[maverickronin]

Quote:

True. Come to think of it you're using memory foam... A) Where'd you get this? B) Isn't that going to seal pretty well all by itself?
 
And, randomly, on the topic of pads and that article on innerfidelity. The article talked about bass dips due to clamping force/squishiness of pads. Call me crazy, but the pad vibration often gives the bass an insane "This is intense bass" feeling which can't be measured by the dummy head. You could probably eq bass heavily sub 70-80Hz and replace with vibrators inside the pads. I wouldn't do it, but how many people off the street would even notice? I'm not saying this has an application in any way shape or form really, but interesting to think about in terms of measuring a headphone, getting back to the original article. And this is also one of the reasons I think mass loading the baffle can have a positive effect on the sound.

I haven't ordered the memory foam yet, but this is the site I found.
 
It should conform to my head pretty well so there won't be any air gaps but if the outer covering of pad is porous then some of the pressure will leak through anyway.  I don't know how much or if it will make a difference in bass response but I'm not in the mood to spend 3 or 4 straight days sewing several different pairs of pads made from expensive materials to find out if sealing it with the plastidip does make a difference or not.  I'd rather go overkill with the planning beforehand because its much less tedious.

 

[crimsonOkami]

khbaur: Have any luck with flexible magnets or laminates yet?  Neither the one person for magnets or two people for laminates that i contacted have gotten back to me yet, it's been more than 3 days, how long does this usually take?

 

[khbaur330162]

Smaller companies like the ones we're dealing with are usually on top of this. I've been getting responses same or next day on average. 
 
Like I said I've got an A4 sheet of Ultralam on its way to me now. Not much of it at all, and on the thick side, but enough to make two pairs of drivers. They make thinner stuff, but there's a fee even for sample quantities. I've got a sample of some Aluminized Mylar meant for tinsel or metallic yarn coming my way too. This stuff is out of India. After speaking with one of their technical sales guys I'm worried the Aluminum layer will be too thin as they measure it in angstroms. Yikes. He says it's reflective, however, so hopefully it won't be the same problem as we went through with that Homefly stuff. Dupont said they'd send me some Pyralux (also pretty thick) samples and asked for shipping details. I gave that to them and never heard back so Idk how/if that's going. I'm just waiting to see if it shows up on my doorstep. I've contacted a few other places, but I've not found anything truly promising yet. 3um Aluminum on 6um Mylar for cheap would be the holy grail. 
 
Magnets.com asked me for confirmation when I told them how narrow I wanted the roll to be. I asked for a quote on 4mm wide, 3mm thick strip roll at 180cm. I'll probably get a response today, or tomorrow. These are the only magnets I'm interested in getting quotes on. If the rubber neo's don't pan out I'm looking at these with the intent to cut them with a Dremel straight guide and diamond drill bit. Since they're kind of thick I might have to modify the straight guide to allow me to shave off a few mm's sort of like a fly-cutter. The straight guide is actually part of the Dremel adjustable circle cutting attachment. I want to use it to cut ~3.125"OD x ~3"ID spacers out of scratched burnt CD's I've got lying around. They seem to be the perfect thickness. If it doesn't work out I'll have to look into laser cutting services.
 
I know I'm dreaming, but how cool would it be if you could print your circuit with whatever layout you wanted at like 5"x5", place over a magnifying glass with a pre-measured length tube and non-reflective inner coating for desired size reduction, place over diaphragm material for exposing and just shrink the shadowed image. I don't know enough about photography, or optics, but I'm relatively certain the magnifying glass would have to be pretty darn huge. Looking at some of Jennifer's photos the resolution of the Puretch looks pretty amazing. I'm just playing with ways you could make a driver as small as you originally wanted to. 

 

[crimsonOkami]

well you seem to be getting all the luck with finding and convincing companies for samples, I only found one more company that deals with 8 MGOe rubber magnets,  after that there's a company that has 4 MGOe magnets and a few companies with 2.4 MGOe magnets, but anything less than 8 is a waste of time to me.  I'm pretty sure i've searched the whole internet for both suitable laminate and flexible magnets.  I sure hope that magnets.com works out
 
"3um aluminium and 6 um mylar"  don't you mean the other way around?  3 um mylar and 6um aluminum.  From what i've seen that'd give us the best flexibility while still being usable as far as conductivity.

 

[khbaur330162]

No, I meant it how I said it. 3um should be fine for impedance. And yea, you could go thinner on the Mylar, but good luck finding some.
 
I found a company with 3um peelable copper on an 18um substrate. You'd have to laminate the etched circuit onto/into some other material like how the Ultralam is meant to be used. Aptiv film by Victrex has properties that look just about perfect for us. Only problem is the melting point of the Aptiv film is crazy high compared to polyester (probably what the other company is using as a backing), and how in the world would I ever go about getting this stuff laminated in my garage? >< 
 
http://www.victrex.com/en/victrex-library/press-releases/detail/detail.php?id=645
 
I'm guessing the Ultralam is using Aptiv film, or some custom mixture very similar to it, as it's backing. Notice the melting point of the Ultralam? I'm hoping the peel strength will be high enough that I don't have to worry about any lamination process. (If I'm even using that measurement correctly) For these reasons I'd say I'm most interested in Rogerscorp's line of materials, but heck, ERAudio is selling stuff just about perfect for us at ridiculously low prices. In all honesty, this should be the only stuff we're looking at right now.

 

[crimsonOkami]

ok, the only reason i asked was because i read somewhere that the aluminum layer should be thicker or as thick as the mylar layer, not the other way around.  But that was just a post by a diy-er.
 
