Focus Enhancements MX-4DV power question

I finally found a version of the MX-4DV that has a barrel jack instead of the multi-pin power jack. On the unit itself the power requirement is given as 12VDC, 20W max (thus, 1.67A current draw). However, polarity of the DC power connector is not given. Does anyone know if it is center positive or center negative? It is not stated in the manual, so asking other owners is my best bet before opening the device to look inside.

Update: center positive is working.