The Rocktron ValveSonic Black Plate + is an all-tube guitar preamp built for 19-inch rack mounting, developed by Rocktron together with LA Custom1. Rocktron describes it as capturing the tone of the iconic American combo known for its pristine clean sound and smooth overdrive when cranked up, covering 50s "Hybrid Tweed" through the 60s classic "Black Plate" Panel and the hot-rodded tones of classic California amps1. It is a four-tube design running 12AX7EH tubes1.
What it is and how it fits a rig
As a preamp, the Black Plate + shapes the guitar signal but does not drive a speaker itself. It has no power amp section, so in practice you would feed its line out into a power amp or a full-range setup, or use the instrument out into the front of an amplifier. Rocktron gives it a front panel input jack as well as rear inputs, both 1/4" mono unbalanced, which makes it usable as a plug-in-and-play tube front end in a rack or on a bench1. For players comparing rack preamps, Rocktron's line also includes the VooDu Valve, the Chameleon and the ValveSonic Plexi, the latter another all-tube ValveSonic design1.
The controls
The front panel carries a conventional preamp layout with a few Rocktron-specific twists. Rocktron describes each control as follows1:
| Control | What it does |
|---|---|
| Bass, Middle, Treble | Determine the amount of these various frequencies present in the signal |
| BRIGHT | Five-position switch providing four different bright variations, with 0 off and 5 the brightest |
| EQ 1 & 2 | Replicates two American amp EQ styles: up (1) is the 50s "Tweed" EQ with a more modern midrange emphasis, down (2) is the 60s "Black Plate" Panel EQ |
| DRIVE | Sets drive into the preamp's gain stages |
| AFTERBURNER | Works with the DRIVE control, adding another gain stage after the EQ section; when On it emulates a post phase inverter master, and Drive adjusts the amount of drive in the AFTERBURNER stage |
| Boost and "+" | With Boost On and "+" down you get an extra gain stage; with "+" up you get an additional gain stage, essentially adding an entire tube to the front end |
| Master | Determines the output level of the preamp |
The EQ 1 & 2 switch is the heart of the American-amp concept: it flips between two EQ voicings drawn from different eras of amplifier design, so the same tubes and gain stages can lean toward a 50s Tweed character or a 60s Black Plate character1. The AFTERBURNER stage sits after the EQ, which means it pushes the signal once the tone shaping is done, in the way a post phase inverter master volume behaves in a tube amp1.
Power and connections
The unit runs on mains power, not a pedal-style DC supply. Rocktron lists the power requirements as 100 ~ 120VAC/1.0A or 220 ~ 240VAC/.05A, with a power consumption of 20W1. Inputs and outputs are all 1/4" mono unbalanced: a front and rear input, and a line out and instrument out on the output side1. Input impedance is 1M Ohms and output impedance is under 100 Ohms1.
Because it is a rack preamp rather than a pedal, it belongs on a rack shelf rather than a pedalboard power setup. It is a full-width 19" unit, 6.5" deep and 1.75" tall, weighing 5.5lbs1.
Where it sits in Rocktron's range
Rocktron has built the ValveSonic line around all-tube rack preamps developed with LA Custom, and the Black Plate + is described as "another four-tube monster preamp" in that series1. Players who want a similar tube preamp approach aimed at British rather than American voicings can look at the ValveSonic Plexi, and those after programmable tube-plus-DSP designs can compare the VooDu Valve or the Gainiac 2. For a broader view of where a preamp fits a signal chain, see Preamp Pedals.
Questions
Is the Rocktron ValveSonic Black Plate + a rack unit or a pedal?
It is a rack preamp. Rocktron lists its dimensions as 19 inches wide, 6.5 inches deep and 1.75 inches tall, which is a standard single-space 19-inch rack format, and it weighs 5.5lbs (2.5kg). It has a front panel input jack as well as rear inputs, so it is meant to sit in a rack rig rather than on a pedalboard.
What tubes does the ValveSonic Black Plate + use?
Rocktron describes it as a four-tube preamp, and lists the tube type as 12AX7EH. The 12AX7 is the standard dual-triode preamp tube used in most guitar amplifiers, so replacements are easy to find. Because it is all tube with no digital modeling section, the tubes shape the whole character of the preamp.
What does the Boost switch do on the ValveSonic Black Plate +?
The Boost switch works together with the "+" switch. With Boost On and the "+" switch down you get an extra gain stage. With the "+" switch up you get an additional gain stage, and Rocktron describes this as essentially adding an entire tube to the front end of the preamp.
Does the ValveSonic Black Plate + have a power amp?
No. It is a preamp only, meaning it shapes and boosts the guitar signal but does not drive a speaker. Rocktron lists line out and instrument out jacks, both 1/4-inch mono unbalanced, so you would run it into a power amp, a powered cabinet or the return of a guitar amplifier.
Sources (1)
- ValveSonic Black Plate + Guitar Preamp, Rocktron (rocktron.com), 2024-08-28
