PA17-79 ANC - Having Problems
Thread Starter
Joined: May 2006
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From: Down South, preferably inverted
PA17-79 ANC - Having Problems
This is NOT another "Which Headset" thread.
I've been through 3 sets of PA17-71's (in a year) and am currently trying out the PA17-79 as I keep getting a persistent problem.
After approx 30-40 minutes of a flight I get a very high pitched electronic squeal in my ears and the only way to stop it is to turn the set to passive.
At first both Pilot Communications and I thought there was a fault with the headset and they exchanged it with no problems. Then... when the same thing happened with the new set, we thought it could be an intercom issue with the airplane, so I then swapped my lessons around 3 - 4 different PA28 Warriors. Same thing.
Pilot upgraded the PA17-71 to a PA17-79 which I immediately charged up, and tried this week end - guess what - same problem.
Are there any headset electronic "experts" out there who've got any bright ideas??
Pilot sell 1000's of this type of headset and have done for years...so we just don't understand what could be causing the issue.
and....I just have to say that Pilot communications have given me absolutely fantastic customer service throughout this little experience - nothing has been too much trouble
.
PS - I don't want to give up with them because, quite frankly, the headset is the most comfortable I've tried - no clamping, no head aches.
I've been through 3 sets of PA17-71's (in a year) and am currently trying out the PA17-79 as I keep getting a persistent problem.
After approx 30-40 minutes of a flight I get a very high pitched electronic squeal in my ears and the only way to stop it is to turn the set to passive.
At first both Pilot Communications and I thought there was a fault with the headset and they exchanged it with no problems. Then... when the same thing happened with the new set, we thought it could be an intercom issue with the airplane, so I then swapped my lessons around 3 - 4 different PA28 Warriors. Same thing.
Pilot upgraded the PA17-71 to a PA17-79 which I immediately charged up, and tried this week end - guess what - same problem.
Are there any headset electronic "experts" out there who've got any bright ideas??
Pilot sell 1000's of this type of headset and have done for years...so we just don't understand what could be causing the issue.
and....I just have to say that Pilot communications have given me absolutely fantastic customer service throughout this little experience - nothing has been too much trouble
.PS - I don't want to give up with them because, quite frankly, the headset is the most comfortable I've tried - no clamping, no head aches.
Joined: Jun 2003
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From: EuroGA.org
I bought the PA17-79 a few years back and it's a piece of junk.
It's a very long story, running to dozens of emails and faxes, and eventually I was able to return it to where I bought it from (a U.S. mail order outlet) for a refund. In the process I discovered that every advertiser was putting out bogus attenuation claims on this headset - 44db I recall - following misleading figures from the manufacturer. I have graphs of my actual headset showing a far lower figure and a confirmation from the mfg that this headset is in spec.
Mine whistled a little but the worst bit was that the attenuation was poor.
Then I did a test of a load of headsets, bought a Bose X and never looked back. Just make sure you get one of the current model ones; Bose were selling duff mikes for a few years and the amnesty for getting them exchanged has now expired. They still worked OK, better than most headsets in fact, in most (but not all) intercoms.
It's a very long story, running to dozens of emails and faxes, and eventually I was able to return it to where I bought it from (a U.S. mail order outlet) for a refund. In the process I discovered that every advertiser was putting out bogus attenuation claims on this headset - 44db I recall - following misleading figures from the manufacturer. I have graphs of my actual headset showing a far lower figure and a confirmation from the mfg that this headset is in spec.
Mine whistled a little but the worst bit was that the attenuation was poor.
Then I did a test of a load of headsets, bought a Bose X and never looked back. Just make sure you get one of the current model ones; Bose were selling duff mikes for a few years and the amnesty for getting them exchanged has now expired. They still worked OK, better than most headsets in fact, in most (but not all) intercoms.
Joined: Jan 2006
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From: Oxford
I'm no expert on headsets, having only just started flying, but I do know a bit about acoustics and audio electronics. It sounds like a flaw in the noise-cancelling electronics. But the fact that it does it on different headsets and different aircraft is weird.
Do you notice the squeal from televisions (the old cathode ray sort, not flat-panel ones)? If so, does it sound anything like that?
Are you quite young? Perhaps you've got exceptionally good high-frequency hearing? High-frequency hearing deteriorates with age, from late teens onwards IIRC.
Are there any controls on the headset for the electronics? If so, does the squeal persist at different settings?
