[CQ-Contest] CM-500 headset

Larry pacer99 at aol.com
Wed Nov 21 14:43:01 EST 2018

Using headphones that block external sound becomes a trade off. Effective noise cancelling headphones tend to be heavy and bulky. That's fine for the casual user but become uncomfortable after a long period of time. Contest users beware.
I had replaced my Heil boom headset with the CM500 and have been extremely satisfied. The microphone has outstanding sound quality, they block most of the external noise and most importantly they can be worn for long periods of time without discomfort. They do not seem to be affected by RF.
At around $60 I believe that they are a great bargain and would recommend them to all operators that require a boom mic/headset.
Good contesting,

-----Original Message-----
From: Jim Brown <k9yc at audiosystemsgroup.com>
To: cq-contest <cq-contest at contesting.com>
Sent: Wed, 21 Nov 2018 19:23
Subject: Re: [CQ-Contest] CM-500 headset

On 11/20/2018 4:57 PM, Art Boyars wrote:
> Do you have any experience or other info about the CM500's effectiveness in
> blocking external sound?

Mics reject "external sound" two ways -- by virtue of directivity, and 
by inverse square law (that is, distance from the sound source). Most 
room noise we hear on the air is the result of mic gain being turned up 
much too high, combined with excessive compression. Good EQ settings 
that maximize talk power by cutting low frequencies and slightly 
emphasizing 2-3 kHz do a lot to reject room noise.

As near as I can tell, the mic in the CM500 is not directional. Nearly 
all directional mics are cardioids, which are essentially half-space 
mics. At best, they reject no more than 3-6 dB of room noise.

73, Jim K9YC
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