Home-Made IEMs
Feb 25, 2021 at 1:36 AM Post #12,407 of 15,910
@Aldo40 I owe you an apology, and a thank you, after listening for a while I settled on red dampers on the 31736 like you suggested :)

I will post more details soon, but I am close to done with this project now.

Two dual 32257 and one 31736 in a universal shell, with a 1.27mm 2x6 header to pin out the drivers for plug and play circuits.

I cut the wires on the dual 32257 so I could pin out individually, the 31736 I left wired in parallel.

I have... many... hours into this, but it has been a learning experience and I feel the flexibility was worth the hassle.

Still have to double check the acoustic tubing. I have a channel imbalance and I have ruled out electrical issues, so it is either tubing or drivers. I can recreate this project with knowles and bellsing instead of no name drivers, so not too worried about that. After one more check I will totally glue/seal the housings, I did open the vents on the 32257, should I expect a change in low end if I totally seal the shell? I could always heat up a needle and poke a vent if there are negative consequences to being totally sealed.


I will encapsulate the circuits with UV glue so I can safely swap without shorting anything.

Circuits so far are:

4x series 32257 with a -2db Lpad mostly for impedance correction, .68uf high pass on 31736.

2×2 series/parallel 32257 with 7uf crossover on 31736. The low crossover on 31736 is a lazy impedance correction. But, I can easily try new circuits with the pin out.

Series sounds way better so far. Open to suggestions on different circuits because I can make a new set pretty easily.

I can post freq and impedance graphs if anyone is interested.

My phone software and/or the forum have changed, I can't preview the post anymore or thumbnail/spoiler the pic,
so I hope the it attaches and is not huge.

P.s. that was me with the recent planars, very tricky but I do have room eq wizard files with some tuning notes if anybody wants them.

Edit: fixed a typo, and even with an edit I can't fix the pic, sorry.

Another edit: I intentionally flipped the connector on one side so I could build identical circuits for both sides. Got enough problems here without trying to solder mirror images.
 

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Feb 25, 2021 at 3:18 AM Post #12,408 of 15,910
@Wgibson do not apologize, it is a place of exchange nothing more :wink:
For the opening of a shell with a small hole, I think that will be anecdotal to listen, most often open on DD but on BA it is not systematic, it is necessary to try and judge by ear. The best is to make the hole with a dremel with the smallest drill example 1mm and then you have all the time to close the hole with the resin if it never brings anything
 
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Feb 28, 2021 at 2:12 AM Post #12,409 of 15,910
Also seems like thread uses mostly BAs I assume due to simplicity. But what if I wanted to make a hybrid?

I believe the very first build I saw was a 1 6mm DD and a BA which name escapes me atm.

Lots of the cheaper 1DD 1BA hybrids (KZ, TRN, CCA, etc) typically use a 30095 BA with a single cap high pass crossover, wired in parallel with a DD. Sometimes a resistor on the DD to equalize volume, but still pretty simple.

You can fit a 30095 inside most nozzles, but then you might not have room to use dampers. Can still use foam or acoustic fabric to knock off the treble peaks.

I may try a DD and BA hybrid soon.

Has anyone used planar and electrostatic together in an IEM yet?
 
Feb 28, 2021 at 2:52 AM Post #12,410 of 15,910
Lots of the cheaper 1DD 1BA hybrids (KZ, TRN, CCA, etc) typically use a 30095 BA with a single cap high pass crossover, wired in parallel with a DD. Sometimes a resistor on the DD to equalize volume, but still pretty simple.

You can fit a 30095 inside most nozzles, but then you might not have room to use dampers. Can still use foam or acoustic fabric to knock off the treble peaks.

I may try a DD and BA hybrid soon.
If you want to dampen a BA that will go inside the nozzle you may want to try this:
Guys, I wanted some opinions on this.

Many budget IEMs (KZ, TRN, etc) have BA treble drivers installed right in the nozzle, directly under the nozzle/earwax screen, with no tubes or dampers at all. While I don't need to be reminded that this is NOT the 'right way' to build IEMs, it remains a fact that a large number of budget manufacturers practice this behavior whether it is the 'right way' or not. That doesn't mean something can't be done to improve the situation.

As you know, undampened BAs have undesirable treble peaks, as the driver manufacturer intends them to be dampened. Therefore, I had an idea for a possible mod that would allow an improvement to these budget IEMs (as well as DIY IEMs).

Due to the space constraints in the nozzle, the only possible way to add a damper to the driver (and still be able to fit under the nozzle/earwax screen) is as follows:

1. Obtain 1.37mm plastic Knowles dampers. Why the 1.37mm plastic dampers? Because that size fits perfectly on the BA nozzle. Since I intend to use this on treble drivers (30095 as an example), I went with the often-recommended green dampers (BF-3039 Green 1500ohm).
1.jpg

2. Cut a small ‘slice’ of BA tubing (1.0mm ID/2.0mm OD), similar to a rubber band.
2.jpg

Note how incredibly small these parts are! Yes, I know I didn't cut the piece of tubing perfectly straight, but it doesn't need to be. As long as the bottom cut is as square as possible, it will fit fully on the BA nozzle.
3.jpg

3. Now place the plastic damper on the treble BA nozzle (this is not easy, but it is doable). Note, I am using a bare BA assembly as a model only. This allows us to visualize what’s going on with the mod much easier.
5.jpg

4. Now slip the piece of BA tubing over the damper (this is not easy, as it’s a tight fit, but it is doable). Secure/seal the bottom of the tube with epoxy if needed.
6.jpg

5. Done. Notice that from the side, the damper is basically even with the nozzle. That means it will still fit under the nozzle/earwax screen of these budget IEMs.
7.jpg

Now, I am aware that Knowles designs their dampers to be placed a certain distance away from the driver nozzle (I think they recommend 8-10mm). They do, however, indicate that the dampers CAN work at a closer distance; they will just have a slightly lower effective resistance. I still need to do FR measurements and testing with various damper resistances, but I think I can compensate for the lower resistance by simply installing a higher resistance damper. In other words, perhaps a red damper installed right @ the nozzle might be 'equal' to a green damper installed in the tube.

