The new series of Behrenger mixers uses a switching supply rather
than hunky wall wart transformer, and unsurprisingly puts out birdies
(promoted as not putting any AC hum in the audio, which is true).

The UB1204-PRO in this case, but no doubt they all do it.
http://www.zzounds.com/item--BEHUB1204P

The older MX series is fine but apparently no longer made or sold.
Fortunately I have 3 of these and they're all working. The finest
way to deal with multiple radios and audio filters, recording one
and listening to another.
--
Ron Hardin


On the internet, nobody knows you're a jerk.