[melka]

Hi Everyone
 
I'm new to this forum, even though I've been looking at all the threads I could for some time now.
To make it short : I'm in the process of designing my perfect headphones. Everything would be custom machined. I'm not saying that I'll definitely do it, but I may have the opportunity to do so in a few months, so I'm starting to model the parts, design the electronics, etc...
 
I'm here to get your feedback and advices on some aspects that are a bit obscure to me. I'm not a pure audiophile, but I can make the difference between some cheapo headphones and mid-range ones. I currently own a Koss Porta-Pro and a Sony MDR-V500, but I find some defects in both and I'd like to make my own, just for the sake of it
 
Here are the features that I'm planning on getting:
- Over-the-ear leather cushion
- 40mm Sawafuji SZ-2T drivers
- Noise cancellation
- iPhone/iPod remote with mic (I'd get an Apple cheap headphone and just keep the remote/mic part)
- Volume and noise cancellation adjustment knobs on the headphones
- Made out of aluminum + anodization and chroming (a first prototype might be made of wood to test design)
 

 

 

 
Everything will be open source, I'll share the design files with anyone when they'll be finished.
 
I'm still working on the headband, articulations and electronics. The potentiometer used is temporary, it was just to test the mechanical design of the knob. Same thing with the noise cancellation mic.
 
Finally, here are my questions :
- Do you have any idea about how I can design the sound chamber to get the most of the SFI drivers ? Maybe some acoustic design software, or books that I can compulse ?
- Will the ouput from an iPod or iPhone be enough for the SFI drivers or do I need to use an amp ?
- Where can I find infos on a small noise cancellation circuit that could be used ?
 
Sorry for the long post and I hope I'm not bothering you with my newbie questions
 
Edit : Changed the thread title
 

 

[jezz]

Some thoughts/responses to questions; I've been going through a similar exercise, although electrostatic and out of plastic:

• For the SFI ribbon tweeters, you should try posting/reading the Orthodynamic Roundup thread. There's a very chance some of the regulars that post there will know of them, and how to best design around them. You might consider a different driver with a higher impedance.
• The iPod output should be OK for SFI drivers, but I seem to recall the 32ohm version of the driver is preferred. I don't recall the reasoning on that though.
• I would suggest foregoing the noise cancellation, and instead try to get a good seal with the headphones/pads. I might also suggest foregoing the volume control, just to simplify the design.
• Unless you own your own CNC milling machine (do you?), you might find that milling Al and having it anodized/chromed in small quantities is prohibitively expensive. I seem to recall prices on the orders of $100's. I've been looking at 3D printing in nylon, where prices are on the order of $10's.
• If you're looking at an over-the-ear headphone, you can probably drop down to having 6 screws around instead of 8 and save some time/money on milling.
• Is the outer cover attached with friction? I can't seem to figure out how you'd tighten the screws otherwise.
• You should leave some more space in the back so you can fiddle with damping. It looks like you've only got 1cm or so, which is a little tight.
• You might consider flipping everything upside-down, such that the screws go in from the earpad. I think it would make them easier to work with.

Your headphones look really nice. Good luck!

 

[melka]

Thanks for the infos, Jezz.
- I've been reading the infamous Orthodynamic Roundup thread, but long thread is long, I haven't finished going through the 1100+ pages yet.
- I think I'll remove the noise cancellation mic from the first prototype, but I'll keep the machined pocket in case one day I finally understand how it works
- About the milling machine, that's what I was talking about when I was saying "I might have the opportunity in a few months". I may move to another town and I know someone there that have all the required equipment for machining (CNC & conventional lathe and mill + all the tooling you want). I'm not quite sure about the finishing process & materials I'll use. I'll have to judge when (if?) I have the product in front of me
- You're looking into 3D printing : are you thinking about stereolithography like shapeways does or something more along the lines of makerbot and reprap ? I've never seen a piece printed in FDM (fused deposition modeling, technology used by Reprap and such), so I'm a bit worried with the surface finish and accuracy.
- I think I have a lot of room for improvements, like dropping some screws, refining the wall thickness, etc... to get a lighter and easier to work with end product. Right now I'm working on the headband and arms, once I've finished with the general design, I'll start cleaning it.
- Actually, the outer cover is attached with a M40-1.5 thread. The threading depth is not that great, so right now I'm thinking about adding an o-ring to "push back" on the thread, adding a bit more friction. I'll also add more depth to the cavity to work with damping (right now I have something like 5mm between the end cap and the back of the driver housing), as you said, that should help with the thread.
 


