[Dulalala]

Yes, this is actually trivial from a CAD perspective. There are taobao sellers selling these in either plastic or metal (can't find links on whim, but you can probably find them in related products). I could re-create the CAD models for you if you want, it'll only take a minute or 2, I'll need your specific driver's dimensions and printer's precision. I personally don't like using them because they add quite a bit of bulk, and can make 9.2mm/10mm drivers impossible to fit into shells. Consider using wider heatshrinks to adapt them down, instead.

+ a shameless plug for my SE846 structure, since it's my go-to DIY shell for comfort and internal space. Shoot me a PM if you want the stl/sldprt files to modify/print them yourself.

Thanks for the offer! However I was just curious what type of filament people were using for them.

 

[Firedrops]

Thanks for the offer! However I was just curious what type of filament people were using for them.

Those taobao guys are most likely doing injection moulding, looks like pvc but I'm not sure.

For personal prints, it's easiest to use proper ABS filaments that easily get vapour smoothed by acetone. PLA is a far more common filament, but it takes much more exotic and dangerous chemicals to vapour smooth. Vapour smoothing helps fill in the boundaries properly, so sound doesn't leak out through the gaps between the printing layers.

 

[Makahl]

Hey guys, I'm bit concerned about what would be the best method in a single BA project. I made this to try to help:

Looking to the 1x2mm tube it looks like it will decrease the ba's nozzle diameter and I was wondering if that would affect bass response, so I'd use the "ring" version to create a perfect seal and not changing the BA's diameter. But that's just random thoughts, any advice would be really helpful! Thanks!

 

[Rabid86]

Hello! I am quite new to this forum but I have been lurking about for a while.

I am building a pair of in-ear monitors using the Knowles SR-series of balanced armature drivers: http://www.knowles.com/eng/content/download/5775/92032/version/3/file/SR-32453-000.pdf

If you can see in the frequency response, it has quite a nasty peak at 3kHz. I have tried reducing it with acoustic filtering (both sonion and knowles dampers), but I have not found a good way to fix just that peak. If anyone has any suggestion of any material or other ways that can filter it I would be more than happy to know!

Since it was not so easy to fix it using the acoustic filtering I instead turned to electrical filtering and found some interesting pages such as this one: http://www.learningaboutelectronics.com/Articles/Notch-filter-calculator.php

I used the "Narrowband Twin-T Notch Filter" and tried to calculate the 3kHz formula. Though, I did not have the correct values of the capacitors, I used 22nF for C and 68nF for C2. I used small ceramic capacitors for this task, and the resistors are rated at 0.25W, if that makes any difference.

I made a crude drawing of how I connected the components outside of the shell: https://i.imgur.com/wRcmCiS.jpg

When I tested this filter, it turned out very good! The problem, which is a big one, is that it drops to probably a 1/4 of the volume. So, my question is: Do I have any way of keeping the volume at a good level but still using a passive notch-filter? These in-ear monitors are only supposed to be used with a smartphone, not an external amp.

Are the components that I used to hard to drive for the phone? Is there any other way of making a notch-filter that I seem to have missed? Did I connect something in the wrong way? Any help would be greatly appreciated!

Thank you very much!

/Anders

 

[ForceMajeure]

Hello! I am quite new to this forum but I have been lurking about for a while.

I am building a pair of in-ear monitors using the Knowles SR-series of balanced armature drivers: http://www.knowles.com/eng/content/download/5775/92032/version/3/file/SR-32453-000.pdf

If you can see in the frequency response, it has quite a nasty peak at 3kHz. I have tried reducing it with acoustic filtering (both sonion and knowles dampers), but I have not found a good way to fix just that peak. If anyone has any suggestion of any material or other ways that can filter it I would be more than happy to know!

Since it was not so easy to fix it using the acoustic filtering I instead turned to electrical filtering and found some interesting pages such as this one: http://www.learningaboutelectronics.com/Articles/Notch-filter-calculator.php

I used the "Narrowband Twin-T Notch Filter" and tried to calculate the 3kHz formula. Though, I did not have the correct values of the capacitors, I used 22nF for C and 68nF for C2. I used small ceramic capacitors for this task, and the resistors are rated at 0.25W, if that makes any difference.

I made a crude drawing of how I connected the components outside of the shell: https://i.imgur.com/wRcmCiS.jpg

When I tested this filter, it turned out very good! The problem, which is a big one, is that it drops to probably a 1/4 of the volume. So, my question is: Do I have any way of keeping the volume at a good level but still using a passive notch-filter? These in-ear monitors are only supposed to be used with a smartphone, not an external amp.

Are the components that I used to hard to drive for the phone? Is there any other way of making a notch-filter that I seem to have missed? Did I connect something in the wrong way? Any help would be greatly appreciated!

