Unable to record/capture sound using a microphone
Gene Heskett
gene.heskett at verizon.net
Tue Jul 20 03:48:52 UTC 2004
On Monday 19 July 2004 18:04, Rick Stevens wrote:
[...]
>
>Does anyone still use ceramic mics? Wow! I mean, this IS the 21st
>century, isn't it?
Sorta off topic I think, but here goes.
Not very often, and their extremely high impedance virtually precludes
using them with most modern solid state inputs, which are rated at
47k at best. If you get anything, its the esses and tees but no bass
at all.
If a low impedance dynamic mike is plugged in without a 150 ohm to 47k
ohm matching transformer, it will sound ok, but the levels will be
very low, probably too low to be usable.
This is the domain of the internally amplified electret condensor
mics, which typically will have an AA or AAA battery in them
someplace. These usually have superior sound quality too since they
are basicly a condensor mic with a permanently charged high voltage
(the "electret" part of the name) to polarize the condensors
diaphrams, and generally, the better condensor mics can reach from
below 40hz on out to 15khz even for a $15 radio shack model. Good
ones can make you wonder why you paid $600 a piece for those
Caughneaughts(sp) or Neumans. Until you hit them with over 125 db
spl that is, then you understand right quickly. Hell, 50 years ago,
one of the tests they put an Altec M-21 through was to crack off a 45
ACP across the top of it at about 6" and watch the scope trace for
any flat-topping. There wasn't, even though the output pulse from
the shot was several tens of volts... They were fairly sensitive
too, I recall doing a recording session with the Iowa State Scottish
Highlanders (about 30 bagpipes if everybody showed up), and had to
pad the _line_ input down about 20db on a broadcast grade Tandberg
tape recorder running at 15 ips.
It was raining, and we were all packed into a quonset hut. My ears
rang for a week.
Yeah, I'm an old fart broadcast engineer.
>(getting into my Tin Lizzy, advancing the spark and getting my pal
> to crank it over...)
You'll want to fully retard the spark if you ever want to sucker that
friend into cranking it the second time. They were rather famous for
breaking arms if there was too much advance. Been there, done that.
Saw it done even.
> - - Microsoft Windows:
> Proof that P.T. Barnum was right -
Yup. :-)
--
Cheers, Gene
There are 4 boxes to be used in defense of liberty.
Soap, ballot, jury, and ammo.
Please use in that order, starting now. -Ed Howdershelt, Author
Additions to this message made by Gene Heskett are Copyright 2004,
Maurice E. Heskett, all rights reserved.
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