round_peg Posted June 12, 2012 Report Share Posted June 12, 2012 I am trying to track down an issue using my Lightspeed 20XL headsets in the CT. When I started flying the CT I dragged these "old" sets out of retirement*. They needed new ear seals but otherwise I saw no reason why they should be any less effective in the CT than they were in a Cessna. Right away I noticed that when climbing at WOT the engine noise I am hearing through the headset when I key up is close to deafening. I feel the need to shout over it. Then the other day I was flying X/C and called ATC for flight following. They could barely copy me. It took several tries, speaking very loudly and slowly, to get radar services. I did not have this issue (at least not reported by ATC) on the return flight. But at cruise RPMs I am getting more engine sound bleeding through to the transmission than I can recall hearing when these sets were used in another airplane. Could it be that these headsets are not "tuned" properly to cancel out the higher RPM noise of the Rotax? My partner in the CT hasn't had this problem, to my knowledge, with his ANR headsets. I am mystified, and I don't want to invest in new ANR headsets if the issue could be elsewhere. *About ten years old -- Lightspeed no longer supports them. Link to comment Share on other sites More sharing options...
Roger Lee Posted June 12, 2012 Report Share Posted June 12, 2012 Hi Mitch, It could just be the headset or it may be the settings you have in your radio especially if you have a Garmin SL40. The other thing to try is to make a better ground system for the plane. If the grounds aren't good then things like feedback, noise and instrument fluctuations can take place. Read about better grounding in my other post. Link to comment Share on other sites More sharing options...
round_peg Posted June 12, 2012 Author Report Share Posted June 12, 2012 Roger, could you point me in the general direction? Are we talking better grounds for the intercom system, the radios, or both? We have the Bendix/King com. What's to set? Link to comment Share on other sites More sharing options...
Roger Lee Posted June 13, 2012 Report Share Posted June 13, 2012 At the time I was only working on temps and pressures, but the headset followed right along. It should be better grounds for everything. Like I said this was just a test and it worked out well. So I left it in place. Link to comment Share on other sites More sharing options...
Jim Posted June 13, 2012 Report Share Posted June 13, 2012 Before you go running off too far, make sure the little microphone is facing toward your mouth and not toward the engine... Link to comment Share on other sites More sharing options...
Runtoeat Posted June 13, 2012 Report Share Posted June 13, 2012 Mitch, Jim may have hit on your problem when he refers to your microphone. Our headset mics reject cabin noise. Some do this better than others due to circuitry of the mics and of the headsets. The newer headsets should do this better than older ones although my new Bose A20 headset seems to exhibit cabin noise during wide open throttle operation - this is noticed in my side band so I assume that it is also being heard by those whom I'm transmitting to. I do not recall hearing cabin noise during wide open throttle operation with my David Clarks and Softcoms. All my headsets are quiet during non WOT operation. Perhaps it may be that your old Lightspeed headset/mic may not as good at rejecting cabin noise as your friend's headsets? Link to comment Share on other sites More sharing options...
Roger Lee Posted June 13, 2012 Report Share Posted June 13, 2012 Hi Dick, I'm talking about a buzz or hum noise and nothing to do with any outside noise. Link to comment Share on other sites More sharing options...
Runtoeat Posted June 13, 2012 Report Share Posted June 13, 2012 Hi Roger. It appears that Mitch may be experiencing cabin noise coming thru his side band? Not clear tho because it's hard to tell what Mitch may mean when he says "deafening"? My problem is definately my mic picking up engine noise and this noise ends up in my side band and transmission. A clue might be that those who ride with Mitch do not hear the noise he hears? Link to comment Share on other sites More sharing options...
Roger Lee Posted June 13, 2012 Report Share Posted June 13, 2012 Hi Dick, If you have an adjustable menu driven radio like the Garmin SL40 you can adjust sensitivity levels. Link to comment Share on other sites More sharing options...
round_peg Posted June 13, 2012 Author Report Share Posted June 13, 2012 Before you go running off too far, make sure the little microphone is facing toward your mouth and not toward the engine... I pulled off the mic muffs. It's difficult to be sure without further testing but this could be at least part of the problem. The mics have two virtually identical flat sides but one is marked "talk" feintly. I will make that adjustment and listen for a difference. I notice also that the mics have a gain adjustment pot. I suppose I'd be outright guessing which way to twist it. BTW, the com is the Garmin not Bendix King as I said earlier. What kinds of adjustments might do me some good? Link to comment Share on other sites More sharing options...
round_peg Posted June 13, 2012 Author Report Share Posted June 13, 2012 Hi Roger. It appears that Mitch may be experiencing cabin noise coming thru his side band? Not clear tho because it's hard to tell what Mitch may mean when he says "deafening"? My problem is definately my mic picking up engine noise and this noise ends up in my side band and transmission. A clue might be that those who ride with Mitch do not hear the noise he hears? I think it is engine and prop noise coming through the side band not being cancelled by the ANR. I feel like I have to shout to be heard, though I don't know how that sounds to anyone else. It sounds fine at low RPMs. I flew for awhile with some old passive David Clarks. While the were inherently less quiet I don't recall a need to raise my voice making calls in the pattern. Link to comment Share on other sites More sharing options...
