The PPG Wavecomputer 360 and its successor, the Wave 2, were pure wavetable instruments. Starting with the Wave 2.2, PPG introduced the so-called Transient Sounds – essentially the same what would be called “samples” by the rest of the industry. Since this was at about the same time as the first Fairlight CMI (end of 1979) and the E-mu Emulator (1981) appeared, there wasn’t a widely established terminology yet – so PPG invented their own. So …
What is a Transient Sound?
Essentially, as said, it’s what would sloppily be called a “sample” today – a longer waveform, normally a sampled natural sound, with a part at the end which is looped through until the release part of the voice is finished.
The PPG Wave hardware is designed for wavetable synthesis; support for Transient Sounds wasn’t redeveloped from ground up, but implemented as an extension to the existing hardware. This results in some peculiarities.
Ah … wave-what?
A “wavetable” is essentially a compilation of single waveforms (“waves”) into a table, where one of the waves is selected for playback through a basic selection and various modulation possibilites. In the PPG Wave, each wave consists of 128 digitized voltage levels (“samples”) that together form a single period of the waveform. In wavetable mode, it’s always one of the waves in the wavetable that’s played back in a constant loop. So, this loop starts at the beginning of the waveform and has the length of the number of samples in the waveform.
In the PPG Wave and EVU, a wavetable has a fixed size; there are 64 waves in the wavetable. In the built-in wavetables, there’s always a part of 60 waves that form a relatively smooth transition between some carefully selected waveforms. In addition to that, there are 4 fixed waveforms that are always the same: a triangle wave, a sharp pulse wave, a rectangle wave, and a sawtooth wave.
In addition to the normal wavetable, there is an “upper wavetable” that is identical for all built-in wavetables. This, too, holds 64 waveforms. So, in total, 128 waveforms can be used; in Wave 2.3 and EVU, 8 banks of these can be used simultaneously.
Transient Sound Modes
The Wave 2.2 can handle Transient Sounds in two modes: short-loop and long-loop transient sound. The Wave 2.3, with its much bigger memory range (hey, 8 banks of wavetables instead of just one!), added another mode: double-bank transient sound.
Short Loop Transient Sound
A Short Loop Transient Sound is a simple extension of the wavetable concept.
The Short Loop Transient Sound extends this concept a bit; here, there’s an additional start point from which playback is started. In Wavetable mode, this start point always equals the start of the current waveform inside the wavetable; in a Short Loop Transient Sound, it can be freely selected between the start of the wavetable and the start of the loop, and the loop has the same length of 128 samples as it has in Wavetable mode. The playback start and the loop start can be selected in 64 steps.
Starting with V4 of the Wave 2.2 operating system, there is the built-in wavetable #31, which contains natural sound samples (Piano/Sax). Selection of this wavetable puts the Wave into the Short Loop Transient Sound mode; this is the only way to turn on any of the Transient Sound modes without an attached Waveterm.
Long Loop Transient Sound
The Short Loop Transient Sound is not optimally suited for every kind of sound; the restriction of the loop length to 128 samples can lead to a quite static sound once the loop point has been reached. For more lively sounds, a longer loop can be of advantage; the Long Loop Transient Sound offers this possibility.
A Long Loop Transient Sound has a loop length of 2048 samples in the Wave 2.2 and one of 8192 samples in the Wave 2.3. This increase, however, is bought by some restrictions; the start point can still be selected in 64 steps, but the loop start can’t. In the Wave 2.2, the loop start point can be set in 32 steps; in the Wave 2.3, it’s reduced to 8 steps.
Double Bank Transient Sound
This mode only exists in the Wave 2.3 and EVU, since it needs two banks; the Wave 2.2, however, only has one. It is essentially one of the above, but with an additonal twist: the sound spans two banks instead of one. The start point is always in the first bank, and the loop starts in the second bank. Apart from that, there’s no difference.
Using Double Bank Transient Sounds, a far longer natural sound can be used, but to make up for that, the total number of simultaneously usable sound banks in the Wave 2.3 / EVU is reduced.