7)Using the bias tool, slowly turn the screw on the potentiometer that is adjacent to the switch until the bias meter reads ~ 40 miliamps (mA). Turn the screw clockwise to lower the bias and counterclockwise to raise the bias. Note that there are two ends on the bias tool. Using the end with the recessed screwdriver will greatly facilitate this operation.

KT88 (4)

Output Tubes

Potentiometers

Switches

Meter

Figure 3. Bias switches and potentiometers

12AX7 (1) Input Tube

12AU7 (2) Driver Tubes

8)Flip the switch back into the “run” position thus disengaging the tube from the meter circuit.

9)Repeat the above steps for each of the tubes in both channels.

As it is a quick operation, the tube bias should be checked on a regular basis.

7

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Rogue Audio M-150 owner manual Bias switches and potentiometers
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M-150 specifications

The Rogue Audio M-150 is a high-performance tube amplifier that epitomizes a blend of classic aesthetics and modern engineering. Designed for audiophiles who appreciate the warmth and richness of tube sound, the M-150 delivers a compelling listening experience. Producing 150 watts per channel, it can drive a wide range of speakers with exceptional clarity and power.

The heart of the M-150 lies in its use of EL34 output tubes, which are known for their musicality and detail. These tubes work in conjunction with a sophisticated circuit design that optimizes the amplifier’s performance while minimizing distortion. The M-150 features both balanced and single-ended inputs, allowing users to connect a range of source components, including digital and analog sources, seamlessly.

One of the standout technologies in the M-150 is its unique automatic biasing system. This system ensures that the output tubes operate at their optimal performance level without requiring frequent adjustments. This feature not only enhances reliability but also prolongs the life of the tubes, making it an ideal choice for both novices and experienced listeners.

The M-150 also includes a robust power supply that provides ample current to drive demanding loads. The transformer is custom-designed to deliver low noise and minimal distortion, further contributing to the amplifier's overall sonic quality. The result is a dynamic range that captures the nuances of recordings, from the subtleties of classical music to the aggressive nature of rock.

Additionally, the amplifier boasts a sleek and stylish design, with a brushed aluminum front panel and large, illuminated VU meters that provide a visual indication of output levels. The chassis is stout and well-built, designed to minimize vibrations and mechanical noise, which can interfere with audio performance.

Whether you are a dedicated audiophile or simply someone who appreciates good sound, the Rogue Audio M-150 offers a compelling combination of tube warmth, power, and innovative features. Its impressive audio fidelity, ease of use, and aesthetic charm make it a remarkable choice for anyone looking to elevate their listening experience to new heights. This amplifier is a testament to Rogue Audio's commitment to craftsmanship and quality in audio reproduction.
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