Headset incompatability

[flying snapper]

Wonder if anyone has come across this?

I recently bought a Peltor 8006 headset for a number of reasons. The main ones being that my instructor uses them and I find them comfortable and not too expensive (yes, I am a scot). When I tried it the first time, it was OK when I was the only one plugged in - I could hear ATC perfectly clearly. However as soon as my instructor plugged his older Peltors in, the sound became very muffled. His are 7000 series I think.

My question is this. Is there a basic incompatability between these different models? Is it a Condenser/Electret Mike problem? or do I have a dodgy headset? wired wrongly? or something else?

has anyone had experience of this?
:confused:

[Aussie Andy]

Hi,

Don't know for sure about Peltors, but the fault could be with the aircraft COM setup or with either of the headsets. Electical output circuits are designed with a particular impedance value in mind as the load. If this is either too high or too low you can get less than adequate power transfer, or poor performance of the COM system's output amplifier, or a problem with the Intercom system, possibly leading to the symptoms described.

I think you should try:

a) your new headsets in another aircraft with someone else to see if it happens again;

b) your instructors headsets likewise.

Try to determine if the problem always stays with the same headset or always stays with the same aircraft... then you'll know!

If in doubt, get an avionics engineer to look into it.

Hope this helps,

[flying snapper]

Andy,

Thanks for that.

The problems seems to transfer from aeroplane to aeroplane. My instructors headsets, and he has 3 or 4 Peltors, seem to be fine in all 'planes. It is just when my Peltor 8006's are connected that the problem happens.

Does this mean that the headset has a problem?

[A and C]

You are flying an aircraft with a cr*p intercom or no intercom and the audio run via the radio auidio amp.

In this day and age with the price of intercoms so low I would ask what else is this flying club cheapskating on ?

[flying snapper]

Don't think it is down to the quality of the intercom - the club has just invested in a new intercom for the 'plane I usually fly, and I was told that it was a good one. However the problem was evident before this installation.

I am begining to question the headset more and more now!

[Aussie Andy]

It does sound like you should get in touch with the vendor then mate...

[Keef]

It's nothing to do with the Intercom. If your audio reception is fine with nobody else plugged in, and goes to pot as soon as someone else does, then your headset has an impedance match problem.

It's not electret etc - that's the microphone bit, and we haven't talked about that yet.

There is a "techie" fix, which is to compare your headset's impedance with other headsets, which might or might not get you any further forward.

The second fix is to take it back and tell the supplier it's faulty. That's what I'd do.

The third fix, which will work, is to send it to Richard Holder and have him convert it to ANR. He replaces the crap "pressure units" in the earpieces with some better quality ones, as well as adding ANR.

[A and C]

I beg to differ both the Sigtronics and the PS engineering intercoms can handle all the headsets that are common in the GA marketplace without this type of problem.

[Who has control?]

I had the same problem with a pair of DC10:34s. I turned out that one of them had a dodgy mic that dragged the other one down. It sounds as though you have unmatched headsets.

[flying snapper]

Thanks guys!

I think I will go back to Harry M and let him have a look at the headset!

[A and C]

I will say this one more time ,this thing about matched headsets is rubbish ,if the intercom system is up to scratch then it will take headsets of different types (providing that the headset is servicable).

If you have problems with different headsets then you have an intercom problem.

This could be /1 no intercom fitted and the audio using the radio as an amp. /2 an old intercom probably more than 15 years old ./3 the intercom has lost the amp in one audio channel.

For some reason that I am unable to descover people will except radio and audio problems in aircraft that they would never except with a mobile phone or a hi-fi system and use myths like "matched headsets" to mask the fact that what they have is a sub-standard intercom.

The solution to the problem is to fit an modern intercom the best are in my opinion made by PS engineering , garmin and king with the latest sigtronics units a close second.

[Keef]

Well, A&C, I assume you had checked out the design of those intercoms you talk about.

All those I've come across have used the output of the radio as the direct audio drive to the headsets.

That's very different from the intercom amplifier, which should use a separate preamplifier for each microphone position, to overcome impedance matching problems.

I'm not saying some intercoms don't have 4 separate audio amplifiers for the COM and NAV input from the radios, just that I've never come across one that did. But you, as a licenced A&C engineer, should know. Mind you, 757s might be different from PA28s.

Whichever way, if snapper's headset is fine until another headset is plugged in, he has a problem - whether the aircraft has separate amplifiers for each station or, as in this case, obviously not. I've used a wide variety of headsets in our aircraft (which has no COM/NAV amplification in the intercom) and never had a problem.

The microphones, now, that's a different story and is why we bought a new intercom with four separate microphone amplifier channels.