Graham Dunning

Following on from the recent post about DIY turntable styluses, here are some other uses for contact mics. When I used to teach the Experimental Sound Art evening class I made four suggestions for ways to use contact mics: amplifying small objects, amplifying large objects, amplified surface (scraping table), and making an ‘instrument’. These are covered below, but I’m glad now to add ‘DIY stylus’ as a fifth category.

A good approach I’ve found for contact mic explorations is to use some sort of portable amplification and headphones, so you can monitor what sounds you’re getting in real time. Handheld recorders (like those made by Zoom or Tascam) are good for this as they have easy to use inputs. I used to use a Zoom H4 and have two contact mics attached, then listen on headphones, choosing later whether to use the channels individually or in stereo. One thing to bear in mind is that piezo transducers can output quite loud sounds as well as more subtle ones. Handling noise in particular can be quite harsh – sticking the contact mics down, accidentally knocking them, etc. So I recommend taking the headphones off whilst adjusting the position and gradually bringing the volume up to a level where you can hear what’s going on.

There are plenty of ways to attach contact mics but the main thing to remember is in the name – contact. The disk needs to be secured in such a way that the vibration of the object can pass into the metal of the disk. I often use electrical tape, as it’s not too messy when you peel it off, though it’s also not particularly secure. For permanent attachment it’s possible to drill through and bolt contact mics (thanks Sam Underwood for that tip), or I’ll sometimes use two part epoxy glue (like araldite) if it’s attaching to something hard and not too bendy. This could probably be a whole post on its own, so I’ll keep it brief.

I’m not going to cover making contact mics here, or talk about impedance and pre-amp options, but might do a separate post about these topics further down the line. A great resource on all of this is Nicolas Collins’ Handmade Music: The Art of Hardware Hacking, which I would recommend to anyone interested.

1. Stylus and scraping implement

Over on Instagram, Michael Cella made a great stylus with a 3D printed housing, playable by hand on records and other surfaces. The stylus end was essentially a pin attached to a contact mic, housed in a chunky wand (It reminded me of the Magic Pencil from British kids’ TV show Words and Pictures). Having the holdable part isolated from the pickup is great to avoid handling noise and the potential buzz/hum that can occur when physically touching the metal parts of the piezo disk.

Pretty much anything can be used as the ‘needle’ part of the stylus. Just stick something onto it, and find some things to scrape it on. Some examples might be: cocktail stick, bamboo skewer, knitting needle, drinking straw, biro, stick, jam jar lid, clothes peg, shard of glass… In one workshop I led, a participant sellotaped a ping-pong ball to a contact mic, then spent the entire session with headphones on scraping it along the walls of the room, and every surface they could find. The ‘stylus’ material makes a huge difference to the sound, as does the choice of surfaces you ‘read’ with it.

The size of the stylus is potentially interesting to explore too. I’ve done a couple of projects with amplified sticks and other materials, scraping them along the floor, tracing out spaces for their sonic textures. Field Tracing (2017) maps a terrain in the Black Forest using four different materials, the recordings and videos played simultaneously in an installation along with the styluses themselves. For A Tracing of a Single Tide I walked the length of the beach at Walton-on-the-Naze with a stylus made from driftwood.

2. Amplifying small objects

Possibly the most obvious way to use a contact mic is to amplify the small sounds you can make with a single individual object. It’s fun just to try lots of things out, and for workshops I had a collection of both prosaic and unusual items for people to explore (charity shops are a great resource, as is the pound shop). Off the top of my head some favourites were: pie tray, comb, ladle, slinky spring, pine cone, egg slicer, toy cymbal…

The way you attach the contact mic can make a big difference to the sound. It’s important that the ‘contact’ is good, but also that the object is free to vibrate – so it’s a fine balance. Too much sellotape and your teaspoon will no longer ring when you flick it. Too little and the piezo will fall straight off. It also makes a difference where you hold the object, and how you activate it. Sometimes dangling the item by the wire of the contact mic works well, to let the whole unit vibrate freely. Flicking, brushing, scraping, bouncing, blowing, swinging, twisting, bowing or bending an object may or may not reveal some hidden sound – the joy is in finding out.

