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I have a helicopter plug version

it's OK, for the money .... works ok ( sealing) - on my head when my hair is cut down with a #1 comb....


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I have one, although now relegated to pax, had no problems with it (apart from the fact after about 4 years the black foam material disintegrated - only discovered it when taking a mate to Avalon, when he took off the headset his ears were black - hard to get off so he walked around the airshow with a pair of black ears!).

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Thanks, never any lack of strange sights at Avalon. Let's hope the interruption to the Avalon schedule gives the organisers pause to think about running it a cooler time of year.

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I didn't investigate why. It is not uncommon for different headset brands to be incompatible with one another. May be different these days. This was back in the 90s.

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Thanks, yet another thing to look out for! Now you've mentioned it I have heard of headset incompatibilities, never struck it myself, but I'm certainly alert to the possibility....Thanks

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The only way you're gonna get problems with two different types of headsets connected is if the designer  or the aircraft wiring person  took shortcuts  and paralleled up the earphones ..... Or if the earphones had vastly different sensitivities and there was only one control to drive both and there was no other intermediate adjustment...


or if the microphone on one was maybe dynamic and the other was electret, and the electret bias supply was common (bad) and the dynamic 'shorted'out the common electret bias supply.


all would be poor design or wiring.

I have done alot of aviation intercom troubleshooting over my time and they are pretty much all crap, and wired up by people who had NFI and called themselves avionics techs.





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The Bose A20's active noise reduction does not come close to the best domestic active noise reduction headphones they are generations better.

Here's the thing you can buy one of these


and pair it with something like https://www.ebay.com.au/itm/Sony-WH-1000XM3-Wireless-Noise-Cancelling-Headphones-Au-Stock/142966776219?epid=16031259277&hash=item21497be19b:g:I6UAAOSwAjVfkw5l

You can go to your local electrical retailer and test different brands in the shop for fit and comfort.

This gives you the latest generation ANR super comfortable and you can plug straight into you aircraft's radio.

Just make sure you get the Nomad pro you will want the volume control on the plug leads.

Edited by SplitS
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That stick on microphone is a good idea. We did that a few years ago for some mining workers- using best available NC headphones (not Bose) and a 3D printed clip on noise cancelling microphone insert (from helicopter headsets).

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SplitS, you've opened up a new world of possibilities to me. I've often wondered at the price difference of the A20 type to Bose passenger ANR prices.

The WH-1000XM3 has been replaced by the WH-1000XM4. Very similar, just upgraded from what I've read. Available  for $430AUD.

The nflight mic kit is around $560AUD delivered here (including a Sony adaptor). Still expensive but around $700 cheaper than the A20 with hopefully better performance.

The headset, mike & adaptor is $990 AUD plus some local delivery fee.


Another option is to buy the Bose QC35 11, if bought from nflight that package is $950 AUD delivered.


I live in the bush so I have no chance to visit a retailer to test anything. I have a set of A20's & am happy with them, so I'm inclined to take the Bose option.


Having said that, I'm of an age that was bought up believing that Sony was the only choice for quality sound gear, some forty years ago.


Have you observed any trend in popularity between Sony & Bose using the nflight kit?


Really appreciate you joining in with your thoughts, I had no idea this sort of solution existed.......Peter





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kgwilson, tonight's a night of surprise. First was SplitS post about the nflight, now you tell me Bose is Apple. Certainly explains the pricing. I've been an Apple user for 35 years, in earlier days, it was outstanding gear but expensive. These days it's just expensive.


But like many things in life, once you're into a system & have an investment in dollars & a huge investment in learning time, changing horses is very daunting.

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If you buy the Sony's you have to buy a different size plug adapter


Just something to be aware of if you are a bit remote.

I have the nflight setup but I made a mistake and did not order the pro it works great if its just me but if you have some one else in the plane the lack of volume control on your head set is a pain. While the noise canceling works when the sony is plugged in, none of the volume controls do. BUY the Nflight Pro 🙂


I own Bose A20, and AKG aviation ANR headsets, the nflight is a way better setup IMHO because the headphones are more comfortable and the noise cancellation is sooo much better.


I don't know anyone else using the Nflight system sorry.


Edit just saw nflight now do send the Sony adapter.

Edited by SplitS
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The designed impedance, mono, is 200 ohms to the presented to the intercom amplifier. I think the Bose presents about 160 ohms, DCs about 200 ohms. 


The non aviation headphones are designed to present 32 ohms.

Now, here lies a potential compatibility problem :


The GA headset plug is a mono plug.  An adapter from the 3.5mm 'hifi' plug to GA headset really needs to put the two 32 ohm drivers of the Sony (for example) in series for 64 ohms. I suspect they put them in parallel (16 ohms)

which is sub optimal. The way the adaptor is wired could make a significant difference- IE if the output is low, with the Sonys , dont throw the baby out with the bathwater- could just need a different adaptor cable setup.


Older intercom amplifiers might have series output resistors and you might struggle to get enough level in the headphones-older GA airplanes.

Newer intercom amplifiers are less likely to have difficulty, based on design trends over the past 40 years.


Using an old intercom and a mix of 200 ohm and 32(16) ohm headsets might be a problem if the intercom had only a single amplifier driver both pairs of headsets. (old way). Modern intercoms are unlikely to have this design  style- due mainly to integration and small circuitry/cheaper.


Watch this space, when I get my aircraft, I will make some waves with my intercom setup.


Now, on the MIC side, the grade of noise cancelling (NC)  microphone insert varies substantially, and its really important to use them with a good pop shield, because if one side of the NC mic insert gets filled with what comes out of your mouth, this will prevent the NC from working.

