DIY Leather Pads - How to Make Sound With Leather and Piezoelectric

Welcome to the first part of my experimental mini-series of:

"How to make sound with XXX and piezoelectric"

Since I'm kind of obsessed with musical instruments and while playing around with my trigger module and pre built drum pads, I've always deeply wanted to make piezo-triggered pads from any material (or combination of materials) I think would be interesting and fun to try out and pads wouldn't usually be made of - starting with Leather.

And because I've had a lot of conceptions in my mind - which basically have similar work steps - I decided to summarize two of them in one Leather-Instructable.

Step 1: The Things I've Used

Leather pieces (different types, thickness and color)
Leather Straps
Piezo Triggers
6.3 mm female Mono Jacks
Washer/spanish Coin
Glue (contact glue, hot glue, super glue)
Cellular Rubber
Soldering Tin
PLA Filament (black)
Acrylic Paint (black)
Flexible Tube
Book Screws
Neodym Magnets

Sissors/Cutter
Wire Stripper
Electric Drill
Soldering Iron
Rotary Tool

Trigger Module
Instrument and Audio Cables
Headphones, Speaker
Voice recorder
3D Printer
Mixer - optional

Tinkercad
IdeaMaker
Paint.net
Digital Audio Workstation (DAW) - optional

additional instruments:

Cajon
Snare-Drum-Pad
Kick-Pad
Rods

Please take all necessary safety precautions while working with heat, sharp objects, electricity, vapors or resulting gases, noise, bright light and whatever could endanger your health.

Step 2: The Leather

I ordered different pieces of leather (thin, thick, black, coloured) from a nearby saddlery shop. These are remnants/leftovers (of the furniture and/or clothing industry, I guess).

The shop offers:

eco-friendly mineral tanning
compliance with the PCP Prohibition Rules
production in an environmentally friendly manner
free from prohibited AZO dyes

ds-leder Saddlery Shop (Germany)

ds-leder Saddlery Shop (amazon Germany)

Step 3: The Piezo Discs

I ordered a pack of 15 Brass + Copper + Aluminium Wire Base Piezo Discs from amazon.

Diameter: 27 mm,
Thickness: 0.40 mm
Wire Diameter: 1 mm
Wire Length: 33 cm

Acoustic Pickup Piezo Discs (Germany)

Step 4: The Leather Cymbal Pads

4.1 The Concept

My concept is based on playing the leather cymbal pads foremost with rods or by hand while mounted on a cymbal stand as a supplement or extension for a mini e-drum set or a cajon. It's not meant for the "heavy hitters".

4.2 The Shape and Prototypes

The size and shape of brass or bronze cymbals affect the sound. In my case by triggering the sound, the size and shape are just optical elements. So I decided to go for two sizes and a kind of a pizza-slice shape.
I designed a 2D model in Tinkercad and also made two paper prototypes to figure out the final design and where to add the piezo disc, jack connection and the port for the cymbal stand. The paper models also acted as templates. I transferd the shape to the leather pieces, drilled holes in the pull-up/saddle leather and glued on four magnets in each case and the piezo cables to hold everything in place.

4.3 The Jack

I've connected the cables to the jack by soldering. Please don't forget to put on the tube and the jack cap before soldering.
At least I hot glued two magnets in each case to stick the jack as adjustable as possible on every side of the pad. That was the idea in principle, but in practice I figured out, the magnets weren't strong enough to hold the weight of the jack and the cable.

4.4 The Assembly

Because of the thick layers all together I decided to glue the parts with contact glue.
I've glued

the cellular rubber and a thin leather piece
the first part and the thick pull-up/saddle leather
the second part and a thin leather piece.

I've waited 24 hours in each case to achieve the final setting of the adhesive.

To be honest, my first design didn't visually and esthetically worked out as well as I 've expected, so I ended up with this three layer design. It's presumably not necessary but makes it very sturdy on the other hand.

4.5 The 3D Printing

While working on the knee pad I had various ideas to attach the small cymbal pad to my knee as well, like using velcro or magnets. A closer look at the attachment to the cymbal stand led me to go for this kind of mounting. I made a quick design in Tinkercad and 3D printed the parts in black PLA-Filament. I painted the top part with black acrylic paint and attached black adjustables leather straps to the bottom to fasten the pad to my knee; the straps are closed via a sling, a washer and a knot.

Step 5: The Leather Knee Pad

5.1 The Concept

My concept is based on playing the leather knee pad by hand while mounted on my knee as a supplement or extension for a cajon.

5.2 The Shape and Prototype

I went for a belt-like shape(ca. 28 cm x 6 cm).

I designed a 2D model in Tinkercad to figure out where to add the piezo disc and jack connection.

5.3 The Jack

I've used a female 2 pole open 1/4'' jack with 2 contacts, washer and nut.

5.4 The Assembly

For fixing the jack, I drilled a hole into the leather and connected the cables to the jack.

I've attached the leather parts with book screws, which I highly recommend.

To cover the piezo disc from the back side I glued the cellular rubber onto the leather. The cellular rubber makes it very grippy so the pad won't get out of place. I've waited 24 hours to achieve the final setting of the adhesive.

I attached brown adjustable leather straps; the straps are closed via a sling, an old spanish 25 pesetas coin with a centred hole and a knot.

Step 6: The Sound Tests

After each process step, I performed a sound test. It would have been very annoying to find out after assembly that the piezo trigger has been damaged.

Step 7: The Trigger Module and Sounds

The Trigger Module (TM-2) has two stereo trigger inputs. Via splitter cables the two stereo trigger inputs can be splitted into four mono trigger inputs to connect two more pads - for example a kick bass pad and a snare drum pad.

Instead of using the built-in Cymbal/HiHat sounds, I've placed the audio files (WAV) of the DAW Reason 10 Lite in the folder of the SD card, inserted the SD card into the TM-2's SD card slot and assigned the audio files to the pads. By striking the pads you can play WAV-files, like drum sounds, sound effects, songs or loop phrases as well.

Connecting the TM-2 to a mixer isn't actually nesseray. Well, I have the mixer, I use the mixer.

Step 8: The Leather Cymbal Pad Mini E-Drum-Set Up

I've connected the Leahter Cymbal Pads, a snare drum pad and a kick-pad to the TM-2 and the TM-2, speaker, headphone and voice recorder to the mixer via cable.

The sound was recorded by the mixers OUT to the line-in of the voice recorder.

Please take a look at my short video and excuse my bad timing; I'm working on it.

Step 9: The Leather Knee Pad Cajon Set Up

I've connected the knee pad to the TM-2 and the TM-2, speaker and headphone to the mixer via cable.

The sound was recorded by the built-in microphones of the voice recorder.

Please take a look at my short videos and excuse my bad timing; I'm working on it.

Step 10: Thank You …

... for reading, watching and paying attention.

As always it was a great learning experience and most of all an example for

having patience and
taking the time to reconsider and reinvent at one point or another.

What would I do different next time?

The magnets turned out to be an inappropriate attachment for the jacks because - as I mentioned before - the cables are too heavy. I would try to find another solution for that.

Please let me know if you've made one by yourself.

Hopefully Auf Wiedersehen in one of my next instructables.