5
Preface
Please take time to carefully read and understand
the following information and instructions before
you install or attempt to operate your Audio
Research Reference 750 vacuum tube monoblock
power amplifier. Becoming familiar with important
facts about your amplifier and its correct operating
procedures will help assure maximum musical
satisfaction and reliable operation.
Packaging
Save all packaging accompanying this product.
You have purchased a precision electronic
instrument, and it should be properly cartoned any
time shipment becomes necessary. It is very
possible that this unit could be damaged during
shipment if repackaged in cartoning other than
that designed for it. The original packaging
materials help protect your investment from
unnecessary damage, delay and added expense
whenever shipment of this unit is required.
See separate ‘Unpacking/Repacking Instructions’
card attached to the outer amplifier carton before
attempting to unpack or repack this amplifier for
shipment. Retain unpacking/repacking instructions
for future reference.
Accessories
1 – Phillips-head screwdriver for panel removal.
1 – Plastic screwdriver for front panel potentiometer
bias adjustment.
Fuses
1 – 2 Amp MDQ slo-blo for LV power transformer in
120V units.
1 – T1 Amp fast-blo for LV power transformer in 220,
240V units.
1 – 4 Amp MDQ slo-blo for start-up circuit in 120V
units.
1 – T3.15 Amp fast-blo for start-up circuit in 220, 240V
units
1 – 20 Amp MDA for main power in 120V units.
1 – 10 Amp MDA for main power in 220, 240V units.
CAUTION: When replacing fuses, use
ONLY the value and type of fuse
originally shipped with the amplifier.
Use of a different fuse value could
cause catastrophic damage to your
amplifier and will also void your warranty. Audio
Research selects fuses not only on grounds of safety
but also for their sonic performance.
Vacuum Tubes and Preparation for
Use
Do not attempt to operate this amplifier before
installing the necessary vacuum tubes in their
indicated sockets. The tubes are protectively
packed in a separate carton; save packing for
possible future use.
1.
All input, driver and output-stage tube locations
are clearly labeled with tube type and “V”
number on the anodized plate covering the top
of the amplifier. There is one 6H30 input tube, two
KT120 drivers, and 16 KT120 output tubes. In
addition, two power-supply regulator tubes–one
6H30 and one 6550 – are located inside on the
upper or second-level circuit board. To access this
location,
use
the
supplied
Phillips-head
screwdriver to remove all fastening screws on one
of either of the two side panels; the tube sockets
will be visible near the center of the board.
2.
Match each tube's ‘V’ number marked on the
tube with the ‘V’ number of the corresponding
socket. Insert tubes by carefully aligning tube pins
with socket holes and gently applying downward
pressure. The base of the tube should firmly
contact the surface of the socket. Once the
power-supply tubes have been installed inside the
amplifier, refasten the side panel and proceed to
install the tubes on top of the amplifier.
3.
Note:
In general, contact enhancers are not
recommend for use on vacuum tube contact
pins. With continual exposure to heat and air,
many of these substances can form gummy, dust-
collecting residues which actually reduce
contact and degrade sonic performance. Proper
external use of these preparations – on
interconnect plugs, speaker connections, etc.– is
subject to the discretion of the owner. Contact
Audio Research for specific recommendations.
Installation
To insure normal component life and safe operation
this unit must be operated only in an upright
position. Adequate air flow and proper cooling
can occur only if there is no restriction above the
unit and on either side.
The special non-marring elastomer feet provide
adequate spacing and stability only on a smooth,
hard surface.
For
upright stability, never operate the
unit while it is sitting
on a soft surface such as a thick
rug or carpet.
Due to its unusually high weight, this amplifier must
be supported on a surface specifically rated for
such a load. Standard furniture cabinetry and
shelving are not typically designed to adequately
support this amplifier. Check with the manufacturer