User manual RANE SAC 22

[. . . ] When using a single subwoofer along with full-range cabinets that have internal crossovers, set the 100 Hz FILTER to OUT, allowing the front panel FREQUENCY to control the subwoofer crossover point. When used with biamp cabinets and a subwoofer, set the 100 Hz FILTER switch to IN to allow only frequencies below 100 Hz at this output jack. This way, the SAC 22 almost does the job of a Stereo 3-Way crossover, but without removing that awesome bass from the Left and Right Low Outputs. WEAR PARTS: This product contains no wear parts. Manual-1 INPUT LEVEL control and indicators This controls the overall level without altering the relative settings of the Low and High frequency Outputs. With signal applied, set this control so the +4 dBu LED lights occasionally, indicating sufficient signal. [. . . ] These cut-off frequencies are based on each driver's performance, with a certain safety margin to accommodate more gentle filter roll-offs. The SAC 22 utilizes a 31-position precision DC control voltage potentiometer to select the LOW/HIGH FREQUENCY point. This crossover circuit design assures consistent accuracy from Channel-to-Channel and unit-tounit. This is a distinct advantage over continuously variable designs using ganged potentiometers which can yield large variations in channel-to-channel matching. Even with 31 choices it is possible that the exact recommended Crossover Frequency may not fall on one of the detents on the selector. Not to panic, for drivers have their own gradual rolloffs and tolerance variations. The illustration and table below details the crossover frequencies available on the detents that are not labeled. For best overall system results, try to choose the speaker components so that each operates well within its recommended limits. This provides valuable leeway so that crossover points may be adjusted in order to fine-tune the system. If at all possible, always use some kind of realtime analyzer to tune your crossover, and then fine-tune each system with an equalizer. Keep reading for further alignment details. Setting the Output Level Controls The INPUT LEVEL is an overall system sensitivity adjustment. Use this control to decrease the overall sensitivity of the entire sound system, including the mono subwoofer if you are using one. You will generally want to start with this control in the full clockwise (or 10) position. The LOW LEVEL, HIGH LEVEL and MONO SUB OUTPUT LEVEL controls allow you to compensate for sensitivity variations in amplifiers and drivers. Do not use these to adjust overall system sensitivity unless you plan to re-align the system afterward. 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. 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. [. . . ] IMPORTANT: Compression driver or horn high frequency roll-off, bass roll-off, and room acoustics usually cannot be corrected by the crossover. Now slowly turn up the HIGH LEVEL control so that pink noise is heard from the high frequency speakers. 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. [. . . ]