The SD-1 Super Overdrive is the second overdrive pedal made by the Boss Corporation.[1] Released in 1981 and produced continuously since, the SD-1 was an update to the brand's influential OD-1 Overdrive, adding a tone control and refining its predecessor's circuit for more gain and aggression in its voicing.[2][3] The changes made the SD-1 especially popular within the growing hard rock and heavy metal subgenres upon its release, with guitarists frequently using it to boost already-distorted amplifiers like the Marshall JCM800.[4] The SD-1's design has remained unchanged since its debut, and it remains a pedalboard staple among both amateur and professional players.
Following the releases of the MXR Distortion+ and DOD Overdrive 250 Preamp, both of which combined newly-available op amps with hard-clipping diodes to create distortion, Boss sought a way to achieve a more faithful imitation of power amp distortion through a compact effects pedal of its own.[1] Boss soon patented a unique, asymmetrical soft-clipping design and released the OD-1 Overdrive in 1977, in doing so pioneering the "overdrive" pedal market. However, like the Distortion+ and 250 Preamp before it, the OD-1 featured only level and gain controls, with no option to individually adjust the pedal's EQ behavior.[1] The Ibanez Tube Screamer, which was inspired by the OD-1 but utilized symmetrical clipping to avoid Boss' patent, included a tone knob upon its release in 1979 and quickly became the dominant overdrive pedal on the market. In 1981, Boss released the SD-1 Super Overdrive as their direct competitor to Ibanez's pedal.
Design
The SD-1 carried over the OD-1 Overdrive's compact yellow case and Boss' asymmetrical soft-clipping design, with the asymmetry creating both even and odd order harmonics for a more layered distortion.[5] Like Boss' other compact pedals, the SD-1 has a buffered bypass and runs on a 9v battery or equivalent power supply. The SD-1's largest outward departure from its predecessor is the inclusion of a "Tone" control, in addition to controls for output volume ("Level") and gain (now labeled "Drive" compared to the OD-1's "Over Drive"). The soft-clipping circuit too came with several alterations. Most notable among them is the use of two diodes to clip the waveform's positive amplitude peak and a single diode for the negative, meaning the signal's wave peaks are clipped differently.[5] This leads to a "slightly more harmonically interesting sound" with accentuated even-order harmonics and what is thought to be a more accurate replication of tube amp distortion,[1][5] as this method of clipping better replicates a tube amp's push/pull circuit in which no two tubes are ever perfectly matched.[5] The clipping's updated placement earlier in the circuit also introduces a "slightly jagged, granular drive tone" that helps the affected guitar tone stand out.[6] Tonally, the SD-1 remains midrange-focused (centered around 800Hz) but has less bass roll-off than the OD-1, making for a fuller sound than the OD-1 or Tube Screamer.[3]
In use, the SD-1 adds grit and saturation to both clean and overdriven amps with the gain control set high, while in contrast Ibanez's Tube Screamer is often used more as a boost for its volume and EQ curve with the gain set low.[1] Adding drive with the SD-1 to an already overdriven amp became especially popular in the 1980s in the growing hard rock and heavy metal subgenres, with guitarists frequently using the SD-1 in front of amps like the Marshall JCM800 for more distortion.[4]
Legacy
Boss SD-2 Dual Overdrive
The SD-1 is notable as a staple budget offering—frequently chosen as a guitarist's first overdrive[7]—that is also widely popular among professional guitarists. Users include Jimmy Page, David Gilmour, Kirk Hammett, Steve Vai, Zakk Wylde, Jonny Greenwood, Josh Homme, Mark Knopfler, Prince, and the Edge.[6][7] The SD-1 is often praised for its durability, low price (retailing for under $70),[5] and overdrive character, which pairs well with a variety of amps and music genres.[7] As a result, the SD-1 has been one of the industry's best-selling pedals for decades.[5]
In 2014, Boss introduced a high-end "Waza Craft" edition of the pedal, the SD-1W, which features upgraded components and a custom mode that produces a smoother distortion with more sustain and fullness.[8] This was followed in 2021 by a 40th anniversary edition of the SD-1 (with an inverted color scheme),[2] with the original circuit having remained unchanged since its introduction. Guitar dubbed the pedal one of only a handful to ever achieve "truly iconic status."[7]
Between 1993 and 1998, Boss produced a more complex update to the SD-1, the SD-2 Dual Overdrive. It had two channels, Crunch and Lead, and stacked Level, Tone, and Drive controls for each. The SD-2 also offered users the ability to toggle between channels using an external footswitch.[3]
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