McIntosh MC275 User Manual

Page 7

Installation of Tubes, Tube Cover, Location and Ventilation

Small Signal Tubes:

1. Locate a 12AX7A Tube.
2. On the top left side of the amplifier, locate the Tube

Socket that has the nomenclature V1 12AX7A next
to it on the chassis. Refer to figure 4 and 5.

3. Orient the Tube so the area where no pins are located

on the base of the Tube is aligned with the corre-
sponding area on the Tube Socket.

4. Carefully insert the Tube into the socket until the base

of the Tube is fully seated in the Tube Socket.

5. Repeat the above steps for the remaining two

12AX7A Tubes at locations V2 and V5.

6. Locate a 12AT7 Tube.
7. On the top center of the amplifier, locate the Tube

Socket that has the nomenclature V3 12AT7A next to
it on the chassis.

8. Insert the Tube, following the same procedure as in

steps 3 and 4.

9. Repeat steps 6-9 for the remaining three 12AT7

Tubes at locations V4, V6 and V7.

Caution: To prevent electrical shock make sure the MC275

Tube Cover is installed before connecting the AC
Power Cord.

Before operating the MC275, locate the previously re-
moved Tube Cover and perform the following steps:

Installing the Tube Cover:

1. The Tube Cover has a wide opening along one side

of its longer dimension. Orient this wide opening so
it is facing towards the three large transfomers.

2. Carefully place the Tube Cover onto the MC275

while at the same time aligning the two chassis
mounted ball studs with the Tinnerman Clips in the
cover. Refer to figure 6.

The MC275 can be placed upright on a table or shelf,
standing on its four feet. It also can be installed in a piece
of furniture of your choice. Do not install the MC275 di-
rectly above a heat generating component. Adequate venti-
lation extends the trouble free life of the MC275. The sug-
gested minimum space for operating the MC275 is 22
inches (55.88cm) in width, 18 inches (45.72cm) depth, and
21 inches (53.34cm) in height. Always allow air to flow
through the ventilation holes on the bottom of the amplifier
and a means for the warm air to escape at the top. If the
MC275 is installed in a cabinet, a quiet running ventilation
fan can be a definite asset in maintaining the coolest pos-
sible operating temperature. Refer to figure 7.

Location and Ventilation

Figure 5

Figure 6

Figure 7

12AX7A

12AT7

KT88/6550

Warm Air

Cool Air

Ball Stud Fasteners