Home-Made IEMs - Page 70

The challenge is to get the mold to make a tight fit. I will put a layer of wax on the molds before casting them and see if it helps.

I found mold max 30 from a shop which sells casting and resins for artist and sculptures. They told me it will give me great detail and it does. Made the first negatives in silicone and positives in epoxy. If you can get some release on your silicone negatives, then do that. The ear impression will stick to the cast material. I did not use release and had to take the ear impression to pieces to get them out.

I've grinded and sanded the epoxy pieces to a nice size and now going to make 2nd negative from them. The challenge is to get the mold to make a tight fit. I will put a layer of wax on the molds before casting them and see if it helps.

At the same time I'm experimenting with receivers and crossover.

My 2-way looks like this:

2x2600 tweeter -  ?uF in series - 300 Ohm sound damper

1x 2356 tweeter - 3.3uF in series - 1000 Ohm sound damper

1x3300 woofer - 4700 Ohm sound damper (considering 3700)

I will try to make some pictures

4700 also 3700 too much for 3300 I recommend 2200 or less and use series configuration for woofer.(JH uses this conf.)

1000 is good may be much but you can use a simply resistor instead of caps it will give more detail at every part of spectrum.

or use 2356 with high cut off freq for extension.And 2*2600 with small resistance for keeping high energy.(it can cause distortion.)
Pspice models very helpful but can it help for phase alignment.

4700 also 3700 too much for 3300 I recommend 2200 or less and use series configuration for woofer.(JH uses this conf.)

1000 is good may be much but you can use a simply resistor instead of caps it will give more detail at every part of spectrum.

or use 2356 with high cut off freq for extension.And 2*2600 with small resistance for keeping high energy.(it can cause distortion.)
Pspice models very helpful but can it help for phase alignment.

4700 also 3700 too much for 3300 I recommend 2200 or less and use series configuration for woofer.(JH uses this conf.)

1000 is good may be much but you can use a simply resistor instead of caps it will give more detail at every part of spectrum.

or use 2356 with high cut off freq for extension.And 2*2600 with small resistance for keeping high energy.(it can cause distortion.)
Pspice models very helpful but can it help for phase alignment.

I already made the first IEM's:

2800: 0.1µF in series - coupled in antiphase - 680 Ohm damper - 2mm ID 25mm length

2356: 47 Ohm resistor and 4.7µF in series - coupled in antiphase - 1000Ohm damper - 2mm ID 12mm length

3300: 15 Ohm resistor in series - Normal coupling - 4700Ohm damper - 2mm ID 25mm length

The fitting was now perfect because I used too big tubes and made the molds bigger than my ear canal. So they are not comfortable to wear. Nevertheless I was able to make listening test.

The was a bit lack of bass for my taste. The mid low bass was good and tight but not very much very low bass. The mids were very good together with highs. They sound a bit like the 2356 alone and the 2800 gave a little extra in the highs, but could have been more. Overall the sound is on the warm side.

I also did a measurement on them, and the low frequencies were very flat and not U shaped. I the next ones I will put a smaller electrical resistor and more sound damping to get a slope at the lows. For the highs I will try to get a little more output from 2800 to the overall sound. It might means damping the 2356.

What do you mean 4700Ohm is too much? I found it to be too little. Besides the sound dampers only work for High frequencies. Put the 3300 in series? Why?

Spent the day reading though this, ridiculously interesting. Planning to start my own build soon but with a single driver to make sure it all actually works before I blow a pile of money on parts.

What would the best driver be? After reading this thread I think I'll use the Knowles CI-22955 as suggested by Bilavideo  http://uk.mouser.com/Search/ProductDetail.aspx?R=CI-22955-000virtualkey66550000virtualkey721-CI-22955-000 . Managed to source all the parts except for the acoustic tubing, anyone know where I could find some? Preferably in the UK/Europe but worst case I could import it from the US.

 Preferably in the UK/Europe but worst case I could import it from the US.