Make Noise XPO at a glance

Make Noise's XPO aka Stereo Prismatic Oscillator is an analog tone generator for true stereo patches. XPO provides eleven waveforms at once, divided into five mono and three stereo pairs. The mono waveforms, which are the normal ones of a common oscillator, consist of sine, triangle, sawtooth, spike and sub. The latter is a variation from the STO oscillator. The three stereo pairs are composed of PWM, wavefolding and Vari-Timbre for the left and right side respectively. PWM does exactly what it is supposed to do, as expected. Vari-Timbre is inspired by old Buchla oscillators like Model 158 and 258 and can crossfade from sine to sawtooth. Wavefold also takes sine as its source material, adding metallic-looking overtones to the signal by folding waves. For each waveform there is a variation on the normalized left channel, which is a mixture of the left and right waveforms. The Center parameter modulates the left and right sides together, and in addition each side can be bipolar modulated separately using Modulate L/R. At this point a very wide and lively sound spectrum is created, which is probably unique in this form so far. For the modulation of the frequency there is exponential FM with Attenuverter and a linerar FM input. The latter already has the sub-oscillator of the XPO pre-patched on the input and can be replaced by any other signal. In addition, the intensity of the linear FM can be controlled by a VCA. The pitch control is completed with a hardsync input.

The basic idea behind the XPO is that some polyphonic analog synthesizers from then until today offer voice panning within the voice architecture, but the stereo image is realized in or after the VCA. XPO takes a completely new approach and offers the stereo signal path right at the beginning and adds wavefolding and vari-shape to the classic PWM. The best results with XPO are achieved by combining it with the Make Noise modules QPAS and X-PAN. Of course, any other patching option is recommended, especially those with stereo modules to emphasize the stereo qualities of XPO.