[Elecraft] My KX3 desk microphone project

[Jim Brown]

On Sun,1/25/2015 5:20 AM, Gary - NC3Z wrote:
> In my opinion much, much better words should of been choose than 
> "seriously misguided", they have connotations that one is an idiot. 
> Seriously misguided would be trying to run a 12V device off 120V. 

Why? If an idea is seriously misguided, saying so is entirely 
appropriate. I did not expand on the advice because this is an email 
reflector dedicated to Elecraft radios, not microphones.

There are (at least) three reasons why an array of microphones is a 
really bad idea. First, really good sounding mics to work with our 
radios are widely available cheap. Second, a microphone is an 
electroacoustic device -- it collects sound at a point in space and 
converts it to voltage. A microphone at a different point in space 
collects different sound -- there is a difference in time between those 
sounds, which results in a difference in phase. The difference in phase 
results in peaks and dips in the frequency response, which in the audio 
world is called comb filtering. Third, one mic loads another 
electrically, degrading the performance of each.

Third, those of us working in pro audio learned a long time ago that one 
mic feeding a single channel is always better than one for picking up a 
single sound source like the human voice. Putting more of them in 
parallel does not make them work better.

When you see two mics on either side of a podium, it's an indication 
that whoever put them there didn't understand that. As the talker moves 
side to side, the sound of his/her voice changes due to the 
cancellation. Almost 40 years ago, I did a couple of big outdoor sound 
reinforcement gigs for the President, and the White House sound 
engineers DID understand that -- they studied at the same workshops that 
I did. They had Shure build a special mic for them with three capsules 
in it, each coming out on their own shielded twisted pair. Two went to 
me, the second was for redundancy -- in case wiring for the first one 
failed. Each went to a different input of my mix console. The third went 
to them for their recording.

73, Jim K9YC