#219

From my experience, a buffered contact mic would capture quite a lot of the dynamic range of the glass being crunched up. Would not be identical to a cardioid, to be sure, but would pic up much more than an unbuffered contact mic.

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#220

what does a buffered contact mic do?

#221

An unbuffered piezo is going to unintentionally perform a low-cut on what it picks up. Youā€™ll get neat sounds and transients, and often thatā€™s good enough, but thereā€™s a tinny aspect to it.

Buffering a contact mic lowers the impedance and provides amplification, which can give a more natural sounding frequency response. Results, of course, will vary by microphone.

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#222

Itā€™s about impedances, isnā€™t it? Iā€™ve got a piezo, and I noticed that plugging it into the guitar input on my old Yamaha recorder sounded a lot better than using one of the normal inputs.

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#223

Yes. Piezos need a very high impedance input. A guitar input is good but special piezo preamps have even higher impedance. If you donā€™t have have a special preamp EQing the recording with a huge bass boost gets you near.

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#224

Yup - I suppose most mixer / recorder hi-z inputs are anything from 100k ohm to 1 megaohm input impedance, whereas with piezo contact mics youā€™d want something like 5-10 megaohms to be on the safe side.

You can get separate inline or pocket size piezo buffers for quite cheap - eg. there are pre-built variants of http://www.scotthelmke.com/Mint-box-buffer.html or DIY that oneā€¦ Also, some other off-the-shelf options that are a bit less cheap but still not super expensive, eg. the phantom powered Triton Audio Bigamp Piezo which is built inside a XLR to TĀ®S barrel adapter.

Also, one thing to note is that cable capacitance is part of the equation, so the longer cable you have between the piezo and whatever buffers it, the more that will contribute to frequency loss / attenuation. Because of that, ideally, youā€™d have a phantom or battery powered buffer circuit inside the contact mic enclosure itself like with Marshmallow (which I suppose is one reason people like how it sounds, itā€™s got buffering + preamplification right at the source). Failing that, connecting one of those pocket / inline buffer boxes with relatively short leads to the contact mic, and then longer leads (if necessary) to the recorder / mixer / preamp is almost as good.

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#225

Iā€™m really curious about this. One company made an audio specific, phantom powered accelerometer contact microphone system that was quite a bit like this, but i donā€™t think theyā€™re made anymore. I know these are made to hook up to oscilloscopes normally, how do you interface it with your audio recorder? Is it a 50 ohm coaxial output? Iā€™m mostly interested in the extended frequency response since i like recording at super high sample rate and messing with playback speed.

#226

I donā€™t know of any accelerometer with built-in preamp, at least I never saw any. but you say ā€œcontact micā€, maybe it was ā€œjustā€ that, in the sense that techically speaking accelerometers arenā€™t really contact mics, although you can employ them as such. but Iā€™m no expert and i only happen to know the stuff I utilise (in a not really orthodox manner), i.e. the B&K preamp I mentioned and a few of their accelerometers (like 4374, 4366, etc - all quite old models, some no loger available).
I go from the preamp to the recorder via a BCN-toXLR cable.
oh yes, except for a very specific model (4374 miniature accelerometer, goes from 1Hz to 26KHz), all the other sensors have a frequency range starting as low as ~0.1Hz but go up to 3KHz or 8KHz only (depending which model), not so high since theyā€™re meant mostly to capture infrasonic vibrations.
if you happen to remember details about the one you mention Iā€™d like to know what it is.

#227

I bought a couple ceramic contact mics a while back. They are said to not suffer from the high impedence problemā€™s of regular contact mics but arenā€™t as sensitive. I tested one with test leads the other day and was able to get sound so they do work. They are normally found in ultrasonic mist maker devices. Iā€™m just wondering if anyone here has tried them ?

external-content.duckduckgo.com

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#228

I know Iā€™m late to the discussion, but as people were talking about shielding piezo elements I thought Iā€™d mention the TE Connectivity SDT1, a shielded, folded piezo film transducer available with a cable for about 30ā‚¬.

https://www.te.com/global-en/product-CAT-PFS0010.html

Iā€™ve used them on my instruments for a few years now and am quite happy with how they perform in conjunction with an enclosed preamp with high input impedance. EDIT: by which I mean, after I started using these, the only noise and interference problems Iā€™ve had have been on the preamp and cabling side, never the pickups themselves.

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#229

Iā€™ve wondered about these. They seem like an excellent option since theyā€™re built so sturdily. Iā€™ve bought a couple of TE sensors recently with the aim of wiring them in place of regular gold disc piezos on a zeppelin cortado preamp!

#230

Ooh, thatā€™s cool. Thanks for the tip!

#231

Do you remember where you read this? These look like an interesting alternative.

#232

It took a while for me to find the source but they are mentioned in the comments below this article.

Having taken another look Iā€™m not sure how useful they actually are for our type of applications.

Recorded these to compare the difference. Seems like the ā€˜mist makerā€™ contact mics are a waste of time for music applications. Sounds like theres even more filtering going on with them.

Mist maker is recording on the left , regular contact mic on the right. Boths micā€™s are straight to jack and through a preamp on audio interface. Mics are blue-tacked to radiator. A lot more force (wooden handle of a file) was needed to get the ā€˜misterā€™ sounds.

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#233

Crank Sturgeon (Matt) is great, I use his stuff all the time.

My friend and label-boss Greh in Los Angeles makes some GREAT contact mics (and ā€œnoise-shakers!ā€)

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#234

Heart Sound Omnia. Theyā€™re accelerometers that connect to a preamplifier which is powered through its XLR output via phantom power. It makes me think of your b&k but specifically for audio. There are DIP switches inside the preamp box that shape the frequency response. They claim 1-100000 hertz response but donā€™t say which accelerometer they use so who knows? Iā€™ve sent lots of emails around trying to contact them and it would seem that the company has evaporated.

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#235

i bought a vibraphone a few months ago, which came with a pickup system consisting of contact mics affixed to the bottoms of every bar.

about 8 or so of them have fallen offā€¦ what type of glue should i use to fix it?

#236

Is there a list anywhere of attachment techniques onto a flat surface?

Best Iā€™ve found is low tack double sided tape but I still find a little finger pressure makes a significant difference.

I have some JFR mics and a Schertler which has the green putty but I find itā€™s pretty useless to get a solid contact.

#237

Iā€™m interested how that works. Could you send a picture of it? How is it wired up?

#238

Iā€™ve been recommended to use silicone, specifically the stuff that swimmers use to keep water out of their ears. I havenā€™t tried it.

The Dayton Audio transducers come with some 3M adhesive on their element which is pretty effective (strong enough to peel paint off walls, anyway) but Iā€™ve only used it in contact speaker mode, canā€™t speak to inputā€¦