Microphone setup for 4-channel live recording

[lo.fi.love]

Hello,

I'm contemplating my microphone configuration for recording live shows on-site. I've done live recordings with some success but I want to really refine my setup and assemble something that's versatile and affordable. I record to a Tascam 34b four-track open reel machine, so I'm limited to four mics (I don't want to mix on the spot).

At the last show that I recorded, I used two Marshall MXL-604s in a XY pair near the front of the house. I used two Naiant XS miniature omni condensers as well, for room mics and to get a little extra cymbal splash. The Naiants would have been OK if I had put more thought into mic placement. Lesson learned.

My issue is that I'm lacking some serious low-end, and I'm trying to figure out how I'm going to solve this problem. I'm curious to see what you folks think about this, and your recommendations/advice will certainly be helpful.

For the XY overheads, I want to upgrade to a pair of AKG c1000s mics. That's item #1.

Item #2 is that I want to use only one omni, placed well to pick up the house/audience.

Item #3 is that I'm considering using a Crown PZM microphone to help capture more of the low-end that I'm currently lacking. Where I'm going to place it, and where it might go in the mix, are two things that I'm unclear on. I also don't fully understand how best to use a PZM mic.

The shows that I record are usually in warehouse spaces. Concrete floors, and either brick or drywall for the walls. The bands set up on the floor - no stage. Where I'd set up the PZM mic is the big thing. Behind the drums? Between the bass cab and the drums? On concrete? On a sheet of plexiglass somewhere?

And if anybody wants to take a crack at this - where would I mix the PZM, when I'm mixing this at home? I could figure it out myself, but maybe someone has a suggestion based in their experience.

So, yes. The questions are:
1. Is a PZM mic a good choice for this application?
2. Does anyone have suggestions on where to place the PZM mic?
3. Any other considerations?
4. Is there anything that I'm overlooking, or assuming (and shouldn't)?

Thank you!
Jeff

 

[mshilarious]

Item #3 is that I'm considering using a Crown PZM microphone to help capture more of the low-end that I'm currently lacking. Where I'm going to place it, and where it might go in the mix, are two things that I'm unclear on. I also don't fully understand how best to use a PZM mic.

If you want more low-end out of a PZM, you need to put it on a larger surface. Like a wall, for example.

 

[lo.fi.love]

If you want more low-end out of a PZM, you need to put it on a larger surface. Like a wall, for example.

Here's where I'm unclear on exactly how PZM microphones work. Does the surface need to reverberate at all in order for the mic to pick up a good signal? For example, the friend who told me about PZM microphones said that he sometimes uses them on a piano.

Would a brick wall be a suitable surface?

Hmm, looks like I need to read up on this.

 

[lo.fi.love]

I just read something about the Shure Beta 91. Any tips on whether this would be good for capturing bass frequencies from the kick, bass cabs and guitar cabs?

Sorry for the string of questions, but as you can see I'm not clear on what I need to achieve the results that I want.

 

[Treeline]

A pzm mic uses the surface upon which it is placed as the actual "microphone". PZM stands for "pressure zone mic." These work well as conference mics because they are placed on a large table; any voice waves that hit the table will affect the table as a whole and a signal is picked up by the mic. So - a brick wall will work with the mic's design; a wooden wall will work better, and a down jacket around the mic will not work well at all.

The mic element is placed a little bit above the pad on which it is mounted. The pad allows for a stable mount and forms a pressure zone between the pad and the mic element. The mic is sensitive to minute changes in this pressure zone and creates a signal. Because the element is directed at the plate and responds to the change in the pressure zone, the mic is not as sensitive to reflected sound waves and the interference they can create. No phasing issues and so forth.

To make good use of these you will need a moderately hard reflective surface. I use a piece of 3/4" plywood shelving about two feet long and 18" wide. Place the mic in the center and rest the shelf on a coat or other soft surface a little off the floor. You should pick up quite a lot of low end.

If you have the mic too close to (or inside) the kick drum, it will overload. I'd set it near the band and see what you get.

I've used a pair of AKGs rebranded as conference mics in lots of situations - theater, children's opera and so forth. I've taped them right to the stage floor to catch lines as a character moves across the stage. Pretty cool design. Don't overload them and they should be useful for this application.

 

[Innovations]

A PZM microphone needs to be placed on a solid surface heavy enough to reflect sound.

Sound can be thought of in two ways, either has waves of high and low pressure or as air molecules vibrating back and forth. When viewed as pressure waves increased volume is higher pressure. When viewed as vibrating air it is measured by faster speed of the air molecules.

Ribbon microphones are often called velocity microphones because that is what they measure. It is also why they are figure 8 in pattern because they are measuring the velocity of the air along a particular axis.

Diaphram microphones are called pressure gradient microphones because they measure the pressure changes on their heads.

Now, when a sound wave hits a solid unyeilding surface the air right at that surface has no velocity in the direction perpindicular to the surface. It can't go through the barrier and it can't move the barrier any significant distance so all the velocity energy must be converted to pressure before bouncing away in the other direction. That is the reason for the term 'pressure zone'