John B3
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Feb 18, 2020

A20 Low impedance

Anyone have any ideas as to where you find the Low Impedance Mic option for the A20?

Bose website doesn't seem very helpful - have an aircraft with Low Impedance and LEMO connector and need BT option. Does it exist?

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Jeff_G
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Re: A20 Low impedance

Hey John, 

 

Thanks for posting. Welcome to the Bose Community. 

 

I can certainly look into this for you. Can you please confirm the aircraft you are flying and the country you live in?

 

Furthermore, are you using the A20 for leisure, domestic flights or military purposes? 

 

Thanks, 

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John B3
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Feb 18, 2020

Re: A20 Low impedance

Hi Jeff,

Aircraft is Airbus H145 helicopter.

Units fitted are 324843-2140 HDST ASSY, A20, 5-OHM, 6-PIN LEMO, FLEX PWR.

I need to fit 2 x Bluetooth replacement cable assemblies for use in the cockpit.

 

Interestingly our 135 is High Impedance which makes life interesting in a mixed fleet as headsets not compatible between aircraft!!

 

I guess it made sense to someone?

PartpilotUK
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Mar 12, 2020

Re: A20 Low impedance

Hi John,

The Bose A20 series with Low Impedance Mics only come with Non Bluetooth. I have never heard of a reason from Bose but I would think it is because the Low Imp Mic systems were primarily the early versions of Heli with Military designed Station Boxes, which were designed with Low Imp Pre Amplifiers.

The A109 E (Power) for instance is low imp and unable to accept a Blutooth Mic Assy on an A20, as it has an Electret Mic only. You can plug one in if you have a Lemo Version, and you can hear and listen to music or Telephone, but it won't work with the Heli Station Box as it will only accept Low Imp Mics. And I mean Mic systems, as it is not just the stalk, but the whole electronics right up to the Earphone.

Larry

dmincer
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Jan 9, 2021

Re: A20 Low impedance

Hi Jeff, I’m flying the Beechcraft F-33. I want to buy the BoseA20 but I don’t know what microphone impedance should I choose. Any help?

 

 

thanks

PartpilotUK
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Mar 12, 2020

Re: A20 Low impedance

Hi DMincer, I am not Bose, but maybe able to offer some guidance.

A Beechcraft F33 is most likely conventional Avionics and a standard model A20 should suit. If you have two Plugs on your existing Headset then a Bose A20 with an Electret Mic and Bluetooth should work fine. (This is of course unless you have non standard Avionics installed.) You can go for a 'Coiled Lead' Option or Straight Lead if you prefer.

If you are not familiar with the A20 or X you should be aware they use Batteries for the Noise Cancelling full time on the twin plug versions.

If it is your Aircraft then you may want to consider asking your Avionics Shop for a price to install a 6 Pin (called LEMO) Socket alongside or near your existing Twin Plug outlets, as this can be wired in parallel to the twin Plug sockets but have the luxury of being coupled to your power (12V or 24V) as well - this will instead enable you to buy a LEMO plug aircraft powered version of the A20 which will mean you don't have to rely on Batteries to power the Headset, which makes life in the Air a lot better. The internal Batteries on the Headset will only be used on start up and if you have Aircraft power failure.

I mention this as a lot of my customers don't realise this and buy a twin plug version, then have to buy another Mic solution later once they realise this mod can be carried out to suit a LEMO plug version.

Hope this helps? Drop me a note if you want more advice?

All the best,

Larry