STEREO AUX RETURNS: (48 to 52) 48. STEREO AUX RETURNS
Having entered through the STEREO AUX RETURNS (9) jacks, effects returns are controlled by these knobs, and typically continue on to the MAIN MIX FADER (72). Effect returns are the �wet� signals, to be combined with the channels� original �dry� signals in the main mix. Turned fully up, these controls provide 20 dB of additional gain; the center �U� label is unity gain and fully down is off. These knobs are typically set near unity and left alone.
53. TAPE RETURN
Having entered through the TAPE IN (6) jacks, tape returns are controlled by these knobs, and then sent to TAPE RETURN TO PHONES/C-R (69) and TAPE RETURN TO MAIN MIX (71). Turned fully up, this provides 20dB of additional gain, the center �U� label is unity gain and fully down is off. These knobs are typically set near unity and left alone.
54. METERS
The mixer�s peak metering system is made up of two columns of thirteen LEDs each, with thresholds ranging from -40dB up to �CLIP� (+22dBu at TRS MAIN OUTS (12), +28dBu at the XLR MAIN OUT (16)). The meters display the main mix, post MAIN MIX FADER (72). However, when a SOLO (39) (47) (52) (57) switch is engaged, the meters will instead display the solo information. A good mix will show the meter�s peaks flashing anywhere between -10 and +10dB. Remember that most amplifiers clip at about +10dB, and some recorders aren�t so forgiving either. For best real-world results, try to keep your peaks between �0� and �+7.�
49. TO AUX SEND 1-2
These knobs work just like the channel strip�s AUX (26) 1 and 2 knobs; but here, the source signal is the STEREO AUX RETURNS (9) 1 and 2. Typically, these knobs are used to add effects to the stage monitors. Via these knobs, aux return 1 combines its left and right sides to feed aux send 1; stereo aux return 2 combines to feed aux send 2. Turned fully up, these controls provide 15 dB of additional gain, the center �U� label is unity gain and fully down is off.
50. ASSIGN TO SUB and 51. SUB
These switches allow stereo aux return 4 to be sent to pairs of subgroups, instead of being sent directly to the main mix. Engage ASSIGN TO SUB (50) to divert aux return 4 to the subgroups; use SUB (51) to choose the subgroup pair, 1-2 (switch up) or 3-4 (switch down). For live sound, subgroups allow a group of channel levels (and aux return 4) to be controlled by one or two subgroup faders. For multi-track recording, subgroups can be used to route groups of channels (and aux return 4) to specific tracks of a multi-track recorder. See L/R ASSIGN (59) and SUBGROUP FADER (60) for more information.
ZERO EQUALS ZERO
You may already be familiar with �+4� and �-10� operating levels. Basically, what determines an operating level, besides available headroom, is the relative 0dB VU chosen for the meters. A �+4� mixer, with a +4dBu output signal, will actually display 0dB on its meters. A �-10� mixer, with a -10dBV output signal, will also display 0dB. To eliminate that confusion, Mackie�s compact mixers use a simpler method, where zero equals zero: 0dBu (0.775V) at the output shows as 0dB VU on the meters. If a �+4� output is desired, set the mix levels so the meters �average� at +4dB. If a �-10� output is desired, set the mix levels so the meters �average� at 10dB.
52. SOLO
Engaging this switch isolates the associated signal and sends it to the control room, phones and meters. See RUDE SOLO LIGHT (61) and MODE (63) for more information. Note: In PFL mode, aux returns are not soloed before their master level controls, but are instead summed after the controls into a mono signal and sent to the PFL mix.
55. POWER LED
This LED glows when the POWER (20) switch is turned on.
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