Mackie 1642-VLZ4 Owners Manual - Page 9

Owner's Manual Never plug ­s­ ingle-ended (unbalanced) micro­phones, or ribbon mics into the mic input jacks if the phantom power is on. Do not plug instrument outputs into the mic input jacks with phantom power on ­unless you know for certain it is safe to do so. 2. Line Ins These 1/4" jacks share circuitry (but not phantom power) with the mic preamps, and can be driven by balanced or unbalanced sources at ­almost any level. You can use these inputs for virtually any signal you'll come across, from instrument levels as low as -50 dB to operating levels of -10 dBV to +4 dBu, as there is 45 dB of gain available via the gain [3] knob. Note that channels 1-8 line inputs are intially attenuated by 15 dB. Always make sure to perform the level setting procedure on page 5. To learn how signals are routed from these inputs, see the details lovingly described in the channel strip section. To connect balanced lines to these inputs, use a 1⁄4" Tip-Ring-Sleeve (TRS) plug, wired as follows: Tip = Positive (+ or hot) Ring = Negative (- or cold) Sleeve = Shield or ground To connect unbalanced lines to these ­inputs, use a 1⁄4" mono (TS) phone plug, wired as follows: Tip = Positive (+ or hot) Sleeve = Shield or ground The GAIN controls for stereo channels 9-10 and 11-12 are only used to adjust the Mic inputs. The line inputs are set to unity gain. The GAIN controls for channels 13-14 and 15-16 only adjust the line-level inputs, as they have no Mic inputs. 4. Insert Found only on channels 1-8, these unbalanced 1/4" jacks are for connecting serial e­ ffects processors such as compressors, equalizers, de-essers, or filters. The insert point is after the gain [3] control, but before the channel's EQ [32], low cut [34], fader [25] and mute [30] controls. Insert cables must be wired thusly: Tip = send (output to effects device) Ring = return (input from effects device) Sleeve = common ground ring tip sleeve (TRS plug) SEND to processor tip This plug connects to one of the mixer's Channel Insert jacks. ring RETURN from processor Even though channels 1-8 already have ­direct out [5] jacks , insert jacks can also be used as channel direct outputs; post-gain, pre-low cut, and pre-EQ. See the connector section on page 27 showing three ways to use insert cables. 3. Gain These controls are not in the patchbay, but 3 they are the top row of knobs in the channel strip section. (They are so vitally linked with the inputs, this seemed like a good place to describe them.) If you haven't already, please read the level-setting procedure on page 5. Gain adjusts the input sensitivity of the mic and line inputs. This allows signals from the outside world to be adjusted to optimal internal operating levels. If the signal originates through the XLR jack, there will be 0 dB of gain with the knob fully down, ramping to 60 dB of gain fully up. Through the 1⁄4" input, there is 20 dB of a­ ttenuation fully down and 40 dB of gain fully up, with a "U" (unity gain) mark at 10:00. This 20 dB of a­ ttenuation can be very handy when you are ­inserting a very hot signal, or when you want to add a lot of EQ gain, or both. Without this "­virtual pad," this ­scenario might lead to channel clipping. Owner's Manual 9