Ernie Ball Mammoth Slinky Cobalt (.012–.062) review: the heaviest 6-string Cobalt Slinky Ernie Ball makes

Same cobalt-iron wrap as the rest of the line, more of it. At .062, the low string has more wrap-wire mass moving in the pickup field than any other standard 6-string Cobalt gauge, which pushes the line's signature voicing furthest at this end of the range.

For the full measured Cobalt-vs-nickel breakdown (output dB curves, brightness over a tracking week, bend feel, pickup compatibility), see Cobalt vs nickel Slinky: the voicing difference, measured.

Mammoth Slinky Cobalt is the heaviest of Ernie Ball's twelve standard 6-string Cobalt gauges, and the answer for players whose 6-string lives below Drop C:

• E standard / Eb standard: Regular Slinky Cobalt (.010–.046) is the default.
• Drop D / D standard: Power Slinky Cobalt (.011–.048) or Skinny Top Heavy Bottom Cobalt (.010–.052).
• Drop C / C standard: Beefy Slinky Cobalt (.011–.054) or Not Even Slinky Cobalt (.012–.056).
• Drop B / Drop A# / baritone B standard: This set, Mammoth Slinky Cobalt (.012–.062).
• Drop A and below, or an actual 7-string: step into 7-string Cobalt (Regular 7-string .010–.056, Power 7-string .011–.058, or Skinny Top Heavy Bottom 7-string .010–.062) instead of pushing a 6-string past what it's built for.

The full gauge-by-gauge picking guide is at Ernie Ball Cobalt Slinky gauges explained.

We don't have a primary-source citation for a specific artist on this exact .012–.062 6-string gauge. The documented Cobalt roster skews lighter: Dustin Kensrue (Thrice) runs the two-steps-lighter Beefy Slinky Cobalt (.011–.054), and the players documented on Cobalt in Drop A and below, Jason Richardson among them, are on 7-string Cobalt sets rather than a 6-string pushed to .062.

That's consistent with how the gauge is built: Mammoth Slinky Cobalt is a 6-string answer for Drop B and baritone territory, a smaller slice of the market than standard-tuning or Drop-D-and-up players, so it shows up less often in rig rundowns and artist interviews. If you have a sourced example of a player on this specific set, send it and we'll add it with credit. The full documented Cobalt pro roster, kept current as new citations come in, lives at Who plays Cobalt Slinky strings, the documented roster.

• Drop B (B-F#-B-E-G#-C#) on a 25.5-inch scale. The set's home tuning.
• Drop A# / baritone B standard on 25.5-inch scale electrics built or set up for the extra tension.
• Doom, sludge, stoner, and modern metal rhythm work tuned a fourth or more below standard, where a lighter Cobalt gauge starts to flap.
• Players who want Cobalt's louder, more upper-mid-forward voicing at the bottom of the 6-string range, instead of switching to nickel or going straight to a 7-string.

• E standard or Eb standard. Wildly overbuilt; the .062 low string has no reason to exist at that pitch. Use Regular Slinky Cobalt instead.
• Drop C or C standard. Not Even Slinky Cobalt (.012–.056) or Beefy Slinky Cobalt (.011–.054) sits better; Mammoth's extra gauge step is wasted a full tuning step above where it's built for.
• Drop A and below on a 6-string. At that point you're fighting the instrument. Move to a dedicated 7-string Cobalt set instead of chasing range a 6-string wasn't designed to cover.
• A guitar with no recent setup. Jumping to .062 on the low string from a lighter gauge is a bigger tension swing than most single-gauge jumps in the catalog; skipping a setup pass risks a buzzing, poorly intonated result.
• Floyd Rose floating tremolo without spring recalibration. The tension jump will pull the bridge out of balance until the springs are adjusted to match.

This is one of the largest gauge jumps in the Ernie Ball catalog if you're coming from a lighter set, plan on a full setup pass: truss rod relief, nut slot width on the wound strings, bridge intonation, and possibly spring tension on a floating tremolo. The truss-rod-aware walkthrough is at Heavy-gauge electric string install guide.

Break-in runs about 30–45 minutes of playing before the bright initial top end settles into its played-in voice. Stretch each string before that: press behind the 12th fret, pull up about an inch, three to four times per string, retune, repeat.

If your 6-string lives in Drop B, Drop A#, or baritone B standard and you want Cobalt's louder, more upper-mid-forward voicing at the bottom of that range, Mammoth Slinky Cobalt is the only standard 6-string Cobalt gauge built for it. The .062 low string holds the rigidity that tuning needs; the .012, .016, .024 plain top three still bend like any other Cobalt set.

Don't buy this gauge for anything above Drop C, it's overkill there, and don't push it below Drop A on a 6-string, that's a 7-string Cobalt's job. Match the gauge to the tuning, not the other way around.

Ernie Ball

Mammoth Slinky Cobalt (.012–.062)

.012 – .062

Price tier: $$

Why this one: The heaviest standard 6-string Cobalt Slinky Ernie Ball makes. Drop B and below, where a lighter Cobalt gauge starts to flap.

Drop BDrop A#Metal

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