I get really good results from a CAD KBM412 usually about 50 bucks, it's good for bass drums but better for bass amps, tuba, string bass and capturing low end on a piano or guitar amp. Even used this for a powerful bass vocalist that was crapping out every other mic we tried, he has even started using that mic live. I generally stay away from the usual suspects-bass drum mics- because of the often hyped and rolled off frequencies. This is a rugged mic that has very nice low end characteristics and natural roll off for "bass" instruments.
The down side for mic'ing a bass amp is bleed but this has pretty good off axis rejection.
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