Hum & radio interterence on Ampeg BA115

[some1]

Hey guys, I've recently purchased an Ampeg BA115 online. When I plug my guitar into the amp, I get some radio interference. I've never had this before, so I'm confused. I had another bass & amp combo in the same room, location, etc. before and never had that problem. Is this something expected? Can I do anything to prevent it?

Also, there is some amount of hum coming from the amp. The ones I tried in guitar center didn't seem to have that much hum to me (or maybe it was less noticeable), is this a common thing in Ampeg amps? I used to have a 75W Fender Rumble, and it was much quieter.

[RickenBoogie]

Grounding issue. Check all AC cords and outlets.

[fdeck]

In my amp fixing days, the most common cause of radio interference was a loose ground or dodgy solder joint at or near the input jack. Also, the input jack tends to be the part of the amp that takes the most abuse.

Of course you shouldn't open up your amp unless you are qualified to do so.

[bobba66]

Is it a hum or more of a hissing sound? The tweeter in mine has a nasty hiss 'till I unplugged it.