Hi Pete - sorry, I am not Doug... but you ask about building
microphones... and one can, and I have, done practically what you ask
about re-purposing electret capsules, and similar things.
I have constructed many microphones for various purposes. Some were to
amp various musical instruments, some were for vocal tasks, and still
others were several were for computer speech recognition. I have
purchased replacement dynamic microphone cartridges to mount in various
holders, for example to "restore" an old Shure Unidyne 550 (the original
"Elvis" microphone - I just love that beautiful zinc finish) and I
purchased $2 electret capsules at RadioShack and from a company called
Emkay to disprove the claim proffered by many speech recognition vendors
that one needs a $400 +/- Sennheiser MD431 II Microphone to achieve
best recognition accuracy... sheesh... for an application which, at the
time, utilized a mere 11.5 KHz sampling rate! Heck the original
recognition engines were built using a cheap $50 Shure VR116 microphone!
It was nutty. I proved one can realize equal recognition accuracy
with my raw, unmounted $2 capsules as with many microphones costing 10
to 50 times more. Did I mention it was nutty? I quit the business when
they wanted me to endorse products I did not believe in.
You can purchase all sorts of un-mounted "replacement" dynamic
cartridges and electret capsules of all sorts, and build them into
whatever "deliver system" (i.e. handle) you like. Just wire it up
correctly, and pay attention to various matters like handling noise and
odd acoustics encountered in various shells or holders. Some vendors
sell the Sennheiser ME-3 headworn condenser microphone (sold with
Sennheiser wireless mic systems) - but complained there was a sort of
hollow reverberating toneality to it... so I taught them to just paste a
little electrical tape over the HOLE in the front of the mic boom shell,
which cures the problem. They then sold it as having "proprietary
modifications." Sheesh... so much for the "magic of marketing."
Just Google search for mic parts on the Internet or on eBay and you will
discover all sorts of replacement parts you can play with. I know some
vendors who sell multiple (maybe ten) Panasonic electret condenser
elements for $5 to $7 delivered. These are the type you typically find
in computer gaming headsets like the Yamaha CM-500 headset Jim Brwon
likes (for good reason,) but you could build your own boom arm and
attach one to virtually any headset - I have - and if you get a decent
one, it will sound just as good as the expensive sets. My friend's
CM-500 mic broke, and I replaced it with a boom arm from a cheap $5
Chinese gaming headset I found in eBay. He was thrilled and cannot tell
the difference in transmit audio, and I made a hit with the local crowd
for being the new guy with a talent for home brewing stuff. You know,
how new hams don't build anything anymore... ;-)
Anyway... I sure Doug will have better stories, but I thought I might
chime in as this is one of the few areas I can offer anything close to
technical advice.
Happy trails.
------------------- K8JHR -------------------
On 2/25/2014 11:51 AM, Pete Ferrand wrote:
. Could you share details on how you built the condensor mics?
Or did you take a mic out of a cassette recorder and mount
it in a case?
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