[akatsuki]

Hey. I was looking through the maxx HD800 mods thread and wondering if any of those things are applicable here. Like let’s say I isolate the driver by wrapping the edges in dynamat extreme. And either remove the drivers clamp ring relying on friction fit against the dynamat or maybe make the inner ring solid and also dynamat that?

At one point I am going to further isolate the driver by making the driver hang in the middle using a suspension system using rubber bands like a microphone shockmount system.

Now if only digikey would restock drivers so I could build these various prototypes.

 

[Tofty]

Isolating the driver directly is an interesting idea. I did add some foam around the sides of the driver on my Borealis inspired builds, but didn't add anything soft front or back. O-rings might work as a simple way to dampen the driver from it's surroundings.
A full suspension system might be overkill, but I certainly want to know what you discover.


I think I've finally finished designing my audio-book headphones:

I've just started printing some of the parts. The print materials I'm using are Eryone's Dark Brown Wood and their Silk Copper filaments.

The headband is largely the same as the one used on my TH6 design. The headpad is a DT770/990 type. Earpads are for the M50x.
Drivers are the 40mm Peerless ones. They are angled in by 10 degrees and have an unobstructed, Grado like open-back layout.
The bridge cable connectors are HRS HR10-7 sized ones with 6 pins.
MP3 playback is provided by a DFPlayer Mini board. These things are tiny and really cheap off ebay. It uses a MicroSD card for file storage.
The two large buttons on the side are for Pause/Play, while the three on the back are for power and volume/track change, depending on press time.
The battery is a 3.4Ah li-ion 18650 and there's a USB-C charging/discharge protection board for it. The battery will be retained using o-rings.

I'm a little worried about how flimsy the single sided arms will turn out to be and they may need to be reworked, but other than that I'm relatively happy with the design so far, despite how ugly it looks.

My next design/build will be a variant of this design: https://www.thingiverse.com/thing:5202117, which itself is inspired by the Sony Q010-MDR1 (Qualia 010) headphones.
I plan to use the 45mm Tesla drivers I recently found on ebay. No idea how good they actually are or how similar they are to the ones used in the Beyerdynamic T1s, but why not give them a try.

Then after that I might finally get back to working on the headphone test rig idea.

 

[castleofargh]

A full suspension system might be overkill, but I certainly want to know what you discover.

The driver suspended is a bad idea in principle. My previous suggestion was really for something already shaking/rattling, and someone trying to mitigate that issue. I didn't mean to let anything move more. If the driver isn't more or less fixed in space(from weight or the clamping force on your head), then the push on air by the diaphragm will also cause a counter movement for the rest of driver instead of having most of the energy used to create the sound wave. I have no idea how to try and predict or quantify that behavior, I learned too little mechanic too long ago. Maybe I'm crying wolf over nothing even remotely relevant. But I'm sure it would terrify a true elite audiophile as it's at least theoretically bad.

Personally I've spent the last decade using relatively light headphones and killing the clamping force almost entirely for comfort. I don't even follow my own advice. ^_^

 

[akatsuki]

wWouldn’t the issue with the suspended driver be an issue with shockmount microphones? Since that is sort of the model I am copying.

And it would be suspended by rubber bands pretty tightly. Shouldn’t be too much motion. I suppose bass might cause some slight back and forth movement.

 

[castleofargh]

wWouldn’t the issue with the suspended driver be an issue with shockmount microphones? Since that is sort of the model I am copying.

And it would be suspended by rubber bands pretty tightly. Shouldn’t be too much motion. I suppose bass might cause some slight back and forth movement.

At least in my mind they're different enough. With a mic, it's the air pressure that's providing the energy to push a very light membrane of sort that's not firmly held in place to help push the mic. the amount of energy transmited to the rest of the mic by the diaphragm(capsule, whatever design it actually is) should be really small unless we reach the mic's physical limit and get distortions.
Also the shock mount for a microphone is there to deal with vibrations from the ground(or the table) getting to the mic stand and potentially shaking the mic, not the other way around. Even if it's not theoretically ideal for the mic, it's clearly better than recording footsteps as massive "audio" signals.

