This must have been a pretty decent undertaking! So I don't enjoy saying this doesn't quite look/sound right, at least when comparing to my UA version (API Vision).
Side note, I always used the 550s for drums, for which they are legend - but the graphic was known for electric guitars in my (Nashville) circle of old farts.
What is your baseline EQ for the model? I compared it to the UA-API Vision and it is significantly different. I was wondering how you were going to get 31 bands down to 10 without each band being too narrow...
Screen shots: If you don't already have the amazing Bertom EQ analyzer plugin, go get it right now, it's pay what you want:
https://bertomaudio.com/eq-curve-analyzer.html
This is with the 1kHz band maxed out, the UA version in light grey and your version in green:
Screen Shot 2024-02-28 at 1.18.05 PM.png
Here is the same 1kHz band at +6dB in both versions, same colors as last time:
Screen Shot 2024-02-28 at 1.20.05 PM.png
I suspect you'll never get very close with a 31 band EQ at the heart of the system.
I'm using your template to build a version using two ColoringEQs, since it already does the proportional Q part (just not enough without some extra CV 'help'). But because of that things got complicated.
So I though of the SSL in G mode, and it's great match. But alas, there is no free lunch and the SSL doesn't cover the entire range with the G bands. But I built it anyway because overall, and especially in the mid range, it is almost exactly spot on with the UA API Vision EQ.
For comparison, here are the same two curves, 1kHz at +12dB and +6dB, with the API in light grey and your combinator (modified with SSL EQs) in the green:
Screen Shot 2024-02-28 at 3.27.11 PM.png
Screen Shot 2024-02-28 at 3.28.07 PM.png
Here's the SSL version, should all be working good - it is SO much closer to the original, but that doesn't mean your first version isn't useful - for all I know folks may prefer it to the API!
And note the even though it use the low and high BELL for a few bands, those bands are very similar to your version with the 31 band EQ, so maybe you'll still like the SSL version on drums?
Have fun:
https://www.dropbox.com/scl/fi/2kouj1vz ... pq6u4&dl=0
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