Description:

Up for sale is a genuine SR&D Rockman Sustainor, Model 100A — the flagship rackmount unit from Tom Scholz's Scholz Research & Development, built in Waltham, MA. This is the "brain" behind the classic 1980s Rockman guitar tone: studio-clean compression, edge-of-breakup distortion, and that unmistakable sustain, all in one compact 1U chassis.

Dating & Provenance
The rear panel serial tag reads Serial No. SP11764, dated JUN 08 1987, confirming this as an original first-generation production unit (Pat. Pend. Model 100A).

Sonic Character
The Sustainor line came in three main revisions — 100, 100A, and 200 — and the 100A sits on the earlier, grittier end of that lineage. Compared to the later Model 200 (which was voiced smoother and quieter, closer to the polished "Boston" studio tone), the 100/100A circuit runs hotter: more gain on tap, a touch more hiss, and more edge and grit in the distortion and edge channels. That makes this unit especially well suited to players chasing the more aggressive, in-your-face side of '80s arena rock tone rather than a pristine, low-noise studio sound. The onboard compressor still delivers that signature ultra-even Rockman sustain, and the dual-channel Dist/Edge/Clean/Clean 2 modes give a wide spread from glassy clean to searing lead tone.

Front Panel Controls

• Preamp/Compressor: ¼" guitar input, Preamp Gain slider, 3-stage Compression LEDs (T / 10 / 20+), Sustain Longer switch (0 / 8 / 15 / 21)
• Gate: Trigger threshold slider (0–20), Hi Cut on/off switch
• Distortion/Filters: Overdrive Threshold, Overdrive Modifiers (Gain Boost / Auto Clean / Semi Clean), dual-channel Mode selection (Dist / Edge / Clean / Clean 2) with independent sliders for Channel 1 and Channel 2, Freq slider, Dist/Edge EQ Trim, and a switchable Phase Notcher with kHz control
• Output: Treble Boost, PA Amp/Guitar Amp voicing slider, Rhythm Volume, dual Volume 1/2 outputs
• Front-panel hardwired Bypass switch and Power switch

Rear Panel
Dedicated footswitch jacks for Bypass, Volume, and Channel switching; a full effects loop (Dist/Edge Return, All Return, Send — loop situated post-comp/gate, pre-distortion per the rear panel legend); ¼" output with 1kΩ minimum load spec; and an integrated 120V/60Hz power inlet (3W draw).

Condition
Photos show the unit opened up for internal inspection — main PCB is intact with original components (CD4053/CD4066 switching ICs, TL072 op-amps, original ribbon cable harnesses, factory foil shielding). No visible blown or leaking capacitors in the photos, but given the age (38+ years) a full recap/service check is recommended before heavy gig use, and buyers should budget for that as a possibility. Selling as-is; exterior shows honest cosmetic wear consistent with age (see photos for chassis and control panel condition).