I can't talk about how our own movements impacts a driver, maybe it's bad, but I believe that a driver has an electromagnetic force strong enough to mitigate most issues. Sadly it's that strong force that might be strong enough to potentially move a "free" driver(bigger the volume of air moved, and/or lightweight and poorly fixed driver= more chance for the driver itself to move and all that energy being lost instead of used to create the wave)

Beside my unreliable, non engineer, mechanical knowledge, maybe it's also worth considering how drivers in headphones and speakers are usually fixed. There might be a good reason for that.
Sorry if I'm killing your project with my doubts. It's very possible that as I said before none of it really matters in practice for our ears. I hate people who declare something bad without any concept of the magnitudes involved, yet I'm kind of doing just that here. I wouldn't trust myself too much based on that alone.




Question to all: How much time do you spend before getting the measurements right, the right 3D model, and right prints?
I look at @Tofty's last design and even though a bunch of things come from previous projects, I imagine that I might need ... IDK.. a good month, maybe more depending on how many things I needed to take into account but didn't until the 9 hours print was done and didn't fit.

 

[akatsuki]

For me I don’t have any measurements at all. I basically took another design and mostly maintained the driver distance and left it alone.

I spent some time thinking about how to design a driver test rig. You would be able to slide the driver forward and back as well as adjust how open the sides in front of the driver were and maybe even some sort of iris system for the rear to close it off incrementally.

Then once that was all dialed in I could redesign my standard print to reflect those measurements. And additionally try all those crazy AliExpress drivers in the same rig (the Beryllium ones as well as other pricey ones)

But without measurement gear it felt a bit pointless. And I really can’t justify buying a GRAS for just this. I am not stating my own headphone company.

 

[akatsuki]

Anyway, here is the draft version of my suspended driver design. Definitely not refined to any level but just as a test case. I would also need to add yoke mounts.

https://www.tinkercad.com/things/kfLf5F9b2Bg

 

[IvanDrago]

ZMF is using some simple silicon gasket to isolate the driver from the frame.
No clamp cage needed. I´m using 2mm closed neopren cell foam which also works very well.

 

[akatsuki]

Yeah - I am sure there are lots of ways to do this decoupling, this is all for fun for me.

 

[miketlse]

Yeah - I am sure there are lots of ways to do this decoupling, this is all for fun for me.

Yes, in engineering terms there is usually more than one way to achieve something, but the interest can often be in exploring concepts to achieve, the max acoustic fidelity at minimum cost, max acoustic value at minimum cost, most acoustic value at reasonable cost, etc.

 

[Tofty]

Suspending a driver will inherently be more problematic than a microphone; as the driver is actively generating it's own movement, while a microphone is passive. There will also be a factor or more difference in the energy the driver is converting to movement compared to the what the microphone is receiving.
In the ZMF video IvanDrago linked to; it shows damping around the sides of the driver, but not in front of or behind. I'm assuming that it is not advised to dampen any of the driver's forward and back motion, even a little bit.
This is definitely worth testing though as these are just assumptions.

akatsuki I'm afraid I don't understand how your suspended driver design goes together. I must be missing something.

Question to all: How much time do you spend before getting the measurements right, the right 3D model, and right prints?
I look at @Tofty's last design and even though a bunch of things come from previous projects, I imagine that I might need ... IDK.. a good month, maybe more depending on how many things I needed to take into account but didn't until the 9 hours print was done and didn't fit.

For the above design it must have taken me over a month on and off to get the design to a point where it was ready to print, although this was probably my most technically complex design due to all the parts that needed to be accommodated, plus all the wiring paths.
I have a decent amount of experience with the results of my printer, so I could make the dimensional adjustments needed at the design stage ( mostly just adding 0.5mm clearance around any parts I needed to integrate).
Accurately modelling the parts being used really helps with being confident that it will all go together during assembly. With this project I was fortunate that other people had already created useable models for some of the switches, the MP3 Player and battery charging PCBs, saving considerable time.

Unless the part came out completely unusable; I tend to use it even if it looks a bit rough. The nice thing about printed parts is you can easily take a knife to it and reshape areas that require a little fettling. I used to print lots of parts all in one go but I've moved to printing the larger parts individually. so each part takes a few hours at most and can be worked on as the next part prints. Also, as headphones consist of largely mirrored parts; I try and print one side completely before the other, so that if I identify something that needs to change, I only scrap one side, rather than both. A number of my headphones have different earcups on either side as I thought of an improvement when building up the first side but it wasn't such a big deal to need to scrap it.

