The Master Effects Super Three Hundred is a bass preamp pedal based on the Ampeg SVT. The maker describes it as "our interpretation of the classic 300 watt Ampeg SVT behemoth bass amplifier," and its product page states that "The Super Three Hundred pedal is based on the classic 300 watt Ampeg SVT bass amplifier."1 The original SVT, whose name the pedal's title plays on, was a 300-watt all-tube bass amplifier; as one account of its history puts it, "the team came up with a 300-watt all-tube phantasmagoria they called the Super Vacuum Tube-or SVT, to save on vowels."2
An Ampeg SVT-style preamp in a pedal
The SVT itself has a documented place in bass history. The design team was led by amp designer Bill Hughes and Roger Cox, with input from Bob Rufkahr and Dan Armstrong.2 The Super Three Hundred brings that amplifier's preamp into a pedal format, sitting alongside Master Effects' other SVT-family preamps such as the Super Two Hundred, the Super Eight Hundred and the Super Eight Hundred Plus, and its broader line of preamp pedals.
"The Super Three Hundred pedal is based on the classic 300 watt Ampeg SVT bass amplifier."
The controls and Mid Freq switch
The pedal carries five knobs: Level, Treble, Middle, Bass, and Gain.1 Alongside them are two switches that shape the midrange in particular:
| Control | What it does |
|---|---|
| Level | Output level1 |
| Treble | Treble EQ1 |
| Middle | Middle EQ, with its center frequency set by the Mid Freq switch1 |
| Bass | Bass EQ1 |
| Gain | Gain1 |
| Mid Freq switch | 5-position rotary switch setting one of 5 center frequencies for the Middle EQ: 220, 440, 880, 1800, or 3500 Hz1 |
| Ultra Low switch | Adds a mid notch filter between 500-600Hz to scoop the mids1 |
The Mid Freq switch is the feature that sets this apart from a straightforward three-band EQ: rather than a fixed mid control, you choose which part of the midrange the Middle knob acts on, from low-mid warmth at 220 Hz up to a presence-focused 3500 Hz. The Ultra Low switch works in the opposite direction, cutting a notch between 500 and 600 Hz to scoop the mids.1
Outputs, bypass and power
The Super Three Hundred uses soft touch relay true bypass.1 Its balanced 1/4" TRS output gives you the option of sending a direct signal straight to the board or an audio interface, and that output is always on, even in bypass mode, so the pedal can serve as a DI on stage or in the studio.1
The post-July 2024 version of the pedal takes a 9V DC power supply ONLY and generates a -9V power rail to run at the equivalent of an 18V supply, with a recommended 150mA minimum. There is over voltage protection: if more than 10V is supplied, the pedal will not turn on, protecting the charge pump circuitry.1
Build and warranty
The pedal is built on a professional high quality FR4 PCB, with a 4-layer PCB for lower noise, in a powder coated enclosure with UV printed artwork.1 Each pedal comes with a 1 year warranty on parts and labor, which does not cover damage due to improper power supply or misuse.1
Price and availability
The price is $239US + shipping, as listed on the maker's product page as of 26 October 2026. Shipping within Canada and the US is $20US; shipping to the UK, Western Europe, Australia, and Japan is approximately $60US.1
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Questions
Is the Master Effects Super Three Hundred based on the Ampeg SVT?
Yes. Master Effects describes the Super Three Hundred as its interpretation of the classic 300 watt Ampeg SVT bass amplifier, and the pedal's product page states plainly that it is based on that amp. The original SVT was a 300-watt all-tube bass amplifier, designed by a team led by Bill Hughes and Roger Cox with input from Bob Rufkahr and Dan Armstrong.
What frequencies does the Mid Freq switch select?
The Mid Freq switch is a 5-position rotary switch that sets the center frequency for the Middle EQ. The five positions are 220, 440, 880, 1800, or 3500 Hz, so you can place the midrange control where it works best for your bass and the room you are playing.
Does the balanced output work when the pedal is bypassed?
Yes. The balanced 1/4-inch TRS output, which lets you send a direct signal straight to the mixing board or an audio interface, is always on, even when the pedal is in bypass mode.
Where is the Super Three Hundred made?
Master Effects assembles the Super Three Hundred by hand in Calgary, Alberta, Canada, according to the company's product page.
What does the warranty cover?
Each Super Three Hundred comes with a 1 year warranty on parts and labour. The warranty does not cover damage caused by an improper power supply or by misuse of the pedal.
Sources (2)
- Super Three Hundred, Master Effects, 2024-07
- Ron Wood, treblebooster.net (BSM - Finest Treble Booster), 2025