8.jpg

So as far as budget IEMs, this mod can be performed externally, requiring only the removal of the nozzle/earwax screen. Then, after the dampers are installed, the nozzle/earwax screen can be replaced.

Comments? Thoughts? Has anyone ever tried this?
I've tried this on a ZSN and ripped the plasic on the damper filter trying to install it, but if the BA is outside of the shell before building it should be more doable. If I understand it correctly, this way you shouldn't get any of those KZ trademarked treble peaks.

If this is too much effort, I remember that @dhruvmeena96 recently mentioned a good tweeter and said it would work good in a hybrid setup undampened. I just don't remember the page and don't have it saved in my bookmarks.
 
Feb 28, 2021 at 3:22 AM Post #12,411 of 15,910
Question about DIY/custom IEM size:

Has anyone made an IEM that's (in hearing aid terms) In-The-Canal (ITC), Completely-In-Canal (CIC), or even Invisible (IIC) size?
I think it'd be cool to have an IEM that small for watching videos while lying on my side or for others who are side sleepers and like to listen to music. It'd have to be a single BA design, but it's not like single BA IEMS are bad.
 
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Feb 28, 2021 at 4:34 AM Post #12,414 of 15,910
Lots of the cheaper 1DD 1BA hybrids (KZ, TRN, CCA, etc) typically use a 30095 BA with a single cap high pass crossover, wired in parallel with a DD. Sometimes a resistor on the DD to equalize volume, but still pretty simple.

You can fit a 30095 inside most nozzles, but then you might not have room to use dampers. Can still use foam or acoustic fabric to knock off the treble peaks.

I may try a DD and BA hybrid soon.

Has anyone used planar and electrostatic together in an IEM yet?
That's what Ive seen but I'd like to try something among the lines of 1DD, 2BA woofer, mid, tweeter or a 1DD, 3BA subwoofer, woofer, mid, tweeter. Wonder if the latter would be a nightmare to make.
 
Feb 28, 2021 at 7:14 AM Post #12,416 of 15,910
That's what Ive seen but I'd like to try something among the lines of 1DD, 2BA woofer, mid, tweeter or a 1DD, 3BA subwoofer, woofer, mid, tweeter. Wonder if the latter would be a nightmare to make.
The first idea sounds like a FiiO FH3 or SeeAudio Yume, the most interesting part about these two imo is how they tuned the DD. I've seen some hybrid builds here, though most seem to be made by trial and error with a lot of changing something up inside the shell and measuring the changes, with very few using a 3D printed acoustic structure (to be fair these two companies probably had to go through a lot of trail and error to get to these patented acoustic structure designs).

As a newcomer I can say that the community here is very helpful, if you give an approximate budget for the drivers and the type of sound you're looking for I'm sure somebody will be able to help you in the right direction.
 
Feb 28, 2021 at 11:14 AM Post #12,419 of 15,910
The first idea sounds like a FiiO FH3 or SeeAudio Yume, the most interesting part about these two imo is how they tuned the DD. I've seen some hybrid builds here, though most seem to be made by trial and error with a lot of changing something up inside the shell and measuring the changes, with very few using a 3D printed acoustic structure (to be fair these two companies probably had to go through a lot of trail and error to get to these patented acoustic structure designs).

As a newcomer I can say that the community here is very helpful, if you give an approximate budget for the drivers and the type of sound you're looking for I'm sure somebody will be able to help you in the right direction.
Yellow damp DD till you get a lowpass
Highpass the mid and uppermid driver so that it can have F3 rolling point at 300Hz somewhat and you will get SeeAudio Yume style of bass
Flat mids and then a subbass shelf

Simple

It's the experiment which let us innovate weird stuff
 
Feb 28, 2021 at 12:11 PM Post #12,420 of 15,910
Yellow damp DD till you get a lowpass
Highpass the mid and uppermid driver so that it can have F3 rolling point at 300Hz somewhat and you will get SeeAudio Yume style of bass
Flat mids and then a subbass shelf

Simple

It's the experiment which let us innovate weird stuff
Wait so you can use Knowles dampers on DD's too, that's very interesting and makes hybrid seem much easier than I thought.
What would be the best way to go about this, have an acoustic tube directly connected to one of those DD's with a nozzle in front of the driver and then put the damper in the tube? In that case how would you go about pressure equalization, which I thought was necessary on DD's, is a back vent enough to accomplish that or is there another trick to achieve this?
Amazing to see parts of the tuning of such a hyped set dissected and made easy to understand.

Sorry for mislabeling the innovative experimentation to required trial and error, I still have a lot to learn lol!
 

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