Specifications:
Polar pattern: hypercardioid
Frequency response: 50 to 17,000 Hz
Impedance: 6 kilohms
Equivalent noise level: 31 dB-A
Maximum SPL: 148 dB
Cable: 1,14 m (45 in.)
Finish: satin black
Net weight: 43g (1.5 oz)
Item number: CM-312A 6000H50160
CM-312 AE 6000H50170
Boundary Layer Microphones
How to adjust for best fit and to prevent boom bounce
Note: To get the maximum performance out of this microphone, take the time to adjust it to
fit correctly.
For best results, the CM-311A MUST be custom fitted to a single user’s head. This simple
procedure takes only a few minutes.
1. If the microphone is for yourself, we suggest that you use a mirror to double check the fit
as you make adjustments.
2. Loosen (just a little) the thumbscrew located on the outside of the foam block, part way
back on the boom. This allows the boom to slide in and out, and to rotate left and right.
3. Now bend the headband wire to fit your head. Put the foam-block wire behind your ear.
Then you can bend the earpieces to fi t snugly around your ears. The back of the
headband should fit firmly against the back of your neck.
4. Next, adjust the foam pad snug against your head or neck. To do this, bend the wire that
goes into the foam block. CAUTION! Do not bend the boom itself— just the foam-block
wire. A snug fit of the foam pad prevents boom bounce when you move around.
5. Be sure that the thumbscrew is still loosened a little. Move the boom in or out, and left or
right, to center the mic directly in front of your lips. The foam pop filter should press firmly
against the lips. This is necessary because the mic cancels sounds that are not close to it.
Also, it keeps the boom from bouncing. Tighten the thumbscrew and you’re done. Once
you’ve adjusted the headset, it should remain in that position -- no further adjustments are
needed. You can still swing the mic up or down, away from your lips, if you don’t want to be
heard on the P.A.
Architects’ and Engineers’ Specifications
The microphone shall be the Crown Model CM-312AE or equivalent.
The microphone shall be a head worn hypercardioid type of electret-condenser design. The
microphone shall exhibit excellent off-axis response and gain-before-feedback. The
microphone shall have an adjustable headband, adjustable boom with locking thumbscrew,
and foam pop filter.
The microphone shall have a 45-inch (1.14-m), permanently attached, two-conductor shielded
unterminated cable that can be connected to a transmitter. Powering shall be 3–9V from the
transmitter.
Nominal open-circuit sensitivity shall be 2.9 mV/Pa. Maximum SPL shall be 148 dB SPL for
3% THD. Equivalent noise shall be 31 dBA nominal. Frequency response shall be 50 Hz to
17,000 Hz with a uniform off-axis response, over 20 dB down at the rear nulls.
The Crown model CM-312AE is specified.
