ADDAC has pulled the filter out of their ADDAC105 4 Voice Cluster because it sounded so good and deserved to be a module in its own right. The ADDAC604 Dual Filter offers two mono or a stereo multimode filter in the same style and affordable format.
The filter was developed for the 105 module and was placed after the summing mix stage. ADDAC says that when developing something for one module you often come across ideas or electronic breakthroughs that inspire new modules and such was the case here. To make things more interesting they decided to duplicate the circuit to offer two filters and blend some of the controls to give it a stereo mode.
As two mono filters you have regular cutoff and resonance controls and a CV input on the cutoff with an attenuverter. For output you have low, high and bandpass outputs available simultaneously. For stereo mode the left side controls the cutoff for the whole stereo signal and the right side cutoff is bypassed. The resonance is still independent on each channel regardless of the mode.
The manual says that the left side audio and CV is normalled into the right side so you can have a single input running through both filters with a single modulation signal controlling both cutoffs.
I’m really impressed by these recent releases from ADDAC. They’ve been simple, straight forward, immediately useful and affordable. The 604 Dual Filter gives a lot of sculpting possibilities in a single 6HP module. It’s also available as a kit.