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Home-Made IEMs - Page 52

post #766 of 2997
Also, here's a "blank" that I made to play around with. I didn't sand/smooth it at all, but I did take a little off the corner indicated by the arrow. As you can see from the original impression there's a pretty hard corner right there which prevented it from going in smoothly. But once I took that corner down a bit it went it pretty easily and basically isolates as well as the original impression does (which I now use as earplugs). I'm going to play around with this one to figure out the best way to get a smooth finish on it without effecting the shape too much. I know Drew said he used clear nail polish, so that's an option.

post #767 of 2997
Thread Starter 
Good work!
post #768 of 2997
Quote:
Originally Posted by marozie View Post

good, very good, Mark!
I don't think you have taken off important material from the shell, you followed the anatomy of the ear canal, very good the first and the begin of second corner, excellent depth, you were right sanding at that point, because shells go in the ear canal without pains.
Pay attention to remember how to direct the sound output hole.
you can do better but you are a beginner and my vote it's 10+
Many facts and few words!

PS: answering your question a few days ago, yes I use empty shells, it is better to place the electronics at a later time, the work is more clean and precise, the procedure is basically the same used in "in the ear" hearing aids industry. Very important: Materials are biocompatible.
post #769 of 2997
Quote:
Originally Posted by GiuseppeItalia View Post
good, very good, Mark!
I don't think you have taken off important material from the shell, you followed the anatomy of the ear canal, very good the first and the begin of second corner, excellent depth, you were right sanding at that point, because shells go in the ear canal without pains.
Pay attention to remember how to direct the sound output hole.
you can do better but you are a beginner and my vote it's 10+
Many facts and few words!.
Thank you Guiseppe! Well, they are finally done, more or less. I still don't have a completely smooth finish, but I've already put so many coats I want to wait until they've dried completely before I put more on.

Here's a pic of them after fitting into the molds. Note, I used a ~7 ohm resistor as the anode to both DTEC and CI, and a 1uf cap as the anode to WBFK:


Here's a pic of the bottom. I cut holes at the ends of the ear canals to run the acoustic tubing through, and then sealed it off with some 5 minute cure epoxy. It's great because it doesn't adhere permanently to either the tubing of the mold, so when I was done I basically just cracked it off. Note that there's a filter in one of the tubes that obviously isn't deep enough, I just inserted it for testing purposes.


Here are pics after I poured the molds. I again used a few drops of translucent purple enamel to color the epoxy (which I think is a plastic urethane).




And here are some pics after the final touches. Basically, I smoothed out the roughest sections with an agressive bit, but was very careful not to take out too much material. Then I used one of those wire brush bits to smooth it out some, and the round any edges. Then I just sprayed them with maybe 6 coats of high gloss clear acrylic.






I have a white filter in WBFK and DTEC and a red filter in CI. Before they were poured when I still had them as mock ups I tested them by plugging two of the tubes at a time so that I could make sure that I could isolate each individual driver, make sure it was working, try to gauge the balance, etc. The resistors balance the larger drivers with WBFK perfectly, couldn't be better. And the cap on WBFK results in crystal clear, shimering highs. When I was testing them and isolating each individual driver it was amazing, I could clearly tell which driver was the high, the mid, and the low without even having them in my ears, that's how distinctly and acurately each one of them does it's thing. I have to tell you guys, this project sucked up a lot of cash, probably close to $400, and probably 30 - 40 hours of time (partly because I screwed up), but they sound amazing. They sound as good as full size cans. They produce a low end that puts my K701s to shame. I couldn't be happier. I just can't wait until I can have an extended session with them...

post #770 of 2997
hey fantastic work! that looks great! I was wondering though, hope this doesn't happen. As how on earth are you going to replace the drivers if one of them dies or gets damaged?
post #771 of 2997
Quote:
Originally Posted by MaoDi View Post
how on earth are you going to replace the drivers if one of them dies or gets damaged?
Mao, come on man, that's like asking someone who just bought a fancy new car what they're going to do if it ends up getting totalled I mean, clearly there is no way to replace anything that's encased in the epoxy. I guess that would be one clear advantage to using hollow shells, but I still have no idea how you would make those. As I was forced to do, it is possible (and actually not that difficult) to chop them up using wire cutters, the epoxy doesn't actually stick to any of the components so once you get deep enough into the material you can just kind of peel it away from the various elements. So in the event that one of the three drivers in a unit died you could salvage the other two, although you would more or less be starting from scratch in having to fabricate a new one.
post #772 of 2997
Haha, hey gotta expect the worst right? just another thing. So this is epoxy as in...like super glue epoxy? Just wondering as although the work and all is fantastic, just wondering if perspiration would cause this epoxy to release any chemicals that we could absorb and throughout time intoxicate us...
post #773 of 2997
Wow you did it!! They look amazing, really.
Do get to know them better and tell us your impressions afterwards.
post #774 of 2997
Quote:
Originally Posted by MaoDi View Post
So this is epoxy as in...like super glue epoxy? Just wondering ... if perspiration would cause this epoxy to release any chemicals that we could absorb and throughout time intoxicate us...
Well, 1) super glue isn't really an epoxy, and 2) super glue is cyanoacrylate -- cyanide is any compound containing a cyano group, which means that super glue is technically cyanide. Epoxies are a whole different ball of wax, they "thermoset" via a chemical reaction which is catalyzed by adding the hardener (a polyamine) to the resin (an epoxide), and the two polymers are permanently linked by covalent bonds to form a co-polymer. But they can have hazardous chemicals in them. I used Smooth On Crystal Clear 202, which is a plastic urethane (or more accurately, a polyurethane elastomer). Looking over the MSDS it's a bit unclear what the safety of the co-polymerized material (the cured product) is because each chemical is listed separately and referenced in its respective liquid phase. The good news is that neither is mutagenic (mutagens cause DNA mutations = cancer), and that the only potential skin contact hazard is "irritation." All of that being said, I coated them with Krylon high gloss acrylic so what ever the potential chemical interactions with the urethane are somewhat moot. The MSDS for Krylon is similarly vague, not specifying differences between its liquid and solid phases, with "prolonged or repeated exposure" leading to potential skin "irritation." The most hazardous chemical constituent listed is toluene, which is a benzene derivative (benzene is a known carcinogen), but it's also not water soluble so you're not going to absorb it through your skin when you sweat. The thing about spray paints is that most of their hazardous chemical constituents are the volatile organic compounds that are the solvents that keep the paint in liquid phase, with the paint (or acrylic in this case) hardening as they evaporate off. So while toluene might be hazardous, it's also a VOC, so there shouldn't be much of it remaining once it has completely hardened (and de-gassed).

