RDL FP-PA20B Data Sheet

™

FLAT-PAK

SERIES

Model FP-PA20B
Audio Power Amplifier

ANYWHERE YOU NEED...

• 20 Watts RMS Constant Voltage Amplifier

• 25 V Output

• Maximized Audio Level for Output Power

• Audio Quality Superior to Standard Amplifiers

• Input / Output Terminal Block Connections

• Line Level Balanced or Unbalanced Input

• Integral Audio Compressor to Control Clipping

• High Overall Operating Audio Level

• Peak LED to Indicate Audio Compression

• Ultra-compact All Metal Construction

• Convenience of RDL FLAT-PAKs

You Need The FP-PA20B!

The FP-PA20B is part of the group of versatile FLAT-PAK products from Radio Design Labs. The unique
FLAT-PAK case can be directly screwed or bolted to cabinets or shelves. Optionally available rack-mounting
accessories permit single or multiple FLAT-PAK module mounting.

APPLICATION: The FP-PA20B is the ideal choice in many applications where multiple 25 V speakers in a
zone need to be powered from a single audio power amplifier.

The FP-PA20B features a balanced line level input that may be connected unbalanced. A front panel GAIN
control is designed to be adjusted either manually or with a trimming screwdriver. The gain range will
accommodate standard unbalanced levels as well as professional balanced levels. A 25 V amplified output
is provided to drive corresponding speakers in a distributed sound system.

A red PEAK LED is provided to indicate the threshold of the integral compressor. Audio levels that could
cause the amplified output to clip are compressed according to two dynamic time constants. Normal audio
level signals remain unaffected by the compressor thereby preserving audio dynamics and preventing the
compressor from increasing feedback potential when the amplifier is used for paging. The compressor is
designed to remain aurally transparent while maintaining clean, unclipped amplified audio for input overloads
of up to 20 dB. In addition to the compressor, an active filter circuit prevents saturation of the output
transformer at low frequencies. The FP-PA20B produces average audio levels and audio clarity normally
expected of amplifiers delivering much higher output power.

The durable construction and low profile of the FP-PA20B allow mounting in a wide range of locations not
suited to a conventional style power amplifier. Power is provided to the module either through the barrier
block or through the DC power jack. For continuous RMS output power, a 24 VDC 2A power supply is
required. A 1A supply is sufficient for normal program audio levels and content. Power supplies are sold
separately.

Wherever a high quality constant voltage audio power amplifier is needed to provide reliability, compactness
and unsurpassed versatility, the FP-PA20B is the ideal choice. Use the FP-PA20B individually, or combine it
with other RDL products as part of a complete audio/video system.

RDL • 659 N. 6th St. • Prescott, AZ., USA 86301 • [phone] • FAX [phone] • www.rdlnet.com

™

FLAT-PAK

SERIES

Model FP-PA20B
Audio Power Amplifier

Installation/Operation

EN55103-1 E1-E5; EN55103-2 E1-E4

Typical Performance reflects product at publication time
exclusive of EMC data, if any, supplied with product.
Specifications are subject to change without notice.

USE PROTECTED 24 VDC SUPPLY
1 A MINIMUM, 2 A RECOMMENDED

2 A REQUIRED FOR RMS OUTPUT PWR

24VDC 2A

GAIN

O

N
KPE

A

OR

24 VDC

POWER

SOURCE

BALANCED
LINE-LEVEL

25 VOLT SPEAKER 25 VOLT SPEAKER 25 VOLT SPEAKER

+

PWR

PLUS COMPRESSION

20 WATTS RMS

+

INPUT

-

OUTPUT

COM 25V

POWER ON INDICATOR

PEAK LED INDICATES
COMPRESSOR ACTIVITY.
ADJUST SO LED DOES NOT
FLASH CONTINUOUSLY FOR
NORMAL LEVELS.

UNBALANCED

LINE-LEVEL

25 VOLT SPEAKER 25 VOLT SPEAKER

ADJUST AMPLIFIER GAIN

24VDC 2A

GAIN

O

N
KPE

A

+

PWR

PLUS COMPRESSION

20 WATTS RMS

+

INPUT

-

OUTPUT

COM 25V

TYPICAL PERFORMANCE

Input: Line level
(+4 dBu nominal balanced)
(-10 dBV nominal unbalanced)
Input Impedance: 20 kΩ balanced bridging
10 kΩ unbalanced
Input / Output Connectors: Plug-in terminal block
Gain Adjustment: Single turn audio taper
Minimum Input Levels:
Balanced: -26 dBu (to cross compressor threshold)

-10 dB

COMPRESSION

0 dB

Unbalanced: -28 dBV (to cross compressor threshold)
Maximum Input Levels:
Balanced: +23 dBu
Unbalanced: +15 dBV

Frequency Response: 50 Hz to 18 kHz (+/- 3 dB)*
THD+N: < 0.1% (@ 1 kHz)*

< 0.5% (50 Hz to 20 kHz)*
Compressor: Threshold 6 dB below rated output,
automatic adjusting attack and release
Noise: <-80 dB (below 20 W RMS)
CMRR: > 55 dB (50 Hz to 120 Hz)

-20 dB

-30 dB

-40 dB

-40 dB -20 dB 0 dB
INPUT SIGNAL

20 W

OUTPUT SIGNAL

Output Power: 20 W RMS @ 25 V
Ambient Operating Environment:

0° C to 30° C Maximum; 20° C Recommended
Power Requirement: 24 Vdc @ 1650 mA (for continuous RMS power output, Ground referenced)
24 to 33 Vdc @ 1000 mA (for normal program material with minimal compression, Ground referenced)
Indicators (2): Red LED: PEAK LED indicates compressor activity
Green LED: Power ON

*measured at compressor threshold level equaling 4 W RMS output power
Overall Dimensions: Height: 2.30 in. 5.85 cm

Width: 3.25 in. 8.26 cm
Length: 6.04 in. 15.3 cm

891-2115A

Radio Design Labs Technical Support Centers

U.S.A. [phone], [phone]; Fax: [phone]

Europe [NH Amsterdam] (++31) 20-6238 983; Fax: (++31) 20-6225-287