Review: Meris Mercury X

I am, by nature, a skeptic. When something generates a lot of hype, I often reflexively cast doubt on it. Few effects pedals in recent memory have created more buzz than the Mercury X from the audio wizards at Meris, which has built its reputation making high-end guitar pedals. But after using it, I can’t even try to pretend that the Mercury X doesn’t live up to the hype. It’s pretty expensive at $599, but it’s the best reverb pedal on the market, full stop.

That could be the end of the review, honestly, but I know I can’t make a statement that bold without backing it up. The Mercury X feels every bit like the high-end pedal it is and I have no doubts it would easily survive the rigors of tour life.

On the Floor

Let’s start by talking about the build: It’s rock solid. The four footswitches, four potentiometers and three push encoders are sturdy and have a good amount of resistance. The screen is bright and viewable from any angle, and the Mercury X has basically all the connectivity options you could ask for. It has stereo ins and outs, 5-pin MIDI in and out, an expression pedal jack and USB-C, though the latter is strictly for firmware updates right now.

Obviously, the hardware is secondary. It’s the variety and incredible quality of the reverb algorithms (“structures” in Meris’ terminology) packed into the pedal that make it the best available. There are eight in total, ranging from your standard spring and hall reverbs, to more exotic fare like “Ultraplate” and “Gravity”. Regardless of whether they’re more restrained or truly out there ambient washes, they sound incredible.

Familiar Favorites

I am picky about my spring reverbs. I often find that emulations are thin and obviously artificial compared to the sound of a traditional Fender amp. Even the real deal can sound cheap and toy-like when not properly implemented. But Meris knocks it out of the park with a spring algorithm that is convincing and lush at subtler settings, and when you crank it feels like your guitar is running through an impossibly large spring tank without seeming unnatural.

The 78 Room, 78 Plate and 78 Hall algorithms are borrowed from Meris’ collaboration with Chase Bliss (another relentlessly innovative guitar pedal company), the CXM 1978. That pedal is, in turn, modeled on the Lexicon 224, an iconic digital reverb unit from the late ‘70s used by the likes of Vangelis, Brian Eno, Kate Bush and Talking Heads. The difference here is that the CXM has three different versions of each of those algorithms, while the Mercury X only has the “hifi” rendition. These are all incredible sounding as well, but not super realistic. Instead, they mimic the unique character of early digital rackmount units. With the peripheral effects that Meris includes you can really lean into the lofi and imperfect nature of their inspiration.

Ultraplate and Cathedral come from Meris’ modern classic reverb pedal, the Mercury 7. These are epic, in the truest sense of the word. Sure, you can dial things down and get large, but not uncontrollable, reverb tails from them. But they come into their own when you embrace the vast voids of their extremes. The Ultraplate in particular rings out almost for an eternity even with the decay set to halfway.

The last two algorithms, Prism and Gravity, are unique to the Mercury X. They’re the two most out there options. Prism is a “dual tank that allows you to build your own geometric rooms.” That description doesn’t really give you an idea of what it sounds like. I would describe it as dense with reflections, and somehow simultaneously claustrophobic and massive. Gravity is almost granular in nature, it takes small chunks of your sound and smears them out over an infinity. If you want to play big ambient emo melody lines these two are probably going to be your best friend (along with Ultraplate).

Simply having this many incredible-sounding reverb options in a single pedal alone would be noteworthy, though probably not worth $599. What pushes the Mercury X over the edge is the incredible amount of options available for tweaking patches. There are 21 “Processing Elements” onboard, which are effects that you can add to your reverb and place anywhere in the signal chain. They range from straightforward compression to a wild granulator and a hazy lo-fi effect.

The ability to place them before or after the reverb, or even in front of the mix section of the pedal, gives you freedom to experiment. Try putting a tremolo at the very end to chop up those tails, or laying in a vibrato up front so you can use it with no reverb at all. There are even pitch-shifting effects for building your own shimmer reverb that climbs off into sparkly infinity, or rumbles that seem to emanate from deep inside the Earth.

Tweaking Sounds

There are the basic core parameters accessible directly from the front panel, predelay and mod. The former puts space between your actual playing and the reverb, and can even be combined with the Mercury X’s feedback circuit to create a rudimentary delay effect. The mod, on the other hand, adds movement that can bring subtle life at low settings and warped sci-fi chaos when turned up.

If you want to get really wild there are “modifiers,” too. They include an envelope follower, an LFO, a sample and hold circuit and even a sequencer. This gives you the ability to create complex, ever-changing reverb patches. You could use a slow LFO to change the mix so that your dry guitar signal bobs in and out of view like a buoy on rough seas, or use the sequencer to rhythmically alter the decay so certain notes ring out for near eternity.

The Mercury X is absurdly powerful, and that level of depth and customizability could easily become unwieldy, but Meris made some smart decisions with the interface. The default “graphic view” for the menu organizes parameters into pages with rotating spokes. If you want to get really deep into the sound design here you’ll have to do a decent amount of menu diving, but the unique UI is pretty easy to navigate.

If you don’t have the patience for that, you could just rely on the presets Meris has included. They cover almost anything you could want, from infinitely usable and basic plate reverb sounds, to out-of-this-world pitch-shifted chaos that make your guitar unrecognizable. Tt’s great on synths, drums, and vocals, too.

The Mercury X is expensive, but the variety and quality of its reverbs are unmatched, at least in pedal form. To get the same level of sound design tools you’d probably have to turn to a plug-in on your computer. I understand if you have a hard time swallowing the $599 price, but it might be the last reverb you ever have to buy. If you're the type of person who plays live or at home and finds reverb to be a favorite effect to toy with, rather than a set-it-and-forget-it option on your amp front, this is a very compelling tool.