User manual RANE MX 22

[. . . ] OPERATORS MANUAL MX 22 STEREO 2-WAY CROSSOVER QUICK START Whoa, hold on there. Even if you don't read manuals as a matter of principle, at least read this section to avoid hurting yourself or your equipment. Balanced XLR cables are recommended, but if you must convert to ¼" connectors, buy or make a cable like the ones on page Manual-11 and keep them as short as possible. Do not connect the "+" or "­" output pins to ground, as this may cause the power supply to shut down. [. . . ] Adjust the display controls on the analyzer so that it shows the greatest number of 0 dB LED's (green on Rane equipment) below the crossover frequency. Now slowly turn up the HIGH LEVEL control until the display shows the same high frequency output level average as the low frequency section. IMPORTANT: Compression driver or horn high frequency roll-off, bass roll-off, and room acoustics usually cannot be corrected by the crossover. If, for example, you are adjusting the HIGH FREQUENCY LEVEL control and observe a decline in frequency response somewhat above the Crossover point, then set the HIGH LEVEL control for equal display level near the crossover point and leave it there. Without changing any settings on the SPL meter, adjust the crossover HIGH LEVEL control until you obtain a 0 dB reading on the SPL meter. Make any overall level adjustments with the INPUT LEVEL controls and leave the output LOW and HIGH LEVEL controls unchanged. It is possible that you may turn one of the frequency section output LEVEL controls all the way up and still not have enough volume for a 0 dB reading (as determined by previous section levels). This is probably due to different sensitivities of amps, speakers and other level controls in the system. When this happens, re-set the SPL meter so that it reads 0 dB on this frequency section (you may have to "down range" the meter and re-adjust the crossover INPUT LEVEL control). Now go back and re-adjust the previous crossover LEVEL controls, turning these down to get a 0 dB reading on the meter. Manual-7 SOUND SYSTEM INTERCONNECTION Rane's policy is to accommodate rather than dictate. However, this document contains suggestions for external wiring changes that should ideally only be implemented by trained technical personnel. Safety regulations require that all original grounding means provided from the factory be left intact for safe operation. No guarantee of responsibility for incidental or consequential damages can be provided. (In other words, don't modify cables, or try your own version of grounding unless you really understand exactly what type of output and input you have to connect. ) THE ABSOLUTE BEST RIGHT WAY TO DO IT Use balanced lines and tie the cable shield to the metal chassis (right where it enters the chassis) at both ends of the cable. A balanced line requires three separate conductors, two of which are signal (+ and ­) and one shield. The shield serves to guard the sensitive audio lines from interference. Only by using balanced line interconnects can you guarantee (yes, guarantee) hum-free results. Chassis tying the shield at each end also guarantees the best possible protection from RFI [radio frequency interference] and other noises [neon signs, lighting dimmers]. THE NEXT BEST RIGHT WAY TO DO IT The quickest, quietest and most foolproof method to connect balanced and unbalanced is to transformer isolate all unbalanced connections. The goal of transformer adaptors is to allow the use of standard cables. With these transformer isolation boxes, modification of cable assemblies is unnecessary. Virtually any two pieces of audio equipment can be successfully interfaced without risk of unwanted hum and noise. [. . . ] For example, a nominal +4 dBu system that clips at +20 dBu has 16 dB of headroom. hum Unwanted sound contaminating audio paths due to EMI (electro-magnetic interference) caused by AC power-lines & transformers getting into unbalanced, poorly shielded, or improperly grounded connecting cables. Hum has a definite smooth (sine wave) repetitive sound based on the harmonics of 50/60 Hz such as 100/ 120 Hz and 150/180 Hz. If a graphic equalizer's adjacent bands, when moved together, produce a smooth response without a dip in the center, they are interpolating between the fixed center frequencies. [. . . ]