Thank you for your purchase of the Rolls RA280 Power Amplifier. The
RA280 is a stereo 80 Watt/channel RMS power amplifier in a standard 2
rack space format. It is intended for professional audio, musical, and
studio applications. The unit features 80W per channel RMS into four
ohms, 50W per channel RMS into eight ohms, and 150 watts into eight
ohms bridged.
The unit also features MOSFET drivers in a voltage and current gain
circuit, a one-second input turn on delay, and LED power output meters.
The RA280 is built solid and has a painted steel chassis, special high-
performance transformers and a fused power line. The MOSFET output
stage is fault protected and helps the RA280 forgive output shorts.
INSPECTION
1. Unpack and Inspect the RA280 package
Your RA280 was carefully packed at the factory in a protective carton.
Nonetheless, be sure to examine the unit and the carton for any signs of
damage that may have occurred during shipping. If obvious physical
damage is noticed, contact the carrier immediately to make a damage
claim. We suggest saving the shipping carton and packing materials for
safely transporting the unit in the future.
2. Please complete the Warranty Registration Card and return it to the
factory.
INSTALLATION
Connect the power cord to an AC power source, connect the input to the signal
source and to the RA280 via the RCA or 1/4" input jacks . Speakers may be
connected by using 1/4" jacks, or the dual banana posts which are preferred.
When using in bridged mode, the banana connectors must be used.
Turn the Volume controls fully counterclockwise (off), and turn on the power
switch, the power LED should light. With the program material running, slowing
increase the Volume controls until the desired level of sound is present.
We've included the one second turn-on delay to prevent possible speaker
damage in case all equipment is on a single power strip.
FAULT PROTECTION
The fault protection in the RA280 limits the current to the output stage in the
faulted channel and turns on all the LEDs in that channel. This mode is entered
whenever the output stage is called upon for too much power, it may also be
fooled by impedances lower than four ohms which may cause the output stage
to overheat and burn up the MOSFETs.
IMPORTANT: Since the RA280 is convection cooled, the unit radiates heat from
the rear and, depending on it's load demand, it may become very hot if drawn
upon heavily.
Should the unit need service, contact Rolls directly, obtain a Return Authoriza-
tion number (RA Number), and return the unit to us for repair.
SCHEMATIC
BRIDGING
To bridge the RA280, move the Bridging switch to the "Bridge" position. The
Channel 1 knob controls the level of the bridged output, Channel 2 knob is
inactive.
Connect the input to Channel 1 input, then connect the load to the two positive
(red) banana jacks. Make no connections to the black banana jacks. The level
meters will both light, and the output power into 8 ohms is the sum of the LEDs
that light.
MADE IN U.S.A.
RISQUE DE CHOC - NE PAS ENLEVER
SERIAL NUMBER
WARNING:
To reduce the risk of electric
shock or fire do not expose
this device to rain or moisture.
CHANNEL 2 INPUT
CHANNEL 1 INPUT
BRIDGE NORMAL
OUTPUT 2
OUTPUT 1
4A 120V - 2A 230 V
OUTPUT 1
OUTPUT 2
-
-
+
+
MAINS POWER
WARNING
For continued prootection against
risk of fire, replace only with
same type and rating of fuse.
CAUTION
TO REDUCE THE RISK OF ELECTRIC
SHOCK DO NOT NOT REMOVE LID. NO
USER SERVICABLE PARTS INSIDE.
REFER SERVICING TO QUALIFIED
SERVICE PERSONNEL
C O R P O R A T I O N
