PZM Mic Mounting

Question

Hey all,

I have a real quick question regarding PZM mics:

I borrowed 2 Crown PZM mics (they are kind of older) to try out on a venue which has really really low ceilings (8 feet or so) and the crowd applause has never been liked in the mixes from this particular show.

I had the idea of getting PZM mics because I know how this type of acoustic space can rip a condenser stereo pair to shreds.

So, I got the mics and they have the type of fuzzy sticker stuff that is usually found on the bottom of heavy book stops or the insides of nice desk drawers so they shut nicely. I can tell this fuzzy stuff has been added by a user and did not come with the mic originally.

I thought PZM mics worked by placing them flat up against a surface? Wouldn't this fuzzy stuff interfere with it's pickup?

How would you mount PZM mics to a wall? Gaffer tape? Double-sided sticky tape?

Answer 1

Boy are you in luck! Check out this (warning, smallish pdf) document from Crown about boundary mic applications and placement. Also has a nice "how it works" explanation.

I'm not really sure of your application. For stage shows, I generally place them on the stage, at the edge where I'm sure nobody will step. For out in the room, I would take a board, mount the PZM to the board, and put it in a C-stand. Then you can move it around. If that's too ugly, you could probably tape it to the wall with lots of gaffer tape.

Good luck!

Answer 2

It depends. The PZM is generally mounted on a flat plate, or large, flat plane with the "nose" of the mic a minuscule distance away from the plate. That creates the "pressure zone" from which the PZM gets is name, and is necessary for the mic to function properly.

So, if your mic is using the metal plate that Crown supplies with its PZMs, and the fuzzies are on the other side of the plate, then you are in business.

However, Crown also sells just the "business" end of the PZM, the mic itself without a plate, for mounting onto the wall, floor, tabletop, etc. If this is the mic you have, the distance between the "nose" of the mic and the mount surface is crucial, and will have an effect on your HF response. See the pdf that VCProd linked to, if you want to see the relationship between the boundary-to-mic distance and the HF response.

As for mount techniques, I use PZMs with the Crown supplied plate, and mount them with gaff tape.

Answer 3

I actually only used PZMs once so I may be wrong =)

I don't think that the 3-5mm caused by the stickers actually do affect the way PZMs work, since the frequencies that have a wavelenght of 3mm would be around 114kHz (is this correct?!).

My docent back at the SAE used to mount the PZMs on a micstand close to the walls. Don't know if there is a better way, but since he used to construct his own PZMs I kinda trust him.