Rocktron VooDu Valve

The Rocktron VooDu Valve is a professional tube guitar preamp in a single-rack-space unit, pairing a 12AX7 tube stage with 24-bit DSP digital effects. Rocktron's manual describes it as a "24 bit DSP professional tube guitar preamp providing 12 unparalleled effect algorithms"¹², and the company positions its sound as "the warmth and clarity of your favorite old 'plexi' or 'pre-CBS' combo in a convenient single-rack package"³. In practice it is a complete front end: preamp voicings, speaker simulation, noise reduction and a full effects rack in one chassis, with 254 stored presets and full MIDI control¹.

What it is and what it does

The VooDu Valve splits its job in two. The tube preamp section shapes your core gain and voicing, and the digital section supplies the effects: reverb, pitch shifting, phasing, compression, tremolo, chorus, flanging and delay, plus wah-wah, speaker simulation, HUSH noise reduction and a parametric EQ¹². The unit provides 12 fixed configurations that determine which effects are available and in what order they run, giving a wide array of preset sounds without deep programming¹.

Rocktron's own description of the character is worth quoting for what it claims:

The manual goes further on how the tube stage behaves: the Class A tube setting produces non-symmetrical clipping, which generates more even harmonics, while Class B produces symmetrical clipping with the least upper harmonics at moderate gain settings of about 30dB or less¹. For a player, that is the difference between a rounder, softer breakup and a tighter, cleaner one, chosen from the front panel rather than by swapping amps.

Controls and voicings

The preamp's tube stage is shaped through the Low Gain TUBE parameter, which offers Class A and Class B settings. Rocktron describes the difference in terms of how each clips: the Class A setting produces non-symmetrical clipping, and therefore more even harmonics, while Class B produces symmetrical clipping with the least upper harmonics at moderate gain settings of about 30dB or less¹. Each changes how the tube stage reacts:

Around the voicings sit the speaker simulation tools. The Mic Placement parameter works as it would on a real cab: positive values simulate moving the mic toward the center of the speaker cone, negative values toward its edge⁴. The HUSH noise reduction acts as a low level expander, working like an electronic volume control; a 20dB drop in input level causes approximately a 40dB drop in output level¹.

Front panel navigation is simple: a PRESET control scrolls through the successive presets, a RECALL button recalls the displayed preset, and a 16-character display shows where you are¹.

Power and connections

The power is internally processed to bi-polar +/-15 volts¹. Connections on the chassis cover every common routing:

• Input: standard unbalanced mono 1/4" front panel jack, with an INPUT LEVEL control to match your guitar's signal¹
• Outputs: balanced XLR left and right for direct mixer input, plus unbalanced 1/4" left and right for a guitar amplifier¹²
• Headphones: the left unbalanced jack also accepts stereo headphones of 600 ohms impedance or greater¹
• MIDI: MIDI IN on a 7-pin DIN jack, MIDI THRU/OUT on a 5-pin DIN jack, with full MIDI implementation covering program changes, channels and dump/load¹
• Footswitch: a 1/4" mono jack for a momentary footswitch controlling the Tapped Delay feature¹

The OUTPUT parameter selects whether the output is a stereo left and right signal or two mono signals¹.

Foot control and MIDI

The dedicated remote is Rocktron's All Access MIDI footswitch, connected through a 7-pin DIN REMOTE jack. Preset titles, pre-assigned effect on/off functions and a boost option transfer automatically to the All Access³. A PHANTOM POWER 2.5mm jack can power Rocktron MIDI foot controllers through pins 6 and 7 of a 7-pin MIDI cable, so a compatible controller needs no separate supply¹. MIDI program numbers can also be assigned to VooDu Valve preset numbers, for example mapping MIDI program #58 to preset #34¹.

History and the LTD re-release

The VooDu Valve name goes back to Rocktron's 1990s rack era. In August 1996 the company offered a VooDu Combo rack package bundling the VooDu Valve tube preamp with a Velocity 120 power amplifier and a Rocktron MIDI Mate foot controller⁵. That same year, Chris Hicks, playing with Reba McEntire, used his VooDu Valve preamp for all live performances with Reba⁵. In 2006 Rocktron announced the Voodu Valve On-Line, a tube driven programmable 24-bit DSP guitar preamp with effects and downloadable presets, keeping the same 19" x 1.75" x 7" dimensions and 470K ohm input impedance.

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