Rotel A-1 Service manual

Technical Information

A-1

Date: April 29, 1997

Model: RB 951

Subject: Custom Installation Applications

The RB 951 Power Amplifier is extremely versatile in its ability to drive almost any
loudspeaker. This versatility is multiplied by the RB 951s ability to operate in three
different modes:
of operation to use for a specific custom installation and how to configure the amplifier
will be recommended in the following instructions.

Please do not attempt to configure the operation of the RB 951 unless you are
confident in your understanding of these instructions. Please ensure that all five (5)
pages of these instructions are included. These instructions will not be needed for
basic Stereo operation of the RB 951.

There are eleven (11) adjustments (jumpers, variable resistors, and one switch)
available to configure the operation of the RB 951. The factory

VR601/2

1.
Turn the set screws fully
head screwdriver to taper the amplifier output for precise speaker level matching.

S603/4

2.
the RCA input jacks. Use the jumper to combine
and
and S604 pins 1-2 to bypass VR602. (You must have the variable input resistors
enabled to taper the amplifier output)

Bridged Mono / Normal Stereo

3.
left of the input jacks (back panel view). Set the switch to the right for

Stereo

operation. (Recommendations regarding which mode of operation to use begins
on page 2)

S602

4.
S604. Use the jumper to combine
Stereo operation. Combine S602 pins 1-2 for Parallel Mono operation.
(Recommendations regarding which mode of operation to use begins on page 2)

: Two dual position shunt jumpers are located on the PCB at both sides of

S604 pins 2-3

and Parallel Mono operation. Set the switch to the left for Bridged Mono

: One dual position shunt jumper is located on the PCB between S603 and

STEREO, BRIDGED MONO AND PARALLEL MONO.

preset

: Two variable resistors are located on both sides of the RCA input jacks.

clockwise

to enable VR602. Combine S603 pins 2-3 to bypass VR601

for maximum signal power. Use a small flat

S603 pins 1-2

: One dual position slide switch is located to the

S602 pins 2-3

for Bridged Mono / Normal

Which mode

positions are:

to enable VR601

Normal

ROTEL OF AMERICA  54 CONCORD STREET  NORTH READING, MA 01864  PHONE: [phone]  FAX: [phone]

4/24/03 - Page 2

P1/2/3

5.
and the power supply capacitors. Connect
Stereo operation. Connect P1 to P2 for Parallel Mono. (Recommendations
regarding which mode of operation to use begins on page 2)

S605/6

6.
the power supply filter capacitors. Use the jumper to combine

S606 pins 2-3

pins 1-2 for high input sensitivity (.775V). This adjustment will accommodate both
high and low output preamps.

S607/8

7.
transformer and the circuit breaker. Use the jumper to combine

S608 pins 2-3

1-2 for Auto Turn On active. This feature will allow the amplifier to be turned on
when a signal is sensed at the inputs. (The front panel power switch must be in to
allow Auto Turn On to operate.)

NOTE
shunt jumpers.

There are

The RB 951 is delivered from the factory in the

• No adjustment is necessary for two channel operation. In the event Stereo mode
operation does not work, please check the settings for numbers 3, 4 and 5 above.

• Specific installations may require control of the variable inputs (numbers 1 and 2
above), input sensitivity adjustment (number 6 above) and Auto Turn On (number 7
above).

: One 18AWG spade jumper is located on the PCB between the back panel

P1 to P3

: Two dual position shunt jumpers are located on the PCB at both sides of

for low input sensitivity (1.5V). Combine S605 pins 1-2 and S606

: Two dual position shunt jumpers are located on the PCB near the power

for Auto Turn On inactive. Combine S607 pins 1-2 and S608 pins

: An asterisk appears on the PCB beside the factory preset position for the

three

basic modes of operation for the RB 951:

Stereo

•

pair of 4 or 8 ohm speakers (or two pair of 8 ohm speakers connected in
parallel) with two channels of music.

Bridged Mono

•

large
Bridged Mono mode for stereo)

Parallel Mono

•

of small 4-8 ohm loudspeakers connected in parallel with one channel of
music. (Use two RB 951s in Parallel Mono mode for stereo)

- Amplifier output provides high voltage and high current to drive one

- Very high voltage and high current output to drive one

8 ohm

loudspeaker with one channel of music.. (Use two RB 951s in

- High voltage and very high current output to drive a number

STEREO

Stereo

for Bridged Mono / Normal

S605 pins 2-3

S607 pins 2-3

mode configuration.

and

and