Thank you very much!

/Anders

I am no expert but just looking at the values of resistors you chose (kilo ohms). it's no surprise you got such dramatic change in spl output.
My advice is that you should use lower resistors values (<50ohms if possible) and calculate the needed capacitors in relation to those.

PS:
also that "nasty spike" as you call it is there for a reason. it's there to compensate for the bypass of the pinna when using iems (the human ear pinna act as a naural amplifier of mid frequencies in that range). it's a debatable subject as how much should the compensation be and where as it is different for every individual in regard to their ear morphology...

 

[Rabid86]

Thank you very much for the reply! I was also thinking that the high values was being problematic, maybe also the wattage rate of the resistors might make a difference?
I do not have the access, nor the tools to preform soldering with surface-mounted components, otherwise they would have been my choice and probably the rating of those would have been far less.

I am trying to figure out how to calculate what they did in the link (http://www.learningaboutelectronics.com/Articles/Notch-filter-calculator.php) but I am not at all good with math. Trying to calculate it myself gives me totally different results.
As you say, I was thinking of doing 1/10th of the values, but maybe 1/20th would be better (ie. 100Ω and 50Ω instead of 2KΩ and 1kΩ). Would the capacitor values be a higher value or lower when lowering the resistor-values? I don't know exactly how I would compensate.

For me personally, I don't really understand the point of the compensation of the pinna. Maybe it is my ears, but I am very sensitive at around 2500Hz up to even 5000-6000Hz. Everything sounds easily sibilant to me, especially in-ear monitors.
This driver is too painful to listen to like it is at the moment, even with an acoustic filter. So an electronical filter would be the best option, to preserve the rest of the frequencies and the sparkling highs.

Again, thank you very much for the reply! Any tips is greatly appreciated!

/Anders

 

[Dulalala]

Would the capacitor values be a higher value or lower when lowering the resistor-values? I don't know exactly how I would compensate.

If resistance decreases, capacitance increases.

 

[Rabid86]

Thank you very much! Now I just need to take out the breadboard and start testing.

/Anders

 

[ForceMajeure]

I haven't check the calculations but my guess is that instead of using capacitors in the nF range you should use capacitors in the uF or mF range. this would make your resistors go down to the "inverted range" like instead of Kohms to ohms.
The wattage of a resistor aka power rating is not important in your case. it's just a number indicating the wattage it can endure before failure (heat dissipation). a thing to consider for certain applications but not with iems current.

 

[Rabid86]

Thank you very much for the input! I have bought capacitors in the uF range now, hopefully that will be good enough. I also managed to figure out how to calculate the values of the resistors and capacitors so now I am back on track.
It is good to know that the wattage doesn't affect anything, so hopefully this time I can make it work. I will let all of you know how it is going.

I apologize for the late reply, I have been working alot, both at work and non-stop with the headphones. In the process I found that the best acoustic filter was three thin sheets of toilet paper. It sounds amazing now and may not be much need for an electrical filter. However, is there anything that can replace the toilet-paper with a more durable and resistant fabric, like cotton or something similar? But still retain the shape of the sound like the toilet-paper has? I will research on the rest of the forum here aswell to see if I can find an answer.

Thanks again!

/Anders

 

[leapof]

Hi guys!
First time poster here! so after a few failed attempts at building my first universals I've finally come up with something acceptable look wise and that sounds good! I used the KZ ZST as a template for the sell and I fitted a GQ with a white damper halfway through the tube inside. It might be juuuust a tiny bit too harsh for my ears but I'm very happy with the overall sound (quite detailed, bass is present!).

https://imageshack.com/a/img924/9173/rguqCs.jpg

P.S. Thanks everyone for your contributions to this forum!! I learnt a lot reading all the posts and enjoyed your creations, great stuff!!

 

[bartzky]

Thank you Santa!

 

[Dulalala]

Does anyone have an estimate on how much liquid of Fotoplast it takes to make a pair of hollow CIEM?

 

[ForceMajeure]

Does anyone have an estimate on how much liquid of Fotoplast it takes to make a pair of hollow CIEM?

You need about ~10-12ml to be able to fill them one after the other (curing one at a time using the same resin) but maybe a bit more also if you plan on securing everything with it and doing the faceplates. you will have a bit resin left from those 10ml at the end of the process. but you need that amount at least to be able to fill them for curing.

Of course that if everything goes according to plan...

 

[Dulalala]

You need about ~10-12ml to be able to fill them one after the other (curing one at a time using the same resin) but maybe a bit more also if you plan on securing everything with it and doing the faceplates. you will have a bit resin left from those 10ml at the end of the process. but you need that amount at least to be able to fill them for curing.

Of course that if everything goes according to plan...

Right ok. Thanks for the info! Merry Christmas too!