The electronics used for active noise cancellation is intrinsically prone to causing a whistle or squeal if it's incorrectly designed or has a manufacturing fault, because it's a feed-back system. Given bose-x's comment about whistle, maybe it's just a design flaw that most customers don't hear because their high-frequency hearing is poorer than yours.
FWIW, I've just bought a Clarity Aloft in-ear set - but I haven't been able to use it yet because of this bloody weather! I'll let you know what I think of it when I've tried it out.
Do you notice the squeal from televisions (the old cathode ray sort, not flat-panel ones)? If so, does it sound anything like that?
Are you quite young? Perhaps you've got exceptionally good high-frequency hearing? High-frequency hearing deteriorates with age, from late teens onwards IIRC.
Are there any controls on the headset for the electronics? If so, does the squeal persist at different settings?
The electronics used for active noise cancellation is intrinsically prone to causing a whistle or squeal if it's incorrectly designed or has a manufacturing fault, because it's a feed-back system. Given bose-x's comment about whistle, maybe it's just a design flaw that most customers don't hear because their high-frequency hearing is poorer than yours.
FWIW, I've just bought a Clarity Aloft in-ear set - but I haven't been able to use it yet because of this bloody weather! I'll let you know what I think of it when I've tried it out.
Thread Starter
Joined: May 2006
Posts: 235
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From: Down South, preferably inverted
Hi IO540,
Well........ for the 30-40 minutes that they work properly, I DON'T have any issues!!
Sound quality is good - everything is much clearer.
So... I've got no problems with Pilot who are quite prepared to get me a refund, with no quibbles, if we can't resolve the problem - but I WANT to keep the headset and find a cure, because I like it.
I'm more interested to know if anyone's enountered any compatability isses with other headsets or can think of something which could cause the almost "timed" problem in the first place.
Well........ for the 30-40 minutes that they work properly, I DON'T have any issues!!
Sound quality is good - everything is much clearer.
So... I've got no problems with Pilot who are quite prepared to get me a refund, with no quibbles, if we can't resolve the problem - but I WANT to keep the headset and find a cure, because I like it.
I'm more interested to know if anyone's enountered any compatability isses with other headsets or can think of something which could cause the almost "timed" problem in the first place.
Thread Starter
Joined: May 2006
Posts: 235
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From: Down South, preferably inverted
michaelthewannabe said
I wish !!! 
I do have very good hearing and can hear sounds on a high frequency that others (my other half) can't, but he's used my headset on a trial lesson and it did it to him too.
And this noise is loud - makes me squirm!!!!
Yep - It's got individual volume controls for each ear cup and a stereo/ mono switch on the back of the volume control. The control is half way down the cable.
I have tried turning the volume up or down before, and playing with the volume and squelch on the airplan's intercomm, but with no change.
The only solution is to turn the active bit OFF.
Are you quite young?
I do have very good hearing and can hear sounds on a high frequency that others (my other half) can't, but he's used my headset on a trial lesson and it did it to him too.
And this noise is loud - makes me squirm!!!!
Are there any controls on the headset for the electronics? If so, does the squeal persist at different settings?
I have tried turning the volume up or down before, and playing with the volume and squelch on the airplan's intercomm, but with no change.
The only solution is to turn the active bit OFF.
Joined: Jan 2006
Posts: 99
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From: Oxford
Have you tried turning the active switch back on again, after turning it off? I've seen circuits (especially feedback circuits dealing with noise) that seem to work fine, but over a long period of time can subtly build up an oscillation (e.g. a squeal) that eventually swamps the system - but resetting them puts it back to square one.
Joined: Jul 2003
Aviation Qualifications: PPL
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From: Canada (Southeastern Québec)
And here I thought this was a thread about the Piper PA-17 Vagabond with its engine uprated to 79 hp...a buddy in fact just finished restoring a PA-16 Clipper, lovely little aircraft.
Thread Starter
Joined: May 2006
Posts: 235
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From: Down South, preferably inverted
Have you tried turning the active switch back on again, after turning it off? I've seen circuits (especially feedback circuits dealing with noise) that seem to work fine, but over a long period of time can subtly build up an oscillation (e.g. a squeal) that eventually swamps the system - but resetting them puts it back to square one.
I'm only a student and tend to have my hands full most of the time
so "stop the noise (distraction)" and get on with what I'm doing has always been the priority. I have to admit to not having tried a simple on/off yet. I'll ask my instructor to humour me next time I'm up, and fly the airplane whilst I "twidddle".
Should a straight on & off do the trick or should I try off, wait a minute, and back on ??
