Why does my vinyl sound so bright?

With vinyl there is always a little feedback of the acoustic vibration to the cartridge. Low frequencies are most pronounced. Perhaps your old TT location picked up more of this feedback, and therefore gave the overall sound a fuller character. The new TT location is probably better, but you need to get used to it.

Perhaps an adjustment to your VTA, lowering the arm a bit. I'm not sure why this would be affected by the move to the wall shelf, but it's worth a try and it costs nothing.

Keep in mind that getting that cartridge aligned and VTA and VFT set just so will dramatically affect the sound. If you are a complete vinyl imbecile then this is likely the problem. Great sound doesn't come easily with vinyl, it's worth a lot to have a very knowledgable friend who can come and help. There are some real guru's on here and vinyl asylum that can and love to help you get things dialed in. Don't be afraid to ask.

After you're SURE the cartridge cantilever is still straight and hasn't been accidentally bent, double check your cartridge tracking force, it is easiest to knock out of whack accidentally. The Blackbird tracks at 2g. Then check your cartridge loading, you can experiment with the GCPH. Then adjust your VTA to be a little negative, that is, so that the back of the arm is slightly lower than the front when the needle rests on an average thickness record.

Eldartford has a point when he says moving to the wall shelf (an EXCELLENT idea, btw) may have changed the character significantly. The improvement here usually manifests as more space between the notes, which could come across as more lively.

ditto the first two posts in combo.