Contrary to what I’ve read online in a few places, the MR-1 cassette deck uses “Pin 3 Hot” for the XLR balanced output. I’ll admit there’s few people who care anymore about a phase coherent signal from a cassette output, but for those that do, the truth can be hard to find.
I contacted Willy Hermann who services these decks (and did an excellent job on mine by the way). He confirmed that the schematic he has indicates that the deck is pin 3 hot. This is contrary to the majority of balanced XLR gear I’ve run into in the states.
A test verified that Pin 3 is correct: I created a 3 pulse waveform with positive voltage and recorded it on a cassette (using an unbalanced input). This is the stereo waveform (L&R) on the left half of the graphic.
I then played out the waveform from the MR-1 and as you can see on the righthand side, the balanced signal from the XLR shows a positive phase on its output. (Using a Pin 2 hot cable, caused a negative phase)
So be aware! Nakamichi MR-1 decks are pin 3 hot and require a special cable when interfacing with most modern gear.