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Ernie Ball string lines compared: Slinky vs RPS vs M-Steel vs Paradigm vs Cobalt

Reviewed by the Change Your Strings editorial team ·

Ernie Ball ships five main electric string lines. Regular (nickel-plated) Slinky is the default voicing; RPS is nickel Slinky with reinforced plain strings for fewer breaks; M-Steel is high-carbon core for tighter tension; Paradigm is coated/treated for 6–10 week lifespan; Cobalt is the cobalt-iron wrap for louder, brighter output. Pick nickel for most things, Paradigm for longevity, Cobalt for high-gain definition, M-Steel for stability, RPS for break-prevention.

The five-line family

Ernie Ball's electric string catalog has two axes: the base construction (nickel-plated, cobalt-iron, M-Steel) and the preservation technology (none, RPS, Paradigm). Each line combines one choice from each axis, which is why there are five main variants rather than eight or ten.

Regular Slinky, the baseline

Built since 1962, Regular Slinky is the reference voicing against which the other four lines are judged. Nickel-plated steel wrap, tin-plated hex-core steel on the plain strings, no coating. It's the sound on most of the last 60 years of rock, blues, country, and session records. Slash, John Mayer, Jimmy Page, Jerry Garcia, and every gigging rock player of the 70s-90s played some version of this set at some point.

When to pick it: almost always, unless you have a specific reason to pick a different line.

When to skip it: if your application is high-gain Drop C (Cobalt wins), or if you can't or don't want to change strings every 1–2 weeks (Paradigm wins), or if your plain strings break at the ball-end regularly (RPS wins).

RPS Slinky, break-prevention variant

Identical to Regular Slinky on the wound strings; the plain strings (.009 or .010 to .013/.017) have a brass wrap around the ball-end. The ball-end is the stress concentration point where most plain-string breaks actually happen, the wire is crimped against the ball, and fatigue failures start there. RPS's reinforcing wrap distributes that stress over a longer section, which shifts the failure mode from "frequent ball-end breaks" to "the string dulls first, then you change it."

Paul Gilbert is the most famous RPS endorser (he's on Super Slinky RPS). If you break high-E strings every session or two, RPS costs the same as Regular Slinky and fixes the problem.

When to pick it: you break plain strings frequently at the ball-end.

When to skip it: you don't break plain strings, or you break them at a fret rather than the ball (RPS doesn't help with fret-end breaks).

M-Steel Slinky, the stability line

"M" for Maraging, a high-carbon steel alloy used in aerospace and some bearing applications. M-Steel Slinky uses a Maraging core wire combined with a specific wrap pattern. The result is tighter-feeling strings at the same gauge, slightly more output than Regular Slinky (but less than Cobalt), and markedly better tuning stability at heavy gauges and drop tunings.

Adam Jones of Tool ran M-Steel at one point; it's a popular line among 7-string players who want heavier-feeling strings without stepping up a gauge. Availability is narrower than the mainline Slinky or Cobalt, some retailers only stock the heavier gauges.

When to pick it: you want tighter feel at a given gauge without bumping to a bigger set, especially for heavy rhythm work in drop tunings.

When to skip it: you're happy with the feel of Regular Slinky, or you need coated-string longevity.

Paradigm Slinky, the longevity line

Ernie Ball's answer to Elixir. A plasma-based surface treatment is applied to the wire before winding, then a nano-thin coating is applied to the finished string. The combination extends string life to 6–10 weeks of daily playing, vs 1–3 weeks for uncoated. The voicing is nearly identical to Regular Slinky once the strings are broken in; the first few days sound slightly duller before the coating settles.

Stephen Carpenter (Deftones), Jerry Cantrell (Alice in Chains), and Brad Paisley are notable Paradigm endorsers. The line is particularly popular among touring players who want to reduce string-change frequency on the road. Some retailers discount Paradigm below Elixir's equivalent Optiweb line, which makes the cost-per-week-of-use math attractive.

When to pick it: you change strings every 1–2 weeks and would prefer every 6–8 weeks.

When to skip it: you already prefer the fresh-uncoated feel of Regular Slinky and don't mind changing often, or you need a specific voicing (Cobalt, M-Steel) that Paradigm doesn't replicate.

Cobalt Slinky, the voicing line

Launched January 2012. The wrap-wire alloy is cobalt-iron rather than nickel-plated steel. Cobalt is more magnetically permeable than nickel, so the string reads louder and brighter through the same pickup. Measured output is 2–3 dB higher; brightness is concentrated in the upper midrange (2–4 kHz rather than the top octave); low-end articulation is tighter under gain.

Slash, John Petrucci, Steve Vai, and Steve Lukather were the launch beta testers. Full roster is in our 30-player Cobalt user list. Cobalt is particularly effective for Drop C and lower tunings where nickel's natural low-end bloom becomes mud under high gain.

When to pick it: high-gain passive-pickup rigs in drop tunings, session situations where you want the guitar forward without compression.

When to skip it: active pickups (redundant gain/brightness), vintage-tone applications (wrong voicing), or budget-constrained players (~40% more expensive than Regular Slinky).

Ernie Ball Regular Slinky (.010–.046), the baseline strings
Ernie Ball

Regular Slinky (.010–.046), the baseline

Price tier: $
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Ernie Ball Not Even Slinky Cobalt (.012–.056), heavy Cobalt strings
Ernie Ball

Not Even Slinky Cobalt (.012–.056), heavy Cobalt

Price tier: $$

Why this one: The Cobalt line at its highest-gain, tuned-down use case.

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Which line for which player

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