Runtoeat Posted June 13, 2012 Report Share Posted June 13, 2012 Hi Mitch. I think that you may be correct in saying that the engine noises aren't being attenuated by the ANR for side band but I'm wondering if this is also transmitted? My thinking is even if I lower my sideband level the cabin noise still remains and this will be transmitted. Having another aircraft that can let us know if the noise is being transmitted during WOT operation and if the noise is no longer transmitted during normal cruise would answer some questions. I believe that you indicated ATC was not hearing your transmission due to background noise? As for the SL40 setting which Roger was refering to, one of these is side band level. The manual provides directions for adjusting the settings. Link to comment Share on other sites More sharing options...
round_peg Posted June 13, 2012 Author Report Share Posted June 13, 2012 Hi Mitch. I think that you may be correct in saying that the engine noises aren't being attenuated by the ANR for side band but I'm wondering if this is also transmitted? My thinking is even if I lower my sideband level the cabin noise still remains and this will be transmitted. Having another aircraft that can let us know if the noise is being transmitted during WOT operation and if the noise is no longer transmitted during normal cruise would answer some questions. I believe that you indicated ATC was not hearing your transmission due to background noise? As for the SL40 setting which Roger was refering to, one of these is side band level. The manual provides directions for adjusting the settings. Good question. I don't know what others are hearing, but my experience with ATC last week suggests that my transmission was badly garbled. I think it makes sense to try the simplest solution first, which is to make sure my mic is directed properly. Changing the side band level on the radio seems like it would not address this issue, only how much of it I am hearing. I also need to fly when I can get someone in another airplane or on the ground with a handy-talkie to monitor the transmissions. General observation: Many of the radio transmissions I hear are garbled and/or weak. This has always been the case. I might be a bit more than normally obsessive and/or self conscious about this, but I have to wonder how many airplane owners think about how well they are being heard, unless they are told by ATC or someone else that they can't be understood. Link to comment Share on other sites More sharing options...
Jim Posted June 13, 2012 Report Share Posted June 13, 2012 Folks, it's sidetone, not sideband. Link to comment Share on other sites More sharing options...
207WF Posted June 13, 2012 Report Share Posted June 13, 2012 I have similar symptoms with my older style Bose. It seems intermittent: more likely during takoff and climb and less likely to happen in cruise. I will be interested in whether radio setting adjustments help! WF Link to comment Share on other sites More sharing options...
round_peg Posted June 13, 2012 Author Report Share Posted June 13, 2012 Folks, it's sidetone, not sideband. I knew that. Link to comment Share on other sites More sharing options...
Runtoeat Posted June 14, 2012 Report Share Posted June 14, 2012 Thanks Jim - sidetone. When I have requested it, I have gotten "hearing you loud and clear" for radio checks but this has been during cruise with power pulled back. I suspect that I have cabin noise during transmission at WOT and will try to get my friend to give me a radio check during this condition. Link to comment Share on other sites More sharing options...
207WF Posted June 17, 2012 Report Share Posted June 17, 2012 I just remembered something else. My ptt switch was going intermittent and I was getting a lot of complaints from ATC. Huge difference with new switches. You might check that. WF Link to comment Share on other sites More sharing options...
Runtoeat Posted June 17, 2012 Report Share Posted June 17, 2012 WF, good thought. Recently my left side switch was intermittent but I squirted some Inox lube in it and this seemed to free it up and elinimate the intermittent problem. I acutally have new switches on hand to replace my old ones. Guess I need to put switch replacement on the squawk list. Link to comment Share on other sites More sharing options...
Jim Meade Posted June 17, 2012 Report Share Posted June 17, 2012 I have a jack issue. I think the seat is hitting the jack and over time has caused an open in the voice circuit. Have to follow up on it a bit. I would like to rewire mine with the LEMO jacks, which I probably will do this coming winter. Link to comment Share on other sites More sharing options...
round_peg Posted June 17, 2012 Author Report Share Posted June 17, 2012 WF, good thought. Recently my left side switch was intermittent but I squirted some Inox lube in it and this seemed to free it up and elinimate the intermittent problem. I acutally have new switches on hand to replace my old ones. Guess I need to put switch replacement on the squawk list. I have also noticed the intermittent issue on the PTT. Probably some contact cleaner would help. But if the switches need to be replaced, do you happen to know the part number? Link to comment Share on other sites More sharing options...
Roger Lee Posted June 17, 2012 Report Share Posted June 17, 2012 The intermittent operation is usually a sign that the switch is on its way out. They are inexpensive and easy to replace. As soon as it starts just buy a new switch from Spruce for $8-$10 and it only takes about 20 minutes to replace. Link to comment Share on other sites More sharing options...
sandpiper Posted June 30, 2012 Report Share Posted June 30, 2012 Twenty minutes for Roger, forty for the rest of us! Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.