Model FP42 User Guide
Stereo Microphone Mixer
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GENERAL
CONTROLS AND CONNECTIONS
The FP42 is a 4-input, 2-output, compact, self-contained stereo
mixer for applications in broadcasting, recording and sound rein-
forcement. The high-reliability FP42 integrates all the operating
features of a professional stereo mixer in a single unit—small and
lightweight enough for location use, but with the reliability of a stu-
dio console.
Power Off/On Switch: applies power to the FP42 circuitry.
Channel Level/Cue Rotary Controls: adjust individual input
channelsignal levels.Each channelcan becued bypulling thecon-
trol knob outward, rotating the knob to the desired level, and push-
ing the knob inward to activate the channel.
Lo Cut Filter Slide Switches: reduce unwanted low-frequency
signals such as wind noise by 6 dB per octave at 150 Hz.
FEATURES
S Wide, flat frequency response, low distortion, and high
Pan L--R Rotary Controls: assign each input channel signal to the
left(L)orright(R)outputchannel, orequally to each outputchannel
(center detent).
output level
S Reliable operation under all temperature and humidity
Master Rotary Control: determines mixed output level at left (L)
and right (R) output connectors. The control is “clutched”: both
channel levels can be set simultaneously, or the left (inner knob) or
right (outer knob) channel can be set individually. The control also
sets the tone oscillatorlevel when the Tone Osc switch is turned on.
conditions
S Protected against RF interference and damage from input
overload and shorted outputs
S Four transformer-coupled XLR inputs, each microphone-line
switchable with low-cut filters and cuing function
Mono/Stereo Slide Switch:selects eithermonophonic outputsig-
nals (both left and right output connectors carry the same signal) or
stereo operation (input channel signals are assigned to left or right
output channels depending on Pan control positions).
S Full-separation pan pots with center detent on each input for
precise spatial positioning
S Phantom power for condenser microphone operation
Limiter In/Out Slide Switch: activates fast-acting, peak-respond-
ing limiter circuit to cut overload distortion during loud program in-
tervals without affecting normal program levels.
S Built-in tone oscillator permits level checking and line testing
S Left- and right-channel transformer-coupled XLR outputs,
with microphone-line and mono-stereo switches
Peak/Limiter LEDS: indicate limiter operation with the limiter in,
and indicate approaching program overload with the limiter out.
The LEDs are activated by the shortest transient peak, but remain
on long enough to provide easy recognition.
S Parallel stereo headphone jacks (1/4-inch and mini) with
level control
S Left and right mix bus jacks
S Active, feedback-type input gain controls for high-level input
L and R VU Meters: indicate 0 VU with a +4 dBm output (recom-
mended for normal use to provide approximately 14 dB headroom
from operating level to clipping level). Rear-panel VU Range +4/+8
slide switch permits changing to 0 VU=+8 dBm. The VU meters are
lit during ac operation only; therefore, the illumination serves as a
visual alarm if the ac is interrupted and the unit has automatically
switched to battery operation.
signals without input attenuators
S Adjustable-threshold limiter with left- and right-channel peak
indicators
S VU meters with range switch and battery check function
S Left- and right-channel master level controls and ganged
headphone level control
Batt Check Momentary Push-button Switch: operates in con-
junction with the left-channel VU meter to indicate battery condi-
tion. With the Power switch on and the switch depressed, a new set
of batteries will give about a +2 VU indication. Battery condition is
good if the reading is above 0 VU: a lower reading means that new
batteries are required for proper operation.
S Powered by ac (120 or 240V—internally selectable) or
built-in battery pack
S Low battery drain provides up to 10 hours operation under
normal conditions
S Noiseless and automatic switchover to and from battery
Tone Osc Off/On Slide Switch: provides a highly stable, low-dis-
tortion 1-kilohertz tone for line tests and level checks. The tone sig-
nal level is controlled by the Master Level control. The tone signal
appears on both the line and microphone outputs, as well as the
Headphones and Mix Bus connectors. The tone oscillator should
be switched off when not in use.
power
S Rugged, durable construction
S Compact and lightweight for field use and transporting
S Rack-mountable with accessory rack mount kit
S Listed by Underwriters Laboratories, Inc.;
Headphones 1/4-inch Stereo Phone Jack and Miniature 3.5
mm Stereo Phone Jack: permit monitoring mixer output through
most stereo headphones. The Headphones rotary control adjusts
listed by Canadian Standards Association as Certified
ꢀ2003, Shure Incorporated
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is recommended for normal use to provide approximately 14 dB of
headroom from operating level to clipping level.
Distortion
0.4% or less THD, 30 to 20,000 Hz at + 15 dBm output; 0.5% or
less IM distortion at +15 dBm output into 600 ohms
The VU meters are illuminated by a single cartridge-type, 6.3V in-
candescent lamp, operating well under its normal rating for a life ex-
pectancy of greater than 10,000 hours. The lamp is only lit for ac
operation. Consequently, the illumination serves as a visual alarm if
the ac is interrupted and the unit has switched to battery operation.
Common Mode Rejection
65 dB minimum with input of – 20 dBV at 100 Hz
Control Interaction
Less than 1 dB with any control combination
The VU meters are connected on the primary side of the output
transformer to assure protection from any dc level on a telephone
line.
