Raging Bull is based on the legendary Moog Taurus Mk I VCF and VCA. It has a lovely, thick Moog-like quality, which is further enhanced by the drive you can get out of its VCA at higher settings.
A big part of the sound of the Taurus was the way in which the VCF interfaced with the VCA, so on Raging Bull the VCA is always in the audio path. A toggle switch allows you to select ‘always open’ or CV control of the VCA from CV input 3.
By sending an ADSR into CV3, the signal will go to the VCA CV input unattenuated and the VCF CV input via the attenuator 2. By sending a gate into CV3, and setting the attenuator to zero, the VCA can be gated while the gate has no affect on the VCF.
Raging Bull uses the no-longer-in-production CA3046, which can still be acquired from suppliers such as Banzai, Das Musikding, Small Bear and some reputable Ebay sellers. ALFA RPAR recently released a CA3046 clone, which can be used instead, or you can opt to use the SMD LM3046 the PCBs has pads for. Or, you can use the UL1111, which is functionally identical to a CA3046 – we sell these, and you can choose to buy one with the PCBs as an option when ordering.