QuarterInchAudioTracks
Well, to look at the neo-pilot tone on the tape from the nagra I played it on a 4 track Akai 4000db. It took me a while to figure out what to expect with the 1-4 stereo, 3-2 switch (not a lot actually), which decides which track to route to the right channel. The machine only has 1 play head. I think maybe “1-4” and “stereo” have the same result.

If you flip the “1-4” to “3-2” the tracks flip but you are still only reading the same two of four tracks. As expected the neo-pilot tone showed up on the inner track. To see the other phase of the neo-pilot tone I had to play the full track tape backward and look at the inner channel again. Conclusion the neo-pilot is there.

On a nagra the pilot heads are narrower than the Akai Ό track head so when the signal from the two neo-pilot heads are combined the starting program material is much less and then it is subtracked from itsself leaving only the programme material due to the mis-match in heads / circuits etc.

When the two neo-pilot tracks are read at once by the full track head they are out of phase so cancel (in a perfect world).

On to play the tape on a nagra next.