The Master Effects Super Forty is an instrument preamp pedal built as a pedal-format re-imagining of the vintage Ashly SC-40 instrument preamplifier, a rack unit Master Effects says was "made famous by Geddy Lee of Rush" and that RockBoard's PedalPedia describes as famous for use by many bassists12. It packs the original's gain stage and semi-parametric EQ into a stompbox, adds a silicon-diode distortion toggle, and offers both balanced and unbalanced outputs, which makes it usable straight into a recording interface or a PA as well as into an amp1.
Internally the pedal runs on a charge pump: a standard boss-style 9V supply feeds an internal SMPS (switched-mode power supply) that generates plus and minus 15V, which Master Effects describes as the equivalent of running the pedal on a 30V supply for plenty of headroom1. RockBoard's independent listing confirms the same arrangement2. The circuit uses JRC4558 op amps throughout1.
What it is and where it came from
The Super Forty is Master Effects' interpretation of the Ashly SC-40, a vintage instrument preamplifier used widely by bassists. Rather than cloning the rack unit outright, the maker has rebuilt its preamp and EQ in pedal form, with the same power-supply trick the original's higher rail voltages allowed: the internal SMPS generates ±15V from a 9V input, giving the headroom of a 30V supply in a box that runs on a standard pedalboard supply12.
The distortion toggle is also rooted in the original. Master Effects says it is "the same mod that Ashly recommended in their user manual to add the clipping diodes in the effects loop of the original preamp"1. RockBoard describes the toggle as engaging symmetric silicon-diode distortion clipping2. In practice it is a documented modification to the SC-40, reproduced as a switch.
Controls
The control set is Level, Gain, and a semi-parametric 3-band EQ, plus an Input High/Low toggle and the distortion toggle12.
| Control | What it does |
|---|---|
| Level | Sets the output volume12 |
| Gain | Sets the amount of preamp gain12 |
| Low band | Shelf-type EQ, ±15 dB boost or cut, frequency sweepable from 20 to 300 Hz1 |
| Mid band | Peak-type EQ, ±15 dB boost or cut, frequency sweepable from 160 Hz to 8 kHz1 |
| Hi band | Shelf-type EQ, ±15 dB boost or cut, frequency sweepable from 700 Hz to 8 kHz1 |
| Input High/Low | Selects attenuation for instrument or line level input1 |
| Distortion toggle | Engages symmetric silicon-diode clipping12 |
The EQ is semi-parametric rather than fully parametric: each band has a sweepable frequency control and ±15 dB of boost or cut, but no bandwidth (Q) control. The low and high bands operate as shelf EQs, cutting or boosting everything beyond their corner frequencies, while the mid band is a peak type that affects a band around the selected frequency12. That mid band, sweeping from 160 Hz to 8 kHz, covers the range where most of a bass or guitar's character sits, so a player can hunt down a specific problem frequency or push a specific resonance. For more on this kind of control layout, see equalization pedals.
Power, outputs and warranty
The pedal takes a standard boss-style 9V power supply; the internal SMPS generates the ±15V rails the circuit actually runs on1. Both balanced and unbalanced outputs are provided, so the pedal can feed a mixer or interface directly as well as a normal amp input1.
The warranty is 1 year on parts and labor and does not cover damage from an improper power supply or other misuse, so the pedal should be run on a correct 9V supply to keep the coverage intact1.
Price and availability
The price is $239 US plus shipping, as listed by the maker in October 2026. Shipping within Canada and the US is $20 US, and shipping to the UK, Western Europe, Australia and Japan is approximately $60 US1.
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Questions
What is the Master Effects Super Forty based on?
It is Master Effects' interpretation of the vintage Ashly SC-40 Instrument Preamp, a rack preamplifier the maker says was made famous by Geddy Lee of Rush and that RockBoard notes was used by many bassists. The pedal keeps the original's preamp and EQ architecture in a stompbox format.
What does the distortion toggle do on the Super Forty?
It engages symmetric silicon-diode clipping. Master Effects says this is the same modification Ashly recommended in the original SC-40's user manual, which added clipping diodes in the preamp's effects loop, so the pedal reproduces a documented mod rather than a new circuit.
Is the Super Forty's EQ fully parametric?
No. It is semi-parametric. Each of the three bands has plus or minus 15 dB of boost or cut and a sweepable frequency control, but there is no separate bandwidth (Q) control. The low and high bands are shelf-type EQs while the mid band is a peak type.
Where is the Master Effects Super Forty made?
Master Effects says each pedal is assembled by hand in Calgary, Alberta, Canada. The company also uses JRC4558 op amps throughout the circuit.
What does the Super Forty warranty cover?
Each pedal comes with a 1 year warranty on parts and labour. The warranty does not cover damage from using an improper power supply or other misuse, so running the pedal on the correct 9V supply matters for keeping coverage intact.
What is the Ashly SC-40 that the Super Forty is based on?
The Ashly SC-40 is a vintage instrument preamplifier that Master Effects says was made famous by Geddy Lee of Rush. RockBoard's PedalPedia describes it as famous for use by many bassists. The Super Forty is a pedal-format re-imagining of its preamp and EQ circuit.
Sources (2)
- Super Forty, Master Effects
- The Super Forty by Master Effects, RockBoard PedalPedia, 2026