Shure FP23 User Manual

Model FP23 User Guide

Microphone Preamplifier

General Description

The Shure FP23 is a portable, battery-powered microphone pre­amplifier 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 condi­tions.

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

2000, Shure Incorporated
27A8726 (TI)

Printed in U.S.A.

Dimensions

43 mm x 94 mm x 140 mm (H x W x D)
(1.7” x 3.7” x 5.5”)

Weight (unit only)

0.56 kg

1.24 lbs.

+1
+0
–1

d

–2
B
u

–3

–4

–5

–6

10 100k20 50 100 200 500 1k 2k 5k 10k 20k 50k

High Pass (Low Cut)

80 Hz

160 Hz

Weight (packaged)

0.86 kg

1.90 lbs.

Certification

Meets FCC Part 15 Class B, Eligible to bear CE mark (see conformance
statement)

Hz

FREQUENCY RESPONSE

Figure 1

46

42

36

FLAT

80

160

28

18

0

GAIN (dB)

ON ON

LIMITER POWER

50

54

58

62

66

123 4 56

Front Panel Controls and Indicators

1 LIMITER/Peak LED

Bi-color LED illuminates amber to indicate limiter activi­ty; illuminates red at 3 dB below clipping.

2 LIMITER Switch

Activates the peak limiter. Limits to +17 dBu output.

3 High Pass Filter Switch

Three-position switch inserts an 80 Hz or 160 Hz corner
frequency filter, 6 dB per octave. Center position of
switch removes the filter from the signal path.

4 Rotary GAIN Switch

Selects the amount of gain from input to output, adjust­able in 11 increments.

5 POWER Switch

Powers the unit when switch is in the up position.

6 POWER LED

Bi-color LED illuminates green when the unit is pow­ered and changes to red when approximately four
hours of battery life remain.

BATTERIES

FREQUENCY RESPONSE

Figure 2

Back Panel Connectors and Controls

7 Battery Compartment

Requires two AA batteries for operation. Insert positive
(+) end of battery first.

8 LINE OUT

Transformer balanced XLR line-level output. +22 dBu
peak output level.

9 PHANTOM Power Switch

Three-position switch selects either 48-volt or 12-volt
phantom power. Center position turns phantom power
off.

10 MIC IN

Transformer-balanced XLR input accepts microphone
level signals.

PHANTOM

48 V

OFF

12 V

MIC INLINE OUT

78910

2