Buchla - 296e Spectral Processor

The Spectral Processor is one hell of a module! It is essentially a multifunctional 16-fold bandpass filter with fixed frequencies for each band. Each band is equipped with an envelope follower and a VCA. Touch-sensitive touch faders with eight segment LED chains for visualization allow you to not only draw filter curves, but also to intuitively view the sometimes complex behavior of the filters. Two filter curves can be created and cross-faded with the morph parameter. The Spectrum Transfer function allows vocoder applications within the module or in combination with a second 296e. And then there's the sound...

The 16 bandpass filters have separate inputs for even and odd bands. The inputs are normalized to each other, but each input has its own gain control and a pre-emphasis control that can counteract the loss of high frequencies. Each filter band has its own VCA, which can adjust the volume of the band and has its own CV input. Each filter band also has an envelope follower, which provides the amplitude of the respective frequency band at a CV output.

The levels of the 16 filter bands can be adjusted via touch-sensitive touch faders. In this way, up to two filter curves can be created, between the values of which parameters can be interpolated via "morph". This parameter can be modulated by CV as well as by audio.

If Spectrum Transfer odd->even is activated, the outputs of the odd-numbered envelope follower control the VCAs of the even-numbered filter bands.

If Spectrum Transfer even->odd is activated, the outputs of the even-numbered envelope follower control the VCAs of the odd-numbered filter bands.

These modes turn the module into a pseudo vocoder.

If you have two 296e, they can be connected internally. The Spectrum Transfer function ext->all offers in this case a "complete" Vocoder mode. Unlike the way a vocoder works, transfer functions can be used in both directions at the same time, resulting in rather unusual sounds.

The touch faders are not only used to adjust the levels. The decay times of the envelope followers can also be programmed in this way. Two further display modes can provide information about the spectrum or the actual levels of the filter bands.

The envelope follower can be stopped via the "Freeze" button or pulse input, manually or CV controlled, to "freeze" the spectrum.

In addition to a mix output where the even and odd output VCA's sound mixed together, there are separate outputs for the even and odd bands. The outputs "Comb odd" and "Comb even" additionally deliver the signal of the even and odd filters at a fixed volume. Filter curves or morph settings have no effect here.

In combination with the Preset Manager of the 206e and 225e modules, all parameters can be saved and recalled.

Please note: Buchla 200e products may have lengthy waiting times, as they are manufactured in small quantities only.