Crown Audio by Harman

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PZM history

Ron Wickersham and Ed Long invented the Pressure Recording Process PRP), which uses a pressure-response omnidirectional microphone facing down toward, and very close to, a sound-reflecting surface. The goal was to:

1. Prevent phase interference between direct and reflected sounds, resulting in a flatter frequency response.
2. Provide identical frequency response for direct sound and random-incidence sound.
3. Cancel sounds above the audio range by phase interference, reducing the need for steep anti-aliasing filters in A/D converters used to record the mic output .
4. Protect the mic capsule (compared to a flush-mounted mic capsule aiming up).

Ken Wahrenbrock built the first commercially available PZM prototype using a hearing-aid type electret condenser microphone and a support structure.

At Syn Aud Con classes, Don Davis showed PZM prototypes built by Ken Wahrenbrock  and took orders for Ken.  You could buy just a pair of capsules, or a kit to make a pair of mics, or actual finished mics.  Don came up with the PZM name. 

In a Syn Aud Con mail list, Crown alumnus Don Eger had this to say about the history of PZM microphones:

"I went to Ken Wahrenbrock at an AES show and ask if Crown could manufacture the mics for him to sell.  Ken said he would get back to me.  By the end of the show Ken ask if Crown would take over the development, manufacturing, and sales of the PZM mics.  This was a surprise to me but Ken wanted more time to do experiments with different designs.

"Crown agreed to take on the challenge.  My boss asked who was going to take on this project and then looked at me and said, 'You have $X to engineer and put the mics into production.'  So I designed the first four models and put them into production.  We used a TDS system made of an oscillator and HP analyzer to measure the microphones.  The cantilever was make of 30% carbon fiber filled nylon, very new at the time.

"Thanks to Don Davis for his work in helping us get the contracts all worked out for the PZM.

"One other quick note, PRP is not just the microphone but is the entire system from the microphone to the speakers and room."

Others in this Category
document Do PZMs need boundaries to reject sound?
document Can I order your PZM 30D/6D with 1/4" connectors?
document What is the wiring for old PZMs (PZM-30GP, PZM-31S, PZM-6S)?
document Have you a schematic for a PX-T phantom power adapter for an older PZM microphone?
document How do I mount a PZM to a panel? Is a PZM waterproof?
document How do I wire a PZM-10LL to my mixer mic input?
document Which PZM should I choose for drums?
document I want to use a PZM-11 or PZM-11LL with a VCR. What do I need to make the mic work?
document How far can a PZM-11LL mic be from the area I want to record voices from?
document Should I use PZM-11 or PZM-11LL for voice recognition?
document Where to place a PZM-11LL to prevent picking up duct noise?
document Would wireless PZM-30D and PZM-185 mics work to record a conference?
document How can I mike a piano with a PZM without using tape?
document Where can I get information on discontinued PZM microphones?
document How far can I mike a conference with the PZM-10?
document Do you have a wall-mount PZM for voice recognition?
document Where should I place PZM-11LL mics for voice recognition?
document How do I connect a PZM-185 or Sound Grabber II to my camcorder?
document Will PZM-185 mics work for audience miking?
document PZM-11LL signal level too low?
document PZM-185 output level vs. Sound Grabber output level
document Choosing the right PZM for recording music
document PZM-185 output level vs. Sound Grabber II output level
document What are the advantages of boundary (surface-mounted) mics like PZM and PCC mics?
document Picking up birds at a nature center
document PZM mounting and waterproofing
document Can the PZM-11LLWR be changed from its line-level output to a mic-level output?
document Miking flute recitals with flat floor mics
document How to mike students and eliminate background noise?
document Sound Grabber II or PZM-185?
document Clandestine listening room