[Xymordos]

Drivers on Taobao are often second hand picked out from used hearing aids/ earphones

 

[arthurY]

anyone had experience with both the sonion 2389 and the knowles 29689? I was planning to use one of them as the tweeter and the sonion 33AJ007i/9 for the woofer and a bit of mid. From where I could get it, the knowles is nearly half the price of the sonion. Will the sonion be worth almost double that price?   

 

[tranhieu]

anyone had experience with both the sonion 2389 and the knowles 29689? I was planning to use one of them as the tweeter and the sonion 33AJ007i/9 for the woofer and a bit of mid. From where I could get it, the knowles is nearly half the price of the sonion. Will the sonion be worth almost double that price?   

They are pretty much the same response wise.

 

[arthurY]

Thanks I think I'll get the knowles anyway

 

[Panohm]

Few Questions, slowly getting supplies to start building.

What are the tubing part  #s used in this video?  https://www.youtube.com/watch?v=LJ55BCSwJkg or any that accept a damper and smaller tubing, can't seem to narrow it down on microsonics.

I forgot to purchase UV lacquer or build up material, how do i find UV resin/nailpolish that is inert to the body. I've tried looking on ebay/amazon for UV nail polish or organic nail polish but i want to be sure.

 

[ForceMajeure]

  Few Questions, slowly getting supplies to start building.

What are the tubing part  #s used in this video?  https://www.youtube.com/watch?v=LJ55BCSwJkg or any that accept a damper and smaller tubing, can't seem to narrow it down on microsonics.

I forgot to purchase UV lacquer or build up material, how do i find UV resin/nailpolish that is inert to the body. I've tried looking on ebay/amazon for UV nail polish or organic nail polish but i want to be sure.

I believe he used in this video #13 normal and #16 normal.
#13 should be 2mm ID thus fitting the knowles damper (2.08mm Diameter). #16 is the small one and fits the spout (usually knowles spout is 1.4 mm diameter), so #16 ID should be 1.5mm and because it fits into the #13 the outer diameter should be 2mm.
 
So small tube  #16 ID 1.5mm OD 2mm
bigger one #13 ID 2.5mm OD 3mm(I guess)
 
Regarding the lacquer you could buy some on taobao.com (egger uv lacquer)
or try http://www.lightningenterprises.com/uvmaterials.html they are based in the US

 

[ForceMajeure]

Got a question, I think it was kinda answered in this thread but I want to be sure.
 
What is the spl gained by doubling the same BA? Can I had a number of decibels gained by using 2 BA to the whole frequency response of the same driver?
 
What a about 3 identical BAs? 
 
Of course connected in parallel.
 
Also is there a way I could increase the impedance of a design using resistors/or design a circuit without affecting the overall frequency response?

 

[tranhieu]

Quote:

  What is the spl gained by doubling the same BA? Can I had a number of decibels gained by using 2 BA to the whole frequency response of the same driver?

 
Around 5-6dB SPL, parallel wiring.
 
Quote:

 
What a about 3 identical BAs? 

 
In theory +10dbSPL
 
Quote:

  Also is there a way I could increase the impedance of a design using resistors/or design a circuit without affecting the overall frequency response?

 
Some drivers are sensitive to impedance changes, some aren't. Either look at their inductance rating or impedance response to determine.
 
Personally I don't like using damping resistors.

 

[ForceMajeure]

thanks a lot

 

[Furco]

I thought I read somewhere that muktiple drivers tuned the same equals a larger sound stage. Any truth to that?

Quote:

Originally Posted by ForceMajeure /img/forum/go_quote.gif

 
What is the spl gained by doubling the same BA? Can I had a number of decibels gained by using 2 BA to the whole frequency response of the same driver?

Around 5-6dB SPL, parallel wiring.

Quote:

Originally Posted by ForceMajeure /img/forum/go_quote.gif

What a about 3 identical BAs? 

In theory +10dbSPL

Quote:

Originally Posted by ForceMajeure /img/forum/go_quote.gif

 
Also is there a way I could increase the impedance of a design using resistors/or design a circuit without affecting the overall frequency response?

Some drivers are sensitive to impedance changes, some aren't. Either look at their inductance rating or impedance response to determine.

Personally I don't like using damping resistors.

 

[tranhieu]

I thought I read somewhere that muktiple drivers tuned the same equals a larger sound stage. Any truth to that?

I don't think so. Case in point: the Savant with only 1 ED sounds tremendously large compared to the early S-EM6 with 2 TWFK.

 

[Furco]

So this begs the question, what influences the sound stage when building IEMs? Better frequency separation among the low, mids, and highs? Longer tubes? Closely matching SPL from your drivers?

I don't think so. Case in point: the Savant with only 1 ED sounds tremendously large compared to the early S-EM6 with 2 TWFK.

 

[Mython]

Phase certainly plays a part in subjective soundstage proportions

 

[ClemBurmingham]

I have been lurking this thread for a long time now, and wanted to take a second to thank everyone here that has shared their knowledge and experience.
 
I just wish I could wrap my head around the casting of the IEM. I can build the connections, but when it comes to curing the lacquer, it "feels" off compared to the the mold done of my ear. I'm sure there is a page I have missed, and I guess I'll keep trying since I know it isn't impossible.

 

[ForceMajeure]

Talking about phases and how to rectify them
 
Can you tell me If I understand correctly, this is how it works:
 
Lets say we only have 2 different drivers, 1 bass  and 1 mid/highs the crossoverpoint is at 1500hz, 1st order High Pass crossover shifts the phase of the mid/highs driver by 45 deg.
 
Now the mid/high drivers leads by 0.0833ms
 
Phase angle (deg) φ = time delay Δ t × frequency f × 360
 
 time delay Δ t = 45/(1500*360)
                         =0.0833 ms   
which means that sound at 1500hz arrive at the eardrum faster buy 0.0000833 sec. So in order to get both drivers in sync I need to make the mid/highs driver sound travelling a longer distance.
 
Assuming the speed of sound at 20 deg Celsius is 343.2 m/s  (though at body temperature it's closer to 353 m/s) the difference in tubing length should be 343.2*0.0000833= 2.85 cm (1.125 inches).
 
So the tube length for the mid/highs driver should be 2.85 cm longer than the tube for the bass driver.
 
what about the rest of the higher frequencies 1501hz-20khz? they have less time delay than the 1500 hz but now they will have to travel along the tubelength appropriate for the 1500hz delay...?
 
also is this right?: 1st order filter shifts the phase forward by 45 deg
                           2nd order filter shifts the phase forward by 90 deg
                           3rd order filter shifts the phase forward by 135 deg
                           4th order filter shifts the phase forward by 180 deg