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  #1  
Old 05-13-2020, 08:34 PM
seagull seagull is offline
 
Join Date: Dec 2019
Location: San Bernardino
Posts: 341
Default strobe audio in headset

Does anyone know what to adjust to eliminate the strobes from making a pulsing noise in the headset?
I can hear the strobes flash when on the ground, (probably because the background noise is lower). In the air it is not noticeable.
I suspect there is an adjustment in the AV-50000a but thought better to ask before making things worse.

audio mixer - AV-50000a
com radio - Garmin GTR-200
panel - Skyview touch
headset - Dave Clark ONE-X
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  #2  
Old 05-13-2020, 11:33 PM
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magiccarpet magiccarpet is offline
 
Join Date: Feb 2013
Location: Switzerland, Europe
Posts: 205
Default same here

I am facing the same issue and simply started to learn to live with it since I also had the same noise issues on PA28 and C172 aiplanes with different headsets.
I have noticed that air humidity influence the noise level on strobe lights. It's the inrush current (especially on modern LED strobes) which creates noise.
Audio noise sometimes is hard to tackle down. A capacitor on the strobes might help and proper grounding is key, but I am not an electrical engineer to provide a clear pathway.

Adjustments on the AudioMixer won't solve the issue.
Sometimes annoying yes, but in my case acceptable.
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Last edited by magiccarpet : 05-13-2020 at 11:35 PM.
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  #3  
Old 05-13-2020, 11:33 PM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 7,557
Default

This is often caused by a ground loop problem (multiple paths to ground). In an already built plane it can be a nightmare to track down.
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  #4  
Old 05-14-2020, 06:42 AM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,201
Default

Make sure that all audio jacks (mic, earphones, music) are mounted with
insulating washers so that there is no metal to metal contact between the
jacks and airframe. If the problem still exists, do not use the airframe for
strobe negative power. Instead, insulate the strobes from the airframe and run
a twisted pair (positive and negative) from the instrument panel to strobes.
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  #5  
Old 05-14-2020, 06:55 AM
pecanflyboy pecanflyboy is offline
 
Join Date: Nov 2011
Location: Granbury, Texas
Posts: 139
Default

Ground loop caused by using the air frame as the ground. This is often a short cut not discussed until one is bothered by headset noise. To eliminate noise, you need to bring all the grounds to a single "forest of trees" grounding block so that all have the same impedance. Unfortunately, retrofitting can be a huge task.

I would suggest a grounding block attached directly to the where you have the battery grounded (on the airframe). Start running ground wires to the components that are making noise.

Make sure the strobe wires are shielded.

As mentioned, make sure your headset jacks are insulated.
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  #6  
Old 05-14-2020, 07:53 AM
PhatRV PhatRV is offline
 
Join Date: Mar 2018
Location: Buena Park, California
Posts: 518
Default

https://www.youtube.com/watch?v=J08_p4OJa1g

This video explains the electrical ground loop problem very well regarding the audio jack.
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  #7  
Old 05-14-2020, 08:03 AM
Jamesey Jamesey is offline
 
Join Date: Feb 2008
Location: Hartlepool, England
Posts: 195
Default Noise Filter

Have the noise filters (KIA page 40-11) been fitted??
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  #8  
Old 05-14-2020, 08:29 AM
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rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,452
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Quote:
Originally Posted by Jamesey View Post
Have the noise filters (KIA page 40-11) been fitted??
That was my first thought.

There was also a revision at some point that changed form having just the mic jacks for the headsets isolated with insulators, to the mic and headphone jacks having them. Check to confirm that they both have insulators.

Additionally, you can do some things to try and isolate how the nose is getting into the audio system.
The first thing to try is to adjust the aux music input volume in the radio menu, down to zero and see if that reduces the noise.
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  #9  
Old 05-15-2020, 05:55 PM
seagull seagull is offline
 
Join Date: Dec 2019
Location: San Bernardino
Posts: 341
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Quote:
Originally Posted by rvbuilder2002 View Post
That was my first thought.

There was also a revision at some point that changed form having just the mic jacks for the headsets isolated with insulators, to the mic and headphone jacks having them. Check to confirm that they both have insulators.

Additionally, you can do some things to try and isolate how the nose is getting into the audio system.
The first thing to try is to adjust the aux music input volume in the radio menu, down to zero and see if that reduces the noise.
Thanks for the input,
I don't know if I have insulators on the headset jacks or if the noise filters were installed. The original builder was electronically savvy so I expect these were done.

I flew it today and tested the aux music volume and at 20% the pulses are a lot quieter, at 0% they are completely eliminated. I normally have the aux volume set at 50% with the aux input switched off. Does this info help track down the problem?
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  #10  
Old 05-15-2020, 07:25 PM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 3,201
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Yeah, just install insulating washers to keep the music jack from touching the
airframe. Or else disconnect the music jack wires at the panel end.
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