Zen of Recording

PZM Microphones, Revisited

by Sven-Erik SeaholmDecember 2013

We had a yard sale here several weeks ago. While trolling through the troves of junk in search of potential money—making contenders, I happened up on a couple of CDs from 2000, Via Satellite’s Wake Up Heavy and Muggles Meshugana Lounge’s self-titled debut.

I took a close listen back through both of those albums and at the risk of sounding too self-satisfied, I was actually… impressed. It was impossible not to notice the amount of ideas packed into the dense arrangements, where every four measures seemed to bring a new surprise. At first, this was due more to the suggestions of my clients than me, but I definitely got into the spirit of things quickly!
In the case of Via Satellite, this was four young men trying to present a definitive artistic statement. They would’ve thrown all of my furniture into those tracks if they thought it would enhance their collective vision! I can clearly remember all of them running around with guitars and mallets, shouting for an open track! It was crazy, fun, maddening, and a lot of hard work in a very short amount of time. I was so proud of them for practically willing that album into being.

Conversely, Muggles Meshugana Lounge was born from chaos and loss, but similarly overcame great obstacles through sheer perseverance. Originally slated to be a duo project, one partner (the singer) quit the day before the first session. Saxophonist, vocalist, and arranger Ed Croft came to me with the news immediately. Between the two of us, we knew some folks we could call to help out: Ken Dow and Mike Sandalwood on bass, Kevin Dow and Josh Siebelman on drums, with Chuck Prada and “OG” Oguere on percussion. The result sounds like a hazy, crazy cross between the Buena Vista Social Club, the Flintstones, and Cheech and Chong. The musicians are superb, Eddie’s muggles character made the songs whimsical and due to the mostly live tracking, there’s an innate sense of fun that permeates the entire listen…

The most notable sonic characteristic that both of these recordings share is the distinctive tone of the drums and percussion — open, roomy, and crystal clear, with extremely wide imaging. The sound is not colored or hyped at all, very smooth down into some very tightly controlled lows.

They were recorded with a pair of Realistic PZM Microphones that at the time could still be purchased for about a hundred bucks apiece at Radio Shack. These discontinued beauties were manufactured by Crown International, a trusted name in power amps, among other things. They can still be found on eBay at a considerable discount.

The PZM stands for Pressure Zone Microphone (also known as a boundary mic), and the way it differs from conventional dynamic and condenser mics is in fact the key to it’s usefulness. The PZM is a one piece construction of two basic components: the electret element and the boundary plate.

The electret capsule is about the size of your pinky and extends halfway across the face of the plate, leaving a slight gap near where it ends. When sound hits the plate, a “pressure zone” is created in this space and the electret detects the changes in pressure rather than moving sound waves. Because of the nature of this process, out-of-phase signals actually arrive coherently in phase and reinforce each other, thus solving potential phase-cancellation issues.

The boundary plate is approximately the size of a CD and it effectively “gathers” the sound info and bounces over it to the electret capsule. That little 5″ square plate, however, can only grab a limited-sized sound wave, leaving your lower frequencies less than adequately represented.

What you need is a bigger boundary. Simply slap your PZM on to any flat surface and voila! — instant mic modification. The possibilities are truly endless. You can hang these little bastards on walls, ceilings, and piano lids. You can lay them on the floor or in a bathtub. Or you can do what I did and get the most consistent performance from them by mounting them to an easel-like contraption I like to call Svenny’s Big Squares of Love, which are essentially a piece of 3/8″ particle board 4’ x 4’ with a PZM screwed to the center. On the back is a 3½’ piece of 1″ x 2″ attached by a hinge at the top. This will give you a very usable 47Hz — 18K frequency response and SPLs up to 135 dB!

For Via Satellite’s drums, I set them up behind the drummer in a wide “V” approximately 120 degrees apart. These were the overall stereo pair I relied on for toms and cymbals, augmenting this setup by adding a Sure SM57 on the snare and an AKG D112 on the bass drum. We also experimented when close-miking amps with the SM57 by using the PZM to pick up room tone, again with great results.

For Muggles Meshugana Lounge, the PZMs were actually set up in front of the drums A-frame style, with a percussionist on each side!

At a certain point, I felt I needed to avoid developing a too-predictable sonic fingerprint and I turned to other miking options. Listening back to these CDs made me go out to the garage and dust off those Big Squares of Love holding my PZMs. I look forward to using them again soon!

If you’d also like to explore this alternate universe of sound, just Google “PZM microphones” for a plethora of options, priced from $30-$350 each. I recommend the Crown Sound Grabber II, which you can find for about $120 each.

Sometimes a little stroll down memory lane can reignite those old fires, ya know?

Sven-Erik Seaholm is an independent record producer, singer, and songwriter (www.kaspro.com). Via Satellite’s Wake Up Heavy won a San Diego Music Award for Best Local Recording.

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