Description
A tube amp power supply that’s quiet.
Tube power amplifiers require various voltages for the plate circuit, bias and heaters. London Power’s super-quiet PSU power supply unit provides an integrated power supply solution that is compact while providing extremely clean support for tube audio circuitry. These supplies are so good, we use them in our own amplifiers!
The PCB accommodates wiring for world-wide mains compatibility. The board itself supports the following:
- dual mains fuses
- 120-240V mains
- plate supply up to 500V or 600V
- accommodates CTed and non-CT windings
- compatible with Hammond 200/300-series
- compatible with Antek toroidals for tube amps
- compatible with Toroidy PTs for tube amps
- active hum filtering for high-voltage plate supply
- bias supply for fixed-biasing
- 6V/12V London Power heater system
- DC stand-off for heater supply (linkable option)
- optimized ground-link-isolater to chassis
- PCB measures 4.6″ x 3.5″ (122 x 89mm)
PSU-TPA can be used with modern or traditional power transformers. Traditional plate windings have a centertap (CT) that is grounded and use a half-bridge rectifier. Modern windings have no CT and are used with a full bridge rectifier. The high-current fast diodes on PSU-TPA can be configured both ways. The paralleled main filter cap positions provide ample ripple filtering and long life, and is followed by an active hum filter to reduce supply-borne noise to inaudible levels
The plate input filter is 440uF in the kits with components. The filters following and within the active hum filter are similarly massive. The bias supply has cascaded RC filters for very low noise in this most important supply. Some CTed plate windings have a tap for the bias supply, which is not preferred, but PSU-TPA can accommodate this sourcing and mitigate some of the usual noise of this arrangement. The bias supply should have its own winding, yet even the modern toroidal options lack this upgrade.
The London Power 6V/12V heater configuration allows the actual heater wiring to be small-gauge wire, typically #20 or #22. Some of the modern toroidal PTs have dual 6V windings that can be wired effectively in series, as the kit notes show, supporting both 6V and 12V tube heaters. Otherwise, the traditional 6V-only heater wiring can be accommodated. In either case, a DC-stand-off is provided for a 30db reduction of heater noise.
Doubled output wiring blocks are provided to facilitate connection of multiple power amps, preamps and auxiliary circuits. All wiring should be #22 twisted as appropriate. Transformer leads should be #18 or smaller., except for the heater where #14 wire is accepted. The heater area has multiple output wiring blocks.
PSU-TPA makes an excellent power supply upgrade for many of the TUT3 (The Ultimate Tone vol.3) projects.
If you want to build a bass amp like the 80W Bassmaster or 160W Custom Special, use the 600V version.
Extra fuse blocks are recommended, as it is highly beneficial to protect every secondary and also to protect each output stage. Use only slow-blow fuses around the power transformer and fast-blow types for output transformers.
Available configurations:
PSU-PCB: PCB and kit notes
PSU-5-COMP: includes PCB, 500V caps, components, kit notes; assembly and installation required
PSU-5-BLT: assembled PSU-5; installation required
PSU-6-COMP: includes PCB, 600V caps, components, kit notes; assembly and installation required
PSU-6-BLT: assembled PSU-5; installation required
