God, I love a tuba in a rock song*. Those sonorous, farty notes are so...unexpected. Swollen. Emphatic. Merry. And mournful. Like you musically captured the character of Falstaff.
A tuba brays, "For-get. For-get. For-or-get."
Kidz, if you really want to replace the bass, try a tuba. You get someone playing that big brass tulip and squatting and pitching on your stage, you got a show!
I'm reminded suddenly of whatever band or other--or stray members of a band--I encountered one night at the Uptowner bar in Milwaukee years ago. It was one of those moments when you walk into something that's in full monkey-swing. We opened the door and the bar, typically full, was chattering, but its din was muted by the duo in at the back of the room. One played a drum, standing up, or maybe guitar, and the other was just singing into the mike, I think, wearing an industrial barrel that he'd cut open at either end and that had the words C*NT LUBE scrawled in paint across its broadest part.
When I first recall that, whatever that was, I think they were playing a tuba. Only they weren't.