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Replacing noise cancelling mic element with one that isn't

Posted: Mon Apr 13, 2009 9:49 am
by Wicho
Well, I'm not versed at all in the proper terminology so I may be butchering it, but here's my question:

Is it possible to replace the noise canceling mic element in an MTS2000 with an element from a Waris series radio that is not noise canceling in order to get higher TX audio w/o having to have the radio right up to the mouth when talking? Another example would be: would swapping the mic element from a 6193 RSM into a 6191 effectively make the 6191 a 6193?

Let's not get into radio adjustments, gain, etc. I'm really just wondering if it's possible and as simple as soldering in a new mic element.

Thanks!

Re: Replacing noise cancelling mic element with one that isn't

Posted: Fri Apr 17, 2009 6:34 am
by Karfield
I've been thinking of how to answer this one. I can't say it would work but then again I've never tried it. I do know that for the Jedi series at least the noise cancelling mics use an additonal 5V line from the controller board to run the mic. This may simply be an AGC control but I never got into that much. All I do know is that without that 5Vdc the mic will not Tx any audio. I would take apart the mic's in question and see what kind of circuitry is in the noise cancelling mic but I don't think changing the mic element in that noise cancelling mic would really make any difference when it comes down to how it works and does it's thing.

Re: Replacing noise cancelling mic element with one that isn't

Posted: Fri Apr 17, 2009 1:37 pm
by Will
The mic element is not noise canceling, the radio housing provides the noise canceling thru a second audio port. The elements are the same.

Block the port on the radio housing and the noise cancel is canceled!

Re: Replacing noise cancelling mic element with one that isn't

Posted: Fri Apr 17, 2009 2:32 pm
by Wicho
Thanks for the answers guys.

Re: Replacing noise cancelling mic element with one that isn't

Posted: Sat Apr 18, 2009 6:50 am
by kf4sqb
Will wrote:The mic element is not noise canceling, the radio housing provides the noise canceling thru a second audio port. The elements are the same.

Will, all of the noise canceling mic elements I've ever seen are made slightly different from "normal" ones. The radio housing does have a second audio port, usually on the side, that is required for the noise canceling function, but the mic element should also have a second audio hole, usually in the back. Most normal electret mic elements don't have this second hole in the back. Other than the hole in the back, they should indeed be the same.

A noise canceling mic element, any type, works by allowing ambient noise to strike both the front and back of the diaphragm inside the element, effectively canceling out any sound that is of equal intensities on both sides. That's why you have to "close-talk" a noise canceling mic for it to work properly; your voice has to be stronger on one side of the diaphragm to overcome the action of it on the other side.

As to the OP's question, it should be equally effective to, as Will said, simply block the noise canceling port in the radio housing. If the MTS2000 housing is the same as the HT1000 housing, and it is, IIRC, the noise canceling port should be located in the depression for the "hook", or bottom, of the accessory port on the side of the radio. If you look in there, you should see, if memory serves, two or three small, maybe 1/32", holes. These provide the path for audio to get to the back of the mic element. Wax might be a good choice to block them. Should effectively block sound from entering, while being easy to remove later, if desired.

Re: Replacing noise cancelling mic element with one that isn't

Posted: Sun Apr 19, 2009 6:30 am
by Wicho
Thanks. The wax idea worked well.

Now I just need to go buy a black candle to make things look better. 8)