It would be interesting to know what kinds of compounds professional manufacturers use for this. Maybe since you have some contacts, Mao, you could inquire?
post #775 of 2997
Quote:
Originally Posted by Llama16 View Post
Wow you did it!! They look amazing, really.
Do get to know them better and tell us your impressions afterwards.
Thanks! I feel like showing them to everyone I talk to at work, but then I remember that they a) most likely wouldn't know what the hell they are, and b) probably wouldn't be half as impressed as any of you guys

I've been listening to them on and off all morning. The Krylon is still degassing so I'm hesitant to leave them in for too increasing my skin contact time with the VOCs.

On a slightly different not, my cord is not really doing in for me. It's just too stiff, and I used 30 AWG wire which I figured would be like a wet noodle. Does anyone know where to source the kind of cable headphone manufactures use, the stuff that's coated in super soft rubber? I might just break down and by a cord from Westone, it would probably cost as much as having to by a spool of wire anyway...
post #776 of 2997
Just looking through Westone's website, they offer the following earpiece materials: acrylic, vinyl, silicone, polyethylene. They have an option with the acrylic of adding something that makes the material body temperature reactive, which I assume means they get softer as your body heat warms them up. Pretty cool. Again, these base materials aren't going to be intrinsically hazardous, it's the solvents they're carried in while in liquid form that are dangerous, so my guess would be that in most cases after the material has hardened it is more or less safe, but I guess it does merrit further study...
post #777 of 2997
Why don't u use smooth on's lifecast material
post #778 of 2997
Quote:
Originally Posted by pdupiano View Post
Why don't u use smooth on's lifecast material
Um, well, because Lifecast is for making casts.

EDIT: Sorry, that was kind of dick-ish. I think the Lifecast material is for making a cast of a body part, like a hand. You then use that cast as a negative that you would pour plaster or something in to make the positive, which is the reproduction. Since your hand is a positive space and your ear canal is a negative space it's a bit confusing, but making a cast of your hand (a negative) is analogous to making an impression of your ear canal (a positive). The other confusing bit is that the end product of reproducing the shape of your hand, a positive space, is also a positive space - hence the term reproduction. The end product of making an IEM is not a reproduction of your ear canal, it is a positive space designed to fill a negative space, so there's an extra step involved: making an impression of your ear canal (a positive), molding the impression (a negative), casting the IEM (a positive). An additional point of confusion might be that the product or process of using a cast -- the cast is the mold -- is sometimes denoted by the word cast, i.e. cast-iron. The shape made out of iron (postive) is not the cast, the mold (negative) used to make the iron is the cast. But again, that process is for making a reproduction of a positive space, which is not what we're doing here.
post #779 of 2997
Wow, those look excellent. I can't wait to hear your impressions, and sounds like even though it was an expensive project it might even have been good value for money.
post #780 of 2997
Quote:
Originally Posted by revolink24 View Post
Wow, those look excellent. I can't wait to hear your impressions, and sounds like even though it was an expensive project it might even have been good value for money.
Thanks! Keep in mind, part of the expense was due to trial and error -- if you don't screw up it should cost more like $300. But then again, I went with a WBFK ($40 x 2) - DTEC ($50 x 2) - CI ($25 x 2) set up. As was discussed a ways back TWFK is a dual driver that consists of WBFK (tweeter) and FK (woofer) and only costs $10 more that WBFK alone. I would imagine a simpler TWFK ($50 x 2) - CI ($25 x 2) set up, which would still be a 3 way design, would sound quite good as well, and would probably only cost $200. If you think about it, the biggest expense (i.e. that which provides the smallest value per cost) are the materials needed to make the shells. The Smooth On rubber urethane was $20, but it's probably enough to make a couple dozen molds; and the Smooth On plastic urethane was $35 and is probably enough to make a few dozen shells. So the actual cost of making one set of molds and one set up shells is about $1 each, but of course you can't buy just enough material to make one set. So it would be ideal to find a few people who want to do this and purchase the materials together to spread around the cost.
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