Our house has a '60s era intercom system with a radio. We like to use it in the morning to catch the traffic and weather report, but lately it has started to hum pretty badly. The power comes from a 24v AC transformer hard wired in the basement.

As a test, I disconnected the power supply and connected the intercom to a 12v DC wall wart. It actually sounded very good with no hum at all, just a little quiet, I'm guessing due to the lower voltage. So I'm wondering if I can just replace the old AC transformer with a 24v DC one? Hopefully somebody knows more about this stuff than I do. The unit is a Rittenhouse RM-2 if that makes any difference.

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1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma