This is an article culled from archive material, circa 1997.
The QFX 4x4 is a product of Peavey's
Audio Media Research division,
although I believe it's identical to the Multifex
effects processor, except for the styling. It provides four independent
effects processors, each with its own audio inputs (stereo, summed to
mono) and stereo outputs. In terms of the MIDI functionality, the unit
shows its age; apart from system exclusive, it only believes in
program changes, although all four processors can be addressed individually
(or as an entire patch, which is where the wet/dry mix is programmed).
MIDI program change response is a little touchy: in particular, program
changes sent too quickly in succession will be ignored.The QFX is partly a preset-based machine, although effects patches can
also be programmed; some have several screens' worth of parameters. It
has never been clear to me how the presets and RAM patches relate to
each other, and neither the manual nor the system exclusive specification
gives much away. Either the presets are
dedicated, parameterless algorithms, or else they are ROM-based sets
of parameters.The actual effects on offer, although basic, are very usable and sound
remarkably good. The gated reverbs in particular are excellent, and
there are some useful algorithms such as parametric EQ. There are even
some multi-algorithms (such as reverb/chorus), with both series and
parallel combinations.I recommend the QFX/Multifex as an excellent bread-and-butter effects
unit, if you can still find one for a reasonable price.