PSU-PRE, our versatile Power Supply Kit for Tube Preamp, is available in two configurations to support up to two tubes or up to four tubes that have standard heater current draws. Select either PSU-PRE-12 or PSU-PRE-24.
PSU-PRE-12 tube preamp power supply can support up to two 12A_7 tubes – enough for a 2-channel preamp, for example, D-PRE or LP-PRE, or S-PRE for a stand-alone bass preamp, or two BFX effects loops, or F-PRE plus BFX, or two F-PRE.
PSU-PRE-24 tube preamp power supply can support up to four 12A_7 tubes – enough for a 3-channel preamp, for example, consisting of our two preamps LP-PRE and Z-PRE, or a 2-channel preamp with effects loop, as D-PRE or LP-PRE plus BFX, or a 2-channel preamp plus reverb as D-PRE or LP-PRE plus REV.
PSU-PRE-24 can support one 6V6 plus one 12A_7, provided the plate supply dropping-resistors are reduced in value. There is insufficient heater current to swap EL-84 for 6V6.
PSU-PRE is a low-profile tube preamp power supply, and will fit inside a 1U rack chassis.
Our PSU-PRE kits use a pair of standard Hammond 229-series transformers to create the heater and plate supplies. Both are DC and well filtered. The plate supply has two nodes that can be individually tapped with paired wiring, The heater supply can be wired for either 6V or 12V; 12Vr is preferred for use with our line of preamp kits and for using our ERK Electronic Relay Kit for channel switching. The heater supply also supports the switching circuits.
The regulated heater output can support up to two/four 300mA heaters at 6Vac or up to two/four 150mA heaters at 12Vac. There are three Links on-board that set the heater transformer wiring and regulator output to “6V” or “12V”. The regulator assures that the heater voltage will be stable and hum free.
PSU-PRE includes our GND Ground-Link Isolator on-board to eliminate ground loops between your project and other mains-powered equipment.
The plate output is approximately 320Vdc at 18mA (PSU-PRE-12) or 36mA (PSU-PRE-24). Two supply nodes are provided if some isolation is needed for the circuits attached. Otherwise, use the best-filtered node for the preamp.
World mains compatibility is as simple as moving two jumpers OR by adding a “115V/230V” switch. Wiring for this switch is accommodated by the PCB for players who travel the world.
PSU-PRE includes flameproof power resistors, metal-film precision resistors, long-life electrolytic caps, fuses and holders, an IEC connector, mains switch and the transformers. Also included are helpful installation notes with schematic and layout diagrams of the kit.
For the ultimate in low noise plate supply, add our QS-LV Quiet Supply active hum filter.
Available configurations (make your choice above):
Standard DIY Kit for Up to 2 Tubes (PSU-PRE-12) – requires assembly; includes flameproof resistors, electrolytic caps, fuses and holders, an IEC connector, mains switch and the transformers. Also included are helpful installation notes with schematic and layout diagrams of the kit.
Built Kit for Up to 2 Tubes (PSU-PRE-12-BLT) – product is pre-assembled; includes the notes.
Standard DIY Kit for Up to 4 Tubes (PSU-PRE-24) – 4-tube version.
Built Kit for Up to 4 Tubes (PSU-PRE-24-BLT) – pre-assembled 4-tube version.
For more info on London Power Preamp Kits, see our Selecting a Preamp Kit page.
Need a chassis for your preamp project? See our Rack-Mount Chassis page, or browse under Building Supplies.
PCB size: 5″ x 4.1″ (127mm x 104mm)
Photo above is of PSU-PRE-12.
Here is the PSU-PRE-24: