What makes a quality mic?

[John T]

What makes a quality microphone in a headset? somethat that doesn't pick
up the cockpit noise, but still transmits your voice clearly?

I've got a project in mind that would require such a microphone. I
thought of using the parts from a reconditioned headset, but I'd like to
get some opinions/options.

John

[Dean A. Scott]

> What makes a quality microphone in a headset? somethat that doesn't pick
> up the cockpit noise, but still transmits your voice clearly?

I've searched for the best performing mic and have found that
the Sigtronics M-80 and M-81 mics to be the best at cancelling
out high noise, yet not muffling your voice too much. Not surprising
as this is what they were designed for... open cockpits with a
screaming 2-stroke engine 5 feet away.

A little steep at $90 from
http://www.sportys.com/acb/showdetl.cfm?&Product_ID=5970&DID=19

Alternatively, Sigtronics makes headsets for EMS/Fire rescue. You
can find a fire supply liquidator on ebay selling headsets with
a 'hard wired' M-81 on a flex boom for $50. Easy to remove the
boom with attached mic and mount on your existing headset. Search
for 'Sigtronics SE-8'

for example:

http://cgi.ebay.com/Sigtronics-Noise-Attenuating-Headset_W0QQitemZ7717678330QQcategoryZ39724QQssPag eNameZWDVWQQrdZ1QQcmdZViewItem



Dean A. Scott, mfa
---------------------------------------
School of Visual Art and Design
southern adventist university
---------------------------------------
http://www.southern.edu/~dascott

[Peter Dohm]

"John T" > wrote in message
...
> What makes a quality microphone in a headset? somethat that doesn't pick
> up the cockpit noise, but still transmits your voice clearly?
>
> I've got a project in mind that would require such a microphone. I
> thought of using the parts from a reconditioned headset, but I'd like to
> get some opinions/options.
>
Presuming that the question is general theory, you are primarily looking for
a headset with a noise canceling mic.

Classically, a noise cancellig mic is two microphones placed either back to
back or a radically different distances from the mouth of the person
speaking. For example, a mic pickup placed one inch from the speakers
mouth, and the second at three inches, so that the evels are radically
different. The two microphones are then wired out of phase, so that the
background noise, which is assumed to reach both microphones equally, will
be cancelled. In addition, sound outside the classic "telephone" band of
300Hz to 2500Hz can be filtered out for a further benefit in
intelligibility.

The low-tech solution above works amazingly well in a large open area,
especially outdoors, and also works well with a noise cancelling hand held
mike when held closely; but has serious limitations in an aircraft cockpit,
especially if the mic boom is not long enough to provide good proximity.

I understand that some of the newer earpeices include a microphone to pick
up a pilots voice, presumably by bone conduction, and include sufficient
filtering to restore a reasomable range of frequencies. In addition, some
of the newer microprocessor based filters may provide far better noise
cancelling than the older methods. However, I have been out of the avionics
industry for nearly twenty years, and have no experience with either of the
last two methods.

I hope this helps.
Peter

[Matt Whiting]

John T wrote:
> What makes a quality microphone in a headset? somethat that doesn't pick
> up the cockpit noise, but still transmits your voice clearly?
>
> I've got a project in mind that would require such a microphone. I
> thought of using the parts from a reconditioned headset, but I'd like to
> get some opinions/options.
>
> John
>

Electret noise cancelling mic.

Matt

[RST Engineering]

This is a bu11$#it answer below.

In aircraft use, the microphone is open on both sides in the holder. Noise
coming in one side is cancelled by noise coming in the other side (i.e. they
both hit the microphone in phase and push and pull the element equally,
cancelling out the noise response). How much they cancel is a function of
how well the mic holder is engineered and tested.

Your voice hits the mic on one side only, and is thus imbalanced. It is
this imbalanced output that you get to use for mic audio.

Again, the ONLY thing that cancels noise is how well the mechanical/acoustic
engineer designed the mic housing to cancel the noise.

Jim


> Classically, a noise cancellig mic is two microphones placed either back
> to
> back or a radically different distances from the mouth of the person
> speaking. For example, a mic pickup placed one inch from the speakers
> mouth, and the second at three inches, so that the evels are radically
> different. The two microphones are then wired out of phase, so that the
> background noise, which is assumed to reach both microphones equally, will
> be cancelled. In addition, sound outside the classic "telephone" band of
> 300Hz to 2500Hz can be filtered out for a further benefit in
> intelligibility.

[John T]

Maybe I should clarify what the project is. I have a cochlear implant
(do a google search....some of you at the Oshkosh RAP party may have
noticed a "wire sticking out of my head" (not really...just from the
magnetic headpiece)). To hear the radio, I just make a direct connection
from the planes headset jack to my belt worn, external processor. I have
a setting that is 100% input from this auxilary jack, thus only the
radio comes through.

