[Elecraft] Microphone

[Jim Brown]

On Thu,10/13/2016 3:29 PM, Joe Subich, W4TV wrote:
> Only broadcast and recording gear use balanced inputs with or without
> high voltage phantom power for condenser mics.  Even general purpose
> public address systems tend to use unbalanced mic connections.

WRONG -- virtually all modern PA and sound reinforcement systems have 
used 3-pin XL connectors for more than 50 years. The exceptions are VERY 
CHEAP junk sold by places like Radio Shack, and those built into 
security systems. Most musical instrument amps have only unbalanced 
inputs. Back in the '70s, I was maintaining lots of paging systems 
professionally installed paging systems that used balanced mics and 
balanced wiring exclusively, and many of them had been in service for 20 
years. I don't remember ever working on a PA system that used unbalanced 
mics except as lavalier mics connected to a wireless mic transmitter.

Communications mics made by companies like Shure, EV, and Turner 
were/are made with output transformers that matched them to balanced 
low-Z inputs for use in professional systems and unbalanced hi-Z for use 
with ham radio, and PTT switches that can either be wired to key a 
transmitter or short/open the audio path. The Shure 444 is a great 
example -- the response is carefully tailored to roll off the low end 
and add a strong peak around 3 kHz to compensate the rolloff of the TX 
SSB filter. This response also works well for paging.

73, Jim K9YC