Boss RPH-10 Phaser
A half-rack phaser that turned the Micro Rack into a modular home studio — and still costs less than a decent pedal.
Overview
The RPH-10 is the phaser at the heart of Boss's Micro Rack Series, a line of compact signal processors that squeezed professional-style outboard into a footprint half the width of a standard 19-inch rack unit. The pitch to the home recordist was straightforward and, judging by the classified pages of the era, effective: buy one, buy a few, and bolt them together. A single RAD-10 rack shelf holds two units in one 19-inch, one-unit-high space, and a BMR-5 rack accommodates the whole family. Boss's own advertising billed the range as "compact, efficient, hi-tech sound processors at prices you could afford," aimed squarely at home recording and live stage use.
The phaser itself shares its control set with the RBF-10 Flanger: Manual, Rate, Depth, and Feedback. Manual sets the center frequency of the effect, and the phaser adds a three-position mode switch the flanger doesn't have — the review of the series noted the phaser's three modes alongside the shared controls, and observed that either unit could be linked to a second for stereo effects. That linking is the real argument for the format. Two RPH-10s, or an RPH-10 paired with its flanger sibling, become a stereo processing chain that a single pedal can't replicate, and the rack adaptor keeps the whole thing tidy.
Power is a detail worth flagging for anyone buying today. The units run on Boss PSA AC adaptors, sold separately, and the series was designed so one adaptor can feed several units — the contemporary write-up pegged a single PSA as good for about 200 mA and suggested it could power as many as four Graphic Equalizers if you added up the current draw. The RAD-10 rack adaptor itself was a modest £20 in the mid-1980s, and the phaser listed at £125 in one dealer's advertising and £110 in another — pricing on this series moved around, so period ads disagree by a few pounds depending on the shop and the year.
What the RPH-10 is not is a set-and-forget box. With Manual, Rate, Depth, and Feedback all on the front panel, plus a mode switch, it rewards fiddling — sweep the rate slow and the feedback high and it will do the slow, vocal, jet-plane thing; push the rate and it turns into a wobble. The half-rack format means the controls are small and close together, and there's no display or program memory, so every setting is dialed by hand and gone when you power down. Collectors should expect to hunt for the original PSA supply or a compatible replacement, since the units were sold without one. The RPH-10 turns up regularly on the used market at prices that make it one of the cheapest ways into real outboard phasing — and one of the few that lets you stack a second unit for stereo without buying a bigger rack.
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