[Clutz]

How are you going to go about placing the drivers within the acrylic when you make the mold? How do you go about creating the channels from the drivers to the outside to transmit the sound waves? One of the things I'm curious about is resonance of the drivers and how you're going to mount them. If you put them close to each other, I'm worried that they could influence each other. I'm following this thread Bilavideo- you may convince me yet.

 

[RubbberDucky]

Quote:

Originally Posted by Clutz /img/forum/go_quote.gif How are you going to go about placing the drivers within the acrylic when you make the mold? How do you go about creating the channels from the drivers to the outside to transmit the sound waves? One of the things I'm curious about is resonance of the drivers and how you're going to mount them. If you put them close to each other, I'm worried that they could influence each other. I'm following this thread Bilavideo- you may convince me yet.

Lets make the mold first, eh?

Hahaha! Its hard to say when nobody has been able to make one yet, save Mr. Epoxy guy from this site.

 

[RubbberDucky]

Quote:

Originally Posted by Bilavideo /img/forum/go_quote.gif HOMEMADE CABLE I'm not patient enough to braid my cable, but I bought several colors of wire (22 gauge I think) off of a seller on Ebay. I took four such wires and made a four-wire cable which is multi-colored, light and extremely strong. I estimate the cost of this four-wire cable to be about $6. Add to it the cost of a right-angle connector and we're talking about $8 plus elbow grease. The home-grown cable brings means that, with the right driver, a sub-$50 BA monitor is possible.

That is great news! I just made a DIY interconnect yesterday, so I am sure this is about the same, if not easier. Can you post a picture or a link to one?

 

[Bilavideo]

Quote:

Originally Posted by Clutz /img/forum/go_quote.gif How are you going to go about placing the drivers within the acrylic when you make the mold?

That's not a major problem. There are different ways to do this. One is to cast the acrylic with pockets just the right size for each driver. Another is to place the drivers, then use a syringe, not unlike the kind used to do earmolds, to squirt in silicone that hardens over time or when hit with UV rays.

As it is, acrylic casting is not a process I've gotten into yet, so it's both a problem I haven't personally solved yet and a problem I don't have yet. Depending on the number of drivers sought, you may not need shells at all. For example, I've been able to build earphones with up to four drivers built inside a foamy earpiece. Depending on the drivers used, you could have as many as 10 drivers without needing a shell at all. The TWFK is so small, you can pack as many as six of these into an earpiece (12 drivers) without having to build an additional shell.

An easy single-driver earpiece (at a reasonable price) is the CI-22955, placed directly into an eartip and soldered. With a hot-glue gun, you put a blob of hot glue onto the ends, as stress relief (so you don't yank out the cables on your first good tug).

Quote:

How do you go about creating the channels from the drivers to the outside to transmit the sound waves?

Hearing aid companies make various gauges of tubing. It's how hearing aids have been made for years. For the longest time, the receiver/speaker unit was so large it had to fit behind the earlobe, with sound being piped around the lobe and into the ear canal via sound tubes and ear hooks. It goes without saying, then, that the sound tube problem has been resolved and the technology there for decades.

I like to use a company called Microsonic:
Earmold Tubing, Accessories & Supplies

Here's a page that deals with nothing but tubing:
Earmold Tubing, Accessories & Supplies - NAEL Standard Tubing Sizes (Single Bend Quilled)

You can get good tubing for a whopping 35 cents per foot:
203 - #12 Standard Tubing - Bulk (by the foot) - 203

We're not reinventing the wheel. We're just taking over the means of production.

Quote:

One of the things I'm curious about is resonance of the drivers and how you're going to mount them. If you put them close to each other, I'm worried that they could influence each other. I'm following this thread Bilavideo- you may convince me yet.

With a single-driver design, resonance is not much of an issue. In multi-driver designs, there are lots of ways to damp the drivers to reduce resonance. Look closely at some commercial designs and you'll see the drivers separated. They're placed in different locales within the shell. Where a material is injected into the mold, that material is used to also damp any resonance between the two drivers.

That said, and I'm speaking as the philistine I am, I've slapped drivers together and heard no difference. As I've said, you can place a material between the drivers to damp the resonance, but even without it, you'd be amazed at how great they sound. The real issue is how you filter the drivers, which takes a little more effort. For $13, you can get a baggie of 10 colored filters (from 680 to 4700 ohms). You only need two filters at a time, which is $2.60 worth of filtering. To fit them to the sound outlet, you'll need a little bit of tubing, which will have to be hot-glued onto the front of each driver filtered.

Here are some links to pictures I've taken from previous projects:http://www.head-fi.org/forums/f6/hom...88/index9.html

Here is a link posted by a fellow poster, showing how the Super Fi 5 separates the drivers: http://www.head-fi.org/forums/f6/hom...8/index10.html

Here is a link showing both how the UM3X does nothing to separate the drivers. It also shows some more pictures of previous projects: http://www.head-fi.org/forums/f6/hom...8/index12.html

 

[musick7]

The Cables aren't a big deal, actually you can purchase the Adapters I believe though DigiKey.com or Mouser.com. Your talking about the Cable that plugs into the Ipod or whatever? You want the little 2 port connecter that is mounted inside the ear mold right? If thats it there really really cheap... maybe 3 bucks probably .50 cents.

