Maxon SD-9 Sonic Distortion

The Maxon SD-9 Sonic Distortion is a distortion pedal in Maxon's 9 Series, a line the maker calls the "black sheep" of the family¹. Its circuit architecture was invented by Susumu Tamura in 1981, the same designer credited with the original Tube Screamer, and Maxon describes the pedal as offering "the best characteristics of transistor and op-amp circuits in one compact unit"¹². At low gain settings the maker says it works as a full-frequency overdrive pedal, while at higher gain it delivers what Maxon calls "gut-wrenching grind and singing sustain"¹.

The pedal is currently listed as sold out on the maker's product page, at a price of £153.00 GBP¹.

What it does and how it is controlled

The SD-9 has three controls: Distortion, Tone and Output Level. On the original Ibanez version, RockBoard's PedalPedia describes the Distortion and Output Level controls as adjusting the intensity and level of the distortion, and the Tone control as letting the player "modify the distortion with bass or treble boost for exciting new colorations"⁵. Maxon calls this the unique Low Boost/Hi Boost Tone control, and says it offers "more low-end beef than other effect pedals"¹.

Vintage Guitar's reviewer described the Maxon SD-9 as a higher-gain version of the OD-9, replacing the OD-9's drive knob with a distortion knob⁶. A build document for the circuit describes the sound as "saturated distortion perfect for screaming leads and thick rhythms," with "smooth distortion, long sustain, and clear articulation"⁷.

The Low Boost/Hi Boost Tone control

The Tone control is the pedal's most distinctive feature, and also its most divisive. Aion FX's analysis of the circuit found that the Tone control produces a mid-scoop between 234 Hz and 867 Hz, and that the gain stage cuts lows with a corner frequency of 1.54kHz, at 6dB per octave⁸. Aion FX also notes the original pedal has no gain recovery section, which they call a design flaw that limits the available output volume⁸.

Analog Man's take on the stock pedal is blunt:

That matches the maker's own account of the pedal's shortcomings, which lists "a loss of low-end on high notes and a Tone control that was basically unusable past the 9 o'clock" setting¹⁰. In practice, players who keep the SD-9 tend to run the Tone knob low, where the low boost side of the control lives.

Scott Henderson and the SD-9

Jazz fusion guitarist Scott Henderson has kept a Maxon SD-9 on his pedalboard for the past 20 years, according to the maker¹⁰. Even so, his complaints about the stock pedal, the low-end loss on high notes and the harsh Tone control past 9 o'clock, are what drove the signature versions¹⁰.

The first was the Maxon SD-9SH, announced in early 2020. It was created by Susumu Tamura with Henderson's suggested tweaks, including reduced treble response, accentuated lower mids and an additional output level, while keeping the same distortion, tone and level knobs as the original⁴¹¹. MusicRadar noted the SD-9SH "has the familiar three-controls; distortion, tone and level as the SD-9"¹².

Later that year Maxon's Custom Shop released the SSD-9 Super Sonic Distortion, another Tamura redesign of the SD-9 with increased output and a retuned Tone control. Delicious Audio reported that Henderson still preferred the stock SD-9 to the new version¹³. After Maxon ended its relationship with Godlyke in mid-2021, Henderson and Tamura took the design to TWA, which released the SH9 Scott Henderson Signature Distortion in 2022, built on the same SD-9 circuit architecture Tamura invented in 1981, with improved bass and lower midrange response²¹⁴.

Where it came from: Ibanez, Maxon and the reissues

The SD-9 began life as the Ibanez SD-9 Sonic Distortion, made in Japan. TONEHOME rates the Ibanez original's collectibility as high¹⁵.

Maxon reissued the pedal in 2002 in the Nine Series under its own name, with a circuit identical to the 1980s version apart from true-bypass switching⁸. Ibanez has also reissued it as the modified SD9M, which TONEHOME lists as in production since 2012¹⁵.

On JHS Pedals' YouTube channel, Josh Scott placed the Ibanez SD-9 in context with its more famous sibling¹⁶:

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Alternatives based on the SD-9 circuit

The SD-9's circuit has spawned a small family of pedals beyond the signature models²¹⁷¹⁸:

• Maxon SD-9SH: Tamura's 2020 signature version with Henderson's voicing changes⁴
• Maxon SSD-9 Super Sonic Distortion: the 2020 Custom Shop redesign with increased output and a retuned Tone control¹³
• TWA SH9: the 2022 continuation of the signature design after Maxon and Godlyke parted ways²¹⁴
• Vemuram Butter Machine: compared alongside the SH9 as an SD-9 descendant¹⁸

Guitar Pedal X's reviewer, comparing the line in 2023, found that "Both the SH9 and Butter Machine have significant advantages over the original SD-9 - with significantly more range on tap"¹⁸.

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