VPS1 Tube Mic Power Supply Kit

The VPS1 kit lets you build a premium power supply for your tube microphone.

Unlike most tube mic power supplies on the market, ours does not use diodes to set the output voltage. Diodes add noise, and allow the output voltage to drift. The voltage drift causes nonlinear behavior from the mic's vacuum tube, which in turn affects the sound of the mic.

The VPS1 power supply was designed by Scott Hampton of Hamptone.com.

2022 Upgrades

We revised the VPS kit in 2022 to improve noise filtering. Filter capacitors on the B+ circuit, both input and output, have been upgraded to our custom formulation low-ESR electrolytics. Filter capacitors on the F+ circuit were also upgraded. The build guide was rewritten and improved.

2023 PCB Options

We now stock two PCB variants. The "L" shaped board is the one we've been selling for years; it fits the Alctron chassis, where the power transformer is mounted to the lower part of the chassis, and the PCB fits around the transformer.

New for 2023 is a rectangular PCB, which fits Shanghai power supplies (e.g. Avantone) where the power transformer is mounted on the PCB.

(Both PCBs could be used with either power supply, with minor adaptations. Using the "L" PCB in a Shanghai PSU requires that two mounting holes (for the transformer) be drilled in the chassis. Using the rectangular PCB in an Alctron PSU requires that the transformer be unmounted from the chassis and reinstalled on the PCB.)

Kit Options

• The "Circuit Kit" includes our custom PCB, plus 100% of components needed to populate it. It includes Neutrik XLR3 and XLR7 connectors, and US-made milspec silver/Teflon wire for all audio connections inside the supply. The circuit kit is intended to upgrade a power supply you already own.

  If you order the "Circuit Kit" version in the same cart as any of our tube mic kits ( 12-251 DIY tube microphone kit , V-251 tube microphone kit, or V-47 tube microphone kit ) you'll also receive the PSU case/chassis (flat black painted finish) and power transformer as part of the 12-251 kit. Said another way, if you order the 12-251 kit and VPS1 Circuit Kit together, you'll receive 100% of the parts needed to build our custom tube mic power supply.

• The "Complete Kit" includes everything in the circuit kit, plus a compatible chassis and power transformer. The PSU lid/cover is our California-made, vented, powdercoated design. This bundle also includes an AudioQuest IEC power cord.

Features & Benefits

• Low drop-out regulator ensures voltage regulation despite temperature and AC line variations
• Adjustable B+ and heater voltages (via internal trimpots)
• Multi-stage noise filtering
• Large heatsinks ensure lower operating temperature and long-term reliability
• Soft-start heater voltage (4 second ramp) eliminates power-on current surge, to extend tube life
• Voltage filtering in pattern selection circuit to eliminate "pops" when changing patterns
• Neutrik XLR3 and XLR7 connectors
• US milspec silver/Teflon wiring

"Circuit Kit" Compatibility

The "Circuit Kit" version of this product requires a compatible "donor" PSU like the one pictured here. We have seen these with brand names such as Alctron, Apex, and Carvin.

Our circuit board is L-shaped, like the one in this photo. If your power supply's power transformer is mounted directly on top of a rectangular PCB, we do not guarantee compatibility with the VPS1 kit.

Power Supply Compatibility

The VPS1 is compatible with the following tube microphones:

• Alctron T11-A (stock, or modified with our Fox 460 kit)
• Apex 460 (stock, or modified with our Fox 460 kit)
• Carvin CTM-100 (stock, or modified with our Fox 460 kit)
• Avantone CV-12 (stock, or modified with our V-251 circuit kit)
• the 12-251 microphone kit
• the V-47 microphone kit
• the V-251 microphone kit

Compatibility with alternative microphones

If you're building this unit, you could certainly change the location of the heater, plate, audio, and ground conductors in order to use the supply with a different 7-pin tube microphone. We can't provide support on this, but we can give you the XLR7 pinout of this PSU:

• Pin 1: plate voltage, 120VDC (adjustable via trimmer)
• Pin 2: heater voltage, 6.1VDC (adjustable via trimmer)
• Pin 3: rear diaphragm voltage (0VDC for Omni, 60VDC for Cardioid, 120VDC for Fig8)
• Pin 4: ground
• Pin 5: audio out from microphone
• Pin 6: audio out from microphone
• Pin 7: ground
• Shield: ground

The VPS1 is known to not be compatible with Rode tube microphones. Use of the VPS1 with any microphone not listed above is at the buyer's risk. We strongly recommend you verify pin-for-pin compatibility and voltage requirements before purchase.

Quirks of the Powdercoated Finish

We use a heat-treated ceramic powdercoat finish on the lid for the VPS1 "Complete" kit. These lids are manufactured in California. Powdercoating gives a very durable finish that is resistant to scratching and physical wear. Due to its origins as an industrial solution for preventing corrosion, its application tolerates minor cosmetic imperfections such as small bumps, dust nibs, and the like.

You'll want an appropriate cable

We strongly recommend pairing this power supply with our Gotham GAC-7 tube microphone cable. We think this is the finest tube mic cable in the world.

One more upgrade option

We developed a drop-in upgrade for the two bridge rectifiers used in the VPS. See our bridge rectifier kit, which replaces the monolithic silicon rectifiers (used in both the B+ and heater circuits of the VPS) with discrete Telefunken sinterglass diodes.

Don't want to build it?

We sell this as a completed unit; see our VPS1 Tube Mic Power Supply.