Overload and Shorting Protection
Shorting outputs, even for prolonged periods, will cause no dam-
age; microphone input will not be damaged by signals up to 3V
Telephone interconnection
Separation (left and right outputs)
40 dB minimum at 10 kHz; 50 dB minimum at 1 kHz
When using the FP42 connected directly to a telephone line, check
to see whether the telephone company requires an interface cou-
pler between the FP42 and the telephone line. If a coupler is re-
quired, make certain the coupler selected and the wiring arrange-
ment are in compliance with local telephone company regulations.
Connect the telephone line to the left or right Output connector and
turn the Pan controls so that the entire output signal is on the tele-
phone-connected output, or switch to mono operation.
Low-Cut Filters
6 dB per octave rolloff at 150 Hz
Limiter
Threshold: Adjustable, +8 to +14 dBm
Attack Time: 3 msec typical
Recovery Time: 500 msec typical
Telephone Line Surge Protection
Peak/Limiter Indicators
When using the FP42 connected directly to a telephone line subject
to lightning-induced voltage surges, the following part (commer-
cially available) can be installed across the output terminals to pro-
vide additional protection for output circuit components: Metal Ox-
ide Varistor, General Electric Co., Type No. V22ZA1.
Limiter out: lights 6 dB below clipping
Limiter in: lights at onset of limiter action
Phase
All outputs in phase with all inputs. Pin 2 is “high” with respect to
pin 3; pin 1 is ground. Tip of mix bus jack in phase with pin 3. Tip
and ring of headphone jacks in phase with pin 2 of left and right
outputs, respectively.
SPECIFICATIONS
Frequency Response (ref 1 kHz)
30 to 20,000 Hz, +1, –3 dB
Tone Oscillator
1 kHz; +18 dBm maximum at both outputs with Master level full
up
Voltage Gain (at 1 kHz)
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OUTPUT
INPUT
Phantom Power
30 Vdc nominal, 3.3k series resistance, automatically disabled
with input switch in Line position
LINE
90 dB
40 dB
55 dB
MICROPHONE
40 dB
MIX BUS
25 dB
–25 dB
–
PHONES
100 dB
50 dB
PHONES (CUE)
Mic
Line
85 dB
35 dB
–
–10 dB
Mix Bus
5 dB
62 dB
Operating Voltage
Inputs
Ac Operation: 120 or 240 Vac 10% (internally selectable),
50/60 Hz, 6W
Dc Operation: 27 Vdc nominal at 30 mA typical no-signal, 32 mA
typical at 0 VU (+4 dBm) output; 21.5 Vdc minimum; battery life
approximately 10 hours with alkaline batteries at +4 dBm output
in continuous use; three 9-volt batteries, type NEDA 1604A
IMPEDANCE (at 1 kHz)
INPUT CLIPPING LEVEL
INPUT
(at 1 kHz)
FOR USE WITH
19–600 ohms
Less than 10k
3.5k
ACTUAL
Mic
Line
1k
–40 to –5 dBV*
+10 to +45 dBV*
0 dBV
66k
3.5k
Mix Bus
*Dependent on input control setting.
Temperature Range
Operating: –18° to 57° C (0° to 135° F)
Storage: –29° to 71° C (–20° to 160° F)
Outputs
IMPEDANCE (at 1 kHz)
OUTPUT CLIPPING LEVEL
OUTPUT
(at 1 kHz)
FOR USE WITH
ACTUAL
–33 dBV min. across150
Dimensions
79.5 mm H x 310 mm W x 230 mm D
(3–1/8 in. x 12–7/32 in. x 9–1/16 in.)
Mic
150 ohms
600 ohms
<1 ohm
ohms
+18 dBm min. across 600
ohms
Line
185 ohms
Mix Bus
3.5k
3.5k
–15 dBV min. across 3.5k
Weight
Headphones
8–2000 ohms
100 ohms
+6 dBV min. across 200 ohms
Net: 2.95 kg (6 lb 8 oz)
Packaged: 3.45 kg (7 lb 10 oz)
Noise
Equivalent Input Noise: –129 dBV (low-impedance micro-
phone, 150 ohms, 300 to 20,000 Hz) into 600-ohm load at full
gain
Equivalent Input Hum and Noise: –127 dBV (low-impedance
microphone, 150 ohms, 20 to 20,000 Hz) into 600-ohm load at
full gain
Output Noise: –70 dBV maximum (output control full counter-
clockwise [off]), –55 dBV maximum (output control full clockwise
[on]) (input control down, 300 to 20,000 Hz)
Output Hum and Noise: –62 dBV maximum (output control
down), – 53 dBV max. (output control up, input control down, 20
to 20,000 Hz)
Certifications
Listed by Underwriters Laboratories, Inc.; listed by Canadian
Standards Association as Certified
ACCESSORIES
The Model A16R Rack Panel Kit consists of a 19 in. x 3–1/2 in.
(483 mm x 89 mm) precut rack panel and necessary hardware for
rack-mounting the FP42 with its cover in place and end caps re-
moved in a standard 19” (483 mm) rack panel.
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