminal of the pot. If you glance at the component side of the board you should see that the other end of this track is connected to a yellow-violet-orange (47K) resistor labelled 'R57'. A glance along the board will show that the other four voice pots each have a similar little track linked to a resistor (R102, R108, R109, R149).

7. Now comes the destructive bit! With your Stanley knife, cut the five small horizontal tracks to break the connection from the pot middle terminal to the resistor. This is easily done by making two cuts about ⅛" apart and then rubbing a clean soldering iron on the small cut out section. After a few seconds it should lift cleanly away from the board.

8. Solder the black, Tag one wire from the sockets to an Accent pot case mounting joint.

9. Solder each of the red, Tag two wires to the appropriate pot middle terminal joint, ie the left hand end of the cut horizontal track.

10. Solder each of the yellow, Tag three wires to the appropriate resistor joint, ie the right hand end of the cut horizontal track.

11. Solder up five coax leads linking 2.5mm jacks to whatever plugs your processing system uses.

Testing

This is to be done with the unit open.

1. Plug in the TR606 to an amp in the normal way and check that it all works normally.

2. Select a pattern that has Bass Drum in it and, whilst it is playing, plug the miniature jack into the Bass Drum output socket. The Bass Drum should be removed from the signal mix.

3. Connect up the other end of the Bass Drum signal lead to your mixer etc and check that you are getting a signal. If you get nothing but everything was okay in steps one and two then you've almost certainly wrongly identified the jack socket tags. Assuming that the black (Tag one) lead is okay ('cos it's the most obvious) try swapping the red and yellow leads.

4. Repeat the tests for all the other outputs.

Assembly

When you're sure everything is working properly you can reassemble. Making sure that you don't displace the four large plastic discs which fit around the pot spindles, slot the board into place being careful not to strain the battery leads. Refit the battery shield with the battery picture sticker at the battery compartment door end. Remove the sellotape straps from the batteries and then lower the top half of the casing onto the base, carefully laying the new wiring over the top of the circuit board. Making sure that none of your wiring is caught in between the two halves of the casing, grip the two halves together, turn it onto its front and refit the seven case screws.