I’m adding a Bastl solenoid module to my drum machine and am trying to do some research on contact mics I can use to capture audio from the surfaces being hit by solenoid triggers. Does anyone have any experiences they can share with either making contact mics or using manufactured ones? I’m under the impression they need some specific pre-amplification in order to get the full audio spectrum and not have a tinny character. I’m going to use 4 mics. Should I just get a small 4 channel mixer? Will the gain on the mixer solve this? Should I just buy some premade contact mic? Do those need a pre-amp?
you might want to look into the koma field kit. I know it can take contact mic inputs, I’m just not sure how many inputs it has.
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Contact mics are about as simple as it gets. The “mic element” is a piezo transducer, often marketed as a buzzer. They’re in all sorts of products being used as cheap speakers (smoke detectors, some kids toys, electronic doorbells, etc) but they’re cheap to buy. I recently ordered some from Mauser and they were about 50 cents each.
They’re two pieces of metal, isolated by glue, with a ceramic wafer sandwiched in between. Many come with wired attached but if not, just solder one wire to each piece of metal (both on the same side to maintain one side being flat) and the other ends of the wires to the jack of your choosing. Any preamp will get their level up to usable.
Frequency range/ response is more determined by the size of the contact mic than by the preamp. They do have a certain sound though, which can be tinny but as you experiment with them on different objects and with different techniques you’ll learn a lot about making them sound how you want.
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I can vouch for the Koma Field Kit, its 4 channels work well with contact mics and you can also drive a solenoid with its DC interface
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Yeah it may be worth getting it just for the mixer capabilities. The rest can be an added bonus. Does it output line level?
yes it outputs line level, there is a useful tone control and it has quite a nice overdriven sound, you can also listen to the radio when your not hitting surfaces with solenoids! Koma do an expansion pack with contact mics in, I am sure there are plenty of YT vids of making contact mics if you want to go down that route
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Yeah I was planning on making my own mics and solenoid triggers. Thanks for the input!
I found another interesting solution. This is a 2 channel piezo specific preamp.
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looks like that could be a space saving option, maybe look at this if you haven’t already
I know this is slightly aged and you may have already found and purchased a contact mic to use… but I just wanted to mention the Marshmallow contact mics. I found them to be very handy and they have a truly impressive sound quality.
I have a pair of the low gain model as well as a pair of the normal gain model, but I prefer the low gain as the normal can clip easily in certain applications. For instance - a piano soundboard could potentially overwhelm even the low gain one (which is at +14dB). I can normally remedy that by mounting them slightly differently, usually with no detriment to the tone.
There’s also a high gain model (+34dB), but I’ve never tried that. Currently only the low gain and high gain are in stock.
Since they feature built in batteries and preamps; they’re very portable, less prone to electrical noise and can readily be used with a wide range of equipment, making them my go-to contact mics.