Capsule Polarization for lollipop capsules?

[Ian]

Can somebody please explain to me how lollipop capsules such as the BLUE/RED and neumann CMV capsules are polarized. I can't seem to wrap my head around how the capsule's backplate gets voltage and the capsules output is sent on the single connector. Maybe I have a fundamental misunderstanding on how capsule polarization works??? I always thought that 60-80v is sent to the backplate and then the center wire on the capsule is the output, is this correct? I saw a thread a while back where a guy modded a CMV m7 capsule to do omni and cardiod, how would this work? Wouldn't omni require more voltage to be put on the back plate of the capsule than regular cardiod, or is the same voltage applied to the backplate and just the outputs of both the front and back of the capsule sent to the mic's amp? I would like to put an omni/cardiod switch on a lollipop capsule I have, but I would like to better understand how the polarization works before I try anything. Thanks so much!

 

[abbey road d enfer]

The polarization voltage is applied through a high value resistor (100Megs to Gigs) to the diaphragm, not to the backplate. This voltage is modulated by the capacitor's value changes. It is transmitted through a DC-blocking cap to the head amp. Very common arrangement (U47FET is just one example). In that case, the backplate is often at 0v, but you can imagine a dual capsule mic having the same voltage on the diaphragms, one body at 0v, and the other variable providing different directivities.

 

[ioaudio]

The polarization voltage is applied through a high value resistor (100Megs to Gigs) to the diaphragm, not to the backplate.

depends on the circuit.

 

[zapnspark]

This might help you visualize the polarizing methods:

Cheers

ZAP

 

[PRR]

> polarization voltage is applied ... to the diaphragm
> depends on the circuit.

Yes, every possible way has been tried.

In fact the condenser only knows the -difference-, does not care where you think the voltage is applied.

For one-diaphragm (omni), ZAP's 2-way picture is clear. There's only two parts (plate and diaphragm). Ignoring the 1gig (it is only there so you can snag audio), and polarity, they work the same.

The "ultimate" condenser is two diaphragms. Now you have three places to put wires. There are a lot of possibilities; elegance leads to basically the three main patterns (omni card bi-di) and maybe two half-way settings. With ample voltage available, and a couple caps and resistors, you can sweep voltage on one electrode and get all possible 2nd-order patterns (including omni as a degenerate 2nd-order pattern).

 

[Martin B. Kantola]

Great pic Zap!

Couple of thoughts. Think I would call the resulting patterns from a dual-diaphragm capsule first order, not second. And if you don't want your audio to pass through the battery or power source (in the first example fig. a), you'll want to bypass it with a capacitor.

Martin

 

[abbey road d enfer]

The polarization voltage is applied through a high value resistor (100Megs to Gigs) to the diaphragm, not to the backplate.

depends on the circuit.

The topic was specific about "BLUE/RED and neumann CMV capsules". All these are grounded-shell type.