[arielsivan]

Haha, unfortunately I don't know which page is that schematics. I know some keep better track.

Is this the correct scheme?
If so, waht are the R1 and C1?

 

[CBTlover223]

Using and ED29689 with a 2389 would essentially give you more head room for whatever frequency spectrum you have them set to. adding a DWFK will sound awesome! Again, its all about how well the drivers work together. Using the same driver in duplicate, such as 4xTWFK, just allows the sound stage to present with significantly less THD and a loss of sibilant crunch. But again, it really comes down to what you set as the design profile for your soundstage. Some drivers just wont get you there some times. Example: you could put 10 RAB32257 in one ear and 10 in the other and still not get a sub signal that makes you FEEL an 808 drum.

Thanks for the response, although not quite I was looking for, I appreciate the advice. I was more concerned about slight differences in acoustic phase making it sound weird. Although I feel like a slight differences in phase wont really be noticeable by the human ear, I don't really have the resources to test it experimentally ATM. For instance, Ignoring the electrical interference between drivers, If I run something like a 2389 and a dwfk together without any crossover circuitry, would the mids sound bad due to interference between the drivers?

 

[piotrus-g]

Is this the correct scheme?
If so, waht are the R1 and C1?

I think the top driver should be marked as WBFK and the bottom should be FK and in that case WBFK should be 1uF and FK should be 20-40uF. Otheriwse it doesn't makes sense to me.
CI wiring is also incorrect. Picture shows shorting positive and negative together - CI would not produce sound in that case. I would argue you need to wire what's marked as "minus pads" (also incorrectly) together and than attach positive to one of the "+" and negative to the second driver's "+" to make series wiring. As for the values anything around 200Hz-500Hz crossover point for low pas, so... 5 Ohm+100uF or 40 ohms + 10uF, use the LPF calculator to figure out values. The more Ohms you put the lower the CI level will be. And the opposite would be true for uF values - bigger uF quieter TWFK and hence louder CI. granted we are looking at CI in series with low pass I'd go for something closer to 40 ohms.

 

[swtnate]

Thanks for the response, although not quite I was looking for, I appreciate the advice. I was more concerned about slight differences in acoustic phase making it sound weird. Although I feel like a slight differences in phase wont really be noticeable by the human ear, I don't really have the resources to test it experimentally ATM. For instance, Ignoring the electrical interference between drivers, If I run something like a 2389 and a dwfk together without any crossover circuitry, would the mids sound bad due to interference between the drivers?

“Bad” , no. is it what you want? Idk. Wire it and listen to it if you cant test. why would there be phase issues if nothing is wired in parallel to the drivers?

 

[CBTlover223]

“Bad” , no. is it what you want? Idk. Wire it and listen to it if you cant test. why would there be phase issues if nothing is wired in parallel to the drivers?

From my understanding, (which very well could be wrong) apart from phase shifts causes by capacitors and inductors, you can physically shift acoustic phase by changing the tubing length or tubing geometry, with these changes being prominent enough to cause interference. Since different drivers will have inherently different acoustic phase and SPL curves, I'm concerned that using 2 different drivers with that will have 20-45 degree phase in certain frequencies differences to cover the same frequency range will cause audible changes to the sound other than those that can be seen on the SPL graph.

 

[musmecca]

Is this the correct scheme?
If so, waht are the R1 and C1?

Go to post 3964 on page 265....that is Piotrus-G's original design. I have made this IEM numerous times and it is still one of my favorites.

 

[swtnate]

From my understanding, (which very well could be wrong) apart from phase shifts causes by capacitors and inductors, you can physically shift acoustic phase by changing the tubing length or tubing geometry, with these changes being prominent enough to cause interference. Since different drivers will have inherently different acoustic phase and SPL curves, I'm concerned that using 2 different drivers with that will have 20-45 degree phase in certain frequencies differences to cover the same frequency range will cause audible changes to the sound other than those that can be seen on the SPL graph.

Everything you are asking requires either testing or listening. The “acoustic phase” you are speaking of, is very easily dealt with by testing. Unless its a build that has been published, no one can tell you how it will sound.

 

[dhruvmeena96]

The man the myth the legend. Say his name and he shall appear. @piotrus-g

Also that dual CI still hits hardcore and he gave it for free
Ages ago........
Fibae 7 Unlimited/Ultimate
Is scary on dynamic range.... I can go louuuuuudddd and it still sounds really goooood

 

[piotrus-g]

Go to post 3964 on page 265....that is Piotrus-G's original design. I have made this IEM numerous times and it is still one of my favorites.

Thanks!

 

[slakoth453]

Go to post 3964 on page 265....that is Piotrus-G's original design. I have made this IEM numerous times and it is still one of my favorites.

Graph looks really nice! Think I'm gonna try making one, only have CI-30120 but that should still work right? I think impedance is only like 2 Ohm lower. Has anyone tried separating one of the knowles drivers with crossover? I'd like to get the TWFK from my GV but I'm scared of damaging it.

 

[swtnate]

Graph looks really nice! Think I'm gonna try making one, only have CI-30120 but that should still work right? I think impedance is only like 2 Ohm lower. Has anyone tried separating one of the knowles drivers with crossover? I'd like to get the TWFK from my GV but I'm scared of damaging it.

I wouldnt even attempt it. The way they are bonded together, its not so easy.

 

[slakoth453]

I wouldnt even attempt it. The way they are bonded together, its not so easy.

Yeah I thought so, gonna have to use an LS TWFK clone then.

 

[slakoth453]

Ok so I tried it and I did get them apart fairly easily using an x-acto knife.

 

[swtnate]

The only issue ive had is the slight separation of the metal when splitting the drivers. Id test the FR to be sure they are identical.

 

[slakoth453]

The only issue ive had is the slight separation of the metal when splitting the drivers. Id test the FR to be sure they are identical.

I'll test that later, thanks!
Doing the wiring (getting rid of the old caps and stuff) first but it'll probably be a few weeks before I can finish the build. Also got another IEM I'm working on.

One more question, when people talk about tube length do they include the part that goes over the spout of the BA or is it measured from the end of the spout?