It doesn’t have anything to do with how the knobs are attached. My guess is that you’re looking at the settings on a vintage unit, or the big box reissue. I have owned all three, and I can tell you that if you were to set the knobs on all of those units to noon, all of their rates will be different, as will the depth, the delay time, and the amount of regeneration. Also, the sweep filter switch on the reissue and xo versions, is original to those two newer, stereo models. The vintage models have a “blend” switch, which when in the off position, grounds out the dry part of the signal from the mix. The sweep filter left both parts of the signal in circuit, but when turned on, seems to “tame” the effect a good amount. I’m not sure what it actually does electronically to achieve its function. If I still had a stereo model, I would open it up and see what it controls, but I fried my XO when I was working on a mod for it, and miscalculated something. I also sold my reissue Polychorus, because I was fortunate enough to pick up a mint condition vintage polychorus, and a very good condition polyflange, and it just doesn’t come close to sounding as good as the originals. Those old SAD1024 IC’s were the most organic sounding delay chips ever.