The bombardon, or E flat tuba, has much richer lower notes.
"Scientific American Supplement No. 819" by Various
You learn to play the bombardon, and I'll be bound to say that it will pull you down.
"The Queen's Scarlet" by George Manville Fenn
The bombardons possess a chromatic compass of 3-1/2 to 4 octaves.
"Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 2" by Various