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Hi Paul, > I've experienced the phase problem with a variety of sources and isolated it > to a problem between the mixer and the amp + speakers. The mixer is an > Alesis32. Monitoring through the mixers headphone output does not exhibit > the same muddy result when panning to center. If you're convinced it's your mixer-to-speakers connections you can certainly check them for correct phasing. Depending on your amp and speakers, it's relatively simple to check them. First, get a ohmmeter or continuity checker (or something that functions like one). Next, confirm that the left and right mixer-to-amp cables are wired identically. For example, for 1/4" phone plugs confirm that if the left cable goes tip-to-tip and shield-to-shield, then the right cable does also. Note that for correct phasing, the absolute pin-to-pin connections do not matter, but the cables must be identical. That is, the left cable could be tip-to-shield so long as the right cable does too. Third, perform the same check on the speaker cables. If the cables check out, you might want to check for improperly wired speakers. The cheapest way to do this is with a battery and a resistor (to limit the current). I usually use my ohmmeter. It's possible to zap your speakers so be careful. Remove the speaker grill so you can see or feel the cone or tweeter. BRIEFLY tap the speaker connections with the battery/resistor and note the direction of cone/tweeter travel (in or out). Repeat with the same polarity on the other speaker. The travel direction must be the same. If everything checks out, that leaves phase reversal in the amp. This is not very likely in a commercial amp. However, some amps have phase inversions switches for bridging and other purposes. Check for such switches. > I have ruled out the source as the problem. The source is fine when patched > directly to the amp (hence no panning to center). Is panning to center > inherently going ot cause a phase problem. Could it be the room or >speaker > position causing a problem? The source is either mono tracks from a digital > multitrack deck, CDs, DJ-600 mixer output or mic input. If I'm understanding you correctly, you patched a stereo source directly to the amp. This will not show up the phasing problems you described. If you have a source-to-mixer phasing problem (by far the likeliest culprit) the problem will show up when you electrically combine the left and right channels. I would not expect to hear it when the stereo source is patched directly to the amp inputs. Also, if the signal goes through an effect loop, that can mess with the phase as well. Hope this helps. Dennis Leas ------------------- dennis@mdbs.com