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  • The Boss Heavy Metal HM-2: New Lease of Life

    by Jim Button June 24, 2022 5 min read

    The Boss Heavy Metal HM-2 Examining The Cult 1800x800 | Boost Guitar Pedals

    The fate of the Boss Heavy Metal HM-2 looked certain to fade into history, but remarkably it has gained a cult-like following in recent years. Today, original made-in-Japan versions can sell for over £200.

    HM-2: The First Metal Distortion

    The Heavy Metal HM-2 holds the distinction of being the first distortion pedal tuned specifically for Metal, released in 1983. It was designed to emulate the sound of a Marshall stack but used some interesting circuit and component choices which resulted in a unique design. Manufactured in Japan until 1988, manufacturing was then relocated to Taiwan. Boss subsequently discontinued the pedal in 1991, citing poor sales as a reason.

    Although players as distinguished (and distinct) as Prince, Eric Clapton, Johnny Marr and David Gilmour have all used the Boss Heavy Metal HM-2 to great effect at various points in their careers - giving it more mainstream exposure than the moniker "Heavy Metal" would suggest - the HM-2's turning point was arguably the 1990 release of Entombed's Left Hand Path, which spawned a whole new signature sound thanks to the HM-2.

    Left Hand Path (1990)

    Formerly known as Nihilist, the Swedish Death Metal band changed its name to Entombed when bassist Johnny Hedlund left to form Unleashed in 1989.

    Entombed's debut studio release, Left Hand Path, was noted as inventing the "buzzsaw", "chainsaw" or "Gothenburg" sound, although it is said to have actually been developed during Nihilist demo sessions by bassist/guitarist Leif "Leffe" Cuzner.

    The sound on Left Hand Path was achieved by detuning to B, cranking all the dials on the Boss HM-2 up to maximum and running it into a solid-state Peavey combo amplifier, treated with some rackmount compression at the desk. The result was an instantly recognisable aggressive, in-your-face sound.

    When Tomas Skogsberg of Sunlight Studios in Stockholm, where Entombed had recorded Left Hand Path, introduced the concept of a dimed HM-2 to other Swedish Death Metal bands who came through the studio - such as Dismember, Carnage and Grotesque - it began to gain popularity in the wider Metal community and its unique sound could soon be heard on albums recorded across Scandinavia and beyond. 

    Various bands adjusted the recipe slightly, some using the HM-2 as a boost into a Marshall valve amp or even into a Boss Metal Zone MT-2 or a second HM-2. But in most cases, the EQ was run at maximum to take advantage of the HM-2's unique EQ section and get the most gritty, cutting sound possible.The Boss Heavy Metal HM-2 1800x800 | Boost Guitar Pedals

    The HM-2 EQ

    The Heavy Metal HM-2 is a surprisingly versatile distortion pedal despite its Metal leanings, thanks to its incredibly powerful console-style EQ which features 3 band-pass filters. These enable the user to boost - or cut - each frequency band by up to 20dB into narrow, focused peaks or troughs.

    In the hands of Swedish Death Metal bands, it was typically used without much finesse: cranking every knob. This actually worked very well, especially in the context of Metal. Two strong peaks at around 88Hz and 1kHz create a scoop at around 200-300Hz, which tightens up the sound considerably - perfect for fast chugging and searing solo runs.

    Because of its unique EQ, the HM-2 has a less expansive sound than almost any other distortion pedal, which naturally leaves space in the mix for other instruments - perfect when recording and playing live.

    Shop HM-2-type Pedals

    The Kink Guitar Pedals Oath Of The Goat brings 80s "chainsaw" metal tones up to date, with suitably demonic graphics to match the sounds it produces. Mark from Kink Guitar Pedals says, "The HM2 is an interesting effect. There are so many tone options available, but people seem to only use the iconic Swedish sound. When I came out with the Oath, I was getting into my pedal collecting. The prices people were paying blew my mind. I figured I could offer something with some Kink personality at a fair price and I'm happy with how it turned out."

    The KMA Machines Wurm 2 is an update on the company's original Wurm, which pays its respects to the legendary heavy rock and metal pedal, the Boss Heavy Metal HM-2. The Wurm 2 takes the HM-2's legendary dual-band EQ and expands it to 4 bands, giving you maximum tweakability - ideal for getting your sound to sit perfectly in a mix or live-band situation. Each band has an internal trim-pot to shift its semi-parametric centre frequency to fine-tune your tone even further. A new internal dipswitch has been added to the Wurm 2 to activate an input filter which tames the high frequencies, smoothing it out and reducing feedback issues, especially when everything is maxed out in true HM-2 fashion.

    The KMA Machines Guardian Of The Wurm is the ultimate HM-2-style pedal thanks to its 4-band active EQ, noise gate and built in effects loop. The EQ-Style toggle allows you to set the overall character: "HM-II" mode gives the classic high-mids sound; "KMA" mode has a wider, more balanced response; "Both" doubles up the tone stack for the best of both worlds. The feature-packed, dual-footswitch Guardian Of The Wurm includes 3 clipping modes and a clean blend, while an External Trigger input allows noise gate control from an external source. And you don't need to be in a band with a name inspired by the occult to click with the Guardian Of The Wurm - the likes of Prince, Johnny Marr and David Gilmour used the HM-2 to great effect during their careers.

    Kurt Ballou and the HM-2

    Although the HM-2 defined a genre, it was not enough to prevent Boss from putting the brakes on - in 1991 the pedal was discontinued. It was only in the late '90s and early 2000s that the HM-2 reached a bigger audience than ever, partly thanks to Kurt Ballou. 

    Kurt Ballou is a founding member of American Metalcore band, Converge. Since 1990 he has been the group's guitarist. In 1998 he established GodCity Studio. Ballou has been one of the biggest proponents of the HM-2 over the last couple of decades, bringing it and its many boutique versions to the attention of a new generation of musicians who have passed through his studio.


    Despite its merits, there are a few drawbacks to the original Heavy Metal HM-2.

    As mentioned at the beginning of this article, prices for as-new made-in-Japan HM-2s are beginning to get out of hand.

    Since these are now at least 30 years old, leaky components and value drift can be a thing, meaning your HM-2 may not sound as it was intended when it left the factory.

    The HM-2 is a noisy bastard - its infamous white noise is constantly there in the background, while the feedback it induces causes squealing at every given opportunity (some might argue this is part of its charm!).

    The Distortion control is notoriously useless, only making a difference in the last portion of its travel. Probably the reason it was usually left at maximum.

    The HM-2: New Lease of Life

    Boutique versions of the Heavy Metal HM-2 have taken it upon themselves to improve the original design, whether by adding further EQ controls for finer control, additional clipping options, and even noise gates.

    Mark from Kink Guitar Pedals says, "It makes me happy to see the variations that have come out from other builders. I like it when a builder's personality comes out through their pedals." 

    At the end of 2021, Boss released a much-anticipated Heavy Metal HM-2 Waza Craft version.

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