Tascam 4 Fretted vs. Open Strings, Region mapping plus PRF, Use of Body Models and Room Models

Additional PRF Tips and Considerations

Short and Long Interval Calibration

If you are going to create both short and long interval settings, be aware that when a long interval is played it first goes through the short interval filter settings and then morphs between short and long settings as the transposed sample exceeds the short interval and approaches the long interval. Because the filters react in this way it is best to create your long interval immediately after creating the short interval by emphasizing the already existing short interval settings, this gives a more natural sounding transition between the short and long interval coefficient values.

Fretted vs. Open Strings

When applying filters to stringed instruments and string ensembles, open string samples do not bend as well as fretted notes since bending an open string on an instrument is not often done. In general, the looser the performance of the original sample, the more successful the filtered transposition becomes. This is due in part because all the players of the ensemble are being transposed simultaneously, instead of with a natural time/pitch variance per player.

Region mapping plus PRF

Another issue to consider is when samples have already been stretched or transposed through region mapping. The further you transpose a sample using the instrument mapping, the less effective the filtering process becomes. Ideally you would want an independent sample for each note region of an instrument. If this is not an option, find PRF settings for every sample that is NOT transposed by the instruments region mapping and then apply those same filter settings to all keyboard regions that contain that sample. For instance, if a sample of C4 is mapped to both C4 and C#4, find the PRF settings for C4 and then apply those same settings to C#4.

Use of Body Models and Room Models

Of course the use of body models contributes greatly to the realism of programmatic portamento, but the use of modeled rooms also helps. Attempting to bend a note as well as the resonance of the instruments body and the frequency spectrum of the room the instrument was played in is quite problematic. Solution: apply the PRF to DRY instruments and add a room model post filter…

Calibrating Decaying Instruments

A decaying sound is harder to calibrate for than a sustaining sound. When the transient sounds different from the decay of a note (eg, Guitars, possibly Timpani, GuZheng), use your expression pedal to audition just the decay portion of a sound. Long decays like guitars allow you to strike a note, gliss to the target note, then fade in, cross referencing the transposed and non-transposed samples until you've matched not their transients, but their decay. Constant sustaining sounds, like a steady mf on trombone, would not require this approach but it might help minimize distractions due to hearing different transients during cross-referencing.

Portamento Time Ranges and Trills

A clarinettist may lip up to a note at the slowest speed that the mono rule offers, almost imperceptibly slow. On the other hand, at the fastest rate the glissando is practically instantaneous. Start with a setting of 20-30 for most instruments that can do quick bends/slides. The clarinet example would benefit from a speed range of about 25-70. Settings lower than 10 are useful for performing trills!

TASCAM GigaEditor 4 Manual 205