Boss SG-1 Slow Gear

The Boss SG-1 Slow Gear is a volume swell pedal made by Boss in Japan between 1979 and 1982¹. Instead of shaping tone, it reshapes the attack of each note: the initial pick attack is filtered out and the volume then rises gradually, so notes bloom in like a bowed violin rather than starting with a strike. Boss describes it as a pedal that "reshapes the note attack to create violin-like swell tones"². Griffin Effects puts it more bluntly: "The Boss SG-1 is a volume swell pedal. Basically it's a reverse noise gate"³.

Boss notes that the SG-1 is "particularly effective when crafting ambient sounds with delays and reverbs"², which is how most players use it: into long delay and reverb, it turns single notes into slow, swelling pads.

Controls

The SG-1 keeps it simple with only two controls⁵:

That two-knob layout is part of the pedal's character. Guitar Pedal X's Stefan Karlsson, reviewing a modern evolution of the circuit, pointed out that "The SG-1 and CE-2 had just 2 controls each"⁵, grouping it with the CE-2 Chorus as an example of Boss's stripped-down early design philosophy.

Power and connections

The SG-1 runs on DC 9V and draws about 4 mA⁴. Its rear panel carries three connections: an input jack, an output jack, and an AC adaptor jack⁴. No battery or bypass details are given here, so treat the power requirements above as the whole picture.

History and the NF-1 Noise Gate

The SG-1's circuit is derived from another 1979 Boss pedal, the NF-1 Noise Gate. Rod Brakes, writing on Boss's own site, describes the SG-1 as a "unique circuit, derived from 1979's NF-1 Noise Gate"¹. The NF-1 was made in Japan from 1979 to 1988⁴⁶ and, according to TONEHOME, Boss's classification scheme should have named it NG-1, but NG could be read as "No Good," so NF-1, for Noise Filter, was chosen instead⁴⁶.

The two pedals work as mirror images of each other⁴:

• NF-1 Noise Gate: the sound decays away naturally but is cut off when it falls below a threshold⁴. Its single Decay knob sets how fast the signal fades out⁶.
• SG-1 Slow Gear: the attack is filtered out, then the sound increases gradually⁴.

Because the circuits are so closely related, Griffin Effects offers a modification service that converts an NF-1 into an SG-1 Slow Gear³, a practical route for players who find an NF-1 more easily than the rarer SG-1.

Who has used it

Aion FX notes that the SG-1 "has notably been used by Adam Granduciel (The War on Drugs) and Billy Corgan among others"⁷. Mattias Johansson, interviewed on Boss's site about touring with The Cure, Dinosaur Jr. and The Black Crowes, said of a possible reissue: "if BOSS ever released a version of the Slow Gear, I would be first in line to get one. That's top of the list for me"⁸.

The SG-1 today

The SG-1 has been out of production since 1982, but its circuit has not disappeared¹:

Originals now command collector prices. Griffin Effects says "SG-1's go for $400 plus these days"³, and Guitar World's review of the PX-1 reports that "the 1979 Slow Gear SG-1 filter pedal can sell for well over $400 used at the time of writing"⁹¹⁰.

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