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MIDI Triggering From Your Acoustic Drum Kit

Tips & Techniques
Published December 1994

George Bourne reveals a cheap and easy project for converting a drum kit to trigger sounds over MIDI.

After having used a drum machine for some time in live performance, I began to look for a way to use my drum kit on stage in conjunction with my drum machine sounds. I eventually settled on an Akai ME35T Audio/MIDI Trigger unit with commercially available 'bugs' so that I could trigger the drum machine sounds from my own kit both live and in the studio.

Around this time, I bought a copy of Recording Musician [now incorporated with SOS] and found myself reading an article entitled 'Beat the System', which described a DIY drum pad system constructed using inexpensive transducers available from the Maplin catalogue. Using the clear instructions provided, I was able to knock together a triangular three‑pad unit to use up the remaining three inputs on my ME35T. However, I soon discovered that my new cheapy triggers at 28p each were also more sensitive to velocity, easier to control and not so susceptible to double or missed triggers as the commercial triggers, which had cost me £18 each! Another problem with the commercial units — which fix to the outside of the drum heads — was that wires had to be run over the drum rims to the attached sockets, which made them rather susceptible to damage.

My answer was to use the Maplin piezo transducers on the whole kit, mounting them inside the drums by sticking them to the underside of the drum heads and wiring them to sockets fixed through the drum shell. My shopping list from Maplin included a generous number of spares and was as follows:

  • 10 piezo transducers, 27mm diameter, part number QY13P.
  • 10 rubber discs, 27mm diameter, part number QY16S.
  • 10 open jack sockets, part number HF91Y.

The total charge, including VAT and delivery, came to less than £10!

Fixing the transducers was accomplished as follows:

1. Remove the drum head and hoop.

2. Drill the shell with a 9.5mm hole around 50mm from the top of the shell.

3. Fit the jack socket to this hole.

4. Solder the transducer leads to the jack socket — red tip, black sleeve.

5. Press the transducer onto the adhesive side of the rubber disk, then, using double‑sided sticky tape, fix the rubber disc to the underside of the drum head (as you refit it) about 40mm from the edge.

The only problem I encountered is that the leads are not very well soldered to the transducer and the vibration can cause them to come loose. A blob of silicone rubber over the joint cures this, and it may help to resolder the leads. Figure 1 shows how the triggers are fitted.

Some form of MIDI converter is required to convert the trigger output into MIDI trigger data but the system works perfectly with my ME35T and with the Alesis D4 drum module. It should also work with most other drum machines or triggers fitted with audio inputs. Even using all 12 trigger inputs on the D4, the cost is still very low, the only extras required being jack leads to connect the transducers. For live use it helps to colour code the leads with coloured tape or use Maplin's coloured jack plugs, otherwise it's easy to get the leads mixed up. In the studio this can be remedied, but when you're playing live, it might be too late by the time you realise that your snare drum is triggering a hi‑hat sample!

The ability to mix both electronic and acoustic drum sounds both live and in the studio opens up interesting new possibilities, while the ability to trigger the sounds from real drums removes the restriction of having to play along to click tracks.