Warbird Information Exchange

Can anybody suggest a better noise canceling microphone element? I upgraded to the PS Engineering's "hi noise environment" unit which helped, but tower, ATC and passengers all complain they can't hear the pilot very well above the wind and engine noise of our TBM Avenger. I saw some company last winter that offered a replacement microphone element for my David Clark's but lost the info. I "think" it was called a "Cobra" microphone, but Googling has come up empty.

I've used a foam muff with a separate leather cover (has a BB sized hole) successfully in my Hatz and in an AgCat. A/C Spruce carries both.

Steve G

Rob, good to see you at Metro if only briefily.

I use the conversion offered by Headsets Inc. or Aviation Headsets of Amarillo and it works fairly well in the Spitfire. You can do the conversion yourself, need to solder some wires, etc, but I sent my David Clark to them and got it back in about a week. So they change the earphones, but I think retain the same D C electrolet mics.

It is ok, not perfect. I can adjust my David Clark intercom so that the automatic squelch works and we have voice activated microphones in both cockpits, BUT it only works at low cruise power, around 34 in and 2000 rpm or below. You can talk if power is above that, but there is lots of background noise. Takeoff power makes talking pretty futile.

I use Bose in my Bonanza, doubt if they might work in real high noise.

Phone me, 925-8036 if you want to talk about it.

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Bill Greenwood
Spitfire N308WK

I have tried one of these (BB-mike muffs). But a test with our tower crew says that cuts down the microphone audio too much. They would prefer to listen to a louder voice along with the louder wind/engine noise. I am now researching http://www.theBoom.com - looks interesting and they are willing to "try before you buy".

Hi Bill - sorry we met just as I needed to leave. I am not as concerned about noice canceling the hearing part as much as the microphone part. I gues the TBM growls and whistles louder than a Spitfire

I have used the David Clark foam muff in a leather cover on my D C M-7 microphone with no audio problem as far as transmitting for years. There is too much background noise picked up if you try it without the muff as for as I have found.
One thing about Merlin noise, it seems to be lower frequency than some of the really loud whine like a T-6 or perhaps TBM . Perhaps it is the prop , the Merlin one only turns at 42%, mine, or 47%, the low altitude version, of engine speed and we use lower rpm, 1800 or 2000 for cruise, or 2400 for cruise climb. So at 2000 rpm the prop is only turning 840 rpm and you don't get that cavitation of the prop tips like some planes.

One other thing, you may have a lot of wind leaks around the canopy that are making noise in the mike.

I did once try one of those classic style leather covered helmets from New Zealand. It was not comfortable for me, but the audio seemed very good, don't know what brand it was, this was years ago when they first came out.

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Bill Greenwood
Spitfire N308WK