[Ivan TT]

Putting my dual RAB’s to a good use...

 

[eunice]

Are these inair tips? What RAB, what zobel?

 

[dhruvmeena96]

Putting my dual RAB’s to a good use...

Daaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaammmmmmmmmmmmmmm

Amazing channel mixer you have

Are these inair tips? What RAB, what zobel?

Zobel might be near ~ 2.3uF and 82.5ohms
Those tips looks like foam tips



@Ivan TT
I tried dual RAB32033 series, and I have to say the bass was too much for my taste and it never felt like a BA sound(even though it never got muddied up). RAF and RAB32257 might be slightly less bassy, but this RAB32033 became a overall monster in bass, even though it had nice mids and good treble(smooth AF treble, cannot go wrong with any person)

The bass was so much that I have to disassemble it.

I am using RAB32063(non vented) in series and it works fine, with amazing bass linearity and good amount of punch and speed and slightly more airy treble.

Best part is high impedance of 44ohms which leads to way less Hiss and good amplifier scaling. Parallel dont scale well if not used with resistor. Series speaker kinda scales pretty well

 

[Ivan TT]

Are these inair tips? What RAB, what zobel?

https://www.aliexpress.com/item/32832429128.html
32257 in series, green filter, 56Ohm/2.2uF
I don't think I'm getting full 26dB attenuation, maybe about 18dB but that's good enough for me.
32257 in series interfaces a bit better with usually hi-Z HP outputs mixing consoles have and after all IEM's were initially designed for live sound monitoring, so why not?

 

[wolkegeist]

@dhruvmeena96 quick question, how do you calculate value for zobel circuit? I wanna use E25ST002, the high impedance one but I see that it has 2 peaks at 3500H and 5500Hz, also a big dip at 8500Hz.

 

[dhruvmeena96]

Are these inair tips? What RAB, what zobel?

@dhruvmeena96 quick question, how do you calculate value for zobel circuit? I wanna use E25ST002, the high impedance one but I see that it has 2 peaks at 3500H and 5500Hz, also a big dip at 8500Hz.

Get the inductance value of driver
Get the resistance at specific inductive frequency

And use a zobel calculator available online
Hard way is to get impedance graph and do hit and trail with capacitor first(so the impedance change cover the resonant peak) and then use a resistor to flatten everything down

https://www.aliexpress.com/item/32832429128.html
32257 in series, green filter, 56Ohm/2.2uF
I don't think I'm getting full 26dB attenuation, maybe about 18dB but that's good enough for me.
32257 in series interfaces a bit better with usually hi-Z HP outputs mixing consoles have and after all IEM's were initially designed for live sound monitoring, so why not?

Aint you over damping the mid and treble with lower resistor value.

Since inductance at 500Hz is 15.6mH and impedance at 500Hz is 66ohms.

I think you took the 44ohm DCR. That will be too heavy treble damping

Well it may be nice for you(I dont know, I have to try 56ohms)

 

[tomekk]

@wolkegeist If you use a zobel to equalize the impedance for the whole project, it is best to use only one, and possibly turn up the sound by shortening the tubes, or correct the zobel with a resistor. Adding 2nd zobel (It summing up) to the tweeter will erase the treble and mute the transparency. If you want to align the impedance graph at the top, check out the reverse phase on the tweeter, or use a second order crossover on the tweeter relative to the mid if you have one.

 

[wolkegeist]

@wolkegeist If you use a zobel to equalize the impedance for the whole project, it is best to use only one, and possibly turn up the sound by shortening the tubes, or correct the zobel with a resistor. Adding 2nd zobel (It summing up) to the tweeter will erase the treble and mute the transparency. If you want to align the impedance graph at the top, check out the reverse phase on the tweeter, or use a second order crossover on the tweeter relative to the mid if you have one.

