Freesound Forums
contact mics
Started March 30th, 2008 · 4 replies · Latest reply by ermine 16 years, 6 months ago
In am very interesed in going deeper into the exploration of resonant objects and vibrating surfaces and after doing some experiments with simple DIY brass piezo mics I´m considering to invest some money in a few already built piezo mics/pick ups since I am very clumsy and therefore lazy to be able to improve too much what I have know. After doing some research surfing the net and the archives of this list, these are the choices I am thinking about:
-------
ACOUSTIC-LENS (( top in my list and the most expen$ive with difference ))
http://www.tranceaudio.com/lens.html
http://substation.co.nz/blog/?p=88 <--- after reading this enthusiastic post on them and listening to some examples I feel very tempted of trying them...
--------
http://www.contactmicrophones.com/
this guy seems to be reliable and has good prices and a variety of basic, improved and more exotic custom-made mics. those are the ones I am considering among his catalog:
10 Foot Buffered Mic - $70 USD each (weight: 100g) -- Buffered Contact Microphone (with Preamp)
10 Foot Mini Stereo Set - $55 USD each -- Basic Contact Microphone
10 Foot Suction Cup Contact Mic - $48 USD each ((( interesting to record body sounds )))
10 Foot Buffered Hydrophone - $85 USD each
10 Foot Stereo Hydrophone - $55 USD each
I find interesting also the piezo-film mics (the response seems to be better according to some comments I read and are good to attach to non- flat surfaces). Not available temporarily from that guy though. I found also this link: http://www.windworld.com/products/msipu.htm
So, I think the use of some buffered / preamp ones would be definitely a right choice to improve the recording of very tiny sounds (one of my aims) without getting excessive noise. With the DIY piezo discs I have now I miss a wider freq range and above all a good low freq response that seems would be resolved with some of those.
Please, tell me about your experience with any of those in particular or with other mics and these kind of recordings in general, which preamps do you use...tricks... whatever....
Also... has anyone used the Acoustic-Lens? I only found that guy using them for phonography purposes and I would like to know more comments on them before even thinking about investing so much $$. Also, since those sellers are in USA/ Canada, tell me if you know any similar alternatives in Europe.
Thank you!
Hi,
I have the buffered Cold Gold/contactmicrophones.com contact mic. If you do a search for "cold gold" most of the sounds I've recorded so far should turn up, but in particular I enjoy this one:
http://freesound.iua.upf.edu/samplesViewSingle.php?id=46907
I have absolutely no experience with any other contact mic except that one, so I can't say exactly whether or not I would be more happy with something else, but as far as I can tell it does exactly what it should and even after I managed to melt the glue a bit after recording a burning hot radiator (see above) several times it still works just like new.
With the DIY piezo discs I have now I miss a wider freq range and above all a good low freq response that seems would be resolved with some of those.Please, tell me about your experience with any of those in particular or with other mics and these kind of recordings in general, which preamps do you use...tricks... whatever....
Your LF response will be sorted by using a high impedance load. The average plug-in-power mic input is about 7k, which is waay too low to give good results with a piezo, which looks like a voltage source in series with about 15nF capacitance. Sometimes it is good to experiment with mass loading on the other side of the piezo disc (not in cotact with the sounding surface). Very carefully - the ceramic is brittle 
Film is probably better than ceramic, as the ceramic discs are designed to have large resonances around 2-5kHz. You can help that with damping the noncontact side, but you lose sensitivity