Joined: Jun 2003
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From: EuroGA.org
IME most training planes have poor intercoms. Many don't have an intercom - the headsets are all (presumably) wired up in parallel and you can get interference problems with a mixture of types.
I am an electronics design engineer too, been doing it for over 30 years, but have never really gone into avionics audio - the way it's wired is really weird at times.
The 17-79 was a comfy headset, but the attenuation was poor. The ANR feature contributed very little. A Bose X is a complete revelation in comparison, and their current mike is a further revelation over the previous one (presumably due to better noise cancellation). However, despite recent drops, it's about 2x the price of the Pilot one.
I am an electronics design engineer too, been doing it for over 30 years, but have never really gone into avionics audio - the way it's wired is really weird at times.
The 17-79 was a comfy headset, but the attenuation was poor. The ANR feature contributed very little. A Bose X is a complete revelation in comparison, and their current mike is a further revelation over the previous one (presumably due to better noise cancellation). However, despite recent drops, it's about 2x the price of the Pilot one.
Joined: Jan 2006
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From: Oxford
Should a straight on & off do the trick or should I try off, wait a minute, and back on ??
If that doesn't work, switch it off, wait a few seconds, then turn it back on.
If that doesn't work, unplug the headset and plug it back in.
If that doesn't work, do the same but with a pause before re-plugging.
If that doesn't work... I'll be confused (not an uncommon state, I might add).
good luck!
Joined: Jan 2006
Posts: 99
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From: Oxford
Many don't have an intercom - the headsets are all (presumably) wired up in parallel and you can get interference problems with a mixture of types.
Does the problem always occur with the same instructor, or with instructors wearing the same type of headset? If so, and if my last suggestion doesn't work, perhaps you could try to get your instructor to wear a different headset for a lesson?
Thread Starter
Joined: May 2006
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From: Down South, preferably inverted
Hi michaelthewannabe
Yes, I'm normally with the same instructor, or with an instructor with the same headset brand. Although some have the passive David Clarkes and one (my main instructor) has done the mod to convert his passive set to active.
But a couple of weeks ago I flew with someone who had a passive Peltor and had the same problem at about the same 30-40 minute mark.
Yes, I'm normally with the same instructor, or with an instructor with the same headset brand. Although some have the passive David Clarkes and one (my main instructor) has done the mod to convert his passive set to active.
But a couple of weeks ago I flew with someone who had a passive Peltor and had the same problem at about the same 30-40 minute mark.
Thread Starter
Joined: May 2006
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From: Down South, preferably inverted
Michaelthewannabe said
Me again - Bad Wx stopped play over the last couple of weeks, so I went up again yesterday.
My partner took the headset for a trip with someone before my lesson, just under an hour, and the headset was fine the whole time.
I went up for 1 1/4 hours and I got the same high pitched squeal as before but at about 1 hour 5 mins (Oh good - 20-30 minutes more reprieve!!).
I turned it on and off quickly, twice, with no effect and then turned it off, waited 3 seconds and back on again and the noise was gone - Option 2 on your list.
Could you write me an "engineering" lingo explanation of what you said it could be re: the oscillation, so that I can e-mail Pilot who can give it to their engineer. Then you can use as much technical language as you like because you won't be trying to explain it to a totally NON electrical engineering pleb.
PM me if you don't want to post.
Also.....As I got 20-30 minutes more time before the squeal this time - could electronic circuits need to be run in?? i.e. warmed up a few times.??
Thanks
MG
Flick it off and on, quickly.
If that doesn't work, switch it off, wait a few seconds, then turn it back on.
If that doesn't work, unplug the headset and plug it back in.
If that doesn't work, do the same but with a pause before re-plugging.
If that doesn't work... I'll be confused (not an uncommon state, I might add).
good luck!
If that doesn't work, switch it off, wait a few seconds, then turn it back on.
If that doesn't work, unplug the headset and plug it back in.
If that doesn't work, do the same but with a pause before re-plugging.
If that doesn't work... I'll be confused (not an uncommon state, I might add).
good luck!
My partner took the headset for a trip with someone before my lesson, just under an hour, and the headset was fine the whole time.
I went up for 1 1/4 hours and I got the same high pitched squeal as before but at about 1 hour 5 mins (Oh good - 20-30 minutes more reprieve!!).
I turned it on and off quickly, twice, with no effect and then turned it off, waited 3 seconds and back on again and the noise was gone - Option 2 on your list.
Could you write me an "engineering" lingo explanation of what you said it could be re: the oscillation, so that I can e-mail Pilot who can give it to their engineer. Then you can use as much technical language as you like because you won't be trying to explain it to a totally NON electrical engineering pleb.
