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5. Envelope following in VPS Philta XL
1 Philta XL gives you serious control with its two independent filters and envelope follower. We’ll use the two filters to create a notch filter, before employing the envelope follower and LFO to add a funky wah-wah effect to a Rhodes loop. In a 120bpm project, load Rhodes.wav on a new audio track, then load an instance of Philta XL on this channel.
2 Notch filtering lets us carve out some signal from a band of the spectrum. By default, Philta XL is set to band-pass, so we’ll change the mode to Notch by flicking the switch in the centre of the interface. Notch mode automatically moves both filters to their extreme settings, so move the Lowpass dial to 350Hz to raise the cutoff and bring some signal back in.
3 Each filter’s cutoff slope can be set between 12 and 96dB per octave. We’ll make the cutoff a bit steeper by changing both filters to 48dB – just click 48 in each filter section. We can also adjust the resonance width and amount independently for each filter: add bite by changing the Lowpass filter’s Width to 85% and Reso to 50%.
4 It’s a bit dull-sounding at the moment, but we can bring the high end back by lowering the Highpass dial to about 4000Hz. We can give the high-pass filter a bit of emphasis by adding in a slight peak at the cutoff point. To do this, turn the Highpass Resonance to 40%. Now we’ve set up our notch filtering, we’ll make each filter move using the envelope
5 Click on the Envelope tab to open the envelope follower. This uses the input signal to automate the filter cutoff. The movement of each filter can be set independently, allowing different settings for body and the high-end transients. Turn up the LP Str dial to +80% to get the low-pass filter’s cutoff sweeping upwards when a peak is detected.
6 Head to the HP Str dial and pull it down to -100%. This will make the Highpass filter sweep downwards when a peak is detected, meeting the Lowpass filter on its rise upwards. For extra movement, click on the LFO tab to access the LFO. The HP Str dial controls the amount of LFO sent to the high-pass filter. Turn this up to +100% to make it sweep up and down.