London Power’s Tracking High-Voltage Regulator (SV3) is 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.
Is SV3 for you?
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 our SV1 kit, so we combine two kits to Power Scale these big amps. Our SV1 kit is used to control the screen and bias. SV3 is added to control the plate supply.
SV3 Technical Details
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.
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
Standard DIY Kit: Requires assembly. 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.
Built Kit: PCB is pre-assembled. Includes 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.
For more information about Power Scaling Kits, see also:
Who can install Power Scaling for you?
Licensed Power Scaling Builders and Installers