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Double Bass SM57 feedback, impedance matching

Woot, I got a Czech made Amati bass. I mounted my SM57 on it between the bridge feet with some twisted elastic cord ala some thread I saw and sorely disappointed.

Mic lead into (nominal) 250 ohm to 50kOhm impedance transformer jack, into trace bass amp. Speaker in corner on top of bloody great house subwoofer.

With the mic at 45deg and 20mm off the body and tail of mic in the tail length of the strings I get nasty high pitched feedback, at almost no volume. If I lower the mic it gets incurably woolly bassy but at least gets some more volume before the same feedback.

I have a vintage 1950's DeArmond bass mic pickup thingie which came with the bass, unused since the late 70's so the owner couldn't tell me anything about it. It's 1/4lb ,metal slug that gets pressed against the body by a attachment on the top of the tailpiece. it's missing a plug for the lead, just bare wires. Link Removed (ever wonder how ampeg got its name??)
De Armond Bass Viol Pickup - dbc Double Bass Forum, Upright Bass Chat not encouraging to bother messing about with it.:hmm:
 
Woot, I got a Czech made Amati bass. I mounted my SM57 on it between the bridge feet with some twisted elastic cord ala some thread I saw and sorely disappointed.

Mic lead into (nominal) 250 ohm to 50kOhm impedance transformer jack, into trace bass amp. Speaker in corner on top of bloody great house subwoofer.

With the mic at 45deg and 20mm off the body and tail of mic in the tail length of the strings I get nasty high pitched feedback, at almost no volume. If I lower the mic it gets incurably woolly bassy but at least gets some more volume before the same feedback.

I have a vintage 1950's DeArmond bass mic pickup thingie which came with the bass, unused since the late 70's so the owner couldn't tell me anything about it. It's 1/4lb ,metal slug that gets pressed against the body by a attachment on the top of the tailpiece. it's missing a plug for the lead, just bare wires. Link Removed (ever wonder how ampeg got its name??)
De Armond Bass Viol Pickup - dbc Double Bass Forum, Upright Bass Chat not encouraging to bother messing about with it.:hmm:

Many players have had good results with that setup. Have you tried going straight in the board? How does that sound?