[TenTec] In praise of older technology

[Richards]

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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