Thanks all for the answers!
tmd3:
When I see this question, I suspect that you're trying to use 48VDC phantom power, from a mixer or something like that, to power an electret. I've done that, and it worked quite well. If that's what you're trying to do, or something like it, say so, and I'll try to remember how the gizmo worked.
Yes, this is exactly our task 
If you can remember how the gimzo works, it'll be really good.
Concerning the suggestion of use a LM317HVT it could be a good idea!
vasquo:
Yes you can use a regulator to regulate that down to 9V. Just use a big heatsink.
I'd suggesting using a LM317HVT <--- note: HV type
Is it possible that the sound card phantom power isn't able to sink enough current to make work properly the 7809 or LM317HVT converters?