If i ended up buying some of the film from ER audio i would most likely end up making my own computer speakers in addition to the headphone drivers.  Using some enamel paint as etch resist since the traces will be larger and over a wider area.    They'd be like miniature magnepan's

 

[khbaur330162]

Looking at spec sheets from Yamaha and many other ortho manufacturers it doesn't hold much weight in my mind. Note that headphone drivers don't need as much current which is why I think we could get away with 3um traces. That statement might be to try to keep impedance and heat dissipation down in a speaker design, yet still maintain a very low moving mass. Don't know.
 
Sounds awesome. Fun project. I'd probably waste it all on stretchy annulus "experiments," lol. 
 
Got that CAD image done? How do you plan on getting the housings made? 

 

[crimsonOkami]

Quote:

Got that CAD image done? How do you plan on getting the housings made? 

 
You mean the one for the octagonal cups?
http://img217.imageshack.us/img217/2718/screenqqu.png
 
the picture doesn't show the headband or the ear pads, only the places where they would attach.  I plan to make the cup from layers of cut thick veneer that i glue together.  For the headband i plan to use a non-swivel design so it's not going to be the best, also since spring steel is very difficult to form and shape i'm gong to have to use aluminum.
 
I havn't come up with any cad drawings for the larger 80mm drivers, or any drawings for the drivers, but those are pretty simple so i'm not worried.

 

[khbaur330162]

Just contacted these guys for a quote.
http://www.dingshengalu.com/pid81054/electric+capacitor+foil.htm
Looks perfect. 6.35um total.
 
 
I found an odd wooden rolling pin-esque thing of questionable origins at Goodwill that I was able to chop up for two easy housings in my bass plugs. You never know what you'll find in places like that. Looks good so far.
 

 

[rhythmdevils]

Great deal on a pair of HP1's on ebay. 

 

 

 
http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=160758879542&ssPageName=ADME:B:SS:US:1123
 
The description of the phones combined with the price is...um...special

 

[khbaur330162]

http://www.inmat.com/products.shtml
Is that not the coolest material ever for an isodynamic stretchy annulus?
 
http://www.faqs.org/patents/app/20090097693#b
Basically dense layout of magnets on the back and not so densely laid out magnets on the front with an emphasis on the center of the diaphragm. Pretty neat. Reminds me of one of the AKG K1000 brochures on the wiki where they talk about acoustic openness coefficients. HifiMan also seems to be playing with this idea, obviously. I wonder if it strays any further than just cost of magnets. Ortho's don't seem to have issues with midrange/hi freq extension, imo. Maybe it's to do with imaging. There's also some things that seem to hint at the distance between magnets and the diaphragm increasing from the perimeter to the center point, but not sure if that's true. If you scroll all the way down they have graphs depicting an explosion of patents concerning planar magnetic and ribbon transducers in recent years.
 
http://www.icknowledge.com/misc_technology/PhotoChapter.pdf
Really nice info on photolithography for anyone interested. Even stuff on optics/reflection/refraction/etc when exposing photo resists for etching purposes. 

 

[nick n]

Quote:

Great deal on a pair of HP1's on ebay. 

 

 

 
http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=160758879542&ssPageName=ADME:B:SS:US:1123
 
The description of the phones combined with the price is...um...special

yeah but you have the original video to go with it! for your archives, that's better than the original box isn't it?
 
I wonder when we'll see the day one breaks the $1000 mark. It's coming. Maybe one that has a receipt and original bag too.
Inflation, man, can't forget inflation. So if you actually think about it you're saving a hundred bucks! Ya know $800 and you're getting them today at the price of $699. Hard to argue the math.
 
Good old Macaroni Bellini designed some good haydfones back in the day. That and the one sonics headband piece for sound great individual lifelike orthotics.
 
I may sell mine but include a photo album of them in various exotic locations as long as the camera angle doesn't show some of the cardboard backgrounds, just like the occasional trips those abducted garden gnomes take. That'll add some value. 
Guess I went on a bit here. Just couldn't resist having a bit of fun.

 

[crimsonOkami]

Quote:

http://www.icknowledge.com/misc_technology/PhotoChapter.pdf
Really nice info on photolithography for anyone interested. Even stuff on optics/reflection/refraction/etc when exposing photo resists for etching purposes. 

 

that's pretty in-depth, couldn't read it all so i just skimmed over the pages.  Not sure if i saw anything that would change the process that i have in mind for the photoresist exposure though because it's all pretty technical and require complicated set-ups.  Did you find any helpful hints that would gets us higher resolution?

 

[khbaur330162]

I was mainly reading it for the optical reflection/refraction and interference portions starting on page 36 extending to page 51. No, it didn't change the process I've had in my mind. I just find it interesting. I haven't read it all yet, either, and this is just one chapter... If I can take one thing away from this to apply to my process I'll be elated.
 
http://www.google.com/patents?id=uFouAAAAEBAJ&pg=PA1&dq=3833771&hl=en&sa=X&ei=4INbT6D8PIeQgweS7N2tCg&ved=0CE8Q6AEwCQ#v=onepage&q=3833771&f=false
Ortho-Vari-Motion already patented. Note that they specifically say the diaphragm would need to be very stiff in comparison to conventional isodynamics which is what I was assuming. While rummaging through patents I found some unusual ones where an electrostatic diaphragm was sandwiched between foam block stators and an isodynamic design that had a domed piece of foam at the rear of the diaphragm supplying tension. Perhaps acoustically transparent foam could be used as a restoring force and permit a thinner/lighter diaphragm material (in comparison to paper or foam), yet still promote pistonic motion. 

 

[crimsonOkami]

Interesting find with the patents, its cool that they just have this stuff out there for anyone to read.  I wonder how many of those patents have even been implemented, or if the reason why they weren't implemented was because it's just theory and it doesn't scale up to real life.  If magnepan is experimenting with all these different types of isodynamic speakers then you'd think that the ones that work best are the ones they currently use.