PSX - Power Scale Control Switch


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PSX provides an easy interface between ERK Electronic Relay Kit and multiple Power Scale controls.

In a 2-channel amp fitted with Power Scaling, it is sometimes desireable to have two different Power Scale settings to more completely distinguish the amp sounds. ERK can handle the preamp switching tasks but cannot directly switch the Power Scale controls - PSX allows that interface.

PSX includes the Power Scale control, interface circuitry, a jfet to be driven by ERK, and a small PCB that is supported by the control itself.

For a 2-channel amp two PSXs are required.
For a 3-channel amp three PSXs are required.
...and so on.

Note that some means must also be provided to switch the Drive Compensation controls. Usually these require series switching; a relay, such as our RLY Mechanical Relay, is most suitable. To drive RLY from ERK requires adding a BJT and base-stopdriven by one of ERK's outputs, and powered from the same supply as ERK.

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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