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Description
The AT933Rx/ML is a wide-range miniature
condenser microphone with a MicroLine
polar
pattern. It is designed for quality sound reinforce-
ment, professional recording, television, and
other demanding sound pickup applications. The
AT933Rx/ML is furnished with a vinyl-coated steel
hanger adapter that allows it to be adjusted for
correct positioning.
The microphone features a 50' (15.2 m)
permanently-attached miniature cable. Its free
end connects to the provided AT8533x power
module via internal solderless screw terminals
for simple cable-length adjustment in the field.
It can be powered from any external 9V to 52V DC
phantom power supply. A recessed switch in the
power module permits choice of flat response or
low-frequency roll-off to help control undesired
ambient noise.
Four additional interchangeable elements
are available to permit selection of angle of
acceptance from 90° to 360°.
The microphone is enclosed in a rugged
housing with a low-reflectance black finish. It is
also available in white as the AT933RWx/ML.
Installation and Operation
The combination of small size and excellent
response makes the AT933Rx/ML ideal for
suspension over choirs, instrumental groups or
theater stages. A uniform 90° angle of acceptance
provides well-balanced pickup over a narrow
area. The microphone should be located forward
of the front-most source, above the rear-most
source, and “aimed” between them (Fig. 1).
Increasing the height of the mic above the sources
will tend to equalize sound levels between them, but
may also increase background/reverberant sound
pickup. Whenever possible, the distance from the
mic to the rear-most pickup should be no more
than twice the distance to the front source, to
maintain front-to-rear balance (Fig. 1).
Width of pickup is approximately 1.5 times
the distance to the closest performer. If additional
mics are needed for wide sources, they should
not be closer together laterally than 1.5 times
the distance to the front source, to avoid phase
cancellation (Fig. 2).
To orient the microphone in the proper
direction, twist the housing slightly in its wire
holder (clockwise rotation moves the microphone
to the right; counterclockwise rotation moves it
to the left). Adjust the vertical angle by changing
the number of loops the cable passes through in
the steel hanger.
The provided foam windscreen simply slips
over the MicroLine element, effectively reducing
noise from wind or ventilation air currents.
AT933Rx/ML
MicroLine
Miniature
Condenser
Hanging
Microphone
Output is low impedance balanced. The
output connector of the power module mates with
XLRF-type cable connectors. The balanced signal
appears across Pins 2 and 3, while the ground
(shield) connection is Pin 1. Output is phased so
that positive acoustic pressure produces positive
voltage at Pin 2, in accordance with industry
convention.
To shorten the cable, remove the three
screws from the base of the power module and
slide the outer case up the cable to reveal the cir-
cuit board and screw terminals. Loosen the three
terminal screws and remove the cable from the
module. Next, slide the case off the cable, cut the
cable to the desired length (allowing a few extra
inches) and slide the case back onto the cable.
Tie a single knot in the cable about two inches
from the cut end. Following Figure 3, cut the
cable off 1" down from the top of the knot and
carefully remove
1
/2" of the outer jacket. Strip
the mic cable wires and attach them to their
respective terminals (Fig. 4). Make certain
that the terminals are clamped on the
conductors, not on the insulation,
and that there are no loose
strands of wire which might
touch other terminals.
Replace the case, being
certain that it goes
over
the case grounding
contact and that the
roll-off switch is
accessible. Finish by
replacing the three base
screws and testing for proper operation.
While a modern condenser microphone is
not unduly sensitive to the environment, temper-
ature extremes can be harmful. Avoid leaving the
microphone in the open sun or in areas where
temperatures exceed 110° F (43° C) for long periods
of time. Extremely high humidity should also be
avoided.
LESS THAN 2 TIMES “X”
DISTANCE “X”
90°
ANGLE OF
ACCEPTANCE
MIC A
1.5 TIMES
DISTANCE “X”
MIC B
90°90°
Figure 1
Figure 2
Frequency Response (Typical)
LEGEND
Roll-off
12" or more on axis (flat)
Frequency in Hertz
Response in dB
10 dB
20k
10k
5k
2k
1k
500
200100
50
Figure 3
Figure 4
Shield strands,
fully twisted
Yellow-Yellow
Red-Red
1
/
8
" strip reds
and yellows
1
/
2
"
1"
Terminal
screws
Case
grounding
contact
Yellow-Yellow
Red-Red
Shield
PC board
switch side
SYR