Polarisation voltage quiz!

Here's a little quiz!

Capsule - diaphragm connected to the FET input. We are considering cardioid only setup with disconnected back diaphragm.
Backplate polarisation set to -84V
Diaphragm polarisation set to 10V

What voltage see diaphragm and what see backplate?

Voltage is usually measured between two points, so that's a bit of a trick-question

Do you mean, what are the diaphragm / backplate voltages with respect to ground? Or what's the voltage across the capsule?

If it's the latter, it's obviously 94v.

I don't know

Am legally drugged and this thing blow my mind today

What's the prize?

micaddict said:

What's the prize?

Click to expand...

My happiness without use of Tizanidinum and Diclofenac

It still confuse me as always polarisation voltage applying

When diaphragm is grounded and backplate polarised for 60V, then diaphragm is polarised -60V referred to the backplate.

How it looks here?

If backplate is -84V and front diaphragm 10V,  do the diaphragm is polarised 74V referred to the backplate?
It wouldn't be more safe to reverse connection?
Diaphragm -84V and backplate 10V?

ln76d said:

If backplate is -84V and front diaphragm 10V,  do the diaphragm is polarised 74V referred to the backplate?
It wouldn't be more safe to reverse connection?
Diaphragm -84V and backplate 10V?

Click to expand...

Would you care to explain how your math works, on that?

No matter how i look at it, if one end of a capacitor is at -84v and the other end is at +10v, the difference between the two ends will always be (+10v) - (-84v) = 10v + 84v = 94v.

If the diaphragm was biased at -10v, then the 74v difference would be correct; otherwise, no way

My math doesn't work at all here, it's guessing
It's total abstraction for me

Thanks!

So the diaphragm see 94V?

The diaphragm itself "sees" whatever voltage you apply to it. Since the capsule is a capacitor, after all, the more important part is the voltage that is across it (ie. the voltage difference between the backplate & diaphragm)... isn't it?

A schematic would be helpful, but yes, the total potential voltage between the two nodes (as I think you've described it) would be 94V.  Provided the capsule could withstand that polarization voltage, it wouldn't matter if the two potentials were reversed, the capsule wouldn't care. 

Some advocate that the front diaphragm (e.g. the one that faces the source of audio) be at the lowest potential.  This is because particles in the air tend to be negatively charged, so having the front at the lowest voltage would tend to repel contamination.

But electrically it doesn't matter.

I wish to have schematic for it...
Anyway you understand it correct.
Whole thing is just because i get that microphone with disconnected capsule.
With reversed polarisation it stress diaphragm a little that's why i wired as described.
Then i had to reverse polarity of output wires so it looks like in original higher potential was on the diaphragm.

If it's a cardioid-only capsule, the only thing that changes, one way or the other, is the phase of the output signal
Plus there's that dust-attraction thing, but that's not totally on the audio level

In fact, the pin2/3 swap is an integral part of Zapnspark's ChinaMicMod ;D (together with applying bias to the backplate instead of the diaphragm)

In Zapnspark mod polarisation is applied to the diaphragm

Any swap of polarisation will change phase. So it's not a mod to swap wires but a must

Hmm... My memory seems to be kinda "selective" - i DID remember the backplate was grounded in the stock circuit, but i guess i mixed up the node where the signal's taken from...

On the other hand, if one applies the bias to the backplate and directly-couples the diaphragm to the impedance converter, that should have the same net effect, right? Without the need for XLR wire-swapping...

I might be on the brink of confusing myself ;D

Don't remember
I always swap phase when i hear that is need

Hear? As in, compared to an unmodded mic, side by side?

No, when hear when phase is reversed.

You're... you're not seriously claiming you can hear absolute phase, are you? :|

I don't know how people can't hear phase swap...
Give me bunch of microphones and preamp with phase switch and i will tell you which one is reversed!
But!
There might be a catch in my tests
During next testing of microphones i will use some typical monitor like NS10 for example and check is that still possible

Ha!

Found on wikipedia
Yay, i'm not insane

The ear is sensitive to the periodicity of a waveform at low frequencies; tests have shown that absolute phase can sometimes be heard by test subjects listening under monaural conditions (a single loudspeaker, or headphones sending the same signal to both ears.) Audio engineer Douglas Self concludes "there is a prima facie case for the audibility of absolute phase", especially for high impulse sounds such as percussion.

A ltitle update.

Maybe i'm sick...
Saturday am going examine hearing.
Maybe i have damaged cochlea in the ear ...

I did test on NS10 and yes i still hear huge difference.
My girlfriend said that she only hear something "like a little change of level".
I did test using vriable HPF build in my preamp and i hear difference in whole possible spectrum, not only at low frequencies.
Since in theory i shouldn't hear that, there's a chance that something is wrong with my hear.
I have very sensitive hearing...