Audio research sp 6a owners manual

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Rev. D
3/28/79

MODEL SP-6A PREAMPLIFIER
INSTRUCTION MANUAL

audio research nornnratinn

2843 TWENTY-SIXTH AVENUE SOUTH
MINNEAPOLIS, MINNESOTA 55406

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11.

SPECIAL NOTICES SECTION

Read Before Operating Unit

USE CAUTION

It is important to note, before placing this unit in operation, that the
SP-6A is a vacuum tube device, with special circuitry for exceptional
dynamic range and wide bandwidth.

The nature of this circuitry is such that a high amplitude sub-sonic surge
is generated at it's output both at turn-on and at power off (also generated
if the AC power line voltage is interrupted).

Two provisions have been made to protect the power amplifier and the speakers
used with this preamplifier:

1. A separate on-off switch is provided for the switched outlets so
that the preamplifier may be turned on and warmed up (5 minute wait
recommended) before the power amplifier is turned on.

Conversely, the outlet switch should be turned off (again, a 5 minute
wait is recommended) prior to turning off the preamplifier so that
the amplifier can discharge it's energy storage (before the pre-
amplifier is turned off).

2. A mute" switch is also provided. This allows the output of the
SP-6A to be opened internally during warm-up and turn-off to
eliminate stress on your amplifier even when it is not on.

(Some manufacturers' solid state amplifiers use very low voltage
components that could be damaged by these pulses.) The "mute
switch should also be used to protect speakers from low frequency
signals when a tone arm is moved.

When pickup cartridges or head amplifiers are changed, the input
selector should also be switched to an unused position, to minimize
the need to wait for the SP-6A to internally restabilize (with the
mute switch on also).

POWER LINE VOLTAGE INTERRUPTION HAZARD

The SP-6A has Well regulated power supplies that are immune to normal line
voltage fluctuations. However, if your power line voltage is interrupted
(summer lightning storm, etc.) the same problem outlined above will occur.

To avoid possible speaker burnout, it is essential that your speakers be
fused with appropriate size fuses. This is a highly desireable procedure
in all audio systems, since this also provides protection to your speakers
in the event of an amplifier, preamplifier or program source malfunction.
If you do not know the proper size fuses for your speakers, we strongly
urge you to obtain the speaker manufacturer's recommendation for the
appropriate fuse.

Proper fusing can save you much inconvenience and costly speaker repairs.