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Nov 18, 2020

Compatibility BOSE A20 with C-130J

Evening everyone!

I have bought the Bose A20 headset with U174 pin (NO Bluetooth), which perfectly fit in the C-130J audio receptacle.

The headset seems to work fine, but when connected to the plane with the "noise reduction" ON every transmission becomes a feast of shrieking noises.

This happens either in VOX or transmitting on any radio. I have changed cables (audio cables in the plane) and position in the cockpit.

Funnily enough this happens both in Pilot and Copilot seat but not in the Third member seat!!! (on the third member the Headset works fine!)

 

I am wondering if the headset may possibly have impedance issues.. do you have any inputs???

 

Ps I have used the headset without the noise cancelling and the mic itself works! 

 

Thank you very much in advance!

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Re: Compatibility BOSE A20 with C-130J

                        ***UPDATE***

I have tried the headset on different planes, and tried all the possible settings on the aircraft... nothing changes! 

Still on all the aircrafts on PILOT/COPILOT seats the Headset will make terrible noises while Third member or Loadmaster radio plugs will work perfectly!!!

 

On top of this in my squadron many other pilots have the Bose and have never had such issue.

 

Ps I can confirm that the MIC is low impendance type.

 

Please if you have any input let me know!

Thanks!!

 

 

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Mar 12, 2020

Re: Compatibility BOSE A20 with C-130J

Hi Stefano, I keep scanning past this post and see no one has responded. I guess it's because it is a tricky one. Some thoughts for you:-

It's a Mil Aircraft so highly likely low impedance Mike if it is U174 Plug. Makes sense then no Bluetooth.

From your defect analysis it may be likely that the two Pilot Sockets have Voltage available for Headset Power perhaps? Have you asked your Avionics Tech that question? As it seems to work OK elsewhere in the Aircraft.

Another possibility is that the Mil Aircraft may have (I think) 150 Ohm Mic Inputs, which are also classed I guess as Low Impedance - I came across a Bose A20 recently which had one - I changed the Mike & Downlead for a 5 ohm Low Imp U174 and it worked OK on his Jetranger and wouldn't before.

I would ask your other Pilot Friends for their Bose A20 Part Number and check if it actually matches yours? This can also be checked by calling Bose Technical?

Keith_L is a Bose Moderator on this site - he may be able to help given these extra suggestions? Let's see if he is not too busy!

All the best and good luck,

Larry

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Re: Compatibility BOSE A20 with C-130J

Oh, and another thing - did you know there were two NATO Style U174 shaped plugs?

One is a chrome/Silver colour and the NATO is a Brass colour. They are slightly different sizes for info and don't work on each other's sockets.

Larry