User manual RANE SAC 22

[. . . ] Now, feed the SAC 22 some program material. Start by turning up the LOW LEVEL and HIGH LEVEL to the 0 dB marks. Slowly increase the INPUT LEVEL, even if it goes all the way to 10, so the +4 dBu (green) light blinks occasionally and the OL (red) light stays out. This delivers the best signal-to-noise performance. [. . . ] Set the 100 Hz FILTER switch to the IN position. If a mono subwoofer is not used, the FILTER switch setting will not matter. The front panel LOW/HIGH FREQUENCY control determines the frequency division between the high and low drivers, and the subwoofer also receives the low frequencies below 100 Hz. Manual-4 OPERATING INSTRUCTIONS Selecting Crossover Frequencies Most speaker manufacturers supply low and/or high frequency cut-off points for each driver, especially if these are supplied in a system. 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. When in doubt, choose the higher Frequency setting. 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. This also yields higher system reliability. 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. [. . . ] 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. Return the LOW LEVEL to the previously recorded setting. Now the low and high speakers are set at the same level. Make any overall level adjustments with the INPUT LEVEL controls and leave the output LOW and HIGH LEVEL controls unchanged. [. . . ]