Rane FDA 28 User Manual

Professional Audio Products Data Sheet

General Description

The Rane FDA 28 Distribution Amplifier is
a two-input, eight-output splitter/distribution
amplifier capable of providing eight discrete
balanced outputs from two balanced inputs (mic
or line level). Each output’s level may be
adjusted individually via the concentric level
controls on the front panel. Each Input has its
own GAIN control. The MASTER control
affects the level being delivered to the bus prior
to any splits. This allows the user to achieve an
overall level adjustment that is independent of
the OUTPUT controls (lets you turn everything
up or down at once).

Each Input is set to either mic or line level
via a rear panel MIC/LINE pushbutton. PHAN­TOM POWER is available for individual mic
use and is activated by rear panel push switches.

FDA 28

STEREO DISTRIBUTION AMPLIFIER

Located inside the FDA 28 are eight (8) Pre/
Post switches allowing the user to determine
which, if any, outputs should be controlled by
the OUTPUT controls only, and not the MAS­TER control. (See Block Diagram on rear.)

The separate STEREO/MONO switches
allow mixed stereo and mono applications.

Each output stage incorporates a fully
balanced output line driver of the cross-coupled
design. This allows long lines to be differentially
driven with confidence.

As is true with all Rane Flex modules, the
FDA 28 sports a ground lift switch to guarantee
freedom from ground loop induced hum and
noise. Signal and chassis ground are available at
each output. Euroblock connectors are used for
easy installation, and accept up to 12AWG wire.

Features

• TWO BALANCED INPUTS

• MIC/LINE INPUT SWITCH

• PHANTOM POWER SWITCH

• STUDIO NOISE PERFORMANCE

• MASTER LEVEL CONTROLS

Parameter Specification Limit Units Conditions/Comments

Mic Input Impedance 1k 1% Ohms Balanced 500 + 500
Line Input Impedance 20k 1% Ohms Balanced 10k + 10k
Mic Gain Range +26 to +65 2 dB Excludes Output Gain
Line Gain Range -7 t o +32 2 dB Excludes Output Gain
Phantom Power +15 4% VDC
Output Impedance 50 10% Ohms Balanced 25 + 25
Output Drive Level +22 1 dBu 10 VRMS Across 600 Ohms
Output Cable Length 1000' (305m) typical Belden 8451 or equivalent
Output Gain Range Off to +6 0.5 dB
Mic Equivalent Input Noise -128/-108 (Max/Min Gain) 2 dBu 20kHz Noise BW; 150 Ohm Source
Line Signal-To-Noise Ratio 85 2 dB re +4dBu, 20kHz BW, Unity Out
THD+Noise 0.02 max % +4dBu, 20-20kHz, Any Gain
Output Pre/Post Switches Yes: 8 Internal Slide Switches
Frequency Response 10-150kHz 3 dB MIN to 9 Gain

30-150kHz 3 dB MAX Gain
Crosstalk 75@1kHz / 50@20kHz 2 dB Any Input to Any Output
Maximum Current 650 mA RMS Current From Remote Supply

• PRE/POST OUTPUT ASSIGNS

• SEPARATE STEREO/MONO SWITCHES

• OVERLOAD INDICATORS

• 8 CROSS-COUPLED BALANCED OUTS

• EUROBLOCK CONNECTORS

FDA 28

STEREO DISTRIBUTION AMPLIFIER

Rear Panel Block Diagram

Professional Audio Products Data Sheet

Application Information

Use of the FDA 28 is straight- forward. Wire
the balanced inputs to the Euroblock connectors.
Then follow the silkscreened labels to take the
balanced outputs from the Output Euroblocks.
The Euroblocks accept any 12 to 28 guage wire.
Expansion is done by jumpering the Input to a
second FDA 28, and so on.

The above diagram shows the uncomplicated
nature of the FDA 28. Active fully differentially
(instrumentation) balanced inputs condition the
signal being split or distributed. The MIC/LINE
pushbutton changes the gain range of the
amplifier stages from 26 to 65 dB for MIC and
–7 to 32 dB for LINE level Inputs.

Keep an eye on the OL indicator when setting
the Gain. Always use the most gain possible
without allowing the OL indicator to light steady.
Occasional flickering is permitted. Setting gain
this way, maintains the best signal-to-noise
performance for the system. Separate A and B
GAIN trims allow level matching and balancing
as required.

Your exact application determines the use of
the internal PRE/POST switches. In the PRE
position, the OUTPUT operates independently
from the MASTER control. In the POST position,
the OUTPUT is a direct function of the MASTER
setting. By using the PRE/POST switches, it is
possible to program each output so the MASTER
control affects only those areas desired. As an
example, this means you could turn down all the
zones in the dining areas of a restaurant without
affecting the lounge.

Mixed stereo and mono applications require
setting the separate STEREO/MONO switches.
By moving any of these switches you program
any of the output pairs for mono use.

Each Output of the FDA 28 uses high current
cross-coupled balanced line drivers. Use of the
cross-coupled design allows the same gain
whether used balanced or unbalanced. When used

unbalanced, it is mandatory that you ground the
unused output. Outputs may be paralleled for

driving extremely long lines (a mile or more), or
where extra current (greater than 60 mA) is
necessary.

©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5098 TEL [phone] FAX [phone] WEB http://www.rane.com

Printed in the U.S.A. on Recycled Paper

All features & specifications subject to change without notice 520-353 MAY96