Posted by
May 6, 2021

Colombo Audio Eruption

The death of Eddie Van Halen in October of 2020 has spurred a series of guitar gear releases dedicated to the influential musician. Italian Colombo Audio Electronics‘ way to pay tribute to the legend was to design a Plexi-style pedal inspired by the guitar tone in the first six Van Halen albums: enter the Eruption.

The amp used in those records was a Marshall 1959 Super Lead head, which was modded by adding a Variac transformer to regulate the power supply. This, apparently, was due to a technical misunderstanding that led to a happy accident:

The legends about the esoteric modifications made to this amp stem more from the fact that, after buying it, Eddie did not realize that he should have set the head to operate at 110V, the voltage of the American mains which is exactly half the European one. To solve the problem of too low volume caused by the reduced voltage, Eddie added a Variac transformer to regulate the power supply, finding that he could even take it up to 140V without compromising the tubes. A dummy load between the head and the cabinet allowed him to play with all the controls at maximum and still have a manageable volume. This is, in short, the secret of the under-powered amp that gave birth to one of the most epic rock sounds.

That mod is recreated in the Eruption in the Variac control, which recreates the effect of varying voltage which, when that knob is raised, simulates the tone of an under-powered amp. At zero setting, the Eruption will sound like a regular Marshall Plexi.

Check out the videos of the Colombo Audio Eruption, below. We added it to our article about the Best Plexi-Style Pedals.

Eruption is a Distorsion Pedal designed and developed to get the guitar sound of the first 6 Van Halen albums, the one Eddie Van Halen used to call the brown sound.

Eddie in fact records all the first 6 albums of the band, the most important in his discography, with the same amp, and you can easily understand why on it hovers a multitude of stories and legends that still survive today.

The truth is a blend of determination, chance, luck and skills. The famous ’68 Plexi that Eddie bought second hand from England was a very regular Marshall 1959 Super Lead head. The legends about the esoteric modifications made to this amp stem more from the fact that, after buying it, Eddie did not realize that he should have set the head to operate at 110V, the voltage of the American mains which is exactly half the European one. To solve the problem of too low volume caused by the reduced voltage, Eddie added a Variac transformer to regulate the power supply, finding that he could even take it up to 140V without compromising the tubes. A dummy load between the head and the cabinet allowed him to play with all the controls at maximum and still have a manageable volume. This is, in short, the secret of the under-powered amp that gave birth to one of the most epic rock sounds.

Talking about secrets is, however, very simplistic as reliable sources state that Eddie Van Halen was very jealous of his secrets and very often he could be seen playing live giving his back to the public just to keep his guitar tricks hidden. More than once he was also seen covering his equipment with blankets.

What the Eruption pedal aims at is to achieve the brown sound through the Variac control, just like in Eddie’s Plexi, with the possibility to manage the virtual voltage through this simple control which, if kept at minimum, the character remains the same of a stock Plexi. As this particular control is raised, the same frequencies of an under-powered amp are reduced to emulate the physical phenomenon that reproduce the Variac.

Eruption is therefore a dual function pedal: those who are fond of the original Plexi sound can keep the Variac control down and get the typical Marshall historic sound (with even more gain available); those who want to recreate the brown sound of Eddie Van Halen have the possibility to choose the amount of virtual voltage drop thus generating the typical harmonic response that takes you back to 1978.