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.

Location and Ventilation

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.

KT88/6550

12AX7A

12AT7

12AX7A

12AT7

Figure 5

Ball Stud Fasteners

Figure 6

Warm Air

Cool Air

Figure 7

7

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McIntosh MC275 owner manual Installation of Tubes, Tube Cover, Location and Ventilation
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MC275 specifications

The McIntosh MC275 is a legendary vacuum tube amplifier that has maintained its reputation for delivering exceptional sound quality since its introduction in the 1960s. This iconic amplifier represents the pinnacle of audio engineering, combining vintage aesthetics with modern technologies to cater to discerning audiophiles.

At the heart of the MC275 lies its push-pull quad output configuration, powered by a pair of KT88 vacuum tubes that produce up to 75 watts per channel. This setup is renowned for its ability to provide a rich, warm sound with an impressive dynamic range. The combination of vacuum tube warmth and solid-state precision results in an audio experience that is both engaging and detailed, making it suitable for a wide array of musical genres.

One of the standout features of the MC275 is its unique quad-balanced design. This architecture minimizes distortion and maximizes clarity, allowing the amplifier to engage with the very essence of the audio signal. The implementation of a high-fidelity transformer enhances the low-frequency response, ensuring that bass notes are robust yet controlled.

The MC275 also showcases McIntosh's innovative Autoformer technology. This proprietary feature allows the amplifier to deliver the full rated power into 2, 4, or 8-ohm speakers without compromising audio quality. This versatility ensures compatibility with a wide range of loudspeakers, making it a perfect choice for both small setups and larger audio systems.

Additionally, the MC275 is equipped with McIntosh's signature Power Guard circuitry, which prevents clipping and distortion by monitoring the output signal in real-time. This feature safeguards both the amplifier and connected speakers, ensuring that listeners can enjoy loud volumes without concern for damaging equipment.

The amplifier's stunning design includes a striking illuminated analog meter, providing visual feedback on output levels. The classic black glass front and chrome chassis not only exude elegance but also emphasize McIntosh's rich heritage in high-fidelity audio.

In conclusion, the McIntosh MC275 is a remarkable fusion of classic and modern technology, offering audiophiles a powerful and aesthetically pleasing amplification option. With its impressive power output, advanced technology, and iconic design, the MC275 continues to be a sought-after choice for those who appreciate the art of sound.
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