http://www.azdencorp.com/shop/custom...2&cat=3&page=1
This minature 3-channel microphone mixer allows you to add and mix sound from 3 microphone sources simultaneously.
The mixer features 3 MONO 3.5mm input jacks and 1 STEREO 3.5mm output jack.
Comes with a STEREO-to-MONO output cable.
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Donny and belinda
sounds like a jack/cable issue
maybe one of your mic cables are stereo and your pluging it into a mono channel - usually this doesnt matter but with some mixers it does.
maybe belindas adapter from her mic to the cable isnt right -
look at the boom mic jack - is it like the other jacks?
the stereo jack usually has 2 or 3 rings around it the mono has one.