[dhruvmeena96]

Clarity shootout:

Spoiler: Clarity Graph 4x RAB vs Bellsing 6 vs Bellsing 6 + Zobel vs Knowles GV

Well my doubt was sort of right.

Clarity increase is mostly shown at those area where impedance is damped to linear. Amount of impedance damped equates to amount of clarity improved

RAB shows way higher quality in 3kHz and treble because 3kHz was 200ohms and 20kHz was 384ohms

 

[dhruvmeena96]

Whats better now

Bellsing 6 + zobel is really crazy spec. GV is not even near, according to his graph.

RAB series is outperforming everything in treble clarity. Zobel will even raise it further. So it might be the best mid and treble .

GV needs zobel as I have seen impedance graph and it has two big peaks, which if damped properly by zobel, will raise treble clarity above bellsing.. Cannot say about bass

 

[dhruvmeena96]

Clarity shootout:

Spoiler: Clarity Graph 4x RAB vs Bellsing 6 vs Bellsing 6 + Zobel vs Knowles GV

Was the RAB zobelled or not

@eunice

Is this RAB32063

 

[eunice]

Yes, it was Zobeled.

 

[eunice]

Was the RAB zobelled or not

@eunice

Is this RAB32063

Oh man. The 4x series is actually RAF32873 with zobel. I am very sorry for working this sloppy. The 4x RAB is not yet finished.

 

[eunice]

Regarding the discussion about the polarity of caps.

In electrolytic there is a small oxide layer between the plates preventing the plates from shorting out. If you apply a voltage in reverse the oxide layer dissolves slowly until the cap shorts out. If you apply a voltage in the correct direction the oxide layer will be replenished. Due to that fact, they will probably last quite some time in an AC circuit, but I would not recommend doing it.

In tantalum caps it is a different mechanism, it turns into a crystal which is much more conductive. Tantalum caps are safe to be used with a reverse voltage up to about 10-15% of their forward voltage rating.

Just because it’s cool, let me quote NASA as a source about tantalum caps:

I. Bishop and J. Gill from AVX Corp. [3] believe that the reverse-bias failures are due to high density currents flowing through very small areas of microcracks or other defects in the dielectric layer. This results in creation of hot spots in the amorphous tantalum pentoxide and causes its conversion into the more conductive crystalline form. The crystallization can eventually cause a short circuit failure of the capacitor.

https://nepp.nasa.gov/DocUploads/E1231E3B-4D58-4788-B5F2E13DAE968AA0/Reverse_Bias_Behavior.pdf

Does anyone know what the maximum peak to peak voltage of a headphone amp is, when in use with a CIEM?

I have seen values of around 3.3Vpp on the internet, that means -1.15V to +1.15V. So if you use a 10V rated tantalum cap you do not need to worry about polarity.

 

[Kulgrinda]

1) Setup

Out: AudioQuest Dragonfly Black (USB DAC/AMP with 3.5mm out)
Driver: Knowles CI-22955
IN: MiniDSP UMIK-1 (Measurement microphone with USB)

2) Wiring

Ring of 3.5mm (R in the picture) to Terminal 2 POSITIVE on the CI.
Sleeve of 3.5mm (GND in the picture) to Terminal 1 NEGATIVE on the CI





3) I played a simple Kickdrum and recorded it back:



Since the attack phase is a little delayed, I matched the wave forms so the end is the same.

That way the polarity of recorded wave form looks identical to polarity of output waveform.

If these 3 assumptions are correct:

1) Swing up in .WAV file is converted to swing up in voltage on the 3.5mm output by the Dragonfly
2) Swing up in air pressure is converted to swing up in recorded WAV by the UMIK-1
3) Wiring of Dragonfly is correct

Then you should connect the + (center of mmcx) to the + of the driver and not the other way around.

But to be honest, I am not sure.
Audacity Project.zip

Interesting measurements, thanks! For the argument's sake - have you tried the same test with reversed polarity on CI?

 

[Kulgrinda]

Clarity shootout:

Spoiler: Clarity Graph 4x RAB vs Bellsing 6 vs Bellsing 6 + Zobel vs Knowles GV

So out of 4 setups 4xRAF would be brightest sounding, correct? People were saying Bellsing 6 was already too hot in some areas, so 4xRAF might be unlistenable at all... Clarity is good, but sibilance and harshness is a show stopper

 

[Ivan TT]

So out of 4 setups 4xRAF would be brightest sounding, correct? People were saying Bellsing 6 was already too hot in some areas, so 4xRAF might be unlistenable at all... Clarity is good, but sibilance and harshness is a show stopper

Not really, RAB/RAF don’t extend as far as BS6 does, even with horn and zobel.
Well, at least using same filters (ie green).
Actually, they are quite balanced, even U-shaped in x4 configuration, so don’t worry about it.

