Since its original release in the early 80’s the Sonic Distortion has gained a huge cult following among tone connoisseurs, including the likes of guitar legends Scott Henderson and Mike Landau.
Maxon’s current-production reissue captures all the magic of the original with the added benefit of true bypass switching.
The SD-9 provides a smooth distortion that covers a wide range of Gain levels from mild overdrive through pseudo-fuzz. Regardless of the Gain setting, the SD-9 remains articulate and responsive to note dynamics, providing excellent sustain without crossing over into super-compressed Metal territory.
The SD-9’s Tone knob has plenty of top end on tap, yet notes still retain a round, full-bodied tonality with the low end presence usually associated with amp distortion. The pedal’s midrange response is smooth and even – present without seeming spiked.
Since its humble origins to its current place in the pedalboards of the stars, the Maxon Sonic Distortion has proven itself to be a timeless classic that has only improved with age.
Input signal goes through a simple High-Pass filter into a transistor that’s set up as an emitter/follower (high input impedance – low output impedance). After this it’s into an Op Amp stage designed to give a gain range of 67 to 567and a Low-Pass Filter with a corner frequency of approximately 1540 Hz.
From here it’s on to a set of opposing-direction diodes to ground and a tone control that is reminiscent of the Boss DS-1 (kind of a Big Muff dual High and Low cut – ending up with a mid scoop that has a high frequency limiting resistor with corner frequencies of 867Hz and 234Hz respectively).
The SD-9’s dual diodes to ground give a crunchier, chewier distortion than the popular 808-style “diodes in feedback loop” configuration. Likewise, the SD-9’s mid scoop is practically the antithesis of the 808’s infamous mid hump.
After the tone control section it’s through to a volume control and into another E/F transistor to provide a low impedance output and then on to the true bypass switch.
The SD-9 features Mechanical True Bypass switching via a Fujisoku 4PDT switch – Input is switched to ground when bypassed.