PSU-PRE - Power Supply Kit for Tube Preamp


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NOTE: At the moment only PSU-PRE4 is available, so ordering PSU-PRE  gets you the larger power supply.

PSU-PRE is available in two configurations to support up to two tubes or up to four tubes having standard heater current draws. Select either PSU-PRE2 or PSU-PRE4. PSU-PRE is low-profile and will fit inside a 1U rack chassis.

PSU-PRE2 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-PRE4 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-PRE4 can support one 6V6 or EL-84 plus one 12A_7, provided the plate supply dropping-resistors are reduced in value.

PSU-PRE uses 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; where 12V is preferred for use with our line of preamp kits and for using ERK for channel switching. The heater supply also supports the switching circuits.

The regulated heater output can support up to two/four 300mA heaters at 6Vdc or up to two/four 150mA heaters at 12Vdc.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-PRE2) or 36mA (PSU-PRE4). 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.

If you would like to receive PSU-PRE pre-assembled, add PSP-BLT to the order.

For the ultimate in low noise plate supply, add our QS-LV Quiet Supply active hum filter.

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)

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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