Keith Merrow's guitar strings: the 7-string solo rig, sourced

What's on the guitar

Keith Merrow's rig sits on the technical side of modern metal:

Guitars: Schecter KM-7 MKIII (current signature), Schecter KM-7 MKII (previous generation), 7-string neck-through construction.
Strings: Ernie Ball 7-string Cobalt Slinky, custom .009–.062.
Tuning: 7-string Drop A (A-E-A-D-G-B-E) as the primary tuning for Conquering Dystopia and solo material.
Pickups: Fishman Fluence Keith Merrow signature humbuckers (bridge + neck) on the current KM-7 MK-III Hybrid. His earlier-generation KM-7, used on Alluvial's 2017 debut, ran Seymour Duncan Nazgûl (bridge) + Sentient (neck).
Amps: Fractal Audio Axe-Fx III, Kemper Profiler, and a long history of Peavey 6505 / 5150 profiles.

Merrow is one of the original "YouTube-first" metal guitarists, his public gear documentation has been unusually detailed across a decade of videos, rig rundowns, and Sevenstring.org forum activity. That's part of why his string spec is easy to source.

Endorsed vs. verified use

The relationship is signature guitar endorsement with a factory Ernie Ball string set. Schecter's KM-7 MK-III Hybrid spec sheet lists the factory strings generically as Ernie Ball 7-String (.009/.011/.016/.026/.036/.046/.062), without naming the Cobalt line. The Cobalt wrap is confirmed separately: in a 2017 Wired Guitarist interview, Merrow and Wes Hauch state plainly, "Strings used were Ernie Ball Cobalt .9-46 with .62 low on the 7 string guitars," describing the rig used on Alluvial's debut album. Community discussion on Sevenstring.org corroborates the same gauge, though that's forum chatter rather than a manufacturer confirmation.

Why .009–.062 on a 7-string

Most 7-string sets run .010 or heavier on the plain high E. Merrow's .009 is a deliberate choice for lead playability, faster runs, wider bends, lighter picking attack on the top strings. The heavier .062 low A anchors the low end on the KM-7's 26.5-inch scale (Merrow does not play a fan-fret, the KM-7 is a straight 26.5-inch neck).

The Cobalt wrap choice matters most on the .062 low string. In Drop A, even on a 26.5-inch scale, the low note sits near the bottom of a comfortable tension range. Cobalt's higher magnetic read translates that low note into a more defined rhythm attack than nickel would at the same gauge, which is the entire engineering case for the 7-string Cobalt line.

Sources

Schecter KM-7 MK-III Hybrid, official spec sheet: strings listed as Ernie Ball 7-String (.009/.011/.016/.026/.036/.046/.062), no line name given. https://www.schecterguitars.com/Keith-Merrow-Km-7-Mk-Iii-Hybrid
Keith Merrow's own 2014 KM-7 launch post; original signature lists the identical gauge. https://keithmerrow.com/blogs/thank-you/posts/2683262/keith-merrow-signature-schecter-guitar
Wired Guitarist, "Geared: Keith Merrow and Wes Hauch of Alluvial" (2017): "Strings used were Ernie Ball Cobalt .9-46 with .62 low on the 7 string guitars." http://www.wiredguitarist.com/2017/01/28/geared-keith-merrow-and-wes-hauch-of-alluvial/
Extended Range Guitar Nerds, Schecter KM-7 MK-III review (26.5-inch scale, 24 stainless frets, Fishman Fluence Keith Merrow signature pickups). http://ergnerds.com/review-schecter-km-7-mk-iii-artist/
Sevenstring.org "Keith Merrow EB string gauge" thread, community discussion, not a manufacturer source. https://sevenstring.org/threads/keith-merrow-eb-string-gauge.311770/
Conquering Dystopia rig documentation and Merrow's own YouTube rig-walkthrough videos.

Re-verified 2026-07-08 against Schecter's current KM-7 MK-III Hybrid spec sheet.

If you want this rig

Ernie Ball

7-String Regular Slinky Cobalt (.010–.056)

.010 – .056

Price tier: $$

Why this one: Closest off-the-shelf match on the wound strings: this SKU's .026/.036/.046 middle gauges match Merrow's custom set exactly. The plain strings run a touch heavier (.010/.013/.017 vs. his .009/.011/.016) and the low string is .056, not .062, a shade lighter for Drop A. For the exact factory spec, an Ernie Ball Hybrid Slinky Cobalt 6-string pack plus a Cobalt .062 single reproduces it string for string.

Drop CDrop BDjent

View on Amazon

Full Cobalt line breakdownCobalt Slinky review Adjacent 7-string prog rigsMark Holcomb <a href="/artists/jason-richardson">Jason Richardson</a>, <a href="/artists/wes-hauch">Wes Hauch</a>Drop C tuning guide for 6-string equivalents

Frequently asked questions

What strings does Keith Merrow use?

A custom Ernie Ball 7-string gauge, .009–.062, called out on his Schecter KM-7 MK-III Hybrid signature spec sheet. Schecter lists the gauge but names the strings generically, not by line; the Cobalt wrap is confirmed separately by Merrow's own account. The .009 plain high E is lighter than most 7-string sets.

Why does Merrow use .009 on the high string?

His solo material leans heavily on fast picking and wide-interval melodic phrasing, which reads more easily on a lighter plain string. The Cobalt wrap compensates for the lower output .009 would produce on a nickel set through a passive pickup.

What tuning does he play in?

7-string Drop A (A-E-A-D-G-B-E) is the Conquering Dystopia and solo default. Some material extends lower. His 6-string work sits in Drop C or E standard.

Is Merrow endorsed by Ernie Ball?

He's endorsed by Schecter Guitar Research (his signature KM-7 MK-III Hybrid), which ships factory-strung with a custom Ernie Ball 7-string gauge, Cobalt wrap per Merrow and Wes Hauch's own account. The string endorsement is brand-to-signature-guitar rather than a direct EB signature artist contract.

What pickups are on the KM-7 MKIII?

Fishman Fluence Keith Merrow signature humbuckers (bridge and neck), per Schecter's current KM-7 MK-III Hybrid spec sheet. His earlier-generation KM-7 guitars, the ones on Alluvial's 2017 debut, ran Seymour Duncan Nazgûl (bridge) and Sentient (neck) instead; Schecter switched the signature line to Fishman Fluence for the MK-III.

Is the Schecter KM-7 MKIII the same guitar as earlier KM-7 models?

No, the MK-III Hybrid is a newer design than the original 2014 KM-7, but the factory string gauge hasn't changed. Merrow's 2014 KM-7 launch spec and the current KM-7 MK-III Hybrid both list the identical Ernie Ball 7-String .009/.011/.016/.026/.036/.046/.062 set.