Unable to record/capture sound using a microphone

[Gene Heskett]

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.