PM me if you don't want to post.
Also.....As I got 20-30 minutes more time before the squeal this time - could electronic circuits need to be run in?? i.e. warmed up a few times.??
Thanks
MG
Joined: Jun 2003
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From: EuroGA.org
The whistling noise could be either a problem with the noise cancellation circuit in the headset (this uses a feedback loop and can thus go unstable) or it could be due to the aircraft intercom not liking the impedance of the headset.
Joined: Jan 2006
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From: Oxford
The whistling noise could be either a problem with the noise cancellation circuit in the headset (this uses a feedback loop and can thus go unstable)
or it could be due to the aircraft intercom not liking the impedance of the headset.
Does the headset have a battery, or does it draw power for the active circuit from the intercom? If the latter, then that could cause it to be dependent on the combination of headset and intercom: if the intercom isn't supplying quite enough welly, the active circuit might malfunction and go unstable. Or it might even be an oscillation on the power supply from the intercom - rather unlikely, though.
Mad Girl: Well done on getting into the sky (better than I've managed recently!). And glad you've found a fix. The rapid switch off/on probably doesn't work, because the circuit stores a bit of residual charge and needs to be switched off for a couple of seconds to actually power down, and restore the circuit to its starting condition.
I can only speculate at the cause, but my best guess is this...
[geek]
There appears to be a fault in the design or the manufacture of the active noise reduction circuit, which causes it to go unstable after a sustained period of time in the presence of normal cockpit noise levels and usage. This instability manifests itself as an oscillation high in the audible frequency range (probably around 10-18 kHz from the description), gradually increasing in amplitude, and taking 60-90 minutes to become audible. Powering-down and re-powering the ANC circuit clears the fault. It might be dependent on the type of intercom, though this is less likely as the problem occurred in a number of different aircraft.
[/geek]
Also.....As I got 20-30 minutes more time before the squeal this time - could electronic circuits need to be run in?? i.e. warmed up a few times.??
It'll be interesting to find the cause, if Pilot set their engineer on the case! Happy squeal-free flying.
mtw
Joined: Jun 2003
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From: EuroGA.org
ANR headsets are powered; one can't draw enough power from the audio signal.
I agree the whistling is most likely a feedback issue with the noise cancellation circuit (which uses a mike inside the earcup, wired to achieve a null sound level pressure inside the earcup with zero audio signal) but
It would be very surprising if the input impedance of the headphone changed significantly when the active circuit is turned on. So I think this is more unlikely.
this is still possible because e.g. presenting an excessively capacitive load to a badly designed audio amp could make it go unstable.
But, as I've said before, I think the 17-79 is a crap headset in terms of performance.
I agree the whistling is most likely a feedback issue with the noise cancellation circuit (which uses a mike inside the earcup, wired to achieve a null sound level pressure inside the earcup with zero audio signal) but
It would be very surprising if the input impedance of the headphone changed significantly when the active circuit is turned on. So I think this is more unlikely.
this is still possible because e.g. presenting an excessively capacitive load to a badly designed audio amp could make it go unstable.
But, as I've said before, I think the 17-79 is a crap headset in terms of performance.
Joined: Sep 2005
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From: Norfolk UK
I've used the 17-79 headset in a variety of modern and old aircraft over the last two years ,as has a pal of mine.
We have had no trouble and think they are brilliant,you can pay a lot more just for a name.
Lister
We have had no trouble and think they are brilliant,you can pay a lot more just for a name.
Lister
Joined: May 2009
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From: sherston
17-79 headset squeal
I've just had the same problem with one of my 17-79s which till now worked well.
There's a painfully loud, medium-frequency, feedback-type squeal any time the ANR is switched on.
The problem IS NOT related to the intercom system as the headset squeals when disconnected; the mic isn't part of the active feedback loop causing the trouble because the problem still occurs with the mic unplugged.
I've sent it back to Pilot Comms to look at with the comment that the problem is potentially a flight safety issue because the noise is loud enough to be debilitating.
I wonder whether it's worth continuing this thread for flight safety reasons?
There's a painfully loud, medium-frequency, feedback-type squeal any time the ANR is switched on.
The problem IS NOT related to the intercom system as the headset squeals when disconnected; the mic isn't part of the active feedback loop causing the trouble because the problem still occurs with the mic unplugged.
I've sent it back to Pilot Comms to look at with the comment that the problem is potentially a flight safety issue because the noise is loud enough to be debilitating.
I wonder whether it's worth continuing this thread for flight safety reasons?
