Published On: Thu, Dec 3rd, 2009

Seymour Duncan Twin Tube Mayhem

Seymour Duncan’s new Twin Tube Mayhem stomp box: A versatile pedal that’s perfect for metallers but not for the faint hearted.

We loved the Seymour Duncan Twin Tube: it’s an ideal way to turn a non-master volume valve amp into a three-channel tone machine. Some players, though, have complained that it isn’t gainy enough. Cue the SFX-04 Twin Tube Mayhem – an all-valve distortion/boost designed around a pair of mini military spec Phillips-Sylvania 62051 pentode tubes and voiced for ‘old school metal, new metal, thrash, death and doom’.
Not all valve pedals are what they seem, but the Mayhem’s valves run at full plate voltage to work at their full potential and provide maximum dynamic range. However, the signal path isn’t all-valve, as added gain is achieved with a high-voltage, low-noise, discrete Class A input stage.
The control layout and features are virtually identical to the Zenith’s. You get Gain, Volume, Bass and Treble knobs, plus a Mid control with two user-selectable frequency ranges – High (1.4kHz) and Low (600Hz). The treble and Bass knobs both offer +/- 12dB at 2.93kHz and 126Hz… pretty much the frequencies that sound engineers will sculpt to shape a rock tone.
The On switch is true bypass, and there’s a clean boost footswitch, too. You can pre-select the boost level with the 4dB/8dB switch. Build quality is impressive, both inside and outside: the chassis is heavy duty steel, and the pedal has a dedicated 16v power supply to cope with the high 560mA current draw.

Turning on the Twin Tube Mayhem for the first time is pretty thrilling. It’s slightly noisy and nowhere near as refined as the Zenith, and you can forget subtle overdrive: that’s not what it does. Forget clean boost, too, because the Boost is not independent – it’s there to provide a lift for solos without changing the basic tone. Despite the Mayhem’s very high-gain nature, the response is unmistakably valvey. Add humbuckers and it’s instant ZZ Top with tons of pinched harmonics and endless sustain.
With humbuckers the Mid control is more useful for cutting rather than boosting, especially if you’re into scooped metal. Applying a 600Hz boost gives a bit of that old-school Marshall tone, and a 1.4KHz boost adds a hint of nasal honk that helps solos cut through.
Rather than being the kind of pedal you kick on and off when required, the Mayhem can form the basis of your tone. It doesn’t clean up from a guitar volume particularly well, though, so best look elsewhere for really subtle overdrive.


The Arteffect Zenith is extremely versatile, but accessing its features isnt entirely ergonomic. If youre tweaking sounds at home or in the studio its fine, but it might have been more sensible to assign the gain boost or clean boost functions to a footswitch rather than to a push/pull switch. The Twin Tube Mayhem has that one sussed, but its a shame that the Boost doesnt work independently of the distortion. It provides far less tone variety and drive-shaping potential than the Zenith: if you like the basic sound that might not matter too much, and this lairy device is not for the faint-hearted.

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