[piotrus-g]

BA driver mounting/securing question... I know these don't function like traditional dynamic drivers, but when playing, do they generate any physical vibration at all, even if very very smalll? When it comes to securing them to the shell, does it make any detectable difference in sound/listening experience if they are secured with a hard attachment like a bit of Fotoplast then cured as opposed to a softer attachment like RTV silicone? I know either way probably wouldn't affect the sound coming out the tube(s), but I would imagine the ear canal is a very sensitive area, so any vibration whatsoever transferred into the shell I would think would be noticeable in some way. And if so it would enhance listening at all or on the other hand create fatigue after a while. Probable overthinking, probably a non-issue, but had to ask.

The BAs do vibrate (some more some less) and it's recommended that you glue them to the shell. Otherwise they will rattle, if not from its own vibration then from you moving around.
Filling shell with silicone will change the sound of the BA to a warmer tone and dramatically improve THD (in my measurements typically 4x reduction), but then you can't really use vented drivers such as 3800 etc.

 

[mattmatt]

It's in red, orange, yellow and brown - aren't those colors quite close to each other? Plus grey on white background making it nearly invisible, not to mention I only now realized there's 680 ohm damper too, but since it's white and they put white on white you almost can't see it! Graph description is all over the place with no particular order which further makes reading the graph quite hard.
I understand that they tired going for color of damper = color on the graph but then why green is yellow!

Oh my god! I did not see those red flags! I hope I don't bring my blindness in picking a girlfriend! Everything you pointed out is so true. I never paid attention to it but now that you did, I cannot wrap my head around it.

 

[Xymordos]

The BAs do vibrate (some more some less) and it's recommended that you glue them to the shell. Otherwise they will rattle, if not from its own vibration then from you moving around.
Filling shell with silicone will change the sound of the BA to a warmer tone and dramatically improve THD (in my measurements typically 4x reduction), but then you can't really use vented drivers such as 3800 etc.

I used to like filling them solid but then they became impossible to repair if anything broke sadly :\

 

[stegeoc]

i want all my iems to fit inside the conch so i can lay on my side with them in. honestly, this is the biggest issue i have with my blessing 2s, they stick out way too far. if i fall asleep with them in i have a 50/50 chance of waking up with a tonne of ear pain. plus i cant use my fiio utws3 with them because the shape of the utws pushes my ear forward a bit, and the blessing 2s push my ears back a bit basically resulting in a pinching which once again hurts a bunch if i wear them for more than an hour in a day.

That sounds very familiar! I also had those problems with Blessing 2s too. Got them professionally reshelled and really liked them, though they were still a little big. I lost them in the end and that was the catalyst I needed to start making my own. My UTWS cases have been modified a bit on the inside to allow customs to fit. It's not really the size of the customs but the position of the connector on the iem is sometimes awkward for the standard compartments

 

[stegeoc]

Thin film resistors also add considerably to the THD as well. MELFs will not. They are significantly quieter.

Are there different types of MELF? I see many advertised as 'thin film MELF', are they also preferable?
And when adding resistors in series, am I right in thinking that that does not increase distortion, and it is mainly the parallel resistors that we need to be wary of?

 

[stegeoc]

The BAs do vibrate (some more some less) and it's recommended that you glue them to the shell. Otherwise they will rattle, if not from its own vibration then from you moving around.
Filling shell with silicone will change the sound of the BA to a warmer tone and dramatically improve THD (in my measurements typically 4x reduction), but then you can't really use vented drivers such as 3800 etc.

How are you measuring THD? I tried using STEPS, but I wasn't sure how to interpret the results. One set I made recently sounds very nice at low volume but I am sure there is high distortion in the mids when I play it loud. It has a reverse polarity crossover which I believe is cancelling out some of the true signal at the crossover point and the different distortion characteristics of the drivers are therefore not being cancelled as much, so making up a higher proportion of the eventual signal. That's my theory anyway, haven't been able to prove it yet!

