RE: [all] stereo to mono phase problems

[Hans Lindauer <hans@ernieball.com>]

Concerning phasing problems:

You may have a speaker which is internally wired incorrectly.  If the 
woofer
and tweeter are out-of-phase on one side, then the pair won't sound right
which ever way the cabling from the amp to the speakers is phased.  Hook up
a battery to the speaker terminals to get the woofers properly in-phase.  
As
far as the tweeters go, you probably won't be able to see any excursion 
with
the battery test (and you are more likely to fry them).  Looking at the
color of the wires going to the terminals will tell you if the two speakers
are wired differently.  

If you have a pro audio house in town they can rent you a phase tester
(often referred to as a "cricket"), which is very handy for tracking down
phasing problems.

For cables from your mixer to amp, you should probably use 1/4" unbalanced
-> RCA cables.  Try to keep adapters to a minimum; all those connections
aren't good for your signal.

-Hans