Electronic Mesh Drum Trigger Using Speaker

This is a fairly simple way of making drum triggers using speakers that give you a quiet mesh-head drum that's very responsive. I tried making some mesh drum triggers using transducer discs but found they couldn't reproduce a series of fast hits without missing some , and thought I'd try something else . It may be my transducers weren't very good , but these speaker triggers are really good and accurate so I'm pleased . They are velocity sensitive , the output obviously changes as the coil of the speaker moves further and faster with a harder hit. (YouTube clip https://www.youtube.com/watch?v=ObvPNQIU1A4&feature=youtu.be )

The parts you'll need are :

An eight-inch speaker. (Other sizes will do, see below)

A sheet of fairly strong board , plywood or similar , about 15mm or 20mm thick should do. I used chipboard for mine because it's what I had around. You will need a piece 12-14 inches square for an eight inch speaker.

Some strong thin rope or thick cord , about 3 meters. Something that won't stretch.

A three inch bolt and nut , M10 preferably or thicker.

A jigsaw.

A drill and bits.

Staple gun.

Mesh for the drum head. This needs to be a very strong mesh. I used the mesh from a garden recliner , I think it is probably fibreglass.

A piece of foam sheet about 10mm thick.

Glue (UHU , Bostick)

Some epoxy filler.

Masking tape

Scissors or a craft knife.

Step 1:

Start off by choosing your speaker. I used different speakers that I had lying about , ones I had reclaimed from the dump or bought very cheaply on the internet. You can pick them up new or second hand for a few pounds each.

The main issue with smaller speakers is that they might not have a high enough output . There is a possibility that even eight inch ones may fail to give enough oomph , but all the ones I've tried have worked fine. They need to be working properly , when you push the cone in it should be stiff and springy and not scrape . Test that they work just by wiring them up to an amp if you have one , or a radio with an extension speaker socket . If they respond to an electrical signal by vibrating , then they will create an electrical signal when vibrated.

The board needs to be strong . Plywood is stronger than chipboard so you could use a thinner board.

Step 2:

Put your speaker in the middle of your board and draw a line around it.

Then draw another line two or three inches outside the first line .To do this mark a couple of points the right distance outside your first line and then find a plate or something round that fits the new points and draw round that .Or put the pen on the end of a piece of string and pin the other end to the middle point so it draws a circle.

Mark points at the four quarters as accurately as you can , around the middle of the outer ring and about 3/4 of an inch in from the inner line , and one more in the centre.

Then make points between the points you just made so there are eight outer and eight inner points.

Then divide the outer ring again into sixteen points.

(This is for the pattern of stringing I used. You might have other ideas for how to do this)

Step 3:

Make a mark on the inner line and drill a large enough hole for your jigsaw blade , and then cut around the OUTSIDE of the inner line. You want the speaker to fit inside the outer ring and also a layer of the mesh which is quite thick , so make sure that when you have cut there will be enough space for the speaker and mesh to slide inside the outer ring.

Step 4:

Now you need to drill the holes where you have marked points. The holes need to be big enough to thread through the rope or cord you are using. I had some "parachute cord" I'd bought on the internet . The hole in the centre needs to be as big as the bolt diameter.

The nut has to be fixed to one side of the board , so you can drill a small rebate to hold it if you feel like it , but you don't want the board cut too thin so it may be safer just to let it sit on the surface . It has to be held in place , so once the hole for the bolt is cut , put the bolt in and tighten up the nut and then glue the nut in place on the board by surrounding it with epoxy filler. The bolt still has to be able to move --DON'T GLUE THE BOLT TO THE NUT!!.

Step 5:

The mesh makes contact with the speaker cone via some bits of foam. I used a piece of camping mat. The part that meets the cone needs to be cut to fit whatever the shape of that particular speaker is . The top needs to touch the mesh for a reasonable distance. I chose the flared shape you see , other shapes would work as well or maybe even better.

Two pieces of foam are cut so they interlock and then trimmed so they sit just above the top face of the speaker . That way the mesh is slightly pressing the come down when it is in place.

The foam can be glued in place with a dab of ordinary glue. Or if you're unsure about damaging a speaker you might want to reuse , just let the foam sit . As long as the mesh is pressing down on it slightly it won't move.

Step 6:

The mesh came from a garden recliner like this one .

Put your outer ring on a flat surface , and cover it with the mesh , then push the speaker down inside the outer ring. Make sure you push the speaker right in and perhaps a bit more . Later when the ring holding the mesh is tightened down you want it to be pulled slightly below the level of the drum face , so there has to be enough slack in the mesh for it to do that. It helps it to stretch to shape if you warm it by a radiator. Not too hot!!

Staple the mesh down around the outer ring inside the line of the holes.

(Photos from here on are showing a different speaker, same size. I made this one with a slightly wider outer ring piece, but I think it's overwide and I'll end up trimming it down with the jigsaw.)

Step 7:

Now is the time to make sure you have two wires soldered to the terminals on the speaker . You can add a jack socket if you need one.

And make sure your bolt is turning freely in the nut and the nut is fixed to the circle of board.

Step 8:

Put the parts together , the speaker pushing against the mesh , then the board circle with the nut facing towards the magnet on the back of the speaker.

Now you have to lace the cord or rope through the holes. If your holes are quite small , you can make life easier by wrapping a piece of masking tape around the end of the cord and rolling it to a point.

When it is all laced up , go round it tightening the laces without losing the shape , the rear circle of board should stay aligned parallel with the front of the speaker. It doesn't have to be really tight .

Because once it's fairly tight and knotted off , the final tensioning can be done by screwing the bolt up against the magnet of the speaker. Again , warm the mesh up a bit to help it stretch to shape.