Rogue Audio Stereo 90 owner manual Setting the Tube Bias

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SETTING THE TUBE BIAS

Tools required: bias tool (provided with amplifier)

The output tubes (the big ones) need to be “biased’ with a grid voltage that controls the flow of electrical current through the tube. Tube biasing on the Stereo 90 amplifier has been designed to be both simple and effective. On some amplifiers biasing is done for two or more tubes simultaneously. With this method, the total current flowing through the group of tubes may be correct, but the current flow through any individual tube may vary significantly from the optimal value. With the Stereo 90 amplifier the bias is set individually for each tube so that the correct operating point is assured. An added benefit to this approach is that, should a tube fail prematurely, the single tube can be replaced without having to purchase a matched set. Use the following procedure to set the tube bias:

WARNING – There are dangerous and potentially lethal voltages inside this amplifier. Do not touch any part of the amplifier other than as described below. If you are uncertain about any of these instructions, please contact your dealer and have them bias the amplifier for you.

1)Allow the amplifier to warm up for at least 30 minutes.

2)Turn the preamplifier volume completely off so that no signal is entering the amplifier.

3)Remove the top cover. The bias tool is snap attached to the inside top of the deck lid.

4)Locate the rotary switch and associated small potentiometers (they are blue and have a small screw in the top). There are four, one for each tube. Note the biasing meter.

5)Position the rotary switch into the corresponding tube position (ie. V1 for output tube V1).

Note – There is a small leakage current of 5mA that flows through the meter’s shunt resistor during the tube bias setting operation. To accurately account for this, set the bias current at 5 mA lower than the desired setting.

6)Using the bias tool, slowly turn the screw on the potentiometer that is adjacent to the switch until the bias meter reads ~ 35 miliamps (actually 40mA.) 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.

7)Repeat the above steps for each of the four output tubes.

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Contents Stereo Table of Contents Introduction Unpacking the Stereo 90 Power AmplifierConnecting the Stereo 90 to the Loudspeakers Installing the Stereo 90 Into Your SystemConnecting the Stereo 90 to the power outlet Connecting the Stereo 90 to the preamplifierAmplifier Location Operation of the Amplifier Triode/Ultralinear switchSetting the Tube Bias Owner and Warranty Registration Form TroubleshootingFuse Values SpecificationsLimited Warranty

Stereo 90 specifications

Rogue Audio Stereo 90 is a high-performance power amplifier that stands out in the competitive landscape of audiophile equipment. Renowned for its exceptional sound quality, the Stereo 90 embodies a blend of innovative technology and classic design principles, making it a favorite among music enthusiasts and professionals alike.

At the core of the Rogue Audio Stereo 90 is its all-tube design, which delivers a warm, rich sound that many audiophiles cherish. It utilizes a pair of KT90 output tubes, known for their high power handling and superb linearity. This tube configuration enables the amplifier to produce up to 90 watts per channel into an 8-ohm load, making it versatile enough to drive a wide range of speakers with ease and finesse.

One of the standout features of the Stereo 90 is its push-pull topology, which enhances the performance of the amplifier by minimizing distortion and improving overall efficiency. This design approach allows the Stereo 90 to maintain clarity and detail across the frequency spectrum, delivering a lifelike and engaging listening experience.

In addition to its exceptional sound quality, the Rogue Audio Stereo 90 also boasts a robust, high-quality build. Its chassis is constructed from heavy-duty steel, ensuring durability while also minimizing vibrations that can negatively impact audio performance. The amplifier is equipped with high-quality components throughout, including premium capacitors and transformers, which further contribute to its reliability and sonic excellence.

For ease of use, the Stereo 90 features a front-panel bias adjustment, allowing users to easily set the bias on the output tubes for optimal performance. The amplifier also includes a variety of input options, including RCA inputs, making it compatible with a broad range of source components.

The aesthetic appeal of the Rogue Audio Stereo 90 cannot be overlooked. Its classic design features an attractive black chassis with chrome accents, giving it an elegant yet timeless look that will complement any audio setup. The rotary controls add a touch of vintage charm while also providing intuitive access to its features.

In summary, the Rogue Audio Stereo 90 is a powerhouse amplifier that combines advanced tube technology with meticulous craftsmanship. With its ability to deliver stunning audio fidelity, it has become a cornerstone in many audiophile systems, captivating listeners with its detailed soundstage and dynamic range. Whether used for casual listening or critical listening sessions, the Stereo 90 proves to be an exceptional choice for anyone looking to elevate their audio experience.
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