How important is diaphragm material in how a microphone capsule sounds?

[Icantthinkofaname]

I know stuff like backplate construction and spacing contributes the sound of a capsule, but what about diaphragm material? Like how different would a capsule sound if you switched from gold sputtering to titanium, aluminium, nickel, or graphite?

 

[Khron]

All other things being equal, i would say not at all.

The actual real-life variable would be the sputtering thickness (and thus the mass of the diaphragm plus the "electrode"), which could be offset by a different tensioning to end up with the same resonant frequency.

I myself am somewhat skeptical about "transient response" differences being perceptible by ear (or even measurable) given such a microscopic diaphragm weight etc.

And i'm quite sure capacitors (which condenser capsules are) don't at all care what material their electrodes are made of, in these sub-nanoamp(?) current ranges. That may(?) only come into play influencing ESR in the mA-and-up ranges (but i'm just speculating).

 

[rogs]

I think what voltage is applied to the capsule to bias it will probably be more significant?
I have taken a cheap Chinese LDC capsule and applied c.60 volts DC to it.
Taking the same capsule, and applying 3 or 4 volts of RF AC volts at 8MHz instead, and it seems to 'sound' different...
(Although I'll be the first to say that observation is subjective, and I can't actually measure any differences, with my limited test kit).
I think capsule material - all other things like resonance, tension and backplate patterns being equal - is probably a bit down the list of significant factors in determining how the capsule 'sounds' ?.....

 

[Icantthinkofaname]

All other things being equal, i would say not at all.

The actual real-life variable would be the sputtering thickness (and thus the mass of the diaphragm plus the "electrode"), which could be offset by a different tensioning to end up with the same resonant frequency.

I myself am somewhat skeptical about "transient response" differences being perceptible by ear (or even measurable) given such a microscopic diaphragm weight etc.

And i'm quite sure capacitors (which condenser capsules are) don't at all care what material their electrodes are made of, in these sub-nanoamp(?) current ranges. That may(?) only come into play influencing ESR in the mA-and-up ranges (but i'm just speculating).

I think what voltage is applied to the capsule to bias it will probably be more significant?
I have taken a cheap Chinese LDC capsule and applied c.60 volts DC to it.
Taking the same capsule, and applying 3 or 4 volts of RF AC volts at 8MHz instead, and it seems to 'sound' different...
(Although I'll be the first to say that observation is subjective, and I can't actually measure any differences, with my limited test kit).
I think capsule material - all other things like resonance, tension and backplate patterns being equal - is probably a bit down the list of significant factors in determining how the capsule 'sounds' ?.....

So let's say somebody reskins a vintage SDC capsule like a Schoeps CMT541 (assuming that's doable, I don't know what the physical construction is like), because the nickel capsule wasn't working. With the right tension it should be mostly the same sound? I'm planning on buying those or anything (because I see them being listed for like $900 each), but was curious about vintage capsules like those being repaired.

 

[mad.ax]

CMT541 is a mylar capsule.
SCHOEPS CLASSICS: The CMT Series - reliable until today

 

[Icantthinkofaname]

CMT541 is a mylar capsule.
SCHOEPS CLASSICS: The CMT Series - reliable until today

Ah, that's good to know. I think I misread the Schoeps website and mistook it as saying they were the last to use nickel capsules.

 

[chrisheule]

I use mylar/aluminum for my capsules. it's a matter of taste. but, the material definitely affects the sound.

heulemik.ch

 

[k brown]

Do you mean aluminum-sputtered (aluminized) Mylar?

 

[gyraf]

The diaphragm base material probably influences function in several ways, e.g. 1) stiffness vs tension 2) weight 3) plasticity 4)humidity absorption

In general, good quality PET-film (high-density polyethylene) is considered a really good compromise. Capacitor film is the high grade.

For the metal making up the conductive layer, you want it to be relatively conductive and non-corroding. Note that aluminum is only non-corroding when applied in a relatively thick layer (it auto-corrosion-protects by very quickly corroding outer layer into non-conducting oxide). In reality you actually need very little conduction, at least for DC-biased capsules - I've had pet-film with a little handsoap coating working just fine, though I don't know about its long-term properties

Back when materials were unavailable for us mortals, I'd cut open and unroll polyester capacitors for membrane material. Marked working voltage directly reflect base material thickness

/Jakob E.

 

[living sounds]

I was on the phone recently with Peter Drefahl regarding reskinning an M7 capsule. He told me that there were no measureable difference between PVC and mylar if set up correctly...

 

[gyraf]

yes and no.. in ten years they will probably be very different

 

[living sounds]

yes and no.. in ten years they will probably be very different

Yes, that was his reason for no longer using PVC (+ the much more difficult setup).