Frequency Central ECG VCF
10HP Eurorack DIY kit
The Frequency Central Vogue VCF/VCA is a faithful clone of the Moog Rogue VCF and VCA on 10HP. Vogue… rhymes with… Rogue… rhymes with Moog.
Vogue has two outputs, VCA and VCF, so the module can be used as a VCF and VCA combined, or you can bypass the built-in VCA altogether and use the module as a stand-alone VCF. The VCA CV input is shared with VCF CV input #1, although it is not affected by the attenuator – so you can feed an ADSR into this CV input, attenuate it for the VCF, but still have the VCA kicking out at full gain. I thought this was a cool way to add the extra functionality of the Rogue’s quirky VCA without needing any extra panel space!
As an alternative, you can choose to build the PCB into an Electro Cardiogram VCF/VCA. The ECG uses 6 x 3mm red LEDs in place of 6 x BC547 in the filter ladder. Diode ladder filters have a different sound to transistor ladder filters, and if you’re gonna use diodes, why not use LEDs and get a free light show too – the LEDs will brighten as you turn up the cutoff of the filter, or when a CV is applied. For maximum visual effect using my translucuent red acrylic panels, I like to mount 3 LEDs on either side of the PCB. There are a few other very minor differences between the Vogue and ECG builds (documented below), the inspirations for these changes was the Roland TB303 filter.