 
- Right now, you just need to unscrew the "cap" (the piece with a bit of wood) and you have access to all the screws and internals of the earpiece.
 
And some new pictures :
 

 

[jezz]

I've been looking at Shapeways because they can (allegedly) get 0.1mm tolerances with some materials. I also don't have access to any FDM prototyping facilities. I wouldn't trust either with creating threads though; I've been leaving spaces to add nuts flush with the parts to work around that.

For the orthodynamic thread, I'd suggest reading the first few pages to get a feel for it, and then use http://headfi.qix.it/ to search the thread.

 

[melka]

I don't know about your design, but if you need large diameter threads with fine pitch instead of screws around the perimeter of your part, one possible solution would be conversion rings for camera lenses. It's a thought that just popped into my head and I might apply it to my own project, it would be a whole lot easier that trying to thread the pieces themselves.

 

[melka]

Ok, I received some SFI 120Ohm, waiting for cable and connectors, and I'll try to train my ear on a modded Kanen KM880 with the SFI drivers before doing this build. I plan on reading "Loudspeaker and Handphone Handbook" before milling anything...

 

[melka]

I've been scaling down my design a whole lot, so that I can build a first prototype to test it quite easily. I think that the bent plywood is a nice cheap beautiful material. I'll have to cut a slot for adjusting height, design some pads for comfort, and last but not least, I got a lot of work on the cups.

 

[melka]

Ok, so here are the first build pictures. Like lots of people, I've ordered Kanen KM-880 headphones to act as a donor for this first prototype. I'm planning on using the cups as a template.
First thing first : opening those cheap chinese cans, but not without giving it a try. I was suprised at how they sounded, pretty good for the price. They got some decent bass but lacks in precision.


 
I then installed the SFI drivers, using a bit of rubberband to keep them in place without having to use glue (some kind of compression fitting), so that I can remove them at a latter time.


 
Next step, braiding some 28AWG Teflon Coated SPC wire. This was the first time I worked with this kind of wire, and I love it. It's a dream to solder, real flexible, etc... I braided it just for aesthetical purposes, I'm not too worried (yet) about skin effects and such. I used this method.





 
I then sleeved all this cable in techflex, soldered it to the drivers and a tiny 3.5mm plug I had laying around. I found the sound to be a bit too "brilliant" (sounded like some kind of high-frequencies reflecting on the wood), so I filled the cups with sheep wool my mom uses to make pillows. I still have to play around a lot with damping etc... but so far, I have to say I'm surprised.


 
I've been listening to these cans for a few days now, and I'm starting to understand what I need to do.

1. As expected, 120Ohms is a bit much for the iPhone / mac, so I'll need to build a cmoy or another amp to drive them without having to always turn the volume at 100%, or find some 32Ohms.
2. The headband is a real pain, irritating the s**t out of my skull.
3. The earpads are a bit small, in diameter and in thickness. I've experimented with bigger pads I slipped between the ear and the cups and I gain a little bit in SQ, and a whole lot in comfort.
4. I think I'm getting a little bit of saturation with the low frequencies, but as I'm a beginner head-fier, I don't know if it's coming from the source (lossless CD Rip, but you never know...), the equalization, or the fact that I have iTunes' and the soudcard's volume at 100%. I'll have to investigate...

 
That's it for today. Cheers !
 

 

[owacle]

Dude, AMAZING. I look forward to your updates massively! Do you have a closeup of the techflex covered wire? It looks like you've hidden all your hard work (I think your colour choice is great). Anywhooo, enough blah-blah. Nice work.

 

[skeeder]

I just subscribed to this...love it.

 

[fueltank]

Just wanted to say I've subscribed and looking forward to see you progress with this project
Nice work so far!

 

[melka]

Hey
Sorry for the long delay since my last post.
Just to let you know that I'm still working on it, but reaaaally slowly.
A Fablab just opened here, so I'll have a few stuff to show in the coming weeks / months.
Stay tuned

 

[WiR3D]

MOAR!!!!!

 

[melka]

So, a small update.
 


 
This is a failed first try at bending plywood for the headband.
I ordered some veneer, so I'll use another technic for this part of the headphones.
In the mean time, I got rid of the techflex. It's too rigid and the microphonics are starting to bother me.
I went with a regular paracord sleeving, way more flexible and less noisy. I may also get rid of the braiding, it's not necessary with a sleeving.

 

[Mooses9]

wow, very cool design concepts, very interesting to see this come to fruition. awaiting more updates!