Hi, I'm insane so I decided a number of years ago that I really wanted to have a polyphonic modular setup. Basically the inspiration was the Oberheim 4/8 Voice. I love the idea of setting each voice individually and getting those small variations that add depth and dimension to the sound. Probably a product of having PTSD from growing up in the overly digitalized 80s and having only all digital or very contained hybrid synths for a long long time.
Anyway, a little over a year ago, I finally started to put it all together after I discovered the NiftyKeyz case and figured it would be about as perfect as I could get for what I want.
The only real downside is it's only 4 voice (6 or 8 would be cool), and only 112 HP, so I really had to whittle down what I wanted to squeeze everything in. I ended up going with some System 100 VCOs, a Doepfer Quad VCO, 2 banks of Doepfer Quad Poly VCFs, 2 banks of Doepfer Quad Poly ADSRs, 2 Rides the Storm QAMs (4x3 active mults so my voices stay in tune), 2 Doepfer 2x3 passive mults, Doepfer Stereo 4 channel mixer, and a 2HP Verb (stereo reverb) for good measure.
For the most part, it sounds pretty dang cool and works as intended (I still need to get around to calibrating the Doepfer Quad VCO though, but it's reasonably close, I already did the Behringer VCOs) . But if I try to use fast attack times, I get this sort of low end "thud" sound. I'm still going through fully troubleshooting it, but I wanted to see if anyone had any ideas.
My initial thoughts on likely sources are filters being overdriven too much (but I still get it even with the input at about half mast), some kind of envelope issue with the Doepfer Quad Poly ADSRs, VCAs being overdriven (oh yeah, I have a Plum Audio ARBA for that purpose), or possibly a power supply issue? But the NK is good for 1500/1000/1000 and on here my rack is showing at under 800. I am also using stacking cables to get the 2 banks of VCOs into the 1 bank of VCAs.
It seems like if I run the VCOs straight to the output of the NK, that's fine. Or even the VCOs through the filters. Again, I haven't gone through every possible permutation, but I figured I'd come here for advice. I could also theoretically be overdriving the output stage of the NK.
I will say the whole thing is sounding a lot better at this point than with the original Doepfer Quad VCA. I couldn't get that thing to cooperate but I missed the return window so now it sits in a box unused.
So really I'm just looking for things to try to identify the source of the problem and/or mitigate/eliminate the problem. Basically it sounds almost like when you're palm muting on a guitar with the lows turned up too much (think And Justice for All by Metallica for an approximation, but it's not exactly the same). I'm hoping I don't have to replace the whole back end of the synth with different components. I've ony just barely squeezed everything in as it is, so I would likely have to lose either the 2nd bank of VCOs or filters (the Doepfer has individual wave outs though, so I could still have a bank of saws and a bank of squares filtered differently, for instance) if I had to add anything else, or replace with a wider unit.
Anyway, the rack should be visible on my profile, please chime in with any thoughts and thanks in advance.