Rane SM82S Operation Manual - Page 7

OPERATING INSTRUCTIONS CIRCUIT DESCRIPTION Learning to operate the SM82S might be a bit easier if you glance at the Block Diagram below. All eight stereo Inputs operate in exactly the same way. Signal applied to the Inputs is acted on by a radio interference filter (we have assumed that local broadcasts should not be a part of your music) and is then routed to a stereo LEVEL control. If you are using a mono source, connect it only to the LEFT Input to send this mono signal to both the Left and Right sides of the input circuitry. The output of the Level control sections is applied to a unity gain buffer to prevent the LEVEL control from adversely interacting with downstream circuitry. The Input overload sensor monitors here to alert the user via LED to any possible Input overload conditions. Left and Right audio is then subjected to the channel PAN control to allow the user to place the stereo image of the source as desired to the Left and Right Outputs. A stereo SEND control adjusts the amount of each Input routed to the Loop Output. All eight stereo Inputs are simultaneously adjusted for stereo placement by the OUTPUT PAN control. The resultant signal is added together and fed to the OUTPUT LEVEL control, which has it's own Overload indicator. The main Outputs are fully actively balanced, allowing the use of correctly wired long cables. Block Diagram RIGHT INPUT CHANNEL 1 LEFT INPUT (MONO) INPUT RFI LEVEL FILTER +6 dB RFI FILTER +6 dB RIGHT INPUT LOOP RETURNS LEFT INPUT (MONO) RFI FILTER RECEIVE LEVEL +6 dB RFI FILTER +6 dB LOOP EXPAND INPUT RING TIP RIGHT LEFT INPUT OVERLOAD OL SENSE RIGHT MAIN RIGHT SEND LEFT MAIN LEFT SEND INPUT SEND BALANCE LEVEL RECEIVE OVERLOAD OL SENSE CH 2 L L R R CH 3 L L R R CH 4 L L R R CH 5 L L R R RECEIVE BALANCE CH 6 L L R R CH 7 L L R R CH 8 L L R R EFFECTS LOOP The LOOP SENDS receive their audio from the Send bus which is the sum of all the Inputs as determined by the Input SEND controls. This Output may be used to drive a stereo effects processor. The output of the effect device is returned to the SM82S through the LOOP RETURNS. The level of the returned effect is determined by the RETURN LEVEL control on the front panel. The return section also provides a BALance control for image placement. PAN / BALANCE CONTROLS These operate as 'PAN' with a mono signal plugged in the LEFT input only, and 'BALANCE' with a stereo signal (both jacks plugged in). These do not increase the level of either Left or Right signal. As the controls are moved toward one channel, the level of the other channel is only reduced. HIGH NOISE IMMUNITY One of the most unusual features of the SM82S is its inherent immunity from noise. All eight of the stereo inputs may be turned all the way up without increasing the internal noise of the mixer. This is critical due to the wide variation in output levels found in musical instruments and tape devices. A fairly low-level guitar may be combined in the same system with a high level synthesizer without any undesirable side-effects. The SM82S eliminates the concerns normally associated with mixing so-called -l0 dBV units with +4 dBu types. OUTPUT BALANCE OUTPUT LEVEL OUTPUT OVERLOAD OL SENSE 0 dB +6 dB SUMMING AMPLIFIERS 0 dB +6 dB BALANCED DRIVERS RIGHT MAIN OUTPUTS BALANCED DRIVERS LEFT RIGHT RING LEFT TIP MAIN EXPAND OUT RIGHT 0 dB SUMMING + L+R AMPLIFIERS LEFT 0 dB RIGHT LOOP SENDS LEFT (MONO) MAIN EXPAND INPUT RING TIP RIGHT LEFT ©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5000 USA TEL 425-355-6000 FAX 425-347-7757 WEB rane.com Manual-4 107271