[Aldo40]

Hey guys,

I've been reading stuff from this thread for a while now and finally decided to get into making my own IEMs. I’ve taken a lot of time to research this stuff, but it’s still quite hard and I don’t yet understand everything. My plan is to order a IEC711 & impedance curve measurement device from taobao, then use those two measurements of both drivers in VituixCAD to design the electronic crossover. Obviously if I succeed, I will report back with the exact values I used so anyone who wants can copy the design.


I wanted to design a dual driver setup with a similar frequency response to the Etymotic ER3XR, same bass, mids, and upper treble but with slightly less pinna gain (3Khz peak). My idea to achieve this is to use a CI-22955 for bass and mids 20~800Hz and ED-29689 as a full range driver. To not let the CI make the midrange too warm I want to dampen it and use an L-pad, if I understand it correctly this should make the ED treble comparatively lower. To get similar upper treble as the ER3/ER4P on the ED I wanted to use a horn to boost the upper treble, but in combination with the right damper filter so it doesn’t bring up that 5K peak.


My questions are: does this seem achievable with these two drivers and could this design be improved in some way?

I would say that your Lpad should be reviewed because I don’t think the impedance is linear with these values, try 4R7serie and 10R// to begin with, the impedance should be linear. You’ll force the 4R7 if you get too many bass.

For your CI tube I think you can use yellow damper at the end of tube, you can start with a 4700 and added to adjust.

On the ED29689 you can use a green damper in a tube of 1.5mm ID over 10mm long to start.

If you lack extensions or performance on high frequency, you can increase the length of your tube by a few millimetres to adjust but for this it is better to measure at the same time to see the evolution on the response curve

 

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[Wgibson]

@amemisome I'd skip the 711 and just get a dayton imm6, and also make your own impedance jig (very easy compared to making an iem, just connectors and a 100 ohm resistor.) You can use room eq wizard software (free, but this reminds me I need to donate!) That will get you up and running for a very reasonable cost.

Edit: in a pinch, you can use electrical wire insulation as a sound tube, easy to find anywhere locally, if you are waiting for your real tubing to arrive. Or if you want to see the effects of different sizes on the frequency response.

 

[Luffytaro]

Hi all

Can anyone help me on this?

I am building 26E25wt02/9 and 38D

How can I design high pass filter for 26e25? Or only use damper?


For 38D, i think I can use 12 ohm resister and 100uF cap as Right On using.

 

[amemisome]

@tomekk @Aldo40
Thanks for the help, I'll be sure to only use 2mm ID tubing then. I'll also try out both of your crossovers in REW/Vituix first before trying anything else on my own.
The idea is to make a custom so I'll use 20mm on the CI and 13mm on the ED.

@Wgibson
The 711 I found is actually about the same price and since I'll have to wait for the drivers, tubing and stuff from Soundlink anyway, shipping time isn't that much of an issue either. I think I'll still order it because I think it's neat, though for the price I doubt it's going to be any more accurate than what you suggested.
Thanks for the tips though, I didn't even know about the Dayton imm6 before and it's also good to know that the acoustic tubing can be substituted with any plasic/pvc tubing of the same size.

 

[tomekk]

Hi all

Can anyone help me on this?

I am building 26E25wt02/9 and 38D

How can I design high pass filter for 26e25? Or only use damper?


For 38D, i think I can use 12 ohm resister and 100uF cap as Right On using.

26e25 - 2600 full range, e25 factory mounted 100uF or change it to 220uF, 2mm*13 Brown or white filter. 38DX full range (it is factory lowpassed by Sonion acustically) 2mm*20, parallel, reverse polarity to 2600 I think. Maye any resistor for coherence with 26e25. You will get cool sounding project with these drivers.

 

[Luffytaro]

26e25 - 2600 full range, e25 factory mounted 100uF or change it to 220uF, 2mm*13 Brown or white filter. 38DX full range (it is factory lowpassed by Sonion acustically) 2mm*20, parallel, reverse polarity to 2600 I think. Maye any resistor for coherence with 26e25. You will get cool sounding project with these drivers.

Thanks Tomekk,

could you please explain while we use tube 2mm instead of 1.5 or 1.0 mm to fit with spout of 38D? I guess to inscrease bass.
And for 38D, we don't need cap to cut high freq, don't we? I really don't understand this point.

And one more, we don't need high pass filter for 26E25 because have cap on E25, don't we? I just fear low freq on 2600 will impact to 38DX.

Thanks so much.

 

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[Luffytaro]

Hi
The 12 ohm resistor 100 uf capacitor is for dual 38D1XJ00 not for single and connected all in series and reversed polarity

I'm also testing the 38D1XJ00 with low pass filters with Acupass and without Acu pass to see the difference of the Acupass .

If you are a basshead like me and you want sub bass thunder and pure sub woofer you must do a low pass filter .

Photo is a 38D1XJ00 without Acu pass

Christos

Hi Right On

You mean that Resister + cap + driver are series together?

As i know with low pass filter circuit, cap parallel with driver, why do we connect series in this case?

And reverse polarity mean that + pole of driver connect - pole on jack and reverse? If yes, is it make reverse phase or net? And the reason for connect reverse polarity?

Thanks for your support.

 

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[tomekk]

Thanks Tomekk,

1. could you please explain while we use tube 2mm instead of 1.5 or 1.0 mm to fit with spout of 38D? I guess to inscrease bass.

2. And for 38D, we don't need cap to cut high freq, don't we? I really don't understand this point.

3. And one more, we don't need high pass filter for 26E25 because have cap on E25, don't we? I just fear low freq on 2600 will impact to 38DX.

Thanks so much.

1. It doesn't matter on the spout. The 1mm spout can also be in a 3mm tube. You glue it to the driver e.g. with UV glue, no sealing rings are needed.
2mm tube is standard in audio world, smaller diameters are for experienced professionals and specific types of speakers that can work with smaller tubes. In DYI audio, smaller tubes than 2mm will make your design weaker than one built on 2mm. Trust me.
2. Sonion engineers were thinking when they came up with Acupass to get rid of the complications associated with an electric lowpass. I guess
The 3800 with Acupass has great rolloff without an electric lowpass, so adding an electric lowpass is unnecessary and has a negative effect on other drivers.
There are two ways of making designs, the modern one of maximum simplification (full range modules, acoustic low pass, no corssovers etc..) and the old school type (based of big speakers science, electric lowpasses, lots of acoustic filters etc.). In DIY the most important thing is to make projects as simple as possible, the more complications without supported experience or "reverse enginering" can kill many projects.
3. One more thing about inverted phase, some full range speaker connections can effect phase cancelation of the sound. To avoid this there are two ways: invert the phase of the speaker (for example bass driver) or use a hypass/midpass/ instead of a full range (mid driver). If you want a lighter sound instead of in parallel + ---- ++ -- ---- - you can connect them in series + --- + -+ - --- -

 

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