Hello good people of the internet!
The short version is: I want to transform my Sony WH-1000XM4 into an aviation headset
This is nothing new, I've seen plenty examples of people building aviation headsets from consumer headsets. There are even companies (I know of 4) whose sole business is selling these adapters (for $200-$300, which seems a bit steep). On diyAudio, I read this topic and that topic but they don't answer all of my concerns. I know very little about audio but I'm handy enough with a soldering iron and 3D printer.
What I understand:
What's a bit hazy: If I go from the mono audio signal of the panel to my stereo headphones, will I need to wire L&R in parrallel? Will that divide my impedance by two?
I don't want to damage the aircraft's equipment, nor my fancy headset...so, should I use an impedance matching transformer? If it's not 100% necessary, what's the drawback of not having one?
How to choose it? Does it need to be specifically, say 300:20 or can I use any transformer that has a ratio around 10:1?
Should I include a potentiometer?
Thanks for your future answers
The short version is: I want to transform my Sony WH-1000XM4 into an aviation headset
This is nothing new, I've seen plenty examples of people building aviation headsets from consumer headsets. There are even companies (I know of 4) whose sole business is selling these adapters (for $200-$300, which seems a bit steep). On diyAudio, I read this topic and that topic but they don't answer all of my concerns. I know very little about audio but I'm handy enough with a soldering iron and 3D printer.
What I understand:
- the aviation panel expects a load (is it called a load?) around 300-600Ω
- I measured the resistance (with a multimeter in DC, I don't have a function generator, nor would I know how to measure an impedance with one anyway) of my cheap headset between 130Ω et 1300Ω (there is a potentiometer that makes the value change)
- Sony says the WH-1000XM4's impedance is 16Ω when turned off (but wired) or 40Ω when turned on (still wired). I will use them turned on 99.99% of the time since the goal is to have active noise reduction.
- This article says around 17.6Ω average, I guess it was with the headphones turned off
- I measured the resistance (still with my multimeter) of the WH-1000XM4 at around 50Ω (turned on or off. This isn't surprising since the article above showe impedance is way above 16Ω at low frequency)
- Some people use an impedance matching transformer in their designs, some people say a potentiometer is enough
What's a bit hazy: If I go from the mono audio signal of the panel to my stereo headphones, will I need to wire L&R in parrallel? Will that divide my impedance by two?
I don't want to damage the aircraft's equipment, nor my fancy headset...so, should I use an impedance matching transformer? If it's not 100% necessary, what's the drawback of not having one?
How to choose it? Does it need to be specifically, say 300:20 or can I use any transformer that has a ratio around 10:1?
Should I include a potentiometer?
Thanks for your future answers
If I were in your shoes, I would start with a different set of questions:
1. What physical size must this adapter be? Smaller than X by Y by Z? Does it need to be waterproof? Vibration-proof? Will it routinely be dropped onto a concrete floor from a height of H meters?
2. Must this adapter be entirely passive? In other words, must it have no power supply at all -- neither 9V battery, nor coin cell, nor solar panel, nor connect to the aircraft's 12V / 24V / 48V DC power ?
3. If the adapter DOES require a power supply of some kind, what are the permitted options? Lithium Ion 3.6V "18650 cells"? 4xAA? 2x9V? How long must battery life be // how much juice can it draw from the aircraft?
4. How many different brands and models of headsets must the adapter support? Will I have access to one of each of them during testing and verification of the adapter?
5. Will I have continuous access to the aircraft during the development of the adapter? Will I be able to make many dozens of experiments / tests / measurements of the aircraft-to-adapter interface? Or do I get only one chance, it either works or it fails?
6. Am I willing to purchase new electronic test gear that I don't already own, to increase the probability of success of this adapter project? What's the maximum amount of money I am willing to spend on new test gear?
7. Why do I reject the option to buy a commercially available, pre-made adapter? What would change my mind and cause me to reconsider buying instead of building?
1. What physical size must this adapter be? Smaller than X by Y by Z? Does it need to be waterproof? Vibration-proof? Will it routinely be dropped onto a concrete floor from a height of H meters?
2. Must this adapter be entirely passive? In other words, must it have no power supply at all -- neither 9V battery, nor coin cell, nor solar panel, nor connect to the aircraft's 12V / 24V / 48V DC power ?
3. If the adapter DOES require a power supply of some kind, what are the permitted options? Lithium Ion 3.6V "18650 cells"? 4xAA? 2x9V? How long must battery life be // how much juice can it draw from the aircraft?
