First question: How long is your cable run? I know that when I have cable runs totaling around 30 feet, I get local radio stations. When I go longer or shorter, I'm fine. The reason I am asking is that also occurs in balanced cables. (Also, the FM antenna in your car is actually around 30 feet from connection point on the board to tip).

Second question: Have you checked for a grounding problem?

if you unplug the mic and turn the preamp gain all the way up and monitor the signal you can get a pretty good idea of how much noise the pre is adding to the chain..... it really shouldn't be much at all... If it has a bass rolloff punch that in and it should clear up a lot..... condensor mics are a lot more sensitive, so you are bound to hear things that you couldn't before..... i was doing a session yesterday and it was raining pretty good outside... i cranked the gain and recorded with almost perfect clarity the sound of the rain outside in a somewhat sound treated room.....

K

hm... a grounding problem?

i live in a 90 year old house, and some of older outlets are the 2-pronged variety. this means they're ungrounded, right? (which probably means the rest are ungrounded too)

short of ripping all the wiring out of the walls and replacing it (and i assume that's how you would remedy it) is there something else i can do?

kswiss, thanks for the tip - it never even crossed my mind!

Call your local electrician. Really. It's worth every penny because if you make a mistake, that only asks for disaster. I used the old "if it has a conduit running to the box then just attach the ground wire from a three prong to the conduit or box" advice and eventually started a fire credited to that because my situation was a little different than the advisor's. Just ask the electrician about grounding only what you need grounded (cheaper that way). 99% of the time there won't be any wall-ripping. Ask him for the most cost-effective solution and make sure its someone who won't rape you with their price.

Kswiss wrote: if you unplug the mic and turn the preamp gain all the way up and monitor the signal you can get a pretty good idea of how much noise the pre is adding to the chain..... it really shouldn't be much at all...
K

Need to be careful here - the preamp is facing an open circuit with no mic attached. This raises the impedance at the preamp's input and raises the self-noise of the preamp to a higher amount than when the mic is attached. The mics are typically lower impedance and then the preamp works to a lower input impedance and, thus, presents a lower noise.

Of course, now how do you know where the noise is from? One thing I have found is when you raise the preamp gain with a mic attached you will notice a point where the noise increases *significantly* as you increase the preamp gain from a slighly lower gain. IMO, that's the preamp's way of telling you 'too much gain' and the noise floor is now being set by the preamp and not the mic