The Master Effects Tetragon is a preamp pedal based on the preamp found in the Mesa/Boogie Mark IV amplifier1. Instead of a simple gain box, it puts the Mark IV's tone-shaping stage on a pedalboard, with a full set of EQ controls and a 5-band graphic EQ on top. Master Effects describes the EQ as a gyrator-based design that runs at the equivalent of 30V for headroom and transparency1.
The controls and the 5-band EQ
The Tetragon carries six rotary controls, covering gain, level and the classic three-band tone stack1:
| Control | What it does |
|---|---|
| Volume | Sets the pedal's output level |
| Drive | Sets the amount of preamp drive |
| Master | Sets the overall level after the drive stage |
| Bass | Low shelf of the tone stack |
| Middle | Midrange of the tone stack |
| Treble | Top end of the tone stack |
On top of the tone stack sits a 5-band boost/cut graphic EQ, the kind of slider array found on an amplifier's graphic EQ section. Its center frequencies are 80, 240, 750, 2200, and 6600 Hz1.
Master Effects explains the design behind it:
"This is a gyrator-based EQ that runs at the equivalent of 30V for incredible headroom and transparency."
A gyrator EQ uses active circuitry to behave like the inductor-based filters in a vintage graphic EQ. The Tetragon's graphic EQ is a gyrator-based EQ that runs at the equivalent of 30V, which the maker credits for its headroom and transparency, and it is a 5-band boost/cut graphic EQ1.
Power, bypass and build
The pedal runs from a standard Boss-style 9V power supply, the usual center-negative barrel supply most pedalboards already carry. Internal circuitry boosts that input up to ±15V, and the EQ then runs at the equivalent of 30V1. The switching is soft-touch relay true bypass, which Master Effects describes as being for improved reliability1.
The warranty does not cover damage from using an improper power supply or from misuse, so the Tetragon should be run from a correct 9V center-negative supply1.
The enclosure is powdercoated with UV printed artwork, and each pedal uses a professionally assembled PCB, assembled by hand in Calgary, Alberta, Canada1.
Price, shipping and warranty
The Tetragon lists at $259 US plus shipping as of 26 October 2026. Shipping within Canada and the US is $20 US; shipping to the UK, Western Europe, Australia, and Japan is approximately $60 US1. Orders typically ship within 2 to 4 weeks1.
A few buying notes from the maker:
- Each pedal carries a 1 year warranty on parts and labor1
- The warranty excludes damage from an improper power supply or misuse1
- Customers outside Canada are responsible for any customs, import or VAT charges their country applies1
Where it fits
The Tetragon is part of a wider run of preamp pedals from Master Effects, including the Master Effects Transmission, the Master Effects Seventh Son, the Master Effects Super Forty, the Master Effects Cross, the Master Effects Marauder and the Master Effects JC-Pre. For more on the type, see Preamp Pedals.
Questions
What amp is the Master Effects Tetragon based on?
Master Effects says the Tetragon is based on the preamp found in the Mesa/Boogie Mark IV amplifier. It is a preamp pedal rather than a distortion pedal, so it is designed to put that amp's gain and tone-shaping stage on a pedalboard, with Volume, Drive, Master, Bass, Middle and Treble controls plus a 5-band graphic EQ.
Is the Master Effects Tetragon true bypass?
Yes. The Tetragon uses soft-touch relay true bypass, which Master Effects describes as being for improved reliability. A relay bypass uses a small electronic switch instead of a mechanical footswitch contact, so the signal path is fully bypassed when the pedal is off.
What power supply does the Master Effects Tetragon use?
The Tetragon runs on a standard Boss-style 9V power supply. Internal circuitry boosts that input voltage to plus and minus 15V, and the gyrator-based EQ runs at the equivalent of 30V, which Master Effects says gives the EQ headroom and transparency. A standard 9V center-negative supply is all that is needed.
Where is the Master Effects Tetragon made?
The Tetragon is assembled by hand in Calgary, Alberta, Canada. Each pedal uses a professionally assembled PCB in a powdercoated enclosure with UV printed artwork.
What warranty does the Master Effects Tetragon have?
Each Tetragon comes with a 1 year warranty on parts and labour. Master Effects notes the warranty does not cover damage caused by using an improper power supply or by misuse, so a correct 9V supply matters.
How much does the Master Effects Tetragon cost in the US?
The price is $259 US plus shipping as of October 2026. Shipping within Canada and the US is $20 US. Customers outside Canada are responsible for any customs, import or VAT charges their country applies.
Sources (1)
- Tetragon, Master Effects