Now, what I want, is basically a headset with a boom mike, much like
those lightweight, wire-like headsets being offered these days for mucho
bucks, but with only the boom mike. I contacted a couple of these
manufacturers, one was willing to try, but he misunderstood that I
didn't need the audio jack and volume control, and qouted me for that. I
asked for a corrected qoute, but never heard back from him.

Anyway, I'm thinking of designing a boom mike only headset. That is my
project. First thing is to find the microphone, then design a thin arm,
elbow (or whatever you call the part where the boom meets the headset),
and headband. Not only would this save room in my flight back, but look
really, really cool! :)

I have also thought of buying a computer headset, but I don't think
their mikes are geared for a high noise enviorment.

John

[Dean A. Scott]

> I'm thinking of designing a boom mike only headset.

Then follow what I said in my first reply...

"... You can find a fire supply liquidator on ebay selling headsets
with a [permenantly mounted] M-81 [high noise cancelling electret mic]
on a flex boom for $50 [not an articulated wire boom, this is a single
flexible "gooseneck" tube-type boom]..."
http://cgi.ebay.com/Sigtronics-Noise-Attenuating-Headset_W0QQitemZ7717678330QQcategoryZ39724QQssPag eNameZWDVWQQrdZ1QQcmdZViewItem


In other words, get this cheapo headset (actually only one earcup is
noise reducing, the other is slotted to let in outside sound, the boom
is mounted on the closed cup), remove the boom by unscrewing a single
nut inside the earcup, discard everything else, mount the boom to your
own headset's ear cup (3/8" hole I beleive), and connect the two mic
wires to a cable with a suitable plug for your radio's mic input jack.

Or, contact Sigtronics Parts and order a replacement boom mic assembly
for their SE-8 headset, but I guarantee it will be more than $50!




Dean A. Scott, mfa
---------------------------------------
School of Visual Art and Design
southern adventist university
---------------------------------------
http://www.southern.edu/~dascott

[Bushy Pete]

What about throat mikes?

Someone may be able to suggest a source for one?

Peter


"John T" > wrote in message
...
> What makes a quality microphone in a headset? somethat that doesn't pick
> up the cockpit noise, but still transmits your voice clearly?
>
> I've got a project in mind that would require such a microphone. I
> thought of using the parts from a reconditioned headset, but I'd like to
> get some opinions/options.
>
> John
>

[John T]

Thanks Dean,
I did a search on your earlier suggestion for the sigtronics SE-8, and
didn't get any hits. That headset looks like something to use.

John

[Dean A. Scott]

> but there aren't any on Ebay at the moment.

There's ALWAYS an SE-8xxxx on ebay being offered 'Buy It Now'
from Fire Equipment Liquidators
<http://stores.ebay.com/id=37098259&ssPageName=VI:SIB:StoreView>.

Currently it's item number 7717678330.

This guy/company sells one at a time, but apparently has dozens
in stock since he's been listing this headset for at least the
last 6 months.

FYI, this is what did. I was increasingly displeased with a
Flightcom A9 mic... just not good at open cockpit/engine noise
reduction. A friend had an SE-8 that sounded exceptionally clear
and engine noise free over the radio. I was envious and went
looking for a way to get one of those M-80 mics. Found this
ebay seller and got his SE-8SRPTT headset. The SRPTT part
means Slotted earcup, Radio Push To Talk. I didn't realize that
until after getting it. Wanting what my friend had, I called up
Sigtronic Parts and ordered two, undrilled, closed (un-slotted)
earcups ($12 ea) and a speaker (the slotted earcup obviously
doesn't have one). I then went about converting/rebuilding the
SE-8SRPTT into a regular SE-8 (no volume control or PTT switch
on the boom mic earcup). Another thing is that the SRPTT comes
with a helicopter plug (double ring). I replaced it with a
standard 14/" stereo plug for the now stereo headset speakers
and a 1/4" mono plug for the mic. The AVIATION version of this,
the S-8, costs around $230. I rebuilt to the SAME specs for at
total of $97.





Dean A. Scott, mfa
---------------------------------------
School of Visual Art and Design
southern adventist university
---------------------------------------
http://www.southern.edu/~dascott

[John T]

Dean,
Thanks for the info. Could you clear this up for me: if I use this boom
mike, it will work like a regular aviation headset mike? That is, just
talk for intercom, and push the PTT to talk on the radio?

John

[Dean A. Scott]

>> if I use this boom mike, it will work like a regular aviation headset mike?

> That functionality isn't determined by the mike - it's determined by
> the intercom. If you have an intercom that will do that, this mike
> will do that.

Yes. Ditto.




Dean A. Scott, mfa
---------------------------------------
School of Visual Art and Design
southern adventist university
---------------------------------------
http://www.southern.edu/~dascott