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E&MM Analogue Electronic Drum System

Reader Marek Bokowietz has constructed a complete electronic drum kit from E&MM's own percussion modules, the Syntom, Synbal and Synclap.


A step-by-step guide to constructing a complete electronic drum kit out of E&MM's Synclap, Synbal and Syntom II analogue percussion modules. Marek Bokowietz

I started construction ot this project in September 1983, mainly because I wanted some form of convenient practice kit. An electronic kit (together with a pair of suitable headphones) seemed to be the ideal way of going about things without unduly upsetting any of the neighbours! It's also one of the most satisfying ways of learning to play drums, since it's easy to mix the output of the kit with that of a cassette player, enabling the budding percussionist to play along with as many recorded examples of great drumming as time will allow.

10" flower pot saucers were used for the drum pads. This may sound like an unlikely choice, but in practice they work very well and have the added advantage of being very cheap - about 50p each from any garden centre. A circular piece of 18 gauge aluminium was cut and mounted into the bottom of each saucer in order to provide some additional rigidity, and a piece of 1" foam rubber was inlaid on top of each of these to isolate each pad from the rest of the kit.

The pickup device is mounted on a piece of veroboard inlaid into the foam. A small piezoelectric sounder (normally used as an audible warning device) was used for the pickup itself: using this 'the wrong way round' gave the best sensitivity. A few strips of gaffa tape can be stuck over the pickup and foam to reduce the sensitivity slightly and to make sure everything is held firmly in place.

The housing for the seven modules was constructed from a piece of 3/8" laminated chipboard (Contiplas), glued and pinned together and then covered with black Rexene leathercloth. The front panels were cut from a piece of 16 gauge aluminium sheet. This aluminium was also used to make small right-angled brackets which hold the PCBs at right-angles to the panels.

Controls



These are miniature plastic knob presets that were soldered directly onto a small PCB, etched to suit the control spacing. This board is mounted on the rear of the front panel, held off from the panel with quarter-inch brass spacers. Connections from the control PCB and main PCB are via short flying leads.

Using Letraset lettering on a clear acrylic sheet as a master, a panel print label system was employed to give the desired professional finish to the front panels.

The pickup outputs are connected to standard quarter-inch jack sockets mounted at the side of each saucer.

For the actual playing surface, I was lucky enough to find a local DIY shop that was selling large sheets of polycarbonate for only £2.50 each, more than enough for a seven-piece kit. The polycarbonate was then cut to size using a bandsaw, the pieces then being laid to rest on a small lip that runs around the saucer's perimeter edge, approximately a quarter-inch below the rim. Some ordinary draught-proofing strip, cut to length and stuck around the circumference of the saucer, holds the surface firmly in position.

The pads can now be bolted through some old aluminium shower rail (or something similar), which is in turn bolted through the stands.


Stands



The stands themselves were made up from secondhand music stands: even new, these represent a considerable saving over standard cymbal stands. For the bass drum mounting I hunted round a scrapyard and came up with a metal base and a one-inch wide bar. A frame was cut to size and the entire assembly was then welded together by a local garage. The 'bass drum' saucer is bolted straight through a one-inch bar, again using a piece of cut aluminium as the saucer base.

The finished panel/PCB modules were then screwed directly to a rebate in the housing, the power and bus connections being made with flexible wire.

The rear panel was cut from the 18 gauge aluminium and contains seven quarter-inch jack inputs, seven phono sockets, four quarter-inch jack foot-switch inputs, and two further jacks are provided for stereo output and a hi-hat open/close switch respectively. The phono sockets are used as individual module outputs for additional control via a mixer.

An under-the-carpet-type security pressure switch was used for the hi-hat open/close selector, and this works surprisingly well, providing a fair measure of feel and requiring only a small tap of the foot to be activated.

Modifications



Some modifications should be made to all three types of E&MM percussion modules, though none of these is particularly complicated.

First, it's a nice idea to select different frequency ranges for the metallic voicing circuitry of each Synbal module being used. To this end, the values of C8 to 13 should be changed from 10nF to 220pF for the first module, 330pF for the second, and 680pF for the third.

Secondly, it was found necessary to change two of the Synclap's resistor values in order to increase the signal level feeding the stereo bus. The components affected are R36 and R42, which should be changed to 4K7 and 1K respectively.

Lastly, E&MM have proposed a few changes to the circuit design of the Syntom II modules, the main one being the addition of a stick click, and these should bring their sound closer to that of competing ready-built analogue electronic kits, and these are detailed in the accompanying (modified) circuit diagram.

Summing Up



It's not inconceivable that you may have problems in obtaining exactly the same materials as were used in the prototype kit, but the only components that may cause serious headaches are the piezoelectric sounders and the knob presets. In fact, both of these are standard RS Components products and should be available from your local component retailer. They'll probably cost about £1.50 each and 75p each respectively.

So how does the kit sound?

Well, I've played on a number of commercially available kits, and while the best of these undoubtedly sounds superior to the set-up described above, at a total cost of about £130 I think the E&MM system is hard to beat.

Modified Syntom II circuit diagram.
(Click image for higher resolution version)


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Previous Article in this issue

Powertran MCS1

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Patchwork


Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.

 

Electronics & Music Maker - Oct 1984

Donated & scanned by: Stewart Lawler

Feature by Marek Bokowietz

Previous article in this issue:

> Powertran MCS1

Next article in this issue:

> Patchwork


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