If the mixer has XLR outputs and the amp has ¼" inputs, use a balanced patch cable with a female XLR at one end and an TRS (stereo) ¼" male jack at the other. Modify it as follows:
{Note: The standard balanced XLR wiring (here at Yorkville and with most companies) is pin 1=ground, pin 2 = positive (+), pin 3 = negative (-) }
If both the mixer and the amp have ¼" connectors, it's best to use a balanced TRS-TRS patch cord modified as follows; (1) Remove one of the ends, (2) Replace it with a standard mono ¼" plug soldering the tip wire to the tip tab and the other two to the ground tab (the longer of the two). (3) Mark the mono-plug end with some tape so that in future you'll know this is the cable for this application and that the mono end goes into the unbalanced jack.
{Note: The standard balanced ¼" wiring (here at Yorkville and with most companies) goes tip = positive (+), ring = negative (-), sleeve = ground }
{Additional notes: (1) This form of "trick" balancing works very well with one small exception; if you switch off the mixer but leave the amp on, you may hear some hum through the speakers. If so, it is because the balancing in the mixer, which is generally an active circuit these days, has also been switched off (naturally), ergo there's no more hum cancelling. Just remember to switch off the amp too. Oh, and one other thing - if you hadn't already figured it out, these balancing tricks work for EVERYTHING; unbalanced mixer to balanced amp, balanced mixer to unbalanced EQ, or crossover, or compressor/limiter, effects units, etc., etc. }
And what do the pros do about 2-Ohm loads? It depends on the definition of "pro". The big touring rigs tend to favor 8-Ohm loads, 4 Ohms minimum. This is because delivered power losses over long cable runs are lower when the speaker impedances are 8 Ohms. They can become very high - 60% percent or worse (!) - into 2-Ohm speaker loads.
Feeling confused? Check out the power loss chart in our on-line Audio Guide in the Speaker section. Club pros, on the other hand, can contend with whatever loads they encounter principally because the speaker cables don't have to be so long hence the cumulative resistance doesn't get high enough to rob large amounts of power.
