Yamaha SPX-90II
Thirty factory presets, sixty slots for your own, and a chorus patch that guitarists are still chasing decades later — the rack processor that put studio-grade effects within reach of working musicians.
Overview
The SPX-90II is a one-rack-space digital multi-effects processor, and the case for it is easiest to make in the language of a spec sheet: thirteen effect types, thirty preset variations each with up to nine separate controls, and room for sixty custom variations that owners can build and store themselves. A period write-up in Recording Engineer (June 1991, p.50) surveyed the house signal processing at Maryland Sound Industries in Baltimore, listing the equalizers, gates, and microphones used alongside Yamaha outboard gear. Yamaha's own advertising for the unit — the copy that ran in the music trade press — billed it as "an encore performance of the most successful digital processor in audio history," a line that tells you as much about the original SPX-90's reputation as it does about the II. The effects roster is broad rather than boutique: stereo echo, stereo chorus and flanging, pitch change, four kinds of reverb, plus reverb-and-gate combinations. For a working studio or a gigging keyboard rig, that's most of the outboard rack in a single box.
The operational details are where the SPX-90II earns its keep. Each custom effect can be given its own title, so a rack full of patches isn't a memory of numbers — you can label a signature sound and find it again. Recall is handled either from the front panel or from a footswitch, and Yamaha offered an MFC1 MIDI foot controller and a dedicated remote controller as options for players who wanted hands-free changes mid-set. The factory presets are the fallback for anyone who doesn't want to program at all, and Yamaha pitched that directly: maximum signal processing in minimum rack space whether or not you ever touch the edit controls.
That pitch landed. By the early nineties the SPX-90II shows up repeatedly in the classified and dealer listings of the American music magazines — not as a novelty, but as the processor studios and keyboard players actually kept in the rack. When a piece of outboard appears in the "current best sellers" column rather than the clearance bin, that's the market talking. A period dealer ad in Bam magazine (undated) priced the SPX90II at $549 — useful context for what "affordable professional" meant at the time, and a reminder that this was never a budget throwaway.
The pitch-shift chorus is the patch that keeps coming up. In a 1990s Electronic Musician feature on home-studio guitar production, engineer Robinett describes dialing in his favorite chorus on the SPX90II with a pitch-shift patch set at eight cents plus and eight cents minus — and then running into the practical problem that the stereo patch diluted the stereo placement of the other instruments in the mix when he tried to drop it onto a guitar track. He loved the sound live; he couldn't always make it sit in a dense mix, and on some songs he reached for an Eventide Harmonizer chorus instead because it worked in mono. That's about as honest a verdict as a piece of gear gets: the SPX-90II's chorus is a signature sound, and a signature sound is not always the right tool for every arrangement.
What the SPX-90II is not, at least from the available documentation, is a reverb purist's machine. The reverb options are there — four kinds by Yamaha's count — but the unit's identity in the trade press is chorus, pitch shift, delay, and the sheer breadth of the preset library. Collectors and working engineers tend to describe it the way the original ads did: a Swiss-army rack unit, not a Lexicon. That's not a knock. It's the reason so many of them are still in racks.
eBay Listings
As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.