[Mike Rivers]

Ludwig77 wrote:
I played a gig using my laptop to play backtrack MP3s.

The MP3s were recorded in stereo. I was running out my laptop's
headphone out jack via a cable that converts 1/8" to 1/4'. I ran that
to a direct box and then to the board.

It seemed that some instruments were missing. Would I be right to
theorize that I would have been losing one of the two speaker's in the
stereo field via this routing?

That's certainly a valid theory. You need to figure out how the cable
you have
is wired. Most likely it has the tip and ring contacts (left and right
channels) of the
mini plug connected in parallel and wired to the tip of the 1/4" plug.
That should work.
But if it's a "balanced-to-unbalanced" cable, the two plugs would be
connected
tip-to-tip and the ring of the mini plug would be connected to the
sleeve (ground).
That would effectively short out one channel.

If you have an ohm meter or other continuity tester, you could check out
your
cable. Or you could make a test recording on one channel, then the other
channel,
and play it back to verify that you get both channels.

Another possibility is that some MP3 encoders do strange things with the
phase
relationship between the two channels which could make a hole in the
middle of
the stereo image and, in mono, make some things drop out.

Does your mixer have line inputs? If so, that makes it easy to
experiment - just connect
the headphone output directly to the line input, using the appropriate
adapter. If, during
your shows, the mixer is located at some distance from your MP3 player,
then using a
DI is a good idea for making that long cable run, but if it's within
reach, you can eliminate
the DI. That won't solve your missing instruments problem, but it will
simplify your
hookup and you won't sacrafice any sound quality.


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