Australia’s MI Amplification has a small stable of top-quality tube amps – currently the Megalith, the Revelation and the Iron Duke. The Megalith is the meanest-looking of the bunch, with understated but decidedly tough-looking cosmetics and an imposing ‘none-more-black’ colour scheme. I tested the Megalith Beta with a matching MI Amplification speaker cabinet with four US-made, 12-inch, 8 Ohm Eminence Wizard speakers in an 18mm void-free plywood enclosure.

The preamp features two independent channels (Clean and Overdrive), each with Gain, Bass, Middle, Treble, Volume and Contour controls, as well as a three-position EQ Shift switch. The Contour control works in the phase inverter, and its effect can particularly be heard in the tightness or looseness of the sound and attack. When turned to the left it emphasises fat mids, while increasing travels to the right scoop out the mids and increase the bass.

The EQ Shift switch selects between three voicings – 0 shifts the midrange frequency upwards and adds more low mids as well; 1 offers a more ‘British’ tone, with a more even frequency spread; and 2 is more scooped and ‘American.’ The Clean channel also includes a three-position Attack switch which further adjusts the tightness and response, while the Overdrive channel has a three-way Mode switch for low, medium and high gain voicings.

In the power amp, things get even more interesting. With four tubes in a push-pull configuration, you can install KT100, KT90, KT88, KT77, 6550 (this is what was in the test model), EL34 or 6CA7 power tubes for between 150 and 200 watts of output power. If that’s too much for you though, you can drop the output power to 40% by selecting the low power mode on the Standby switch.

Around the back you’ll find speaker outputs (16 Ohm, 8 Ohm or two 16 Ohm, 4 Ohm or two 8 Ohm), the jack for the supplied three button foot switch (which controls Channel Select, FX Loop on/off and Master Volume Select), and the serial FX loop Send and Return. The loop is a tube-buffered, line level affair, and the individual channel Volume controls double as send level controls, which means you can fine-tune the loop’s response to guitar-level effects.

The Clean channel is deliciously tactile, and a little delay and reverb through the effects loop plus the highest setting on the Bright switch created some great spacey clean tones that reminded me of some of my favourite ‘direct into a really really nice desk’ sounds. The channel is capable of an airy ‘zing’ with powerfully tight bass, which lends an almost harp-like ring to humbuckers and a nice sense of chime to single coils. When set to a perfectly clean sound it’s a great platform for fuzz and distortion effects (where the Contour control really seems to aid in taming that annoying midrange ‘honk’ you sometimes get with distortion pedals), while higher gain settings introduce a pleasing AC/DC-like crunch, all the way up to a George Lynch-like rhythm overdrive. With the bright switch off, it emphasised the sweet warmth of my Strat’s vintage-spec single coils, but when I plugged in my Ibanez UV777BK with DiMarzio Crunch Lab and LiquiFire pickups, the same exact setting was tough and punchy. As guitarists our ears are really attuned to distinguishing between the fine details of high gain sounds, but the Megalith Beta seems to take a lot of care with how it handles your clean tones too, emphasising the unique characteristics of whatever guitar you plug into it.

The Contour and EQ Shift controls are the keys to getting the most out of the Megalith Beta’s high gain sounds. Low Contour settings and a ‘1’ EQ Shift selection will give you a singing, harmonically rich lead tone with nice sustain and cut, while higher Contour settings hollow the tone out for a more Passion & Warfare kind of lead sound. Flipping the EQ Shift to 2 and cranking up Contour creates an intense, Dimebag-esque metal tone that works especially well with high-output pickups such as the Crunch Lab. It didn’t work so well with the Strat, again demonstrating just how reactive the Megalith is to different guitars.

The three-way Mode switch, which increases the amount of gain, can be used in balance with the actual Gain pot in interesting ways. A lower Gain pot setting in conjunction with the highest Mode setting seems to have a different character to a high Mode setting and low Gain setting. I found that a high Gain level and low Mode setting worked better with the Strat, allowing a nice full sound with nice dynamics and some great rock crunch, Richie Kotzen style, while killer punchy metal tones can be found by setting Mode to high and Gain all the way up, then chugging out on a palm-muted open string while progressively rolling back the Gain control until the ‘kshh kshh’ between notes goes away. Right at that edge there, with the Contour knob more to the left, you’ll find a killer djent tone that worked great with the lowest reaches of my 7-string. In fact, one of the Megalith’s most endearing characteristics is in the way it handles midrange no matter where you are on the neck. If you’re playing high single notes, the mids seem to tame the highs just enough to keep things sounding too harsh. Move back down the neck to the lowest notes and that high end sticks through nice and clearly for definition in metal rhythms, but with enough midrange power to cut through thrashing cymbals and thudding kick drums.

With all that tone-sculpting power over there on the EQ Shift and Mode switches, it’s easy to forget that the Attack switch is waiting back over there by the Gain control. It’s especially handy at higher gain settings where you might really need a raging fireball of distorto-power, but with attack and punch at the start of the note (note that because the Megalith has huge amounts of available gain, the effect of the Attack switch diminishes as the amp gets too saturated). Prog metalheads (like me) will especially love this feature, because it means you can have decent amounts of distortion yet with plenty of articulation. Higher Attack settings really help to emphasise the pick attack for those Petrucci-like neck-pickup alternate-picking runs.

High gain isn’t all the Megalith Beta is about though. EQ Shift 1, Attack 0, Mode 0 and with the Contour and all of the tone controls around halfway up (then tweaked to match your pickups) will give you a killer hard rock rhythm tone – higher Attack settings bring out a bit more Diver Down or Nuno vibe – which can then be enhanced further with a clean boost or an overdrive pedal, in conjunction with switching to a higher Master setting, for a sustaining, harmonic-dripping lead sound.

Want to hear it in action? Here’s a song I whipped up using just the Megalith Beta and matching cab, mic’d with a Shure SM57. The guitar is the Ibanez UV777BK with DiMarzio Crunch Lab and LiquiFire pickups.

MI Amplification Megalith Beta Demo by I Heart Guitar

My only criticism of the Megalith isn’t really a criticism at all, but depending on how you look at it, the layout of the controls is either perfectly logical or a little confusing, since the various controls are not grouped separately by channels but rather by sections depending on what they do: Pre; Post 1, Post 2 and Master. (To be fair, this is more an issue for someone trying the amp out for the first time rather than something that will bother you if you buy and get to know the amp). Pre features the gain controls for each channel along with the associated Bright and Attack switches. The Post 1 and Post 2 sections host the Bass, Middle, Treble and Volume controls for the respective channels (and the three-way Mode switch for the overdrive channel), while the Master section includes Contour 1 and Contour 2 controls as well as Master A and Master B. Blue and red LEDs in each section – blue for Clean, red for Overdrive – will give you more a hint of what’s active in each channel. The Master A and Master B controls are separate from all of this: they are active across both channels and can be used for a volume boost for solos.

The Megalith Beta doesn’t seem to run into any dead ends when it comes to overdrive and distortion tones. There’s so much gain that you’ll never feel the need to look for more, but the lower-gain crunch and overdrive sounds are also fully realised. It’s so common for a high gain-optimised amp to not quite cut it at the lower end of the spectrum, but no matter what you’re asking the Megalith Beta to do, it sounds like it’s meant to be doing it.