SL-MV - Splitter Limit Master Volume


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Techs and amp designers have used various methods to control the gain of the Schmitt splitter as a means of controlling output level. In all cases the current through the splitter is varied, as this parameter affects how much drive to the power tubes will be available. The usual methods are compromises that can introduce scratchy sounds and even "earthquakes" through the speaker as the control is manipulated. Why are these methods used? Often, the player simply wants something "different" - an alternative to traditional master volumes. Sometimes the choice is purely aesthetic - the designer or player does not want a "master volume", because the old-style MVs were known to alter tone.

The splitter control approaches are a way to side-step the master-volume issues while achieving the same goal. The SL-MV achieves this goal without sonic detriment.

SL-MV allows the splitter gain and output to be controlled by the player via a front panel control. A small PCB carries the pot plus the three components left out by everyone else - the ones essential to smooth operation. The SL-MV provides a wider range of loudness control than do the intuitive traditional wirings.

Historically, this control has been called "Limit", "Power", "Variac", "Watts", "power dampening" etc., but please be aware that the benefits to the amp are not as far-reaching as some marketers would like you to believe. Tube life is NOT extended (this is explained in our book The Ultimate Tone Vol. 4 (TUT4). Only properly implemented Power Scaling will extend tube life.

The SL-MV comes with helpful notes including installation tips and schematic diagrams of the kit.

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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