NC microphones vary in output alot. Most aviation ones I have encountered have lots of output, several volts peak to peak. Some of the "communications " headsets for computers, handsfree kits- they are all low level outputs, despite being electret, and are likely to be low into the system.










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SplitS, I picked up on the different size plugs, 2.5 & 3.5, & saw that nflight sells an adaptor.


Thinking about this overnight, if I went with the Bose QC 35 11, that sort of contradicts the line of your original advice, that there are better solutions in the ANR world the Bose.


Now I've just read RFguy's further post which addresses one of my original questions about impedance mismatch. RFguy, my coms setup is via a 5 year old Garmin G3X touch panel, so I assume it would fit your definition of a new intercom. I also assume that the nflight NC mic is up to the job, you'd hope so, at that price.


My existing headset is a Bose A20, about three years old. If I went with the Bose QC 35 & nflight, this would eliminate the need for an adaptor & remove that potential problem from the mix. However, there is still the question that you raise about the 160 ohm (Bose A20) versus 32 ohm (Bose QC 35) load. I hope I've understood your post correctly about this.


Could you confirm that I now understand the potential problems correctly? If I do, can you see a way forward that minimises the risk of ending up with a lemon in actually use in the aircraft?

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The GA headsets I have measured are 160-250 ohms, so approx 200 ohms . and+/- 50% isn't going to matter much, since the volume control on the side will provide +/- 500% variation.


to be most compatible, the 32 ohm stereo drivers need to be wired in series. That's probably NOT  what most mono adapters do.  The difference between being wired in series and parallel is up to  4x  the volume depending on the topology.


Modern chips will drive pretty low impedance loads . They may have resistors in series to protect themselves against shorts- since when you insert a one of those barrel plugs all manner of shorting combinations can occur before the thing is seated.


If there is separate left seat and right seat audio output ( earphone)  amplifiers and controls, then it probably will not matter too much if the two headsets have vastly different impedances- they are independent. If they are wired in the aircraft in parallel - one amplifier driving two headsets, then the lower impedance headset will dominate and pull down the level in the higher impedance headset.  


I don't really know how the Garmin is wired and designed. But the simple test is if you plug in the high impedance (200  ohm) set and listen to yourself , and then plug in the low impedance headset into the other seat sockets, and if the level drops, well you know they are not independent.


Generally about 50mW is required for getting the highest peak  level in headphone driver (speaker). 

For a 200 ohm load , this is : 9V peak to peak (ptp)

For a 32 ohm load , this is  3.5V ptp.... and can be driven from common  4 x AA etc walkman power sources.


When two 32 ohm drivers are in parallel, now you have 16 ohms, and this does become a little harder to drive from small amplifier chips that were designed to drive headphones. Designers will put resistors in series to safeguard the amplifier against shorts, and this will amount to lost power when driving low impedance like 16 and 32 ohm loads. It depends what they did...


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and, further to my post, You can ascertain compatibility by using a cheap 32 ohm stereo headset ($5). I would suggest that a custom (series ) adapter rather than the usual paralelling adapter is needed, but I am not sure exactly what is being sold.

In most cases, the drivers are directly connected to the headset plug, and so you can measure the resistance of the headset with a multi meter. It will read a little lower than the actual audio frequency  impedance of the drivers.

On more advanced NC headsets, the headset may go via intermediate circuitry so you can only measure the impedance by looking at the voltage drop across a series resistor using a scope...


Edited by RFguy
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RFguy, You've raised some interesting points. You'd assume that an outfit like nflight would have thought all these issues thru & perhaps they have.


To be sure, I've emailed nflight a list of questions, based on the issues you raised in your post. I'll post their response when I get one.

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RFGuy, a bit more info that I've found. The Bose QC 35 11 has been replaced by the Bose 700.


Load impedances are;


Bose 700        60 ohm ANR OFF, 455 ohm ANR ON

BOSE QC35    55 ohm ANR OFF, 465 ohm ANR ON

SONY xm4      16 ohm ANR OFF, 47 ohm ANR ON.


The Sony figures make sense when I reread your comments about modern chips driving low load impedance.


I'll be interested to hear your take on these numbers, also any reply I get from nflight & to hear further from SplitS about his views on ANR, Bose vs Sony vs anyone else.



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My setup is


Microair M760 http://www.microair.com.au/products/25/M760-VHF-Transceiver-Q

Side by side seating.

I normally fly with the AKG https://www.akg.com/support/AV100.html

They don't make them any more I find them way more comfortable than the bose A20's

My Partner wears the A20's she thinks these are more comfortable than the AKG's


I also have the Nflight mic paired with Sony 1000-xm3's because I did not buy the Nflight pro it is hard to get the volume to match with the aviation headset it runs a lot hotter (louder) I use it when flying solo because the ANR in the Sony's kills both the aviation headsets and they are way more comfortable. If I had the Nflight pro I would use this setup as my main headset.


In case anyone is wondering I do not sell any of these I have no commercial interest other than improving everyone's experience in GA.

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Sony vs Bose vs Beats etc. I tried all the high end consumer headsets in a couple of shops the sony's seemed to have the best ANR and if you look up reviews they seem to agree that sony have an advantage here. For me they where also the most comfortable.

I use them with heavy machinery Tractors and loader's the reason I found the Nflight setup was because I realized that the consumer ANR was killing the aviation headsets and was looking at how to use my Sony's in the plane. The Bose A20's ANR is not close the the latest generation in Active Noise Reduction once you hear (not hear anything) how good the latest ANR is you wont want to go back IMHO.

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