Boss Pitch Shifter/Delay
This latest release in the popular Micro Rack range of budget signal processors is put through its paces by Mark Jenkins.
Mark Jenkins reports on the latest addition to the popular Boss Micro Rack series of budget signal processors - the RPS-10 Digital Pitch Shifter/Delay.
So what applications could be found for a pitch shifter in the average studio? Most obviously, there's the production of harmonies on vocal or even on instrumental lines, which is why Eventide grabbed the copyright on the name 'Harmonizer'. So the RPS-10 is akin to a harmoniser if you like, but lacks many of the more advanced features of Eventide models and even of the Ibanez Harmonics/Delay series, although these are both of course much more expensive.
Slight pitch shifts when mixed with the original unshifted signal will give thickening effects similar to using two oscillators instead of one on a synthesizer, or using a twelve-string guitar rather than a six-string. Vocals, again, can be thickened up without producing a distinct 'harmony' line.
If you do want distinct harmonies however, the RPS-10 should be able to provide the goods, although there's been no attempt to mark the control settings for common musical intervals such as a 3rd, 4th or 5th. You just have to find them by ear using the coarse Pitch and Fine tune controls. The quality of the pitch-shifted signal and its commendable lack of glitching (cyclical irregularities in the sound) are of paramount importance here, particularly if you whack up the Feedback control setting on a large pitch shift.
This can provide an unusual, rather over-the-top effect that turns simple musical lines into spacey arpeggios and generally makes everything sound as if it's been recorded for an episode of Dr Who. But, as with all other effects, this is just a question of the subtlety with which it's used.
Keyboard control of the pitch amount is possible over a range of a couple of octaves. Simply plug the audio output of any synth into the Keyboard Control socket, use a simple monophonic sound, and the degree of pitch shift is set by the note played over a range of C5 (523Hz) to C7 (2093Hz), with C6 (1046Hz) serving as the neutral, zero shift position. This is the most reliable way to obtain preset pitch intervals, overriding the front panel Pitch control, and although it's no substitute for a vocoder or voice box, it can help create some complex vocal tricks in real time.
The two Pitch Shift modes, A and B, differ slightly in the frequencies on which they're centred. In 'A' mode, the time delay involved is short and some low frequencies tend to take on a tremolo effect rather than being shifted. In the 'B' mode, the delay time is increased with the result that the shift is slightly more stable. The difference is subtle, but can be a problem-solver.
The Delay functions on the RPS-10 are pretty standard, giving a maximum 800ms echo with a (quoted) 15kHz frequency response. But the unusual factor shared by the Delay and Pitch Shift modes is the Invert function, which Boss describe as being similar to "a tape recorder's reverse playback effect". It sounds as if the echo is being read out backwards in sections, because the actual order of notes played remains the same. In Pitch Shift mode, the Invert position gives the most incredible effect the RPS-10 is capable of generating, namely a rising or falling echoed arpeggio on every note played - great for the ends of particularly doomy compositions!
The RPS-10's handbook gives a couple of useful example settings with exotic names such as 'Infinite Score Raising Sound', and even shows how to change the pitch of a whole piece of music, although that's being a little ambitious because, like most budget harmonisers, the RPS-10 doesn't give an amazing shifted signal. Mixed in with the original, it's fine for thickening and small intervals, but around a 5th or an octave shift the quality is degraded and the shifted sound becomes fairly gritty. Boss do have the advantage over other designs that glitching is kept to a minimum, but there is a certain kind of gritty distortion that's all too easily produced with this kind of unit.
On the more over-the-top effects this isn't so significant, and the RPS-10 is quite capable of making you sound like Prostetnik Vogon Jeltz from The Hitch-Hiker's Guide To The Galaxy standing at the bottom of a well. But how often do you need that kind of effect? The RPS-10 is also great for pretending that you're doing fractal synthesis for the Arts Council Contemporary Music Network using a mainframe computer at IRCAM, whereas in fact all you've got is a Casio and a Pitch Shifter.
The bottom line, as always, is cost, and if you're looking for pitch shifting effects in this price-bracket, there's little opposition. The delay functions of the RPS-10 are a bonus and are of pretty good quality, although there's no modulation oscillator so the unit won't double as a flanger as well. But despite unavoidable problems in the quality of the pure shifted sound, which are much less significant when mixed with the original, this unit is still a valuable addition to the Boss Micro Rack Series.
The Boss RPS-10 Digital Pitch Shifter/Delay costs £210.00
Review by Mark Jenkins
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