Broadly this latest project owes more then may be readily apparent to my previous work and the work of others, as there's a load of things that I didn't do, because of having tried them previously. It's all just iteration to an end goal never reached, because I'm only pretending to know what I'm doing.


Annoyingly I ordered the wrong tap for the 12mm switches (they're 0.75mm pitch not 0.5mm. The HRS connectors are 0.5mm which is where I think I misremembered), so I can't yet install them. However the rest of it is done externally and I'm pretty happy with the results. The arms are less flimsy than I had feared they would be, so no need to rework that. The headband is a little light on the clamping force, but just the right side of useable. The battery is a bit tight and hard to remove, but there should be no need to regularly remove it, due to the built in charger. The bridge cable connectors work nicely and were easier to wire up than I had feared. While I'm not super sold on the wood filament, it's fine for what it is and has quite a nice texture. I think it worked best for the stand, rather than the headphones themselves.
Doing all the internal wiring is going to be challenging, but I hope to be finished by next weekend.

 

[castleofargh]

Thank you for the detailed response. So it is about as time consuming as I imagined. Still hope to be able to get in on the fun at some point. Until then, I really enjoy this thread and @IvanDrago’s.

 

[akatsuki]

So my suspended design you basically put the driver holder into the larger earpad plate ring and attach a bunch of rubber bands around the perimeter. Then the clamps go into the gaps to close the rings off and provide structural support.

I just ordered some drivers from Digikey so when I get them I’ll probably get back to printing out a bunch of variations to play with.

But really need to figure out how to get these measured.

 

[dougms3]

Do you have pictures of how the driver was mounted on to the headphone?

I'm curious about swapping out drivers on a headphone.

What kind of wiring are you using to connect the jack to the driver?

I recently swapped out the wire in my Final audio headphones to mundorf silver/gold solder and wire with excellent results.

 

[Tofty]

Thank you for the detailed response. So it is about as time consuming as I imagined. Still hope to be able to get in on the fun at some point. Until then, I really enjoy this thread and @IvanDrago’s.

Thanks. Yeah there aren't really any short cuts, apart from taking a pre-existing design and modifying it, but even then I've found it's quicker to remake the design from scratch, just using the relevant dimensions, than actually modifying another's model files.

So my suspended design you basically put the driver holder into the larger earpad plate ring and attach a bunch of rubber bands around the perimeter. Then the clamps go into the gaps to close the rings off and provide structural support.
I just ordered some drivers from Digikey so when I get them I’ll probably get back to printing out a bunch of variations to play with.
But really need to figure out how to get these measured.

Thanks for clarifying that. Looking forward to seeing how this all comes together, including the headband. Which drivers did you get from Digikey?
Measurement is the bit I'm currently stuck on. I have some MiniDSP EARS, but need to get a suitable DAC/Amp to go with them, then learn the REW software, then test the hundreds of headphones I've somehow accumulated, in a replicable way. Then learn how small changes to various parts affect things. A long journey ahead.

Do you have pictures of how the driver was mounted on to the headphone?
I'm curious about swapping out drivers on a headphone.
What kind of wiring are you using to connect the jack to the driver?
I recently swapped out the wire in my Final audio headphones to mundorf silver/gold solder and wire with excellent results.

Hopefully my build photos below show somewhat how the driver is being clamped; the copper coloured driver cup holds the driver from the front, just around it's rim and the large cover part clamps the driver around the back of it's outer rim. This is basically how I've clamped all my drivers, with some designs having a ring of thin foam around the sides of the driver, and some clamping the back of the driver in multiple places to in theory help with rigidity, but I doubt it makes any real difference.

I've done a fair bit of headphone repair and usually the drivers will be glued into place, although they often use a type of almost silicone sealant type adhesive, which isn't too hard to remove cleanly.

I'm not too sure what wire I'm using currently. I got it a long time ago from a company that made defence electronics so it's fairly good stuff. We used it on some Eurofighter Typhoon pre-production components if I recall correctly. I just use old-school leaded solder, as I have loads of it and I don't enjoy working with modern solders as much.
edit: this is the wire I've been using - Harbour Industries M22759/11-24

Over £50 per metre for the 1mm diameter version is some pricey wiring. At least you don't have to use too much of it per unit. I'm glad to hear you enjoy the results.


Wiring these headphones was a bit of a journey, but it worked out in the end.