CM-1C Instrument Condenser microphone
CM-1C is a 19mm Pencil small diameter open cardioid condenser
for instrument applications-particularly acoustic
It features a vintage style transformer coupled class A head amplifier design.
- heavy mil spec nickel plated steel body for best durability and electromagnetic shielding
- Die cast alloy spider shock mount
- dent resistant 304 stainless steel extended grille
- individually selected low noise Linear Technology LS846 Field effect transistor and bias resistors
- P48 phantom powered
- pure silk damping screens
- nickel/gold sputtered diaphragm
- attenuation and low cut switches
- custom designed nickel core transformer
- individually tested capsule with printed frequency response chart
The goal was to create the warmth of earlier transformer coupled discrete solid state microphones without
the exagerated high frequency peak so common with modern units. An open cardioid pattern was selected
to give a more complete pickup of extended sound sources like acoustic guitar without emphasizing a particular spot.
An added benefit of the open cardioid pattern is reduced proximity effect.
The capsule is a true condenser, not an electret.
The diaphragm uses special 12mm 6 micron nickel/gold sputtered PET construction. This is typically smaller than a usual
small diaphragm condenser, and was selected to offer better polar patterns and less diffraction effects than larger units.
The backplate behind the diaphragm is precision lapped for the ultimate in accuracy. It is drilled with a specific number of
0.66 mm holes to provide proper squeeze film damping and communication to the rear port of the microphone.
the backplate is the phase shift chamber that provides a delay for rear
port entry sound. That delay is adjustable
with a shutter mechanism that variably exposes the silk and stainless mesh acoustic resistance element.
Each capsule is individually voiced at assembly on a special test rig.
Most condenser mic electronics these days are transformerless and based on the concertina FET phase splitter.
We chose a more vintage aproach...a single ended common source FET with bipolar output driver and transformer
Balancing. We didn't choose this just to be more vintage...it gives us more options to control the harmonic structure,
dynamic range, and frequency compensation. The custom output transformer also provides the extremely high
common mode impedance that results in superior balance and noise rejection.
We use selected ultra low noise Linear Systems N channel JFETS.
special feature is the attenuator switch for very high sound pressures.
The usual method is to simply put a capacitor
across the capsule, forming a divider. This works, but it causes the capsule to behave non linearly. Switching in the
capacitor often results in a pop or click.
Since our capsule is a true condenser (not electret) we chose to alter polarization voltage in a gradual manner when the
attenuator switch is actuated. This eliminates the distortion mechanism and pop sounds while increasing dynamic range
due to reduced diaphragm suckin.
We set the output lower than some condenser microphones, but more than enough for any good preamp.
Phantom power is weak, and we don't want to compromise performance just to put out huge output levels.
envisioned this microphone as something designed for recording stringed
instruments, particularly acoustic guitar, mandolin,
similar. I wanted a clear detailed sound, but without the high
frequency hype that so many mics have.
So I went for a fairly flat response without the usual 10kHz peaks. The low frequency response is tailored for micing at about
300mm distance. A low cut filter is supplied for closer distances without undue proximity effect.
The rather small diaphragm gives good off axis HF response....a guitar miced at 300 mm is a broad rather than point source.
Typical frequency response on axis (each unit is supplied with the individual measured response)
Output level: 4mV RMS balanced at 1 Pascal Free field (94dB SPL)
Maximum SPL: 140dB with attenuator
Self Noise: 25dB SPL A weighted
size: 19mm diameter x 182 mm length (without shock mount)
Single microphone $599
Stereo matched pair: $1400
Available with tighter restrictions on capsule and electronic components.
Although all units are already individually tightly controlled for performance this is suggested for XY and other dual
TO ORDER CALL US AT (706) 212-0242 0R EMAIL AT firstname.lastname@example.org