Hi there,
first of all I'd like to tell you how much I like your homepage. It's a very useful source of information. John was so kind to inform me about the fact that there are about 50 words in English with a similar meaning than GREAT. So, great job Russ.
I've seen Altec 150s taped to the floor on the Don Caballero recording pictures in the Kentucky room as well as on the pictures of studio B's liveroom. In both cases the mics were facing the drum kit. I've seen people using stapes and earthworks mics in the same application. I understand that taping mics to the floor minimizes unwanted combfiltering effects.
All these mics mentioned above have typically an omnidirectional pick up pattern. Is there a reason why people use omnis for floormics? Do they behave more like PZMs when taped to the floor than directional mics or do they just capture more of the room ambience? Are the arranged in a decca tree setup with a stereo mic as center mic ?
How would cardioid mics behave in this application. I was thinking about trying directional mics as drum floor room mics just because I also record the rest of the band in the same room and I want to avoid to have guitars and bass on the drum room mics.
Is there a reason why generally speaking omnis are a better choice in this application than cardioid mics?
Thanks, max.
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Somebody please answer this. I'm curious about it too.

By definition, a PZM (Pressure Zone Microphone), or Boundary mic, is an omnidirectional capsule against a boundary (floor, wall, metal plate that is built into a Realistic or Crown PZM).

A cardioid against a boundary would not be a PZM. I'm not sure what the pattern would look like. Try it out and let us know what it sounds like.

Typically, people at Electrical tend to only use 2 on the floor in a triangle with the bass drum.

best,
Bob

I've used cardioid mics like this (with them facing the drum kit) a lot. It catches more of the kit than the room, but the blend is nice. If I'm in a bright sounding room and the hi-hat is out of control this can help. I think it's because the low frequency reception at the rear of the mic filters out the "ssss" and keeps the whoamp of the kick and tom reverb.
Faced away from the kit, there is less direct drum kit and more reverb (Obviously). Depending on where it is in the room, it can be brighter (center of the room), or bassier (facing a corner).
Maybe we should set up a kit and record the differences in a controlled way so you can hear from the website.

max wrote:Hi there,
I've seen Altec 150s taped to the floor on the Don Caballero recording pictures in the Kentucky room as well as on the pictures of studio B's liveroom. In both cases the mics were facing the drum kit. I've seen people using stapes and earthworks mics in the same application. I understand that taping mics to the floor minimizes unwanted combfiltering effects.
All these mics mentioned above have typically an omnidirectional pick up pattern. Is there a reason why people use omnis for floormics? Do they behave more like PZMs when taped to the floor than directional mics or do they just capture more of the room ambience? Are the arranged in a decca tree setup with a stereo mic as center mic ?
How would cardioid mics behave in this application. I was thinking about trying directional mics as drum floor room mics just because I also record the rest of the band in the same room and I want to avoid to have guitars and bass on the drum room mics.
Is there a reason why generally speaking omnis are a better choice in this application than cardioid mics?
Thanks, max.
[/b][/i]

Hey:

An omni microphone on a boundary (the floor) has a hemispherical pickup pattern, with minimal change in sound quality across this hemisphere. A cardioid mic typically has lumps in its frequency response as the signal moves off-axis. In some cases, there is also a pronounced lobing of the sensitivity that varies with frequency. Also, given that the idea of the room mic is to pick-up the diffused room ambience, the less directional, the better.

Unless you figure out a magic sound-stopping raygun, it is unlikely that you will be able to isolate different elements of the room tone (different instruments, for example) once the room has been excited by more than one sound source, other than by using proximity to accentuate one thing or the other.

The boundary effect is exploited by the PZM microphone in a special way: The microphone element is very tiny, and placed in a small air gap above a plate. Since this air passage is so small, it is operating in a pure pressure mode, with flat phase response up to a very high frequency. This concept was presented at Syn-Aud Con in the 1970s, first manufactured by Ken Wahrenbrock and explained here: http://www.pe.net/~tmaki/pzms.htm among other places.

While all PZM microphones are by definition boundary mics, not all boundary mics are PZM mics. In the examples you give, there is no second boundary to create a gap. Well, there is, but it's the roof of the building, and that isn't really the same thing.

Crown (Amcron in Europe), makers of the PZM, made a directional boundary mic using a cardioid capsule on a mounting plate. It was called the PCC (an acronym for Phase Coherent Cardioid) mic. We own one here at Electrical, but it hasn't made its way to the mic page of the website yet, and from my experience, it's nothing to fight your grandmother over.

In the 1980s, there was a minor engineering fad to use cardioid mics as ambient mics, facing the reflective surface opposite the sound of interest (rear of pattern facing the sound source). Not being a big Robert Palmer fan, I never pursued this approach.

The ambient mics in the photos you see are in A/B stereo, which has a poor stereo image from a localization standpoint (too wide to have good phantom center image), but bearing in mind that these mics are usually used to supplement the close mics, it's an appropriate choice. I often use an M-S pair as ambient mics, and even in this case, I will often have the stereo image wide enough to create a "hole" in the center for the same purpose.

good luck,
-steve albini

I've noticed low end boost when putting directional mics on the floor. It can also be viewed as a useful high cut. Personally, I get a lot of bands where the drummer has HUGE, LOUD cymbals and more normal volume drums. When that's the case I put ambient mics low just to avoid brash, abnormally loud cybmals. Many times I'll just leave out overheads in that case.

My recent standard ambient mic choices have been a Beyer M130 and M160 in M/S at waist level or lower. Every time I record drums I try to throw one mic somewhere new or interesting just to see what it sounds like. Many times they get taped over for an extra track, but sometimes they work. Last time I did this I used a 4050 on omni laying behind some amps pushed up against a wall.

Cheers,
Ben Adrian

while i find putting the mics on the floor is a good "safe" room sound bet and one i do use very often. ive found depending on the rooms particular charater and high end brand of splatter, facing "more" directional microphones at the wall can be a good way to get a more vague distant drum sound without contending with cymbals. this only in contrast to putting super far away ambient mics on the floor. however every situation and drummer is different. and usually prefer my room sound to have more locational type qualities to it.

Hey, Ben,

Try your 4050 set to omni inside a large, padded hard-shell snare drum case next to the front of the bass drum. (Keep it on the shockmount so it "floats" near the bottom of the case.) You may have to flip the polarity to get it really happening, but check it out for some extra thump.

Chris Garges
Charlotte, NC

The only genuine pro engineer I know put mics on the floor when he was doing an SSL demo for some Japanese, because they kept stalling him so that they could write down his eq settings. When he set up the mics, they were all out there measuring and poking, wondering how he got such a great drum sound...even though those mics were not routed anywhere.

Nice history of PZM's Steve, not many people know about it.
I did a project in a small studio that was set up in an old church in about '81 and they had some "original" PZM's made by a Syn-Aud-Con member. Great stuff for recording in church's, slapped them everywhere we could think of.
But what I haven't seen manufactured since was the pair of handheld PZM's. A body not unlike a 58 but with the head sawed off flat and a smaller version of the capsule mounting device. Stick that in next to the snare, talk about bright. The other obvious choice would be for horns.