If you play your cards right you can get much if not all for very very cheap. Sonion.com and Knowles.com have the Receivers "Speakers. There is some other places that make them too but those are the top Players I believe. You can Have your Ear Impression done by an Audiologist or do it your self. An Audiologist will charge between $50. - $90. There are Many Websites that will Tell you EXACTLY how to do an Impression. Westone has a great Tutorial along with many others. And once that is done Send them to a place like, In'Tech Industries Incorported - Manufacture of miniature plastic hearing aid component parts, faceplates, battery doors and other hearing aid components.
Which is where I am having my CIC shells made. For my Hearing Aid Project.


Quote:

Originally Posted by RubbberDucky /img/forum/go_quote.gif So there are no other little electronic components necessary other than the Cable and the driver? It would be really cool to put them in a custom mold and figure out how to get a little jack in there that would accept the Ultimate Ears replacement cables. But by that time I would have probably spent more time and money on it than buying some nice dual customs from Alien Ears. Not to mention the fact that they wouldn't be a nice translucent blue acrylic. It would be very difficult to work with custom molds of my ears, at least they are big... However they would be Mine, and I love making things. Maybe I will give it a go in a few months. I always have you guys to ask for help when the going gets rough!

 

[thammuz]

Boy am I interested in this... Haven't read the thread for awhile.

My sister is in her second year of Plastics Engineering. ;p

 

[RubbberDucky]

Quote:

Originally Posted by thammuz /img/forum/go_quote.gif Boy am I interested in this... Haven't read the thread for awhile. My sister is in her second year of Plastics Engineering. ;p

Then have her help us out by making some cheap acryllic molds!

 

[RubbberDucky]

Quote:

Originally Posted by musick7 /img/forum/go_quote.gif The Cables aren't a big deal, actually you can purchase the Adapters I believe though DigiKey.com or Mouser.com. Your talking about the Cable that plugs into the Ipod or whatever? You want the little 2 port connecter that is mounted inside the ear mold right? If thats it there really really cheap... maybe 3 bucks probably .50 cents. If you play your cards right you can get much if not all for very very cheap. Sonion.com and Knowles.com have the Receivers "Speakers. There is some other places that make them too but those are the top Players I believe. You can Have your Ear Impression done by an Audiologist or do it your self. An Audiologist will charge between $50. - $90. There are Many Websites that will Tell you EXACTLY how to do an Impression. Westone has a great Tutorial along with many others. And once that is done Send them to a place like, In'Tech Industries Incorported - Manufacture of miniature plastic hearing aid component parts, faceplates, battery doors and other hearing aid components. Which is where I am having my CIC shells made. For my Hearing Aid Project.

I didnt know they sold the little 2 pin adapter, thanks! Now I need a really cheap place to get some good looking acrylic earmolds!

 

[musick7]

Thought Id give a everyone a one up. Bilavideo and I have been talking for awhile now in PM and I haven't posted to much, I've been keeping my Project under raps, and really only discussed it with Bilavideo.
So let me fill you guys in a bit.
I am in the process of making a Hearing Instrument and I've just about have everything. I'm still waiting on the Knowles Acoustics Transducers and Receivers to come in along with Telecoils and switches from them.

I have had the Digital Signal Processor "DSP's" for about a month now or a little longer, and have just been waiting on everything to arrive.
I Have my DSP Programmer I got in HI Pro which is well known in the Audiology world.
I have all the software that is full blown Hearing aid software. All this was provided by the DSP Company.
I still need to order in the Capacitors and little stuff like that.... Those wont be to much money and fast arrival.

The In Ear Molds or IMPRESSIONS I sent of Tuesday Morning to a Company who deals with some well known hearing aid companies.
I ordered 2 Completely In Canal "CIC" Hollow Shells. They are CLEAR and the guy I talked to said it looks just like GLASS. The Face Plate and Battery Door will be skin tone. And YES I have a Serial # on Each one. You know it! Its my Name dang it!!
The Final Cost of Each CIC shell with Doors and all. Come to $55. for TWO shells. Yes Made on CNC Mills.

Right now I've got $280. in the entire Project. And the only Thing I need to get now is the Resistors and Caps. and 4 SubMiniature Pushbutton Switches.

The Final Cost for 2 Digital Hearing Instruments should be below $330. And the DSP I am using is found in Several Very High End models that sell well over $2000.00 And that price is for One!

I also had a hard time finding the LITZ wire used in Hearing Aids. This stuff is 7 Strand 46 AWG and 7 Strand 48 AWG.
However I got that from the UK and its the only place that makes it I believe It is the size of 5 or 7 hairs put together it seems like it might be closer to 4 hairs....

And a supplier to Make the Ear Impressions I found. They have everything you need to make the Impressions and also Make your own MOLDS for the SHELLS themselves! You could make your own Headphone shells including the impressions if you know what your doing for under 100. And that would get you at least 6 pairs if not 10.
Any questions PM me.

 

[Billyk]

Now that's exciting...

 

[WalkGood]

Been away a while, any pictures yet?

