User manual RANE MX 23

[. . . ] OPERATORS MANUAL MX 23 STEREO 3-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. This device uses low impedance balanced line drivers. [. . . ] With these set to the 0 dB mark and the INPUT LEVEL set to 10, the crossover yields no level change from input to output. This is the best gain structure and provides the best signal-to-noise performance. Crossover Philosophy Now it gets real fun. The idea is to set the output LEVEL controls on the crossover so that the entire speaker system has a uniform, flat response. Unfortunately, the room in which the speakers are placed has a habit of always getting into the act, so things get messy. As a result there seems to be two schools of thought regarding the use of active crossovers. The Set-lt-Once-And-Glue-lt School The philosophy here is to use the crossover to flatten system response as much as possible without room acoustics involved. This means setting up the system outside (unless you happen to have a very large anechoic chamber handy) and with the aid of a realtime analyzer and pink noise source, adjust all of the crossover outputs so that the system is as flat as possible. Once the system is tuned, the crossover is then locked behind a security cover (posted guard is optional) and never again touched. It is then the job of the system equalizer(s) to normalize or flatten the response for each different room. The Fix-lt-With-The-Crossover School Here the crossover knobs get a good workout, for the crossover is used at each location to help flatten the system along with the equalizer. Regardless of which school you profess, the absolute importance and effectiveness of some kind of realtime analyzer in your system cannot be overstressed!An analyzer saves tremendous amounts of time and provides the absolute consistency, accuracy, and plain old good sound that very few ears on this earth can deliver. They are affordable, easy to use and amazingly effective. You owe it to yourself and your audience to at least look into one of today's cost-effective analyzers--you'll wonder how you managed at all without one. Figure 1. See unmarked Frequency detent steps below. STEP 0 1 2 3 85 80 80 85 93 420 4 5 100 6 7 125 8 9 150 10 11 12 200 13 14 250 15 16 300 17 18 19 400 20 21 500 22 23 600 24 25 26 850 27 28 29 30 1000 LOW/MID 80 SCREEN LOW/MID 80 FREQ. MID/HI 350 SCREEN MID/HI FREQ. 102 114 126 140 154 170 189 209 231 255 283 313 346 383 423 468 518 573 634 702 600 750 1000 1500 2000 2500 3200 4000 777 5000 859 950 1000 1000 1000 6500 7000 350 350 350 372 419 472 532 600 676 762 859 969 1092 1231 1388 1565 1765 1990 2242 2527 2850 3212 3621 4082 4602 5188 5848 6593 7000 7000 7000 Figure 2. Frequency detent table with actual frequencies of all detent steps. Manual-5 Setting the Mono Sub Output Level Begin with the MONO SUB OUTPUT LEVEL trim set at MAX. The LOW LEVEL control has no affect on the MONO SUB OUTPUT. Make subwoofer level changes with either the MONO SUB OUTPUT LEVEL or with the amplifier level control. If you are using the MONO SUB OUTPUT instead of the LOW OUTPUTS, be sure the 100 Hz FILTER is switched OUT. Setting Levels With a Realtime Analyzer Any good 1/3-octave realtime analyzer will do, however, Rane makes a rather inexpensive yet accurate one--the RA 27. [. . . ] The key here is to prevent the shield currents from flowing into a unit whose grounding scheme creates ground loops (hum) in the audio path (i. e. , most audio equipment). Do not be tempted to use 3-prong to 2-prong "cheater" adapters to lift grounds. This is a dangerous and illegal practice. It is true that connecting both ends of the shield is theoretically the best way to interconnect equipment ­ though this assumes the interconnected equipment is internally grounded properly. [. . . ]