piezo contact microphones are cheap, easy to diy and usefull tools for sound recording. while most microphones pick up sounds as vibrations that move through the air (more acuratelly – they transduce acoustic energy to electrical energy), contact mics are different in that they will pick up sounds as vibrations in solid materials.
why build and use contact microphones?
piezo contact mics, if properly used, can deliver great sounding results and can be used in a wide variety of situations. they can be used to amplify acoustic instruments and everyday objects, to record extremely quiet sounds without the interference of the surrounding soundscape, as pickups in sound and multimedia installations, as triggers in interactive situations, as mics for field recording, as hydrophones, as body pickups (heart beat, bone movements…) and anything you can think of!
most contact microphones are made from piezoelectric materials (often refered to as piezos). piezoelectricity is a property of certain materials (i.e. some crystals) to produce an electrical charge in response to mechanical stress or pressure. also, if an electrical charge is sent into a piezoelectric material it will vibrate. so, piezos can act both as mics or speakers.
commercialy, piezo elements are often used as cheap buzzers, small speakers in clocks, computers, toys, musical postcards or as tweeters (treble speakers). in the music industry they can be used as acoustic instrument pickups, drum triggers etc.
you can either recycle piezo elements from toys, clocks etc. or buy them new in electronics stores.
here is a picture of different shaped and sized piezos (in comparison to a two kuna coin).
HOW TO MAKE A DIY CONTACT MIC?
what you will need:
> a soldering iron, some solder, a wire cutter and optionally a set of helping hands
> a piezo element
> mono microphone cable (or some different shielded cable)
> a mono 6.35 mm (1/4”) audio jack
> hot glue gun, rubber seal or plasti dip
short – prepare the cable for soldering. put the solder on the shield (a) and the core (b) of the cable on both sides.
long – first, prepare the cable for soldering. get a microphone cable (or some other shielded cable) of your desired length. use the wire cutter to remove 2 cm of the outer layer of cable insulation (on both sides of the cable). when you remove the outer insulation, inside the cable you will see one or more insulated smaller wires and one loose set of copper wires (the ”hairy” part). the insulated wires are the core (a) and the hairy part is the shield (b). you need one core, so if you have more cores cut the ones you won’t use. now remove the insulation from the core (about 0.5 cm in length). twist the shield, so it isn’t ”hairy” any more, but braided. with a soldering iron put solder on the core and the shield. the result should look like this:
short – solder the cable to the jack. connect the core of the cable to the tip of the jack (a), and the shield of the cable to the sleeve of the jack (b).
long – now take your 6.35 mm mono audio jack, unscrew it and pull the cable through the hollow part. the jack consists of a tip and a sleeve. the tip caries the signal, and the sleeve grounds it. so, the core of the cable (a) should be soldered to the tip (a) of the jack, and the shield (a) of the cable should be soldered to the sleeve of the jack (b). see the following pictures:
short – solder the cable to the piezo. core of the cable should be soldered to the center of the piezo (a), shield of the cable should be soldered to the brassy edge (b) of the piezo.
long – the other side of the cable should be soldered to the piezo element. the piezo element consists of a thin layer of piezoelectric crystals (a – the part in the middle) and a brass ring (b). the core should be soldered to the the middle and the stranded wire to the brass part of the piezo (see pictures). the center part of the piezo is very sensitive to heat, so it is easy to damage it while soldering. it is best to get a piezo element with wires already attached to it, or to put a small amount of solder (tin) to the center and edge of the piezo before soldering the cable to the piezo.
test your contact mic.
at this point you should have a working contact microphone. plug it into your mixing board/sound card/ amp and see if it is working. it should not have a (strong) hum.
if you have made a piezo contact mic as described above it will have a series of limitations.
first, because of impedance mismatch your diy piezo will have a lack of low frequenciy response (to fix that you will need some kind of a buffer, usually a preamp). also, piezos don’t have a flat frequency response – they tend to have a specific resonance peak, which will result in a thin and metallic sound. you could try dampening your piezo. one option is to put hot glue over the piezo or to cover it with rubber seal. this will also protect it from moisture (if you want to use it in the field) and buzzing resulting from touching the (exposed) core of the cable.
at the bottom of this page in the links section you can find more diy contact mic guides and different tips for building them.
