[TowerTalk] Bose A20 aviation headset for ham purposes?

[Tommy Alderman]

No doubt the A20 headset is very good, but several reasons (to me) for not
purchasing this headset. First and foremost, at $1095, this is certainly not
a reasonable ham purchase for contesting. And second, it looks to be quite
complex in getting it set up, something else you don't need when contesting.
Even if I were to lose my mind temporarily, and purchase these headphones,
it certainly would not be without at least a one or two contest 'trials'.

What has replaced all of my Heil headsets is the Yamaha CM500 which for $45
relieves me of the 'hot ear' problems with most all Heil headsets. The
headset sound is excellent and reports on SSB audio brings unsolicited
"excellent audio" reports. I suffer no sweaty ears issues after +20 hours
during contest and my IC-7700 or my K3 drives these headphones with
excellent audio. If something were to break on my CM500, instead of paying
Heil another $75 to $100 for repair parts, I just buy another CM500.

73,
Tom - W4BQF


-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Tõnno Vähk
Sent: Friday, September 30, 2011 5:57 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Bose A20 aviation headset for ham purposes?

Hi,

I have been searching for a perfect headset for 48 hour contest operation
and found Bose A20 aviation headset being highly praised by pilots for
comfort as well as noise cancelling. Looks like an excellent product.

I wonder if it is usable for ham purposes with my Yaesu radios and
Microham keyers.

Maybe someone has experience of using aviation headsets?

And I am afraid the impedances of headphones and mic would be a problem?

The A20 manual
(http://products.bose.com/pdf/customer_service/owners/og_a20_owners_en.pdf
) says that:

Microphone (Electret) Bias required: 8 to 16 VDC through 220 to 2200 Ohms.
Sensitivity: Varies depending on bias and AC radio input impedance.
Typical output is 600 mV at 114 dB SPL. To assure proper modulation of the
radio, it is recommended
that an avionics technician adjusts its input to match the output of the
microphone.

Microphone (Dynamic) Impedance: 5 Ohms
Sensitivity: Equivalent to M-87/M-101

The 5 ohm impedance is drastically different from ca 600 ohm level of
Yaesu and Heil dynamic mics. Would this be usable at all for our
purposes??

Or maybe the electret mic with modification could be used for Yaesu
radios?

About headphones the manual says:

Impedance Monaural mode: 160 Ohms ON and OFF
Stereo mode: 320 Ohms ON and OFF


I hope someone who knows more about headphones and mics can help me find
the answer if this headset can be used.

73
Tonno
ES5TV

p.s. any other recommendations on perfect heatsets (that would not kill
the ears in 48 hours like Heil) are also very welcome.
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