man kind of a bummer that this thread stalled a few years ago. Was hoping to find any info I could on harmonizer effects boxes [rack or pedal or whatever].
Anyhow here is a review of the Boss PS-3:
First off, the Boss PS-3 was meant to directly compete with the Digitech Whammy, back when the Digitech Whammy was not the D'tech Whammy IV. That worked out pretty poorly, considering the Whammy has gone through five incarnations (the I,II, XP100, and IV), all of which have really nice tracking and sound, whereas the expression pedal mode in the PS-3 was really quite terrible, the HR-2 Harmonist (its immediate successor) was a special kind of awful sounding, and the PS-5 "super" shifter was easily the most 'digital' sounding pedal [to say nothing of the million gimmick modes and one useful one] i've ever used. That said, the PS-3 was an amazing unit.
Basic in/out - The a/d d/a depth is 12 bit which isn't terrible and surprisingly doesn't color the tone much. The dry mix is nice, although could have perhaps been improved as on the PS-5 [concentric level knobs for effect and dry signal].
Modes - the first three modes are varying flavors of digital delay, going up to 3000ms or thereabouts. It's nice and crisp and sparkling and whatever other adjectives you can think of that people use for digital delays/champagne.
Mode four is a detune + delay. I suppose this is where you can try to fake having an analog delay. I personally haven't found much use for it.
Mode five is slow pitchshift + a delay. The pitchshift range is +/- two octaves and the delay is up to 500ms I believe. Typically with guitar and an octave up for range this sounds like a piercing glassy organ.
Mode six is a fast pitchshift + a delay. Similar to mode five but less interesting, sonically.
Mode seven [!!!!!!!!] is a reversed pitchshift and delay. The beautiful thing about the pitchshift + delay modes is the feedbacks on the delay go back through the pitchshifter again, which for this mode becomes this beautiful string crescendo that sparkles like a bajillion diamonds. It's quite nice and the reason I bought this pedal in the first place.
Mode eight is two detuners. both can set the detune amount manually, which, on a rompler gives that detuned analog sound. This is the wonderful hidden gem mode. It's subtle but amazing when you notice it. Doesn't sound like other chorus pedals at all. This was brought into the PS-5 and was the most useful mode although you lost the second detuner and due to the graduated knobs of the PS-5, a bit of the ability to get "between" notes.
Mode nine is a detune and a pitchshift. Nice but not necessarily the best sounds.
Mode ten was two pitchshifts [manually]. A marked improvement over the PS-2 but otherwise kind of ho-hum, especially if you can play more than one note at once. I suspect it would be quite nice on vocals although I haven't tried it.
Mode eleven allowed you to use a roland ev5 expression pedal to be a j**k and whammy all over the stage. The two 'pitch knobs' for this mode set the toe pitch and heel pitch which was a rather nice feature but would've been better implemented on, say, the PS-5 with its graduated knobs [which they decided was too smart and just made the range +/- 1 octave.
] The tracking on this mode seems worse, but that might just be me.
All in all, this is a wonderful piece of equipment that boss has neglected to put out a proper replacement for - the PS-5 and HR-2 were... not so wonderful, although the PS-6 is getting there. Gotta put the delay modes back in though. Expect to pay between $99 and $335 [!!!] for these and if you ever come across one for less than that, even if you won't use it, you should probably buy it to resell it for more. You'll definitely be able to.
Also, for an example of the PS-3 in action, check out the track 'Souvlaki Space Station' by Slowdive. It is all over pretty much everything in that track.
rating: of the eleven modes, two are absolute gems and six are very useful. nine of ten, and you'll have to pry mine from my cold dead fingers.