Cleeds is correct. But I don’t think a change in overhang would enhance bass. The OP is also correct in thinking that “tail down” usually enhances bass, contrary to his direct experience. I suggest maybe the change in mats is the cause. I agree with Pindac, let the cartridge break in before fiddling. Also “level” is the best start point for VTA with every cartridge I own.
Help with tone arm geometry and bass
After installing a new cartridge, I checked that my SME 309 tonearm was level. The sound of voices especially male voices was a bit bass heavy. so I added a ringmat turntable mat which raised the level at the head shell by 2mm. The bass heaviness disappeared. This is the opposite of what I was led to expect. I always thought head shell up meant tail down and more bass. have I got it wrong?
I would like to dispense with the ring mat so I can use a record clamp on the spindle. But this would mean tone arm level again. Which way do I adjust the tone arm to remove the bass heavyness without the mat?