J Mascis's guitar strings: the Dinosaur Jr. indie-rock rig, sourced
Documented string gauges, brands, and tunings J Mascis uses with Dinosaur Jr. Featured in Ernie Ball's String Theory series. With citations.
Dinosaur Jr. · reviewed by the Change Your Strings editorial team ·
J Mascis uses Ernie Ball .010 to .046 gauge strings, tied by Ernie Ball's own current artist page to the Regular Slinky Cobalt line, a switch he first described in a 2013 interview. His signature Squier Jazzmaster traces to his original 1958, though recent Premier Guitar rundowns show Telecasters, including a purple-sparkle Thinline and his newer 1958-based signature model, dominating his current rig. Tuning is E standard on most current material.
What's on the guitar
J Mascis's rig is one of the most recognizable in indie rock:
- Guitars: A large, ever-rotating collection built around Fender Jazzmasters and Telecasters. His signature Squier Jazzmaster is based on his original 1958. Premier Guitar's most recent rig rundowns (2021 to 2022) show Telecasters doing most of the current work, including a purple-sparkle Custom Shop Thinline and a newer signature model built from his favorite 1958 Tele.
- Strings: Ernie Ball .010–.046 gauge. Ernie Ball's own current artist page ties Mascis to the Regular Slinky Cobalt line.
- Tuning: E standard (current), Eb standard (some earlier catalog).
- Amps: Three full stacks live: two vintage Marshall Super Bass heads and a Hiwatt DR-103, all driving Marshall 4x12 cabinets simultaneously, for the Dinosaur Jr. wall-of-guitar sound.
- Pedals: A long signal chain built around multiple Big Muff-style fuzzes, including his own Wren and Cuff Garbage Face signature, plus a rotating cast of vintage overdrives and fuzz clones.
Ernie Ball artist page · .010–.046
Ernie Ball Regular Slinky Cobalt
Ernie Ball's own blog names this set directly: "J Mascis plays Ernie Ball Cobalt Slinky strings." A 2013 interview documents his switch to the line; recent third-party rig rundowns confirm the .010–.046 gauge without repeating the Cobalt-wrap detail.
Mascis's tone runs the opposite direction from a hyper-articulate prog-metal setup. It's volume, sustain, feedback, and long bent notes through stacks of tube amps, so the strings stay simple and the amps do the work. The Cobalt-line association, per Ernie Ball, is about compensating for lower-output vintage single coils at the string level, not about tightening a rhythm attack.
Endorsed vs. verified use
Mascis is a documented Ernie Ball Cobalt Slinky user, currently featured on both Ernie Ball's String Theory series and its Big Sound series. Ernie Ball's own blog states it directly: "J Mascis plays Ernie Ball Cobalt Slinky strings," linking straight to the product. The Ernie Ball forum thread "J Mascis of Dinosaur Jr. likes Cobalts" documents him describing the switch in a 2013 interview. Independent rig-rundown coverage from Premier Guitar (2021 to 2022) confirms the .010–.046 gauge but names it simply "Ernie Ball Regular Slinky" without repeating the Cobalt-wrap detail, likely rundown shorthand rather than a contradiction, since it lines up with every Ernie Ball source on the exact same gauge.
Dinosaur Jr.'s original lineup, Mascis, Lou Barlow, and Murph, is actively touring as of this writing. Ernie Ball filmed the band for a Big Sound session in Amherst, Massachusetts in June 2026, and per that same page, Dinosaur Jr. co-headlines a US tour with Band of Horses in July and August 2026, playing 1993's Where You Been in full.
Why Cobalts for a Jazzmaster
Jazzmaster pickups are wide, flat, and lower-output than Strat or Tele single coils. Many Jazzmaster players swap pickups for higher-output options (Curtis Novak, Lollar High-Wind) to get more saturation and articulation out of the guitar. Ernie Ball's positioning for Mascis follows a different logic: keep the vintage-voiced stock pickups and get the output bump at the string level with Cobalt's wrap alloy instead of the pickup level.
The same string-level logic applies to any lower-output vintage single coil, Jazzmaster or otherwise: when a guitar's own output reads a little dark or soft through an overdriven amp, a more magnetically reactive wrap alloy closes some of that gap without requiring a pickup swap.
Sources
- "Ernie Ball String Theory: J Mascis." https://www.ernieball.com/stringtheory/j-mascis
- "J Mascis of Dinosaur Jr. likes Cobalts." Ernie Ball Forum, Jan. 2013. https://forums.ernieball.com/threads/j-mascis-of-dinosaur-jr-likes-cobalts.55273/
- "Ernie Ball Cobalt Slinky." Product page. https://www.ernieball.com/guitar-strings/electric-guitar-strings/cobalt-slinky
- "The Top Six Things We Learned From Watching Ernie Ball: String Theory Featuring J Mascis." Ernie Ball Blog, 2017. https://blog.ernieball.com/music/the-top-six-things-we-learned-from-watching-ernie-ball-string-theory-featuring-j-mascis/
- "Rig Rundown: Dinosaur Jr.'s J Mascis [2022]." Premier Guitar. https://www.premierguitar.com/videos/rig-rundown/dinosaur-jr-2022
- "What Happened to J Mascis' Jazzmaster Addiction?" Premier Guitar, Oct. 2021. https://www.premierguitar.com/artists/guitarists/j-mascis
- "Ernie Ball Big Sound Session, Dinosaur Jr." Ernie Ball, June 2026. https://www.ernieball.com/big-sound/dinosaur-jr
- "Equipboard, J Mascis gear." https://equipboard.com/pros/j-mascis
Re-verified on each Dinosaur Jr. tour cycle or Ernie Ball String Theory update.
If you want this rig
Regular Slinky Cobalt (.010–.046)
Why this one: J Mascis's exact set, per Ernie Ball's own artist page. The Cobalt wrap compensates for lower-output vintage single coils by adding magnetic read at the string, not the pickup.