GETTING A BETTER SOUND OUT OF YOUR DIY CONTACT MIC
as mentioned above, passive piezo contact mics are faced with a series of limitations that will drastically reduce their sound quality.
the biggest challenges are impedance, resonance and interference.
a piezo disk soldered directly to a guitar jack and plugged directly into a mixer or amplifier will have a ”thin” metallic sound. the reason for this is impedance ”mismatch” between piezos and regular audio inputs. piezos need to work at a higher impedance (over 1MΩ) and most audio mixers have line inputs at about 50 kΩ. what that means practically is that a piezo plugged directly into an audio mixer will have all frequencies below 200Hz cut off. a more technical explanation of impedance can be found here, here and here.
solution: IMPEDANCE CONVERTERS
there are two types of impedance converters: passive and active. most common passive impedance converters are DI boxes and they are usually used to match the impedance of an instrument (i.e. electric guitar) to that of an audio mixer input. i have not tested any passive impedance converters with piezo contact mics, and generally speaking the second type of impedance converters are better to use in this case.
active impedance converters are the best solution for good sounding contact mics. they contain an actual audio amplifier circuit that will make possible a full frequency response of a piezo contact mic. they usually work by using battery power, or phantom power provided by the mixer or sound recorder. both commercial and diy options are available. during my research i have tried out various kinds of piezo preamps.
on the following soundcloud links you can hear different combinations of piezos and preamps used with an acoustic laptop built by hrvoje radnić. the acoustic laptop is made as a box with two parts, and for every recording there is one contact mic placed on the part of the box with springs and another contact mic placed on the part of the box with a string and music box. the audio files are made as stereo recordings, where the right channel is the part of the box with the guitar string and a music box, and the left channel is the part of the box with the springs. sounds from one part of the box bleed into the other as well. all the sounds were recorded using a Focusrite Scarlett 6i6 2nd Gen sound card
the musician is also playing his acoustic laptop freely:
because of the way they are built, piezo discs do not have a flat frequency response. they usually have a frequency peak somewhere between 2 and 6 kHz that gives them their characteristic metallic sound.
solution: reduce RESONANCE, increase the mass of the disc
one solution to getting a ”flatter” frequency response from your piezo contact mic is achieved by increasing it’s mass. the simplest way to do that is by covering the piezo disc with hot glue. some great tutorials on how to build a good sounding piezo can be found here and here. i have found the JrF C-series pro contact microphones to be piezos with a great sound as a result of the way they are built.
i have made a video comparison between 3 piezo build-types. first one is a diy piezo with no added weight (”naked” element), second one is a diy piezo covered with hot glue, and the third one is a JrF C-series piezo. All contact mics were plugged into Radial Engineering StageBug SB-4 Piezo preamps, and recorded with a Focusrite Scarlett 6i6 2n Generation sound card with the same gain on each channel. as you can hear the naked element gives off a sound with most treble, and the weighted ones give less treble and more mids and bass. i would say that each of the builds has its pros and cons, all depending on what you want to achieve with your recording.
most diy piezo contact mics are made with unbalanced audio cables. thus, when using a long cable electromagnetic interferences can ruin the sound quality. i remember using longer (arround 3m) cables with diy piezos with one of my first sound works back in 2013 (kitchen turntable) and it resulted in piezos picking up radio waves.
best way to reduce the interference on your diy piezo is making it on a shorter shielded cable and pluging it into an active DI box. the DI box will fix the impedance mismatch, aswell as making you signal balanced. then you can use a long balanced cable to connect your DI box with you mixer/recorder/sound card. one more suggestion is to cover the piezo disc with copper tape that is connected to the system ground.
ATTACHING A CONTACT MIC
there are different ways to attach your contact mic to an object you want to record. one suggestion is to use clamps. the other is using a two sided tape or the sticky mass for attaching posters to the wall (in croatia we call it patafix, other name i found online is blu tack). i prefer to use the two sided tape and it works well with clean flat surfaces. patafix is good for rough surfaces. electrica tape is also a good choice since it doesn’t leave any sticky residue on the piezo.
a link to my piezo sound sample archive can be found on this link:
feel free to use these samples any way you like, no need to credit me or anything, although i’d be happy to listen to your works containing these samples!
