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Home-Made IEMs - Page 117

post #1741 of 5605

Perhaps you need to ensure that you’re using the right type of glue, cyanoacrylate glue (loctite) is generally safe after application, but do it in a well ventilated area

post #1742 of 5605

Actually, UM also use superglue to attach sound tubes. It can be done but you gotta be super careful at the same time.

 

Another solution is to use a thin layer of UV glue, or even clear nail polish could do. They provide strong enough bonding while easy to be broken apart at low cost. 

post #1743 of 5605
Anyone here tried a ci(low) dtec (mid) twfk (high) configurations? What were your learnings? What is the sound signature like?
post #1744 of 5605
Quote:
Originally Posted by tranhieu View Post
 

Actually, UM also use superglue to attach sound tubes. It can be done but you gotta be super careful at the same time.

 

Another solution is to use a thin layer of UV glue, or even clear nail polish could do. They provide strong enough bonding while easy to be broken apart at low cost

 

I did think about using UV acrylic, the problem I was having is that I had to hold the tubes very tightly against the sound ports in order to get a proper seal and that is difficult to do while also ensuring that it gets sufficient UV light to cure.

post #1745 of 5605

 

Quote:
Originally Posted by aarontww View Post

Anyone here tried a ci(low) dtec (mid) twfk (high) configurations? What were your learnings? What is the sound signature like?

I'm going to try a CI/DTEC/WBFK combination soon, as I think it's more interesting to try out crossovers.

 

I'm testing out suitable shapes for the universal shell I'll print, but I'm pretty sure it'll be something close to this in size, since it can fit all the drivers into the body. I'll be using a boot printed with some elastic material to hookup the drivers to the ear canal.

 

CI on top, WBFK to the left, DTEC at the bottom. I might still shift WBFK to face downwards directly into the canal since there's space.

 

Ignore the random mmcx connector, it's trivial to add supporting structures on the outside and I just wanted to test the size first.

post #1746 of 5605

Got my first shells completed today.  Thanks Dan Jarros, the UV Nail stuff from ebay works great.  Cures clear, has no sticky residue when completely cured and super cheap.  I found that the top coat material worked better than the base coat.  

 

Went to do a dry fit to make sure everything works.  

 

Right ear, check, sounds great.  

 

Left ear, very quiet and no highs.  

 

I think I killed the tweeter with too much heat when soldering the terminals.   

 

What a let down.  

 

Now I need to wait to get a new driver in.  I think I'm going to try to use the shells for one of my dynamic earphones (Sony MH1c).  Fortunately for me, I have big canals and I can get the MH1cs almost to the very edge of the tip. 

post #1747 of 5605
Quote:
Originally Posted by piotrus-g View Post
 

That's good to start off with 1way IEMs, it lets you understand basics of how BA changes on acoustic terminations.

 

As for measurement - you can buy some some condenser microphone, use cut syringe (to 2cc) as coupler. However I've never done it so you should do some research on it. ARTA software is free (in free version you cannot save your measurements).

Hi!

 

I`m planning on building a jig using a Behringer ECM8000 condenser microphone and either a audio analyzer or a tool such as the M-Audio MobilePre. I'll also build a small anechoic chamber.

 

Do you have any hardware recommendations in particular? I'm mainly concerned about the accuracy of the M-audio MobilePre.

 

Thanks!


Edited by tomtomtom - 6/3/14 at 3:42pm
post #1748 of 5605

Does anyone know what happens in group delay? The time constant is directly linked to cutoff-frequency, hence it's something that passives can't really control well.

 

Also, is it reasonable to use 100uF caps in my filter design? The concept is to reduce the resistance needed to give a better impedance ratio.

post #1749 of 5605
Quote:
Originally Posted by vector1 View Post

 

The concept is to reduce the resistance needed to give a better impedance ratio.

That's a long shot imo. Dampening ratio isn't that important compared to other factors. 

post #1750 of 5605
Quote:
Originally Posted by tranhieu View Post
 

That's a long shot imo. Dampening ratio isn't that important compared to other factors. 

 What other factors am I missing? I have modeled the crossovers using large caps to reduce the impedance presented by the resistors especially for the low pass filters, which has the resistor in series.

 

I'm now preparing the list of caps/resistors that I need for the crossover. I think I'll start with a simple high pass for WBFK and low pass for CI then leave DTEC directly driven. If that sounds bad, then I'll move on to use a bandpass for DTEC, but overall I think it's a bad idea since the peak introduced would most likely screw up the frequency response.

post #1751 of 5605
Quote:
Originally Posted by vector1 View Post

 

Also, is it reasonable to use 100uF caps in my filter design? The concept is to reduce the resistance needed to give a better impedance ratio.

I have read in sonion doc that larger capacitance values should not be used. Not sure why?

I have seen 0.1 to 10uF values in designs.
 

post #1752 of 5605
Quote:
Originally Posted by MuZo2 View Post
 

I have read in sonion doc that larger capacitance values should not be used. Not sure why?

I have seen 0.1 to 10uF values in designs.
 

 Is there a reference I can read? I have not seen that in their application notes, or I must have missed it. :(

post #1753 of 5605
Hi;


Capacitor values affected from your cut-off points. too much capacitor values means more homogeneous distrubution of energy at freuency spectrum. Lesser caps values means lesser homogeneous distributionf energy that means more energy goes to higher freuency.





For damping; It is a good point but you need what happens inside driver and acoustic structure. Mass-Spring -Damper phenomena can help you.
post #1754 of 5605
Quote:
Originally Posted by tsn141 View Post

Hi;


Capacitor values affected from your cut-off points. too much capacitor values means more homogeneous distrubution of energy at freuency spectrum. Lesser caps values means lesser homogeneous distributionf energy that means more energy goes to higher freuency.





For damping; It is a good point but you need what happens inside driver and acoustic structure. Mass-Spring -Damper phenomena can help you.

 

I don't actually understand what you mean. In a RC circuit, the capacitor is in line with the receiver and the source, while the resistor connects to ground. The cut off frequency is dependent on both R &C by 1/(2(pi)RC) but capacitance changes which energy distribution? I had the impression under bandpass the response should be close to unity.

post #1755 of 5605

Once I confirm that my desired case is strong enough to work without breaking, I’m going to order my components.

 

I have scaled back my plans, so I’m only implementing a low pass for CI @ 100Hz, high pass for WBFK@1kHz, and nothing on DTEC. One red filter in the CI tube to reduce it’s presence at 1k/2k.

 

Lowpass = 16ohm resistor, 100uF cap

Highpass = 16ohm resistor, 10uF cap (reduced to match the previous suggestion, or I'd leave it at 100uF)


The main reason is that I’m afraid of phase differences from any lowpass/bandpass for the DTEC affecting the output around 4-10kHz since it still has quite a significant output at higher frequencies.

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