After long hours of experimentation, I finally have a parametric filter setup that is way cool. My early efforts focused on separate filters for bass and mid, or bass and treble, or mid and mid, etc. The problem with these, when combining any two of them, is either limited usefulness, or massive confusion! It's really hard to get one's head around how to get a particular sound, let alone try to duplicate yesterday's sound when one pickup has the bass sweep and one has the treble.
I then made a different filter with a full sweep from 45-4900 Hz, which covers the full range of the bass, and a 9.5dB boost and cut. Keeping with the filter preamp philosophy, I put one of these on each pickup. Much easier to understand: If you want to boost mid, put both frequency knobs somewhere near the middle (i.e. with more separation for a wider boost) and boost both pickups. Or try different boost levels for each, and you get subtle differences in the tone. You can use boost or cut on the pickup of your choice, for example a deep bass boost from the neck, and a slight high mid cut from the bridge. It can get close to all the sounds of a traditional bass/mid/treble boost/cut preamp if you use it that way, but you have full control of the frequency for each filter, and the difference between neck and bridge tones comes through.
I am really excited about this; there is nothing else like it out there for sale, though I'm sure there are some bass nerds out there who have tried it at home! I need to validate the final design, but I expect to have it up for sale in about 2-1/2 weeks.
Really interested in trying this one out when it’s available.
Can't wait to check out the specs!