John Petrucci's guitar strings: the Dream Theater prog-metal rig, sourced
Dream Theater · reviewed by the Change Your Strings editorial team ·
John Petrucci uses Ernie Ball Cobalt Slinky strings and was a beta tester on the line before its January 2012 launch. His documented set for 6-string in E standard is .010–.046 Regular Slinky Cobalt; he plays custom 7-string Cobalt sets on his Music Man Majesty 7. Ernie Ball quote: 'Cobalt Strings feel incredibly silky under my fingers and deliver more punch, output, and clarity than normal strings!' He has been a documented Ernie Ball artist for over two decades.
Strings John Petrucci uses
Sourced by Sleuth · last verified 2026-04-20
What's on the guitar
John Petrucci's rig is one of the most deliberately built in modern prog metal:
- Guitars: Music Man Majesty 6 and Majesty 7 (primary). Signature line since 2015.
- Strings: Ernie Ball Regular Slinky Cobalt (.010–.046) for 6-string. Custom 7-string Cobalt for Majesty 7.
- Tunings: E standard (most material), Drop D (specific tracks), and the 7-string low B dropped when called for.
- Pickups: DiMarzio Dreamcatcher (bridge) + Rainmaker (neck). Active preamp on the Majesty.
- Amps: Mesa/Boogie JP-2C signature.
Petrucci's string choice is notable because most prog-metal players at his output level assume heavier gauges are required. He makes a clean, articulate modern metal tone work on a .010 gauge, the same gauge a blues player might use.
Endorsed vs. verified use
Petrucci is a documented Ernie Ball endorser and beta tester. Both are on the record. Ernie Ball's January 2012 Cobalt launch video features him playing and endorsing the set, and Music Man ships his signature guitar factory-strung with Ernie Ball sets.
Why Cobalts for prog metal
The upper-midrange bump Cobalt delivers over nickel-plated steel is exactly what high-gain prog metal rhythm work needs, more definition per note in fast passages, tighter palm mutes, and less smear when chords contain sevenths, ninths, and the wider voicings Petrucci writes. It's not subtle in a blind A/B against a nickel Slinky of the same gauge.
On the 7-string low B, the Cobalt wrap also reads more evenly through a high-gain rhythm tone than a same-gauge nickel string, another reason the Cobalt 7-string catalog has disproportionate uptake among technical-metal players.
Sources
- "Video: John Petrucci Plays & Discusses Ernie Ball Cobalt Electric Guitar Strings." Guitar World, January 4, 2012. https://www.guitarworld.com/news/video-john-petrucci-plays-discusses-ernie-ball-cobalt-electric-guitar-strings
- Ernie Ball Cobalt product page, featured artist quote. https://www.ernieball.com/guitar-strings/electric-guitar-strings/slinky-cobalt-electric-guitar-strings
- Music Man Majesty product spec pages.
Specific gauges evolve by album and tour. Re-dated on rig updates.
If you want this rig
Regular Slinky Cobalt (.010–.046)
Why this one: Petrucci's 6-string set. The Cobalt wrap adds output and upper-mid definition to a standard .010 gauge, the reason his rhythm tone cuts through dense prog arrangements without going heavier.
Next steps
- Cobalt line deep-dive: Not Even Slinky Cobalt (.012–.056), Petrucci's 7-string Cobalt work sits closer to this gauge family.
- Adjacent prog-metal rigs: Mark Holcomb (Periphery), Jason Richardson, Keith Merrow.
- Drop D tuning guide.