QS-HV - Quiet Supply for High-Voltage Tube Amps


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The QS-HV provides a large reduction of supply-borne noise and hum - typically 60dB from 50Hz to 120Hz. Supply noise is especially problematic for single-ended amps, but the QS-HV will make an SE amp as quiet as a well-balanced push-pull amp. Quiet anything from a Champ, Valve Jr., GA-3/4/5/6 and all the clones, to "big" SE amps using 845s or 211s at 800V, to all those 500V push-pull amps, including Marshall, Fender, Peavey, Hiwatt, Mesa, and pretty much every other amp brand and model.

Note that most single-ended amps for guitar operate at less than 450V and/or have limited space in their chassis. See our QS-LV for these amps.

Push-pull amps benefit from QS-HV's hum reduction, too. Switching to triode mode in most amps causes an increase in hum. With QS-HV installed the supply will be QUIET and so will both triode and pentode operating modes. Tame the noise of your clipped plexi, Trainwreck, Komet , Marshall or other non-master-volume amp.

Supply voltages up to 900Vdc are accommodated. On-board current limiting protects both QS-HV and your amp. In most very high-power tube amps, quieting the supply from the screen node onward achieves good effect.

Proper heat sinking is required. In most amps, the chassis will suffice as the heat sink. In amps over 100W, or that are cathode biased for 30W and over, it is best to add a fan to cool the chassis. An aluminum heat sink is also a good idea on larger amps.

Installation of QS-HV will bring your amp one step closer to achieving the noise performance of London Power's amp line.

PCB dimensions: 2,7 x 1.7", 69 x 43mm

Kit requires assembly.

Kit includes notes with installation tips + layout and schematic diagrams of the kit.

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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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