 

[Kulgrinda]

Not really, RAB/RAF don’t extend as far as BS6 does, even with horn and zobel.
Well, at least using same filters (ie green).
Actually, they are quite balanced, even U-shaped in x4 configuration, so don’t worry about it.

Thanks! My next build will be 2RAB+2RAF series/parallel with Zobel.

 

[Ivan TT]

Coincidentally that’s what I’m contemplating too, blending RAB and RAF together, but in 1+1 configuration (x4 for some reason does not extend as far on either side of the spectrum).

 

[dhruvmeena96]

Regarding the discussion about the polarity of caps.

In electrolytic there is a small oxide layer between the plates preventing the plates from shorting out. If you apply a voltage in reverse the oxide layer dissolves slowly until the cap shorts out. If you apply a voltage in the correct direction the oxide layer will be replenished. Due to that fact, they will probably last quite some time in an AC circuit, but I would not recommend doing it.

In tantalum caps it is a different mechanism, it turns into a crystal which is much more conductive. Tantalum caps are safe to be used with a reverse voltage up to about 10-15% of their forward voltage rating.

Just because it’s cool, let me quote NASA as a source about tantalum caps:




https://nepp.nasa.gov/DocUploads/E1231E3B-4D58-4788-B5F2E13DAE968AA0/Reverse_Bias_Behavior.pdf

Does anyone know what the maximum peak to peak voltage of a headphone amp is, when in use with a CIEM?

I have seen values of around 3.3Vpp on the internet, that means -1.15V to +1.15V. So if you use a 10V rated tantalum cap you do not need to worry about polarity.

Read 4.2 of the pdf you tagged in
Degredation

the behavior of reverse biased capacitors during the third stage of degradation is an
initiation of failures by the bias interruption. In several instances hard failures of the capacitors occurred in time
ranging from a few minutes to a few hours after the voltage was turned off and then reapplied. This effect can be
explained assuming that after the reverse bias is turned off the oxygen vacancies, VO
+, diffuse from the Ta/Ta2O5
interface into the oxide and then, after the bias is reapplied, redistribute back to the interface. Originally, oxygen
vacancies were generated more or less evenly along the Ta/Ta2O5 interface, however after voltage reapplication they
would mostly concentrate at sites with structural irregularities where the electrical field is larger. Similar
redistribution would result in higher than original concentration of the positively charged vacancies at the
irregularities thus increasing the electron emission to the level when destruction of the oxide and a hard failure of the
capacitor would occur.


Haven't you heard the Tantalum catching fire. thats why nobium oxide is there

So out of 4 setups 4xRAF would be brightest sounding, correct? People were saying Bellsing 6 was already too hot in some areas, so 4xRAF might be unlistenable at all... Clarity is good, but sibilance and harshness is a show stopper

Clarity is not about being bright but more about impulse of signal more or less clear.

i was working with 2xRAB

Parallel RAB32257 + 11ohm resistor + new zobel with 3.9mH inductance and 22ohms DCR as new standard for measuring and calculating
Flattest impedance, Flattest phase and way better than series parallel

 

[dhruvmeena96]

Coincidentally that’s what I’m contemplating too, blending RAB and RAF together, but in 1+1 configuration (x4 for some reason does not extend as far on either side of the spectrum).

You can do it
Just make sure which RAB you are using

 

[Bassiklee]

All this talk of the polarity of caps is kind of pointless. We're discussing audio signals here. By definition, they are AC. That means that no matter which way you orient the cap, signal is flowing "backwards" through it half the time. Please correct me if I'm wrong, with proof. I do like learning new things.

 

[dhruvmeena96]

All this talk of the polarity of caps is kind of pointless. We're discussing audio signals here. By definition, they are AC. That means that no matter which way you orient the cap, signal is flowing "backwards" through it half the time. Please correct me if I'm wrong, with proof. I do like learning new things.

Its not about signal but burning capacitor up

Tantalum's work, but burns up(it won't on small signal like iem, but degradation happens)