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Old 28th Mar 2011, 08:32   #1 (permalink)
 
Join Date: Oct 2009
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Build own headset?

Does anyone here have some experience of putting together an own headset?

I once bought a ground service headset (cheap) which I tried to use in a GA aircraft, with no luck. The mechanic at the airfield said it was because it did not have a built in amplifier. And the amplifier is why headsets are so expensive he said.

The headphones did work, but not the mic.

So, is it possible to buy these amplifiers some where?
And with the right technical knowledge you could build your own I guess.
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Old 28th Mar 2011, 08:50   #2 (permalink)
 
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Quote:
Does anyone here have some experience of putting together an own headset?

I once bought a ground service headset (cheap) which I tried to use in a GA aircraft, with no luck. The mechanic at the airfield said it was because it did not have a built in amplifier. And the amplifier is why headsets are so expensive he said.

The headphones did work, but not the mic.

So, is it possible to buy these amplifiers some where?
And with the right technical knowledge you could build your own I guess.
First, the impedance in an aircraft headphone system is 600 ohms, yours are probably 32 ohms or less, this means that you're putting too high load on the system.

Second, the microphone amp is normally fed, not always, with power from the aircraft system, so it's a special design. Not necessarily expensive, but again built not to interfere with the rest of the system.

Third, buy yourself a headset built to be used in an aircraft, probably cheaper in the end.
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Old 28th Mar 2011, 12:41   #3 (permalink)
 
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Firstly regarding aircraft microphones - the vast majority of aircraft comms systems are designed to provide power to the mic, down the signal+ line, with the signal- line acting as the return. So if you measure across the +signal and -signal pins you will see a voltage of between +8 to +30VDC.

This voltage is typically required to provide power to an "electret" mic, although some aviation headsets do use a small pre-amp. Neither are particularly "special".

The matching impedance (the load presented to the headset mic) is typically required to be in the range 50-600 Ohms, though a higher load will work just fine (the system I am most familiar with presents a load of around 1k Ohm and works great).

The earphone part of a headset in most modern headsets typically measures 150-300 Ohms, though it is worth pointing out that some older headsets may measure MUCH lower (the David Clark H10-76 used by many military aircrew measures 19 Ohms...). The majority of comms systems should handle this just fine.

Electret mics are actually fairly cheap and are very common (used in cell phones, etc) and therefore are not the cost driver.

Personally I am hard pushed to explain why some of the more revered headsets are as expensive as they are - it is certainly NOT a function of the components, since there are many better performing headsets used in the broadcast industry for example that cost less.

One reason for the cost may be FAA TSO certification, though not all headsets used in aviation are certified. Certainly certification adds cost.

Obviously headsets that use active noise reduction have an excuse to cost more, since there is a tangible R&D cost to be covered, in addition to the additional circuitry required.

Regards, GY
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Old 28th Mar 2011, 17:52   #4 (permalink)
 
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"Personally I am hard pushed to explain why some of the more revered headsets are as expensive as they are - it is certainly NOT a function of the components, since there are many better performing headsets used in the broadcast industry for example that cost less.

One reason for the cost may be FAA TSO certification, though not all headsets used in aviation are certified. Certainly certification adds cost. "

Thats is the same questions I have been asking myself.

Did some google work and found others who actually made some headsets.
Looks pretty promising and will probably try it out later in the future.
Can't wait to use my Koss Porta Pro in the flight deck, nice and neat!

Homemade Aviation Headset

Sorry for the google cache, the original website seems to be down...

Take care!
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Old 28th Mar 2011, 20:57   #5 (permalink)
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I've got a couple of David Clark units at home in the UK. They were like new when I put them away. I doubt I'll ever use them now, but wonder if a long storage period will have affected them and am loathe to advertise them without knowing they're okay.

What think the team...do they survive several years of being not being used?
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Old 28th Mar 2011, 21:17   #6 (permalink)
 
Join Date: Mar 2007
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I've got a pair of DCs (H10-13.4) that are now some 16 years old. I suspect they're young compared to some. They are as good as when they were new. If you want someone to test your DCs prior to sale, then visit your local flying club - either ask them to test them or go for a flight in the righthand seat yourself if you no longer qualify for the one on the left. You'll probably find a buyer in the same place.

Returning to the thread, why would anyone want to build their own headset, particularly if it risked damage to an aircraft's expensive electrical system? New, they can be bought for little over 100 so why bother. They are also your main communication lifeline to the ground!
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Old 29th Mar 2011, 14:49   #7 (permalink)
 
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Loose Rivets

I used to repair DCs on the side, and if you haven't stored them under water they'll be fine.
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Old 29th Mar 2011, 16:52   #8 (permalink)
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Thanks for that. I'll try to get something to plug them in this summer, though I suspect the pluggery will be hard to match up.
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