EXPERIMENTS WITH PIEZOELECTRICITY
as mentioned above, piezoelectricity as a phenomenon can be observed in various materials. i have grown rochelle salt crystals and used them as piezoelectric contact mics. on the following video the crystal is clamped between two peices of brass on a plastic clamp. a wire is attached to each peice of brass and connected to an audio jack plugged into a piezo preamp and then into my soundcard. by hitting the crystal (with a screwdriver or pen) a small electrical charge is created, resulting in an audible sound (no sound from ‘the air’ is recorded here, only the electrical charge – sound produced by the rochelle salt crystal).
since piezo contact microphones can pick up very low amplitude and inaudible sounds, i have recorded a sound of a guitar string cooling down. first the string is placed onto a piezo, then heated with a candle and it produces an interesting sound effect while cooling down.
i was interested in how certain materials sound when they go through a physical change. so i recorded a sound of melting polystyrene in contact with acetone. also i recorded sounds of piezos being materially altered with different acids (you can find lab recordings in my sound sample archive).
here are useful links for your further piezo research:
the point of departure for the work goldrush is the relationship between geology of planet earth and electronic devices. in it, the artist wishes to focus on the materiality of digital media, especially that of personal computers. in the epoch of the anthropocene and in our post-industrial society there is an abundance of discarded and (purposely) obsolescent personal computers, which, after a period of usefulness, end up in recycling depots or landfills. they are often also transported to poorer countries, where they constitute an ecological problem. what is more, the earth’s resources are exploited for making consumer electronics components. the artist, therefore, wonders just how soft digital media really is, and how much it is based on hard, palpable, earth-derived resources, obtained through mining.
goldrush focuses on the presence of gold in personal computer components (central processors, working memories, graphic cards, modems and connectors). gold is a natural metal, a status symbol and an object of materialist craving. this work suggests an alchemical activity – the extraction of this valuable metal from electronic waste that was once also a status symbol. computer parts are dissolved by nitric acid or a combination of hydrochloric acid and hydrogen peroxide, and the gold is purified by aqua regia, a metal solvent used by alchemists as early as the 8th century, which is a mixture consisting of one part concentrated nitric acid and three parts concentrated hydrochloric acid. the whole process is sonified – the raw sound used in the composition is created by treating contact (piezo) microphones and diy microphones with acids and by recording the sound of the chemical reactions during the process of treatment of electronics and solution of gold. the changes in temperature of the solutions during chemical reactions are recorded by thermal sensors and serve as input information for the modulation of the sound composition that fills this dystopian laboratory. substances change, from waste comes gold, and from that process, sound.
the gold rush installation is presented as a documentation of the chemical process of gold recovery from computers. it is accompanied with a 4.1 soundscape and a description of the process itself. it was first exhibited in the museum of contemporary art, zagreb on the device_art exhibition.
support: luana lojić, marijan sutlović, hrvoje spudić, sara salamon, ivan šaravanja, branimir štivić, m28 contributors: faculty of agriculture university of zagreb, academy of fine arts university of zagreb, čistoća velika gorica, teuta gatolin, talal abedrabbo, karla patalen, ana-marija petričević, dražen klokočki, ante medić, ivan rogoz, petar pečur, bojan crnić, nina kunek, in2 d.o.o., zagreb city libraries. thank you vladimir prelog science school for the given space resources.
download the graphic explaining the process of making goldrush by clicking on the following title.
koreografija utopije, pokret br. 2. is an expanded choreographic research developed through collaboration between sonja pregrad, andro giunio and tin dožić. the work examines modes of codependence seen as an utopian organism. this work is a part of research titled koreografija utopije initiated by sonja pregrad and četveroruka organisation about modes of codependence and sinestesia /// a choreography developed as a proces of codependece in which time is built by the slipping of one media into antoher, the space becomes an amplified resonance of touhes by means of sound, light and movement.
movement: sonja pregrad
sound: andro giunio
light: tin dožić
outer body/ear/eye: gregor kamnikar and davorka begović
machine life in the bush of ghosts / w. colin black
sound art performance (2018)
in this work, the electronic sound of mutated machines rings out across an imaginary soundscape to produce a surreal sonic landscape inhabited by wandering automata. the sound world of “machine life in the bush of ghosts” explores the possibility that inanimate objects can possess a kind of life or spirit in the age of artificial intelligence. the work is the collision of two diverse arts practices: that of tin dozic who repurposes everyday objects and turns them into sound machines and australian sound artist colin black who explores notions of place and site through the use of sound.
through this collaboration, anechoic screams of machines become figures and are given a heighten and poetic context in imaginary sonic scenery. dozic’s dystopian sound machines are made from e-waste and various construction materials: dc electric motors become oscillators, metal and wooden bodies are resonated with speakers, and old tools are given a second life as sound instruments. also, organic structures such as plants become musical interfaces. all of these instruments are made specifically for this collaboration. black’s sound recordings and manipulations serve as the frame in which these machines are placed. prerecorded and live synthesized sounds communicate with the machines and create a whole dystopian world for this setting. this way an organic feedback system connecting the soundscape/local and the machine is brought to life as the machines impact their sonic landscape and this sonic scenery influences the machines.
