SEM - Single-Ended Mod


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The SEM allows the tone of a single-ended amp to be produced by any push-pull fixed-bias or cathode-biased amp. It also allows for any blend of those sounds with a continuously variable control. The SEM also is often described as "poor man's Power Scaling", as it offers a significant power reduction and early overdrive of the amp. This has been a feature of London Power's own amps for many years, and players call it "the tone control I've been looking for on every amp I ever owned".

For players considering "black-facing" their Fender amp, the SEM offers dialable black-face sound without sacrificing silver-face stability.

The installer of this mod should be able to recognize the relevant circuit points without a layout or schematic for the subject amp.

The SEM comes with notes including installation tips and connection diagrams.

About London Power

London Power was founded in 1990 by Kevin O'Connor, after two decades of research into innovative audio amplification techniques. Kevin is an audio designer, author and speaker, known for his proprietary methodology called Power Scaling, and for his eleven books on audio subjects. Whether you seek amps, kits or information, you'll find useful answers here on not just the "how" but the "why" of audio amplifier design. Please enjoy the information on this site, and don't hesitate to contact us with questions.

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