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General Description
The Shure FP23 is a portable, battery-powered microphone pre-
amplifier with phantom power. Designed for high bandwidth 96k/24
digital production, this studio-quality mic preamp is ideal for critical
radio, television, and film production applications.
With its rugged mechanical and electrical construction, compact
size, and high-quality components, the FP23 is extremely durable
and easy to use. This highly reliable mic preamp will provide years
of superb audio performance under the most punishing field condi-
tions.
Features
Audio performance
• Maximum of 66 dB of gain, adjustable in eleven discrete
steps for accurate, repeatable gain settings.
• Dynamic range exceeding 120 dB.
• 20 Hz to 50 kHz audio bandwidth.
• High immunity to RF interference due to transformers, RF
filtering, and all-metal construction.
• High current line output driver capable of driving very long
cable runs.
Transformer balanced
• Premium-quality input transformer provides superior sonic
quality and freedom from interference problems.
• Custom-designed output transformer provides line driving
ability with freedom from interference problems.
Limiter
• Extended range peak limiter uses dual opto-isolators,
making the unit virtually “unclippable.”
Battery power
• Internal battery power (two AA) for convenient, low cost
power.
• Battery life greater than 24 hours.
Durable mechanical construction
• High strength extruded aluminum chassis with protective
metal end rails to withstand punishing field conditions.
• Easy access battery compartment for quick battery
changes.
Phantom power
• Selectable 48-volt and 12-volt phantom power for
condenser microphones.
High pass filter
• Two corner frequency settings.
Specifications
Gain
0 dB to 66 dB input to output, switch selectable
Gain Accuracy
+0.6, –0.1 dB with reference to front panel gain markings
(150 Ω source, 100k Ω load impedances)
Frequency Response (see graph below)
20 Hz – 22 kHz, +0.1, –0.5 dB
–1 dB at 50 kHz
(relative to 1 kHz level with 150 Ω source)
Equivalent Input Noise
–126 dBu (–128 dBV) maximum
(150 Ω source, flat weighting, 22 Hz – 22 kHz bandwidth for gain settings
of 36 dB or greater)
Output Clipping Level
+22 dBu minimum with 100 kΩ load
+20 dBu minimum with 600 Ω load
Input Clipping Level
+4 dBu minimum at the 0 or +18 dB gain setting
Dynamic Range
122 dB minimum at the +18 dB gain setting
THD + Noise
0.05% maximum
(from 50 Hz to 22 kHz @ +4 dBu output level,
22 Hz – 22 kHz filter bandwidth, +46 dB gain setting)
Common Mode Rejection Ratio:
100 dB minimum at 80 Hz
60 dB minimum at 10 kHz
Input
Transformer-balanced, 2000 Ω input impedance
Output
Transformer-balanced, 130 Ω output impedance
Low Cut
80 Hz or 160 Hz (switch selectable), 6 dB per octave
Phantom Power
12V or 48V (switch selectable) per DIN 45 596
Limiter
Limits to +17 dBu output level
10:1 limiting ratio
5 ms attack time, 100 ms release time
Amber/Red LED indicates limiting/clipping
Internal Voltage Rails
+15 V and –15 V, regulated
Power
2 AA batteries, 24 hours life typical with +4 dBu signal into 600 Ω, no
phantom power
Power LED
Green indicates power and good battery.
Red indicates power and low battery. LED turns red when approximately
4 hours of battery life remain.
Polarity
Mic input to line output is non-inverting
Operating Temperature Range
–18 to 57 degrees C
0 to 135 degrees F
Model FP23 User Guide
Microphone Preamplifier
27A8726 (Rev. 1)
2000, Shure Incorporated
Printed in U.S.A.