Rocktron Voodu Valve On-Line

The Rocktron Voodu Valve On-Line is a tube driven programmable 24-bit DSP guitar preamp with effects, announced by Rocktron on September 24, 2006¹. It packs a tube preamp section and a bank of digital effects into a single-rack package, aimed at players who want one box that shapes their core tone and handles time-based and modulation effects at the same time.

Rocktron positions the On-Line as part of the Voodu Valve family, a line the company describes as a professional tube guitar preamp with 24-bit DSP processing². The "On-Line" part of the name refers to its downloadable preset system: presets created by real-world Voodu Valve owners, including players like Gary Hoey and Neil Zaza, available through Rocktron's Patch Bay¹.

A tube preamp with digital effects

The Voodu Valve On-Line combines two stages: a tube-driven preamp section that generates the core gain and character, and 24-bit digital signal processing for the effects. Rocktron says the design gives you "the warmth and clarity of your favorite old 'plexi' or 'pre-CBS' combo in a convenient single-rack package," with high tube gain and minimal digital distortion producing natural, medium-saturated tones reminiscent of a maxed-out half stack¹.

Players can choose between high and low tube gain selections, depending on how much tube break-up they want for their application¹. That choice sits at the heart of the unit: the tube stage sets how hard the preamp works, and the digital side then adds effects without piling on digital clipping.

The Voodu Valve family has a history that goes back further than the On-Line. Rocktron's news pages from October 1996 mention hooking producer and guitarist John Shanks up with a Voodu Valve preamp, which he intended to use for recording in his home studio³. In 1996 the company also offered a VooDu Combo rack package bundling the VooDu Valve tube preamp with a Velocity 120 power amplifier and a Rocktron MIDI Mate footcontroller³. Decades later, Rocktron re-released the preamp as the VooDu Valve LTD, a limited edition version of what the company calls its legendary DSP professional tube guitar preamp⁴.

Voicings, EQ and effects

The preamp section includes voicing controls Rocktron describes as "totally usable features such as Variac, Triode, Pentode and Solid State voicings"¹. These voicings, which Rocktron notes are not found on other preamps, let a player shift the character of the tube stage rather than just its amount of gain⁵⁶.

On the EQ side, the On-Line carries a four-band full parametric post EQ section and what Rocktron calls a comprehensive pre EQ section, so tone shaping is available both before and after the preamp stage¹.

The effects list covers most of what a rack player would want:

• Two-tap chorusing
• Dual-mode phaser
• Two-tap flanger
• Compression
• Frequency programmable wah-wah
• Tremolo
• Reverb
• Delay with tap tempo mode
• Pitch shift
• HUSH noise reduction¹

The broader Voodu Valve manual adds a speaker simulator to this picture, with selectable speaker types of 15", 12", 10", 8" and Full Range, plus mic position and reactance controls ranging from -15dB to +15dB, where negative reactance simulates an open-back cabinet². The manual also lists effect configurations that chain blocks together, such as Wah, low-gain distortion, delay and reverb in series².

Power and connections

The On-Line runs on a 9VAC supply rated at 3400mA¹. The related Voodu Valve manual describes the hardware behind this: a 4-pin DIN power jack that accepts power from the supplied 9VAC/3.4A adaptor, which the unit processes internally to bipolar plus and minus 15 volts².

For connections, Rocktron describes the unit as "studio and stage ready with XLR balanced outs (with level control) and 1/4″ outs"¹. The Voodu Valve manual details the same output scheme: left and right balanced XLR output connectors for direct mixer input, plus left and right 1/4" unbalanced output jacks, with the left unbalanced jack also accepting stereo headphones of 600 ohms impedance or greater². Input impedance is 470K ohms¹.

The front panel display provides 16 characters consisting of 14 segments each, used for preset names and parameter readouts².

Presets from Voodu Valve owners

The feature that gives the On-Line its name is downloadable presets. Rocktron's Patch Bay system holds presets created by real-world Voodu Valve owners, including artists like Gary Hoey and Neil Zaza¹. Rather than factory-only patches, a player could pull sounds designed by working guitarists who used the same preamp.

The unit is also fully wired for control. Rocktron states that all MIDI functions have been employed, including eight parameter continuous control and mapping¹. On the related Voodu Valve, the manual adds that any or all presets may be dumped to a sequencer or another Voodu Valve via system exclusive messages, including parameter values, title characters and controller assignment and limit information². That makes it possible to back up sounds, share them between units, or integrate the preamp into a larger MIDI-controlled rig, alongside rack units like the Rocktron Prophesy or Rocktron Replifex.

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