we ask ourselves, what is the life of machines in this (fictive) world? how do we subvert the techno fetishistic world of modern machine culture? what is our role in this world and who are we (mad scientist, priests or just mediators of machine life)?
the anthropocene is a proposed epoch that begins with an increase in the significance of human influence on the geology and the ecosystem of the planet earth. this series focuses on the anthropocene, emphasizing the important role of technology in that era. by dealing with different modes of recording information and technological artefacts from the close past and present, i want to create loose connections between different anthropocenic symptoms. the work is realised as a collection of found and discarded objects, obsolete technologies and tools, digital glitches in video and sattelite images. i am interested in the impurity in it’s every sense, impurity of pollution, impurity of image transmission, impurity of the way the work is presented, and finally the impurity in the relations between the elements of the installation that generates new meaning.
songs for the anthropocene #1
photos of the installation (documented at gallery miroslav kraljević, 2019)
the work was first presented at prozori gallery in zagreb, and was adapted to it’s specific context (library). from the text by gallery prozori curator irena bekić: ”by referring to some presupposed museum exhibit and referring directly to the actual function of a specific gallery / library space, tin dožić creates a dystopian shelf with artifacts that are the relics of still lasting time. it is, of course, obsolete technological devices with different record formats, from charts to satellite imagery, whose manipulations create new uses and visualizations of metaphors that can suggest future links or be traces of the past. it is precisely in spatial and temporal alignment, that is, the minimum amount of time between the status of a useful device and the status of garbage, that the dystopian tension of this installation becomes evident. it can, at the same time, present an exhibit of an archeological museum from the future, a bookcase of a future imaginary library, an epoch of a time after cataclysm or the scene of a modern waste landfill, creating the complex imaginary of our time. […] the segments of the installation, each represent a different technological system, and are rounded off into fictitious stories, that is, songs produced by transformations of actual topographies. by sampling sound, slowing down the film, moving or disintegrating the image, etc., the author creates records that are in the same time dystopian landscapes, geological strata and lab illustrations, but we also recognize them as fragments of our own history.”
the work was exhibited on a solo exhibition at gallery prozori (2018, zagreb), and at the golden watermelon exhibition at the media mediterranea festival (pula, 2018) where it was awarded the golden watermelon award.
songs for the anthropocene #2
songs for the anthropocene #2 was made as a sister work for songs for the anthropocene. this work is based on the reapropriation of obsolete technologies, and consists of kinetic objects made out of elements taken from obsolete personal computers and other objects found in the trash. all of these e-waste objects are resurrected as zombie media and brought into relation with digital samples of found sound. the sound of google translator narrates all of the materials used to create one personal computer. computer fans rotate and resonate computer cooling units. electricity flows and ressurects.
in this work i am interested in the way we define something as old. in comparison to geological time, all computers are new, but on a micro time scale there are plenty of obsolete and dead personal computers. i bring down these computers to their material, awaken them with mechanical movements thus placing an emphasis on their sound and resonance. wires and cables are spread around as the bare guts of the apparatus. mechanical parts of the installation are driven by a simple system for mechanical programming, we could consider it the most simple form of an algorithm. this algorithm works on an circular principle, thus giving an information if each element is on or off.
the work was exhibited at the sounding d.i.y. exhibition (2018, mkc split).
songs for the anthropocene #3
it is true that software cannot exercise its powers of lightness except through the weight of hardware.
italo calvino, six memos for the next millenium
this work was realised as a hybrid space between an installation and a laboratory, showing media experiments at various stages of their production. constant change and procesuality are set before the finalized “product” in the songs for the anthropocene series. this installation repeats some elements of the earlier steps from the series, introduces new elements, recycles itself, and seeks to explore the materiality and the relationship between technology and the environment.
the work was presented as a part of radoslav putar award 2019. finalist exhibition at mali salon mmsu, rijeka, croatia.
open studio at gmk
open studio was realised in miroslav kraljević gallery during march, 2019. it was conceived as an open platform for experimentation and further development of the songs for the anthropocene series. every week a different set up was presented to the public.
the final installation was based on the research of piezoelectricity of synthetical and natural crystals and research about mechanical sound produced by using electronic waste. on the final exhibition, artist i also presented a sketch of a work in progress based on x-rays.
