Strange phase type issue for guitar

[Guest]

I'm noticing when I play a D chord on my electric guitar amplified through my guitar tube amplifier the sound it makes is nothing like what you'd expect a regular chord from an electric guitar to sound like. It's hard to describe the sound but essentially it's similar to what I would call a phase issue perhaps or but less specifically I would describe the issue as the sound suddenly goes into a tunnel, to my ears, anyway. No I'm not going deaf and I rarely play loud guitar. I tried moving the pole pieces of my guitar and when I did this the odd sound of the D chord shifted to one fret higher but it's still there. What might this be and is there anyone who has known experience with this issue to solve to know what is causing this? Could this be caused by failing electronics in the pickups or bad wiring, etc.?

[CS70]

It’s fairly common, if a tube is not well seated or some other comoponent rattles and it happens in response to specific frequencies. Check the tubes, make sure they are snug and swap them if you can and see if it’s improving

[Wonks]

Some help for us.

Guitar?
Pickups?
All or just one pickup (or mix)?
Amp?