How to wire a retro throat microphone

[unrise_lyrical]

Hey all,

So a little while ago I picked up an old Shure throat microphone for cheap. Its basically two contact microphones that sit on either side of the voicebox and pick up vibrations that way. The jack on it is straight out of a science fiction movie so I figured I would wire in a new one. There is a device that lets you speak or not speak built into the wire (kind of like a walkie talkie speak button) and from that to the jack runs three wires...but from the microphone to the button runs two. My noob question is this: is the signal mono or stereo? I bought a stereo lead because I figured two microphones would mean two signals...but wouldnt only two wires running from the microphone suggest it is mono? and if thats the case...how on earth does that work? if it is summing the signals together isnt there a really good chance of them phasing each other out?

That is a photo I found on the net of the throat mic. basically, those two black little disks sit on your voicebox...

any help much appreciated! thanks guys

[stryd_one]

Hmm... You may be about to hack to pieces a rare collectible there... I'd strongly urge you to get a socket to match, so you can solder a standard jack to that.... No need to destroy a piece of history forever.... anyways...

Depending on the model, the two pickups may be used for simple additional input levels, noise cancelling (phase inversion), redundancy, all kind of things. That pic is really small, but these look like the old military pilot's mics? Do you have a part number etc for it?

You might even find that this mic won't work with your equipment.

Either way, I'd say it's very very unlikely to be a stereo mic. Keep in mind that stereo records only came about in the 60's and this looks like a 50's headset (if not somewhat older - actually it reminds me of the standard mic for US bomber crews from WWII).... Not to mention that having a stereo signal of a mono source would be uhm... weird ;)

[unrise_lyrical]

good eye stryd :) its apparently one of the old bomber microphones from world war 2, so somewhere between 41 - 45. Model number T-30-V. I am all for history and conservation but I doubt this is a particularly rare piece, it cost all of 10 dollars on ebay and I have spotted others on there in the past.

[stryd_one]

Ahh it *is* a T30 :) Yeh the upside of sending millions to their death, is that there's millions of items of equipment left over afterwards. These aren't exactly rare yet. Still, it seems a shame to destroy it. You'll be able to find jacks to match this if you want to.

If memory serves (been a while since I had hands on these), the two mics are used for purposes of redundancy only (and balance, but that's mechanical, and not of interest I guess) - they'll be passively mixed (very little chance of phase cancellation there, it's the same source in both, so a 180degree phase shift would be very strange), and after that, the PTT button should be cutting off the GND line that leads to the instrument panel.

You should be able to do some quick tests with it by clamping alligator clips to the connector. It'll be quite high impedance (not only because of the pair of mics in parallel, but because of the design of the equipment to which it connects), and of course you'll need to hold in the PTT button to hear anything out of it :)

[/tilted/]

its apparently one of the old bomber microphones from world war 2, so somewhere between 41 - 45.

Don't take this the wrong way, but are you by any chance from America?

It's just that I seem to recall the war starting around 1939...  :P

[Screaming_Rabbit]

It's just that I seem to recall the war starting around 1939...  :P

... just that the USA didn't "enter" the war in 1939 already  ;)

[unrise_lyrical]

No, I'm Australian :P born and raised, and yes, I am aware the war went from 39 - 45...but as someone said America wasn't involved the entire conflict.

[nILS]

Group Huuuuug!

[/tilted/]

I was just sh*t-stirring.

I'm very intrigued by the idea behind this microphone. I had no idea such things had been successfully used.

They might be very useful on stage. Not really for performers (not live anyway), I'm mostly thinking for technician communication via headsets.

Of course for recording, they might be very interesting, if a little uncomfortable. I'd reccommend getting a "proper" mic for recording if you want a clean sound, but for a gritty, ear-prickling sound, these would be something a bit different.

Let us know how it turns out.

[unrise_lyrical]

haha, I know :) I just wanted to defend my intelligence a little bit :wink: yea I am really interested in seeing what kind of audio quality comes from them. I am not expecting studio-quality clarity, but I have quite a few gigs coming up this year and the more weird the sound, the better really as long as I can get something useable. As for comfort, I HATE having things around my neck but its actually suprisingly comfortable :) the original elastic fell to pieces when I tried them on so I made a new neck-band for it and I think I could wear it for hours before it really started getting to me :)

[/tilted/]

the original elastic fell to pieces when I tried them on

Not really a surprise for 60 year old elastic...  :D

so I made a new neck-band for it and I think I could wear it for hours before it really started getting to me :)

You might find it's a different story after a while on stage. How easy is it to take off/put back on? You might find the most comfortable way to use it is to just take it off when you're not using it!

[stryd_one]

Video store references for you both...

For an idea of what the old ones will sound like (and what you'll look like with it on), hire a copy of 'Memphis Belle'. In the studio, probably useful for some portishead-style character ;)

For a look at a more modern variant on some navy grunts, see 'Children of the Sun'. Sadly I haven't toyed with those so I can't say what they'll sound like... I know they're designed to pick up a very low whisper/mumble, so I'd say they might be a bit interesting. If you know someone in signal corps, the mic won't be classified, so I'm sure you could get a listen.

tilt, it's funny you should mention that idea... they'd be great for that, because they pick up very little background noise. I dunno why I've never seen it done! Somehow I bet smash has.... ;)

[Screaming_Rabbit]

I had no idea such things had been successfully used.

... they still are used today. When I was in the Army, I was a tank driver and we had them for internal communication. Since my head stuck out of the driver's "hole" and the engine exhaust was right next to my head, you wouldn't had understand a word from me, since the noise of the V10 engine was so loud. - As I recently saw, they still use them.

I can't make a statement about the sound quality of them, since I only was listening to them over the communication system, which had low-cut at about 300Hz and a big boost at 3k... for better speach understanding.

Greets, Roger