Working with metal objects is sometimes tricky, as they can short the connections on the contact mic leading to the sound dropping out (this isn’t dangerous, as there is very little current in the audio circuit). The area to avoid is the side of the disk with the white circle – if an electrical connection is made between here and the edge of the brass disk, the sound will stop. One workaround is to cover the back of the disk with electrical tape to insulate it. It’s also possible (though a bit tricky) to stretch a balloon over a contact mic. Be aware though that any additional dampening will also potentially muffle or change the sound you get – again it’s a process of testing it out. This came up in a workshop with someone pressing a contact mic into a ball of wire wool – it sounded lovely and crunchy but intermittently cut out. We got around it with the balloon technique.

Adam Bohman uses contact mics on small objects to great effect. In improvised performance he uses a table crowded with wine glasses, springs, pieces of polystyrene, clothes pegs and other (carefully selected) tat, and plays these with violin bows, files and other activators. In order to avoid having to mic-up every item individually, he uses clip-on contact mics, and has volume pedals at his feet to mute the signals as he changes mic positions.

3. Amplifying large objects

Larger objects are fun to amplify too. Examples might be bins, fire extinguishers, windows, railings, ladders, a playground slide, a bicycle wheel, a radiator, a sculpture… Again placement and attachment will give varying results and it’s usually best to try a few positions before committing. Here a stereo pair of contact mics can give great results. I once recorded a bottle bank with two contact mics and my zoom recorder, then did the recycling: it sounded uncannily like being inside the bin. It’s worth bearing in mind that attaching wires to large objects in public places might look strange or even suspicious to some people. I’ve never had any issues, or even been approached, but it’s often been in the back of my mind.

Again there are different approaches to ‘playing’ the large object once it has been amplified. Drumming, scraping, flicking, etc all work – and the choice of beater or activator, and where you strike it, can make a big difference. Placing contact mics on a window can sometimes pick up sounds from outside, but they will be ‘filtered’ by the material properties of the glass itself – in practice this means traffic rumble is heard more than, say, bird song. Rain or hail directly hitting the glass would produce great results. Artist Melanie Clifford has worked extensively with amplified panes of glass, often amplifying barely audible high frequency resonances for use in her video work.

4. Scraping table / amplified surface

Almost the exact inverse of the stylus – what if we amplified the record instead?
To make a scraping table involves amplifying the surface and then using it to amplify other objects interacting with it. Again, a pair of contact mics can be used and the resulting recordings can be used to make interesting stereo interactions. The choice of surface is important: a resonant table works well, a dull and deadened table less so. Once a surface is miked up, try: spinning coins, rolling marbles, scattering rice, pouring water, releasing small creatures…

One of my favourite recordings, which I still use often in performances, is the shelf inside a pigeon shed with a pair of contact mics: scrabbling claws dominate, but the pigeons’ cooing comes through surprisingly clearly too (presumably in part through vibrations down their legs). I’ve also made an amplified surface from an old snare drum skin, and a video of playing some objects with it: here. Other things that work well as surfaces are vinyl or shellac records, cymbals, baking trays, corrugated cardboard, the lid off a turntable, plastic chairs.. Again, the material properties of the surface make a big difference, so it’s good to experiment.

Lee Patterson has used contact mics in lots of innovative ways, one of which is a metal plate he uses for amplifying springs and perfume bottles. The plate itself is suspended on springs to isolate it from external vibration which might cause feedback. The resonance of the plate interacts with the springs he attaches to its edge, creating a complex and responsive system capable of a vast range of sounds from very minimal and subtle movements.

5. An “instrument”

Though it can seem quite a daunting prospect, it’s possible to build an instrument of sorts by combining different objects with an amplified surface or box. Baking tins, jewellery boxes, tupperware, drawers etc can work nicely. Once the box is amplified, anything attached to it can be used as a sound source. Elastic bands stretched across make almost-convincing guitar and double-bass sounds. Screws, nails, nuts and bolts can be attached. Anything that twangs or can be plucked works well – springs, cocktail sticks, rulers, brush bristles, hairbands… Choice of plucker / beater/ scraper matters a lot too, so there are lots of options. Here are a few photos from instruments made during one session of the Sound Art course: [link].

Hugh Davies called this type of instrument a ‘Sho-zyg’ named after a volume from an encyclopaedia he turned into an instrument. Anton Mobin calls his instruments ‘prepared chambers’ and they feature springs, motors, contact mics and speakers – making versatile and playable systems for performance and recording.