LeeHarvey
TVWBB Pro
When I light mine, I'll get maybe two seconds of rumbling sound. I've always chalked it up to turbulent flow through the burner tube, as the flame front gets set up into just the right place. Once the flame is in the right spot and the flow becomes laminar, there's no sound at all. Last night when I lit the burner, it never rumbled at all - the ignitor popped, and I had a nice stable, silent flame instantly.