Can I use regular omni as boundary/PZM mic?
Can I use regular omni as boundary/PZM mic?
I've always loved playing with odd approaches to micing and have often thought about picking up a Crown or some-such PZM and playing around with it. Before I buy one though, I'd like to try one out...towards that end will I get the same or similar effect if I just tape a small diaphram omni to the wall? I built a couple of the Tape-Op omnis a while back and I could use one of those. I will experiment regardless as I'm now curious, but I would be interested in knowing the difference.
Thanks
Thanks
- googacky
- pushin' record
- Posts: 295
- Joined: Wed May 07, 2003 2:39 am
- Location: St. Louis, MO
- Contact:
read this thread from the Electrical Audio forum. It'll enlighten you.
-
- ghost haunting audio students
- Posts: 3307
- Joined: Wed May 07, 2003 2:11 pm
- Location: I have arrived... but where the hell am I?
If I recall correctly, for it to be an actual "pressure zone microphone" the capsule should be facing towards the boundary (that is, looking down at the floor) and be placed within some critical distance which I believe is no more than something like 0.3 inches from the surface (which would make sense as 1/2 of a 20kHz wavelength). It then creates the very special circumstance and behavior of a PZM. Of course, if you try it out, you'll find that it can be pretty effective if the mic is facing the other direction (Audio technica makes some ceiling tile & in-table microphones for tele-conference use) or facing sideways. The distance to the surface is still important for minimizing phase distortions below 20kHz (20kHz has a wavelength of 0.678 inches) but the sideways capsules allow for different patterns in boundary mics. Crown makes a half-cardioid and half-hypercard. boundary mic, and MBHO makes the really cool 648-PZ which is a changable capsule boundary that accepts all their standard capsules (I have a pair, they're cool).
So if you have something like a pair of nice omnis, try pointing them at the floor from a distance less than 0.3 inches, and then try taping them to the floor sideways, and see what you like. I do recommend putting some kind of tiny barrier at the floor whether a thin piece of cloth or even just a layer or two of gaff tape to cushion the mic a little - it will prevent any dirt particles from vibrating against the mic body, and keep you from scratching up your nice mics.
-Jeremy
So if you have something like a pair of nice omnis, try pointing them at the floor from a distance less than 0.3 inches, and then try taping them to the floor sideways, and see what you like. I do recommend putting some kind of tiny barrier at the floor whether a thin piece of cloth or even just a layer or two of gaff tape to cushion the mic a little - it will prevent any dirt particles from vibrating against the mic body, and keep you from scratching up your nice mics.
-Jeremy
-
- zen recordist
- Posts: 8876
- Joined: Mon May 19, 2003 12:10 pm
- Location: NYC/Brooklyn
- Contact:
Mic the reflection, not the source....
That is the fun thing about the technique. It "sounds closer to the mic" because the mic is recording the reflection from the boundary. You can rotate the mics to phase grate across the spectrum with various levels of success. Have a crashy drummer? rotate the mic until you get a little 5k notch. Too much boxy kick in the room mics? Rotate until you get a nice little drop at 220 (ish).
Phase relationships take the place of EQ. Even the relationship of the capsule to the wall, or floor, or whatever... other mics obviously....
That is the fun thing about the technique. It "sounds closer to the mic" because the mic is recording the reflection from the boundary. You can rotate the mics to phase grate across the spectrum with various levels of success. Have a crashy drummer? rotate the mic until you get a little 5k notch. Too much boxy kick in the room mics? Rotate until you get a nice little drop at 220 (ish).
Phase relationships take the place of EQ. Even the relationship of the capsule to the wall, or floor, or whatever... other mics obviously....
-
- zen recordist
- Posts: 7484
- Joined: Tue Jun 01, 2004 10:30 pm
- Location: Bloomington IL
- Contact:
Isn't most EQ just screwing with phase electronicly? If so, moving the mic for does make a lot of sense in theory. We already know it works in practice.joel hamilton wrote:Mic the reflection, not the source....
That is the fun thing about the technique. It "sounds closer to the mic" because the mic is recording the reflection from the boundary. You can rotate the mics to phase grate across the spectrum with various levels of success. Have a crashy drummer? rotate the mic until you get a little 5k notch. Too much boxy kick in the room mics? Rotate until you get a nice little drop at 220 (ish).
Phase relationships take the place of EQ. Even the relationship of the capsule to the wall, or floor, or whatever... other mics obviously....
Thanks for all the feedback...sounds like in many ways I may be better off with a regular omni (or card?) than spending a bunch on a mic that can only be used as a boundary...
Joel...when you say "rotate the mics", are you referring to changing the angle of the mics to the boundary?joel hamilton wrote:Mic the reflection, not the source....
You can rotate the mics to phase grate across the spectrum with various levels of success.
-
- zen recordist
- Posts: 8876
- Joined: Mon May 19, 2003 12:10 pm
- Location: NYC/Brooklyn
- Contact:
Yes.logey wrote:Thanks for all the feedback...sounds like in many ways I may be better off with a regular omni (or card?) than spending a bunch on a mic that can only be used as a boundary...
Joel...when you say "rotate the mics", are you referring to changing the angle of the mics to the boundary?joel hamilton wrote:Mic the reflection, not the source....
You can rotate the mics to phase grate across the spectrum with various levels of success.
You wind up hearing the phase grating, like a notch filter sweeping across the sound as you hit certain perfect cancelling distances.... The phase between the boundary and capsule.... and reflection off the mic body... etc...
Try it, it will be obvious.
- Bill @ Irie Lab
- suffering 'studio suck'
- Posts: 401
- Joined: Wed Dec 03, 2003 10:53 am
- Location: Boston, USA
- Contact:
Not a PZM but a quick "field expediency" boundary microphone using a spare front-address omni.
Cut a hole in a large (3'X3' or 4'X4') sheet of thick packing foam the diameter of the mic body. Back the mic through the foam until the capsule is flush with the plane of the sheet. Secure the rear with more foam and rubber bands.
Presto! a large format hemispherical response boundary mic. Tape the gizmo to a couple of mic stands or lean against a chair facing kit, amp, or ensemble.
If you like the outcome make a more permenent rig using sheet rock and more durable stand and mic mounting hardware.
Good clean fun!
Cut a hole in a large (3'X3' or 4'X4') sheet of thick packing foam the diameter of the mic body. Back the mic through the foam until the capsule is flush with the plane of the sheet. Secure the rear with more foam and rubber bands.
Presto! a large format hemispherical response boundary mic. Tape the gizmo to a couple of mic stands or lean against a chair facing kit, amp, or ensemble.
If you like the outcome make a more permenent rig using sheet rock and more durable stand and mic mounting hardware.
Good clean fun!
I&TC - Intonation and Technology Company
Irie Lab Sound Studios
***** Sound Science & Soul *****
Irie Lab Sound Studios
***** Sound Science & Soul *****
Who is online
Users browsing this forum: No registered users and 69 guests