sound installation with kinetic objects (2017)
im)purities is a work dealing with the concept of purity and the purity of the concept. the work is positioned as a media archaelogical inquiery into technological artifacts. this kind of approach is a practice that emphasizes the role of materialism in society and in sound art. this work is possible because of the prevailing material abundance, and wishes to adress the problematics of waste. it also asks questions about the purity of the used medium and is situated between instalation and a sound piece.
the methodology of this work consists in obtaining obsolete materials in valladolid and utilizing them to build kinetic objects. these objects interact with eachother (visually, sonically and physically) and the author interacts with them. this way during the residency a field of objects emerges, and they become related to their sorrounding space. will these objects become an installation or sound instruments is left unclear untill the final exhibition.
sound performance with self made instruments (2017)
re-cycles is a work based on waste materials. e-waste, old tools, and other obsolete materials are used to create electroacoustic and mechanical instruments. components of old electronics and tools become microphones that pick up electromagnetic emissions (coils from power supplies), tone generators (motors), resonant bodies (metal and wood), and moving mechanisms that produce sounds.
during the summer sessions residency in rotterdam, the author collected e-waste and discarded materials through donations and browsing secondhand shops. from these materials he made mechanical objects for sound production. the process of making these objects is improvisational, depending on what is found and its constructional possibilities. the result is a sound performance that uses the movement of the obsolete as a means to give new value to discarded materials. it emphasizes the musical potential of the materials, as well as the problematics of overconsumption and pollution. the instruments and performance were made specifically for the summer sessions residency, instruments were left in rotterdam and performance held once.
this project is produced as part of the summer sessions network for talent development in a co-production of metamedia association and v2_ lab for the unstable media.
sound performance with self made instruments (2017)
the performance of re-cycles is a product of studying and working with outdated technologies and electronic waste. during a two-month residency at the academy of fine arts in zagreb (february and march 2017) the author dedicated to making simple acoustic instruments and electromechanical system for playing on these instruments. by recycling old walkmans, cd players and toys, he collected electromotors that are basis for this performance. electromotors serve as resonators for acoustic instruments. at the same time, the recording of their electromagnetic radiation makes them tone generators. the use of this kind of diy instruments is an attempt of reanimating the old media that results in a performance in free noise style.
electromagnetisms – 14 simple interactions with electronic devices
sound piece for radio (2017)
a coil within an alternating magnetic field makes the conversion of mechanical vibration into electric activitiy possible. therefore one of its applications is found in the production of microphones and speakers as it allows the fetching and generating of sound waves. the coil is also used as one of the main elements of radio receivers, and with all the other elements makes the fetching of radio signals possible. radio technology functions on the principle of transimitting and receiving inaudible electromagnetic waves. these signals are shifted into the hearing range through processes such as the demodulation of the signal and they become the content of the radio programme.
”i was fascinated by the above mentioned simple facts so i made my own pickup coil – a kind of a mirophone that picks up electromagnetic emmisions of electronic devices. since radio receivers are usually callibrated to filter out this sort of intereferentions from the signal i thought it would be interesting to play these sounds on a radio programme. i recorded electromagnetic emmisions of fourteen electronic devices that i use on a regular basis and made them audible. my goal was to make these unwanted sounds wanted, prefering the noise to signal. with this approach i reduce the radio to its most basic elements, and the radio broadcast is taken literally – as an electromagnetic wave. the composition itself was made as a set of spoken instructions of use for each device. i followed the instructions and recorded the devices simultaneously.”
can we learn something about our relationship with electronic devices by listening to their electromagnetic emmisions?
this work is originaly made in croatian and is titled: elektromagnetizmi – 14 jednostavnih interakcija s elektroničkim uređajima. this work is produced for the croatian national radio third program (HR3) show slika od zvuka / picture of sound.
this work is a digital hommage/remix of alvin lucier’s ”i am sitting in a room”. the work focuses on human voice becoming a digital artefact and the instabillity/fragillity of digital media. while lucier was using acoustics of physical space as a starting point and utilizing acoustical phenomenon for his piece, this work takes the digital ”space” as a starting point. through transcoding and databending a live recorded file of the artists voice he searches for its extremes and sonic textures that completely render it functionless. the recording gradually starts to loose its fidelity and through time it becomes completely bent, ending in harsh noise. it is not the voice that is bent, but its medialized version, the audio file. this work takes into account the poetic aspect of lucier’s original work. the text itself is changed and applied to the artists bad english accent.