SV3 - Super-Versatile Tracking High-Voltage Regulator


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The SV3 Is a Tracking High-voltage Regulator used as part of a Power Scaling solution in tube amplifiers with widely separated screen and plate voltages. These "disparate-node" supplies are most often derived from voltage doublers.

Your amp is:
Univox: SV3 + SV1 + RBX
MusicMan RD-series: SV3 + SV2
Peavey TX-series: SV3 + SV2
Fender PS-series: SV3 + SV1
Ampeg SVT or V9: SV3 + SV1

Lower-powered amps like Univox and the MusicMan RD-series (50-120W) use voltage doubler power supplies, with Vs=250-350V and Va=500-700V. Some Ampegs, such as the SVT and V-9, have screen supplies of 350-450V with plate supplies of 700V. The Fender PS-series have Vs=400V and Va=790V. The higher range of plate voltages in these amps is beyond the capability of the SV1, so we combine two kits to Power Scale these big amps. SV1 is used to control the screen and bias. SV3 is added to control the plate supply.

SV3's paralleled mosfets easily regulate the power of these large amps, provided there is ample heat sinking and/or fan cooling. Ironically, it will be the lower-powered amps that players Power Scale (PS), and a local heatsink and fan are highly recommended. In the 300-500W amps, a fan and heatsink are absolutely required.

In more recent amplifiers where Va and Vs are both around 7-800V, use SV-TT + SV3 for Full-PS.

Multiple PS pots are readily added and switched in multi-voice amplifiers. See the SV1, SV2 or SV-TT description for more details.

SV3 allows for up to 900V difference between Va and Vs. As an extreme example, output stages such as for the Traynor Super Custom Special using EL-509 tubes with 140Vs and 560Va. Here, an SV1 can control Vs and bias, while SV3 controls Va. SV3 can be used in other situations where a high-voltage must track a lower one.

WARNING: Lethal voltage! Exercise extreme care with these voltages!

PCB dimensions: 2.2 x 1.5", 56 x 38mm

The SV3 includes PCB, components, and comprehensive notes with installation instructions + layout and schematic diagrams of the kit. The installer must be able to locate the relevant circuit points within the subject amp.

Kit requires assembly. If you would like this kit pre-assembled, add SV-BLT to have the PCB pre-assembled, The assembled boards are bulkier than the loose parts, so shipping is slightly higher.

For more info, see Selecting a Power Scaling 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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