The Sushi Box FX Grand Slampegg is a tube-powered preamp pedal for bass, based on the preamp of the Ampeg B-15N. It uses a 6SL7 tube to produce the warmth and punch characteristic of that classic amplifier, and it doubles as a DI, so it can feed an amp and a front-of-house desk at the same time1. It sits among preamp pedals and bass pedals as an always-on foundation pedal rather than an effect you switch in and out.
Controls and outputs
The pedal carries a Baxandall/James two-band tone stack with Bass and Treble controls, plus a switchable high-pass filter (HPF) that attenuates frequencies below about 90 Hz to clean up low-end rumble1. Bass Musician Magazine's reviewer, Cláudio Ribeiro, describes the Baxandall EQ as offering broad, musical tone shaping instead of aggressive frequency carving2.
| Control | What it does |
|---|---|
| Treble / Bass | Baxandall EQ controls, wide and musical by design2 |
| HPF switch | Tightens the low end by filtering sub frequencies, especially useful on boomy stages or with modern cabinets2 |
| 1/4 inch Pre/Dry switch | Selects whether the 1/4 inch output carries the processed signal or a buffered dry signal2 |
| Volume | Overall output level for the 1/4 inch path2 |
The Grand Slampegg provides both an unbalanced 1/4 inch output and a balanced XLR DI output, with independent volume controls for each1. That makes it usable as a straight-to-desk preamp or as a preamp in front of an amp, with the DI carrying the processed signal to the PA.
No footswitch, by design
The Grand Slampegg's controls are few and deliberate. The Treble and Bass knobs are Baxandall EQ controls, wide and musical by design, offering broad tone shaping rather than aggressive frequency carving2. The HPF switch tightens the low end by filtering sub frequencies, especially useful on boomy stages or with modern cabinets, attenuating frequencies below about 90 Hz1. The 1/4″ Pre/Dry switch selects whether the 1/4″ output carries the processed signal or a buffered dry signal2.
Ribeiro's review frames the pedal as a set-and-forget unit: "In live settings, the Grand Slampegg works best as a set-and-forget preamp," providing a vintage-leaning foundation that sits naturally in a band mix2. Players who switch tones mid-set would pair it with other pedals rather than rely on it for switching.
Power requirements
The pedal requires 9 to 12 V DC power at a minimum of 600 mA to operate properly, with center-negative polarity1.
At a minimum draw of 600 mA1, the Grand Slampegg needs a power supply that can deliver that current on its own output. A low-current daisy-chain output may not run it properly.
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Questions
Does the Sushi Box FX Grand Slampegg have a footswitch?
No. Bass Musician Magazine's reviewer, Cláudio Ribeiro, notes that there is no footswitch, and that the Grand Slampegg is designed to stay on, acting as the tonal foundation of your rig. In live settings he found it works best as a set-and-forget preamp, providing a vintage-leaning foundation that sits naturally in a band mix.
What tube does the Grand Slampegg use?
The Grand Slampegg uses a 6SL7 tube. According to the maker's product page, the tube produces the warmth and punch characteristic of the Ampeg B-15N amplifier the pedal is based on. Bass Musician Magazine's review likewise describes the 6SL7 as the heart of the pedal.
Does the Grand Slampegg have an XLR DI output?
Yes. The pedal provides both an unbalanced 1/4 inch output and a balanced XLR DI output, each with its own independent volume control. A 1/4 inch Pre/Dry switch also selects whether the 1/4 inch output carries the processed signal or a buffered dry signal.
What does the HPF switch do on the Grand Slampegg?
HPF stands for high-pass filter. When switched in, it attenuates frequencies below about 90 Hz to clean up low-end rumble. Bass Musician Magazine describes it as tightening the low end by filtering sub frequencies, especially useful on boomy stages or with modern cabinets.
Is the Grand Slampegg analog or digital?
The Grand Slampegg is an analog circuit. The maker's product page lists the circuit type as analog, and the pedal is described as a tube-powered preamp built around a 6SL7 tube and a Baxandall tone stack.
Sources (2)
- Grand Slampegg by sushiboxfx, RockBoard PedalPedia (rockboard.de), 2026
- Gear Review: Sushi Box FX Grand Slampegg, Bass Musician Magazine, 2026-01-19