the sound trap may be it - just in general those low frequency notes - the waves are somewhere around 10 meters in length. if you are in a room smaller than that (like 99% of us probably are) wavelength is simply far larger than the space in the room and it can get muddy and lost as it bounces/gets absorbed and otherwise ends up distorted as it hits various surfaces and materials.
solution: Be a fat cat and get yourself a concert hall to play in.
Room acoustics is also hard to really fix without going all in, and the effect is usually large and really visible in frequency response graphs.
My room is a pathological worst case, my workspace is up against a flat wall and there is a wall of glass cabinet doors right behind me, under 3m away from the speakers. Acoustically all over the place 
That said, some of the worst can be mitigated by speaker placement - more distance from the wall behind and play with the angle it is at.
I did record a short video, but I’ll be damned if I can figure out how to post it here. Hell, I can’t even figure out how to quote someone. Appreciate everyone’s advice and I am listening to your suggestions, this forum interface is unlike anything I’ve dealt with over the past 20 years and it’s just a pain in the ass to reply directly. Thank you all.
Upload the video on YouTube then post the link here.
How to quote someone like I just did you:
With the left mouse button down, swipe the text you want to quote and release the button. Just above the highlighted text, two options will pop up: “Quote” and “Copy Quote”. Click on “Quote” and the highlighted text will be placed in a Reply box. Add your comments, click on “Reply” and Bob’s your uncle.
@Al1885 ‘s suggestion to use YouTube is the best. You will need to create your own channel on YT and then upload the video to it. Click on the video, then click on “Share”. Copy the Share URL (Ctrl-C), then just paste (Ctrl-V) that URL into a Reply.
You can also set the video to “unlisted” in YouTube and it will require the link to access it.
Copy and paste. Highlight what you want to quote (in blue on .u android) and tap “quote” icon on the bottom left. Done. Videos, I think you have to link your youtube channel. I was helped with the same issue last week. And yes, this format takes a bit of learning compared to all other fora.
ETA: I am late to the party. Lol
Well, I reckon I found my issue and it makes me feel pretty dumb. Started fiddling with the amp and the gain knob and it was completely unresponsive. Called the shop where I bought the amp ( all my stuff, actually) and they told me to bring it in to swap out. My beloved Thunderbird has her full voice back again 
I guess it degraded over time and I didn’t notice it until it got really dull. I never move that knob and didn’t think much of it.
Unfortunately, this situation got me hankering for one of those good looking Orange Crush amps and that itch hasn’t gone away yet. Pray for me
…to get it?
To overcome the temptation of GAS. However, this is the third Rumble I’ve had fail, so that inner voice keeps telling me to “upgrade”.
Mister you came to the wrong place
No politics or religion remember.
@howard is right as usual, buy the amp you want. 
Try Rotosound Swing Bass 66s. They have got a lot of punch and I use them on all my basses. There was an article about Roger Entwhistle from “The Who” who had the same problem. He went to Rotosound and they beefed up the core on the strings and that seemed to solve his issues. Most music stores don’t carry Rotosound strings so I buy them on E-Bay.
