Repurposing Lightspeed ANR headset - squeal

clam · #1 04-06-2020, 10:25 AM

I have a side project going trying to refurbish a military helmet and convert to civilian use. I took the electronics out of an older Lightspeed Zulu ANR headset and installed them in the helmet. I then plugged this into the aircraft and they seemed to work well enough on the ground without the engine running in the passive mode. When I turned on the power for the ANR system, all was well for about 30 seconds, but then a loud, high frequency squeal developed in the left earphone. If I pull that earphone away from my head, i.e., allow a gap between my head and the ear cup, the squeal goes away. Also, if I take the helmet off no squeal is present, but if I place my hand near the earphone, the squeal returns.

So, it appears the ANR in the right earphone works fine. The left earphone works fine until some human body part is placed very near it.

Any ideas?

Plan B is to build up the helmet with a passive system and use CEP in-ear plugs.

Thanks

Alan Bumbaugh · #2 04-06-2020, 11:44 AM

I lost one of the foam inserts in a DC after market modified ANR headset with similar squealing.
Once I replaced them it worked fine.

Kyle Boatright · #3 04-06-2020, 11:48 AM

It might be worth contacting Lightspeed Customer Service. I had a similar problem a long time ago and it was correctable by changing the settings on the dip switches inside the power unit.

n82rb · #4 04-08-2020, 10:08 AM

its feedback between the sensor and the speaker in the earcup. i doubt lightspeed would even talk to you about it if is not in a production headset.

clam · #5 04-08-2020, 01:40 PM

Quote:

Originally Posted by n82rb

its feedback between the sensor and the speaker in the earcup. i doubt lightspeed would even talk to you about it if is not in a production headset.

Correct... they were cordial but not interested in even suggestions to troubleshoot. And I did not really expect them too. This is just a quick attempt before the old headset goes in the trash. I have had a couple responses that similar issues were resolved with a foam pad as mentioned previously, and even a fabric cover fixed the issue for someone.

I'm going to try with foam/fabric pads, and then move on to plan B with a passive system and CEP earplugs. That setup is a known quantity.