Bi-Filter Offers Dual Analog Envelope Filtering

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On display at the Summer NAMM show is the BI-Filter, an analog dual envelope follower with multimode filters and plenty of options to tweak and customize your sound.

The BI-Filter is a single-channel processor, with the outputs of each filter available separately as well as mixed with the input signal in the main output. An effects loop is also provided to insert external effects before the filters, bur after the envelope detection circuitry. The front panel of this rack unit provides direct access to all parameters to encourage real-time fiddling. In addition to using the envelope of the input signal to control the filters, an oscillator is provided along with controls to control the rate and waveform shape. The two filters and their controls are identical, with control of the envelope attack/decay characteristics, filter type, frequency, and Q, and how the envelope and oscillator should sweep the filter. The output sections is pretty straightforward with mix controls for each of the filter outputs and the dry input, plus inversion controls for each filter input and the ability to arrange the two filters in series or parallel. Switches also let you bypass the unit completely, and disengage the effects loop on the fly.

The rear panel of the BI-Filter sports all the connections, including the input, effects send and return, outputs for the two filters and the main output, CV outputs for the two envelope detector units, a pair of CV inputs for manipulating the filters from external devices, and a bypass footswtich jack.

For more information, visit their web site at www.ehx.com.