 

[lars9]

I'm also interested in this thread and eager to start my own DIY single driver IEM.

I'm currently in the stage of choosing drivers. TWFK seems like a good full range driver. But its sensitivity is only 95 dB, which is much lower than BKs(118-126), CIs(125) etc, what does that mean? Will TWFK be hard to drive on portable devices like latop and ipod? Thanks.

 

[Bilavideo]

Quote:

Originally Posted by lars9 /img/forum/go_quote.gif I'm also interested in this thread and eager to start my own DIY single driver IEM. I'm currently in the stage of choosing drivers. TWFK seems like a good full range driver. But its sensitivity is only 95 dB, which is much lower than BKs(118-126), CIs(125) etc, what does that mean? Will TWFK be hard to drive on portable devices like latop and ipod? Thanks.

You are right in concluding that sensitivity is the microdriver equivalent of SPL but a sensitivity of 95 dB will not make the TWFK hard to drive. I've wired them up and they can be quite loud. The CI has a higher sensitivity, due in part to its larger size, which makes it resonate more easily, but it needs the higher sensitivity. If you look at the frequency performance graph for this driver, it's not really a "woofer" on its own. Its biggest area of performance is the midrange. It becomes a woofer through filtering. As you cut out the high end, through mechanical (cloth) filtering, you're essentially wasting a fair portion of this SPL to get only the bass. Even without any electrical crossover, the two drivers tend to even out once you've applied mechanical filtering.

Does this mean that the TWFK isn't harder to drive? Yes and no. Any chance in sensitivity reflects a technical difference in drive-ability. But it's like comparing the PFEs to the Westones. The PFE is "harder" to drive but not really "hard" to drive. The Westones are louder but once you crank up the PFE, it performs very nicely right out of an iPod (though a single driver is not going to have the same range as a multi-driver arrangement with a fantastic tweeter). The TWFK is not the ultimate in high-frequency extension but it's so close, and provides a dual driver platform, that it's hard not to use. For $40 per channel, the WBFK 30019 will technically drive a little higher (with a first and second spike of 104 dB at 4 kHz and 96 dB just after 7 kHz as opposed to the TWFK's first and second spikes of 103 dB at 3 kHz and 96 dB just after 7 kHz). Both top out at 10 kHz with the WBFK 30019 delivering 76 dB and the TWFK delivering 74 dB - but these are very close (and probably less reliable) specs. The real difference between the TWFK and the WBFK 30019 is that the TWFK has a second driver, a woofer, giving it better bass performance (96 dB as opposed to 94 dB at 100 Hz).

As you'd expect, neither driver delivers heavy bass but the relatively flat performance throughout much of the frequency spectrum makes both drivers attractive. But with the dual driver platform, the TWFK (at $52) offers a little better value. For $40, you can make the CI-22955 a double or for $52 you can make it a triple. You can see how manufacturers like the ability to promise a triple at a budget. A purist might go with the WBFK 30019 for that last sliver of treble, relying on the CI-22955 or the SR for the bass end but then use some other driver for midrange. But given the impressive flat performance of the TWFK and WBFK 30019 throughout much of the spectrum (and the likelihood that you won't hear any actual difference at the top), I don't think it's worth it to buy a dedicated midrange when both of these drivers provide it so well. With the TWFK, you get a little push at the lowest end and terrific specs in both the midrange and treble. Pairing it with a filtered CI-22955 is a total no-brainer.

That said, there's an answer for someone who worries about variations in sensibility, which is to double up. The TWFK is so tiny, you could put a pair of them into an earpiece and still take up less space than a single CI-22955. If you did, you'd auomatically have a quad. For my money, there's something cool about the idea of doubling up on TWFKs strapped to a single CI-22955 to create a quint. Bassheads might enjoy the super six, strapping a pair of heavily filtered CI-22955s to a pair of TWFKs.

Whatever the case, driveability is not an issue. These are relatively low-impedence drivers. They'll get as loud as you could ever want.

 

[Bilavideo]

A question was raised about the BKs. They're very cheap ($18/channel) and they sound surprisingly good for the money. The CIs sound better, and for the extra $8/channel, that's how I would go. The difference between these larger drivers and the TWFK is in the high end. The TWFK has a sizzle you won't get from either the CI or the BK. It's really meant to have that dedicated tweeter. I was skeptical about this at first, and even more so when I tried out the CI and found it to be every bit as good as the PFEs. But when I did an A/B test between the CI and the TWFK, there was no comparison. You know how we audiofreaks can sometimes convince ourselves that we're eating the organic banana when we're really just eating the regular banana? Well, that's not the case with the TWFK. The CI sounds great until you hear the TWFK. The sparkling HF of the TWFK stands out and is quite obvious. You can't call it "psychological burn-in." It's there and with such prominence that you'll never want to go back.

 

[meraj.salek]

Quote:

Whatever the case, driveability is not an issue. These are relatively low-impedence drivers.

But then as you keep paralleling drivers, aren't you lowering the impedance? Wouldn't driveability become an issue with 6 drivers in parallel? Or are they wired in a series/parallel arrangement? Or am I just missing something?