This suite of four plug-ins from French group GRM (marketed by Steinberg) comprises Band Pass, Comb Filters, PitchAccum, and Shuffling, provided in both mono and stereo versions. Despite the quality of the algorithms involved (and the elegant metallic-effect graphics), it is the user interface that really brings them all to life. On the right-hand side of each GRM Tools window are 16 numbered preset buttons, arranged in two vertical strips of eight. You can morph the position of every control between presets, over a period of time set by the associated Transition Fader (up to a maximum of 30 seconds). This morphing rate is saved for each target preset and used if the button beneath the fader is activated. You can override the saved rate with the current setting of the fader by deactivating this button. Switching the button back on, at any time during the morphing process, freezes the settings at that point you can save the 'frozen' settings as a preset, should you stumble upon a killer patch.
Further extremes of manipulation can be achieved using the long horizontal Interpolation Fader along the bottom of each window. This has eight numbered positions along its track, each of which can store any of the 16 presets or be set to Off. By dragging the slider along its track you can morph between your preset selections manually, stop at any position 'mid-morph', or instantly jump to any point on the fader's track by clicking there. Setting some of the intermediate buttons to Off gives you finer control between the remaining active presets along the fader's track. Although you can use the PC version with Wavelab, GRM Tools come into their own with Cubase VST, because you can then use them as channel, insert or master effects with any control movement automated as part of the mix.
The Band Pass filter has separate low-pass and high-pass sections, fully variable from 23Hz to 22kHz. With the Super Handle in the graphic window, you can sweep the filter frequencies in parallel by dragging horizontally and also vary the distance between them (the bandwidth) by dragging vertically. Switching between Pass and Reject modes is done with a small button above the graphic window. The stereo version adds a second graphic window so that you can set different responses for each channel and all this in conjunction with the morphing! There are switches to copy or swap channel settings and a Link switch for ganged stereo operation. I've heard plenty of morphed filter sweeps in dance music, and this can do them all with ease.
Comb Filters features five filters in parallel, each with faders for frequency, resonance, and low-pass filter (placed in the feedback loop to control the amount of ringing). There is a further set of three Master controls, which act as multipliers for the values set beneath in the case of the Master Frequency fader, this can be varied between 2.00 (an octave above) and zero (minimum frequency in all five cases). Due to the wide range of available resonance settings you can create ringing harmonic clusters or chords, and turn drum loops into triggered drones. Great stuff!
PitchAccum consists of two 'transposers', each of which can transpose up or down by a maximum of two octaves, delay by up to 2972 milliseconds and mix their output into the basic signal with a gain fader. A graphic window and Super Handle let you change both transpose values simultaneously (horizontal drag) and set the pitch difference (vertical drag). This controlled mayhem can be further enhanced by various forms of modulation: Periodic modulation allows you to vary the transpose value and inter-transposer phase difference using an LFO, while Random modulation offers various esoteric options. The transposed delay has feedback and stereo image-width faders the size and overlap of the fragments used by the transpose algorithms can be set using the Window and Cross-fade controls. The sounds available range from delays and echos to standard pitch-shifting and Radiophonic Workshop-style treatments that defy description.
The Shuffler slices up the audio into short sections, shuffles them around and then spits them out at varying time-intervals. The Fragment length and Envelope shape of each fragment can be varied, as can the amount of randomised Delay before the output of each fragment. There is a simple pitch envelope for each fragment, which can be set using Initial, Final, and Random pitch-value sliders. Overall Feedback controls the number of repeats, while Density determines how often the fragments are output, from 100 percent (every single one) to 0 percent (silence). The results range from space and phasing effects to transposition, polyrhythmic fragment bursts, and cartoon-style pitch sweeps.
For those who love mangling their audio in creative ways (but with excellent control) the possibilities are almost endless and, for once, the product does far more than it says on the box. Highly recommended. Martin Walker