Rotosound Swing Bass 66 (.045–.105): the bright stainless set that defined British rock bass
Reviewed by the Change Your Strings editorial team ·
Rotosound Swing Bass 66 (.045–.105) is the stainless-steel roundwound long-scale bass set that defined British and prog rock bass tone. Brighter, more aggressive, and more harmonically rich than nickel rounds, it's the set Geddy Lee and Chris Squire built their tone on, and what Jaco used on his fretless Jazz Bass. Long-scale (34") standard. Pick it when you want cut, bite, and a singing sustain in a dense mix.
Anatomy
- Model
- Rotosound Swing Bass 66 (RS66LD long-scale)
- Variants
- RS66LD long-scale (34"), RS66M medium-scale (32"), RS66S short-scale (30")
- Gauge
- .045 – .105 (Standard)
- Gauge set
- .045, .065, .080, .105
- String count
- 4 strings
- Core wire
- Hex steel
- Wrap wire
- Stainless steel (Type 66 alloy)
- Plain strings
- High-carbon steel
- Coating
- None, uncoated
- Winding
- Standard roundwound
- Intended scale
- Long-scale (34") for Fender Precision / Jazz / Rickenbacker 4003 and most modern 4-strings
- Intended tunings
- Bass E standard primary; handles Drop D
- Tension behavior
- Medium tension; rougher feel than nickel rounds
- Launched
- 1962 as the original Swing Bass roundwound concept, refined into the RS66 spec with John Entwistle in 1966 ('66' is that year)
- Package
- Single pack
Construction
- Core wire
- Hex steel.
- Wrap wire
- Type 66 stainless steel, the ratio and hardness that gives the set its signature edge.
- Plain strings
- High-carbon steel.
- Coating
- None. This is an uncoated set.
- Scale
- Long (34"). Short-scale and extra-long variants exist as separate Rotosound SKUs.
Tone
The Swing Bass 66 is the sound of "bass that cuts." It's bright to the point of being aggressive on a fresh set, and it stays bright long. Stainless wrap wire has a magnetic response that pulls more harmonic content from the pickup than nickel rounds do, a Rotosound through a Fender Jazz feels noticeably more harmonic and complex than a D'Addario XL Nickel through the same rig.
Compared to other Tier-1 bass sets:
| Rotosound Swing Bass 66 | D'Addario XL Nickel | La Bella Deep Talkin' Flats | |
|---|---|---|---|
| Wrap material | Stainless | Nickel-plated | Monel flat |
| Brightness | 9/10 | 6/10 | 2/10 |
| Fret wear | High | Low | Very low |
| Best for | Rock, prog, slap | Session, versatile | Motown, vintage, fingerstyle |
| Price tier | $$ | $$ | $$$ |
Best for
- Rock and hard rock with pick-attack-forward bass lines (Lemmy, Duff McKagan, Geddy Lee lane).
- Prog and fusion where the bass needs to articulate fast runs (Chris Squire, Jaco Pastorius lane).
- Slap funk where top-end clarity is everything. Less "Motown warmth," more "modern slap attack."
- Jaco-adjacent fretless tone: the defining Pastorius set even though he cut fretless with them.
Worst for
- Motown and vintage R&B. The brightness murders the Jamerson pocket. Use La Bella or Thomastik-Infeld flats.
- Reggae and dub. Too bright. Flatwounds dominate that lane.
- Players with sensitive hands. Stainless rounds have a grippier, rougher feel than nickel rounds, some players love it, some can't stand it.
Who plays them
- John Entwistle (The Who): more than historical. He co-developed the RS66 spec with Rotosound's James How in 1966, after his roundwounds' E and A strings wouldn't vibrate right. The "66" in the name marks that year.
- Geddy Lee (Rush): started on Rotosound's Funkmaster strings, then switched to RS66LD Swing Bass, the set that defines his Rush-era brightness. Still a current Rotosound artist.
- Chris Squire (Yes): ran a standard-gauge Swing Bass roundwound set on his 1964 Rickenbacker his whole career. He credited Entwistle directly for turning him onto them. The Rickenbacker-through-Rotosound sound is the 1970s prog bass benchmark.
- Duff McKagan (Guns N' Roses): running Swing Bass since Appetite for Destruction (1987), per Rotosound's own history. He's quoted on their current artist roster: "One constant in my ever-changing career and thoughts on rhythm has been my Rotosound Swing Bass strings."
- Jaco Pastorius: on Rotosound's own notable-users list. The defining roundwound-on-fretless tone, even though he cut fretless with them.
- Paul McCartney: listed on Rotosound's current artist roster, but not really a Swing Bass 66 story. Period photos put Rotosound Tru Bass nylon tapewounds on his Rickenbacker and Höfner around the 1969 Abbey Road sessions; earlier Beatles-era gear likely ran the Rickenbacker's own stock flatwounds. Accounts of what he used after that vary, but his tone has always leaned flatwound and tapewound, not the bright stainless roundwound lane Swing Bass 66 defines.
- Lemmy Kilmister (Motörhead): listed on Rotosound's current artist roster, and commonly reported to have run Rotosound Swing Bass strings early in his career before later gear changes. His defining Motörhead-era tone, though, is his own Dunlop signature stainless roundwounds (the LKS50105, gauged 50-105), the set most fans associate with him. We couldn't pin down the exact Rotosound years from the sources on file.
- Steve Harris (Iron Maiden): not this set, despite the assumption. His signature Rotosound tone runs on the flatwound SH77, a different lane entirely. See that page for his actual gear.
Install and break-in
- Set the bass on a neck rest or padded surface. Loosen all strings evenly before removing.
- Wipe the fretboard with a dry cloth, stainless rounds get into every pore.
- Install top-down (E first, then A, D, G). Leave ~3 wraps per tuning post.
- Bass strings need more stretching than guitar strings. Tune, stretch by pushing down hard at the 12th, retune, repeat 5–8 times per string before they hold.
- Break-in: 1–2 hours of playing or aggressive thumb-slap practice before the set settles.
Verdict
If you want a bright, cutting, British-rock or prog bass tone, the answer is Rotosound Swing Bass 66. Period. No other stainless roundwound set has the cultural-moment weight of the RS66LD. Spec a medium-scale variant (RS66M) for 32" basses; short-scale (RS66S) for 30".
Related
- Playing in Motown-pocket style instead? See the La Bella Deep Talkin' Flats review.
- Bassist spotlights that use this set: Geddy Lee, Duff McKagan, Jaco Pastorius. Looking for Paul McCartney's actual strings? See his bassist spotlight, he's a documented Rotosound artist, just not for this set. Looking for Steve Harris's actual set instead? See Rotosound SH77.