 

[stegeoc]

BA driver mounting/securing question... I know these don't function like traditional dynamic drivers, but when playing, do they generate any physical vibration at all, even if very very smalll? When it comes to securing them to the shell, does it make any detectable difference in sound/listening experience if they are secured with a hard attachment like a bit of Fotoplast then cured as opposed to a softer attachment like RTV silicone? I know either way probably wouldn't affect the sound coming out the tube(s), but I would imagine the ear canal is a very sensitive area, so any vibration whatsoever transferred into the shell I would think would be noticeable in some way. And if so it would enhance listening at all or on the other hand create fatigue after a while. Probable overthinking, probably a non-issue, but had to ask.

I think in general you'll want they mounted solidly to the shell. Any benefit of having them damped in some way (e.g. suspended in silicone) would surely provide only extremely minor differences and would add a lot of headaches. One common failure with builds is tiny leaks in the connection between the tubes and drivers and not securing them properly to the shell will most likely make that happen more. If you're making clear shells, also remember that you'll see the bits resined/glued to the shell very clearly, and not the other bits

 

[mattmatt]

That sounds very familiar! I also had those problems with Blessing 2s too. Got them professionally reshelled and really liked them, though they were still a little big. I lost them in the end and that was the catalyst I needed to start making my own. My UTWS cases have been modified a bit on the inside to allow customs to fit. It's not really the size of the customs but the position of the connector on the iem is sometimes awkward for the standard compartments

Oh! do you have photos of your reshelled blessing 2? Where did you get them reshelled?

 

[stegeoc]

Oh! do you have photos of your reshelled blessing 2? Where did you get them reshelled?

Itsfit in Hanoi. They were very well done. A little too deep but I filed them down myself and they fitted well. Sound was much better than before too, though I didn't have the means to measure at the time. This is the glass effect that I hope to achieve myself one day!

 

[stegeoc]

BTW, completely random shout out to the 'Savant Pro' (?) (ED + Sonion 2354). Listening to it now and every time I do it amazes me how good it is for such as simple dual driver. It really is remarkable

 

[mattmatt]

Itsfit in Hanoi. They were very well done. A little too deep but I filed them down myself and they fitted well. Sound was much better than before too, though I didn't have the means to measure at the time. This is the glass effect that I hope to achieve myself one day!

those indeed look really great.

BTW, completely random shout out to the 'Savant Pro' (?) (ED + Sonion 2354). Listening to it now and every time I do it amazes me how good it is for such as simple dual driver. It really is remarkable

mind sharing the schematics?

 

[stegeoc]

those indeed look really great.

mind sharing the schematics?

I think this was the final configuration I used. There are various flavours based on the Noble Savant in this thread, I imagine they are all really good

 

[piotrus-g]

How are you measuring THD? I tried using STEPS, but I wasn't sure how to interpret the results. One set I made recently sounds very nice at low volume but I am sure there is high distortion in the mids when I play it loud. It has a reverse polarity crossover which I believe is cancelling out some of the true signal at the crossover point and the different distortion characteristics of the drivers are therefore not being cancelled as much, so making up a higher proportion of the eventual signal. That's my theory anyway, haven't been able to prove it yet!

Yes you can use STEPs but you can just use ARTA - it has an option to measure distortion inside the program. You have to have 64k FFT and sweep sequence length 64k with selected "center peak of impulse response" once you run measurement go to analysis and go to frequency response and distortion. Be advised - THDs rise with volume. It's generally a rule of thumb to set the 1kHz response of the IEM at 94dB SPL for measurement of THD .

 

[mattmatt]

Yes you can use STEPs but you can just use ARTA - it has an option to measure distortion inside the program. You have to have 64k FFT and sweep sequence length 64k with selected "center peak of impulse response" once you run measurement go to analysis and go to frequency response and distortion. Be advised - THDs rise with volume. It's generally a rule of thumb to set the 1kHz response of the IEM at 94dB SPL for measurement of THD .

Since people are asking great questions, just wondering how do you also properly and accurately measure sensitivity at certain power?

 

[piotrus-g]

Since people are asking great questions, just wondering how do you also properly and accurately measure sensitivity at certain power?

Calibrated device would be short answer.
Long answer -you have to measure Vo and Ao to match desired level with multimeter and measure the IEMs at that setting.