4. How many different brands and models of headsets must the adapter support? Will I have access to one of each of them during testing and verification of the adapter?
5. Will I have continuous access to the aircraft during the development of the adapter? Will I be able to make many dozens of experiments / tests / measurements of the aircraft-to-adapter interface? Or do I get only one chance, it either works or it fails?
6. Am I willing to purchase new electronic test gear that I don't already own, to increase the probability of success of this adapter project? What's the maximum amount of money I am willing to spend on new test gear?
7. Why do I reject the option to buy a commercially available, pre-made adapter? What would change my mind and cause me to reconsider buying instead of building?
Alright, I'll play along 🙂
- I'm not too concerned about any of these. Because it doesn't need to be most of these and I'll fly with a backup headset in case my DIY breaks down
- I would like that. All four commercially available versions are passive as far as I know (unless you want your adapter to connect to your phone via BT, which is not my intension)
- Ideally no power needed. If I had to power it, my first thought is a USB power bank (that could also recharge the headset, should 30 hours of battery life not be enough) but I'd be open to anything (alkaline to LiPo)
- Mine: Sony XM4
- It's at the flying club but I can go there and test regularly. And I have a real passive headset I'll use until my adapter is ready
- I'd rather do without them. Note that I have an oscilloscope (the poor soul would ideally need some TLC but I can do that). Maybe I could buy or find a function generator. There's a fablab nearby and I know at least one member has some knowledge about ham radio, he might be able to help me test some stuff
- I bet your current thought is somewhere along the line of "developing a commercial product takes time, effort and dollars, you should buy it" but, on top of the cost...I really like to make stuff 🤷♂️ Sometimes I can learn all necessary new skills myself, sometimes I need more help. Today, I'd like some help to kickstart things
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Do any of you know much about ANC headsets with both inside (feedback) and outside (feedforward) mics? A few years back, I tried to kluge together a feedback-only analog design, mounting tiny electret mics inside one of my SONY MDR-V6 headsets. The mics were appropriate, since they came from National Semi's newly acquired ANC IC design group.
My kluge design's performance was a bit "iffy" - maybe 6 dB better than the passive attenuation.
I settled for a SONY MDR-1000X ANC headset instead, but I haven't totally given up on a DIY.
For pilots - I wish they'd had ANC when I flew on the Concorde in in 1979. The cabin's white noise made their headsets useless, but the unlimited champagne partially compensated.
I flew on B-25 "Grumpy" a few years ago. Prop noise completely overloaded my MDR-1000Xs. I don't know how well the pilot and copilot's David Clarks worked inside the B-25. All digital ANC headsets depend on drone (repetitive) noise. They can't handle impulse noise. I've considered combining a minor, fine tuning analog loop inside a digital headset.
Many years ago, Electronics magazine's annual April Fools issue featured article on a Noise Cancelling setup gone berserk. I wonder if Amar Bose read the article and turned it into a lifelong mission.
I took a ride on a B-17. Little bit bigger. It needed a "vibrator" serviced before they would fly.
I was pretty sensitive to sound at that point in my hearing-loss. I wore plain 3M H10A Peltor Optime 105 Earmuffs, passive plastic cups with foam fill. Very comfortable that way. Actually I was surprised how not-so-loud the B-17 was, with four snarling Studebakers (and Wrights). The turbos do take the edge off.
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All those bulbous headsets level off at ~ 30 dB RSS. There are some thinner headsets. I hadn't given it much thought until 2019, when I tried to find a target shooter's ANC headset. There aren't any, at least for civilians.
If you spend a career around powered jet engines, to meet NIOSH Standards, you might consider wearing both muffs and foam ear plugs. You don't quite get the compounded (30 + 30) = 60 dB RSS, but close. Maybe 50 dB.
So, how did he get through that opening? I'm not very claustrophobic, but.....................................
The aircraft must have some sort of amplifier and that amplifier is supposed to be capable of driving 300 ohm loads, or higher. Locate and purchase an appropriate matching transformer. Put in small box with suitable cable/connectors. Job done.
Anything you do with resistors or pots just wastes power.
Perhaps something like- https://www.mouser.com/ProductDetail/Hammond-Manufacturing/144G?qs=QE4fThmkWqt9r5ag/XYt4Q==
Or others may have a better choice.
Anything you do with resistors or pots just wastes power.
Perhaps something like- https://www.mouser.com/ProductDetail/Hammond-Manufacturing/144G?qs=QE4fThmkWqt9r5ag/XYt4Q==
Or others may have a better choice.