I use zobel for the mid driver, so they probably gonna share zobel. Hmm maybe I’ll use first order crossover for the tweeter, gonna try 960nF first because I tried it with the low impedance version of this driver and succeedes

 

[dhruvmeena96]

@wolkegeist If you use a zobel to equalize the impedance for the whole project, it is best to use only one, and possibly turn up the sound by shortening the tubes, or correct the zobel with a resistor. Adding 2nd zobel (It summing up) to the tweeter will erase the treble and mute the transparency. If you want to align the impedance graph at the top, check out the reverse phase on the tweeter, or use a second order crossover on the tweeter relative to the mid if you have one.

I use zobel for the mid driver, so they probably gonna share zobel. Hmm maybe I’ll use first order crossover for the tweeter, gonna try 960nF first because I tried it with the low impedance version of this driver and succeedes

Its better to make a zobel for a driver which you know you can work with or make a zobel of whole circuit.

First of all, Tweeter BA doesnt have inductance worth while and nobody crosses it at its resonant peak.

Electrostatics or electrets like Sonion EST is too small to get the electrostatic deviation, so it doesnt need a zobel.

And once you cross it, the resonance and rising response kinds flattens down as the driver has to work less


You can go for double zobel or summed zobel in MASM 7 or a very specific project where you need pin point crossing and there, you will need a good beefy tweeter.

 

[wolkegeist]

@dhruvmeena96 @tomekk @Ivan TT
I’m making a pair of Rab-p + tweeter for my friend. He’s on a budget so do you guys has any recommendation for single tweeter? Sadly Taobao ran out of supply for E25ST.

 

[dhruvmeena96]

@dhruvmeena96 @tomekk @Ivan TT
I’m making a pair of Rab-p + tweeter for my friend. He’s on a budget so do you guys has any recommendation for single tweeter? Sadly Taobao ran out of supply for E25ST.

I dont think RAB-p needs a tweeter
You just need to reduce damper to white and add 10 to 20ohm of resistor to whole circuit.

RAB -> zobel -> resistor -> mmcx

And even if you want to add a tweeter, its not possible until or unless you create a 2 driver adapter, and then the RAB-p setup.

 

[Makahl]

Is the Bellsing RAB32277 much worse compared to the Knowles?

I got the Knowles ones for my single BA project a year ago and I liked it a lot for some stuff but... yesterday I dropped the left piece on the floor and now the bass is distorting a lot. I've tried to replace tubes and replaced the damper but apparently, the armature got some damage so time to buy a new one.

 

[dhruvmeena96]

Is the Bellsing RAB32277 much worse compared to the Knowles?

I got the Knowles ones for my single BA project a year ago and I liked it a lot for some stuff but... yesterday I dropped the left piece on the floor and now the bass is distorting a lot. I've tried to replace tubes and replaced the damper but apparently, the armature got some damage so time to buy a new one.

Hmmmm...

Bellsing RAB32257 is kinda a replacement.
The only issues i dont recommend it are:
1. More 3rd order distortion leading to more warmth but less vocal intelligibility.
2. More narrower impedance peak, which make itself apparent.
3. Less treble extension

Zobel is same, and it scales better than Knowles counterpart without zobel.

I recommend zobel followed by 10ohm resistor


But instead of Bellsing RAB, you have Knowles RAF which is cheaper than orignal Knowles RAB and has more in depth datasheet and sounds more enjoyable than both(if you are going for normal tubing and not RAB-p style horn)

 

[HAMS]

I just mod-ed my phonak pfe(1 BA sonion) with detachable connector. And am not sure if I wired it out of phase. Should the out of phase BA sound fuller(or boomier) with wider soundstage?

 

[piotrus-g]

I just mod-ed my phonak pfe(1 BA sonion) with detachable connector. And am not sure if I wired it out of phase. Should the out of phase BA sound fuller(or boomier) with wider soundstage?

Phonak has 10 Ohm resistor wired in series inside the original Y-splitter. You basically decreased your BA's impedance by half.
Also boominess might come from unsealed housing - since the BA is vented the volume behind the driver will affect the response, if you vent the shell you'll create an "infinite" amount of air behind the driver making the bass bloated.