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Re: Contact Microphones

Subject: Re: Contact Microphones
From: "Keith Smith" smith9e499
Date: Tue Feb 17, 2015 10:51 am ((PST))
Hi, Ben.
Radio Shack sells piezo buzzers for a couple of bucks that are nice and
big. The Schallers can be had at most music stores for around $15, I think,
and there are lots of sources on the web, of course.

For *much* better performance you might consider something like this
<http://www.zachpoff.com/diy-resources/alex-rice-piezo-preamplifier/> pream=
p
if you don't mind doing some soldering. Piezo's are high impedance which
isn't a great match for an input expecting to see a low impedance
microphone.

I just use what's known in the music business as a DI (for converting high
impedance guitar outputs to match with mic preamps). They're just a
transformer in a steel box with 2 1/4" TR (I/O)and one XLR output. The
downside of DI's is that they're usually built for rough stage/road use,
are bulletproof and probably heavier than you want. I use a dual one that
weighs over a Kg. Not nice, but I don't hike far and it works very well.
That does make that preamp I linked to look rather attractive if you want
something light.

I'm not sure what the transformer turns ratio is. Hopefully David will pop
back in here with that.  Top transformer brands for this are Sowter in the
UK and Jensen in the US & Canada, but you can do OK with less expensive
stuff if you stay away from the obvious garbage. If you got the
transformers  on their own, you could make up a stereo pair that would be
fairly light weight with small connectors to suit your recorder.

Either way, use something in there to get a better impedance match. The
audio difference is well worth whatever it costs.
k





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