Functions of Mixer Sockets and Controls
The audio mixing console is a core device in PA and recording systems. It creates stereo imaging, enhances sound, suppresses noise, controls volume, and is essential for sonic artistry.
Mixers offer multi-channel inputs for independent processing (amplification, bass/mid/treble EQ, spatial effects) and adjustable mixing. Outputs include L/R stereo, group, mono mix, monitor, record, and aux sends. Below are key sockets and controls.
(I) Input Section Sockets
1) XLR (MIC): Balanced, low-impedance input (Pin 1=GND, Pin 2=Hot/+, Pin 3=Cold/-). Offers noise immunity. For wired mics.
2) Line Input (1/4" TRS/TS): High-impedance balanced (TRS: Tip=+, Ring=-, Sleeve=GND) or unbalanced (TS) input. For non-mic sources.
3) Insert (INS) (1/4" TRS): Normally closed. Inserting a TRS plug (Tip=Send, Ring=Return, Sleeve=GND) routes the signal out for external processing (e.g., compressor) and back in. Labeled "Send/Return" or "in/out".
4) Pad (-20/-30dB): Attenuates strong line-level signals.
5) Gain: Adjusts input signal amplification. Combined with Pad, optimizes signal level for best SNR/distortion (peak LED barely lighting).
6) Low Cut (100Hz): Filters out low-frequency rumble below 100Hz.
7) EQ: Three-band (HF, MF, LF) for tonal compensation.
a. HF: Shelving at 10kHz (±15dB). Affects clarity.
b. MF: Parametric, center freq 250Hz-8kHz (±15dB). Adjusts brightness (higher center) or punch (lower center).
c. LF: Shelving at 150Hz (±15dB). Affects fullness.
8) Aux Sends (AUX1-4): Control level sent to aux buses. AUX1/AUX2 (Pre-Fader) are pre-fader. AUX3/AUX4 (Post-Fader) are post-fader.
9) Pan (PAN): Controls signal placement in stereo field (Left, Center, Right). Crucial for stereo imaging.
10) Fader: Dual function: 1) Sets channel level in mix. 2) Affects perceived distance (higher level = closer). Combined with PAN for spatial placement.
(II) Input Section Controls
1. PFL (Pre-Fade Listen): Monitors signal pre-fader via headphones.
2. On: Activates channel signal to mix.
3. L-R: Routes signal post-fader/pan to Left/Right bus.
4. 1-2: Routes signal post-fader/pan to Group buses 1 & 2.
5. 3-4: Routes signal post-fader/pan to Group buses 3 & 4.
Note: Each input channel handles one source only to prevent interference/distortion.
(III) Output Section
Key Principles:
1) Number of buses = number of output jacks.
2) Each output has a corresponding level control (fader/knob).
3) Each output control has a nearby listen button (PFL for faders, AFL for knobs).
4) Signals entering via Aux Return/Effect Return jacks have level and pan controls.
5) Main L/R or Group outputs usually feature Insert (INS) jacks for processing. Aux outputs lack INS.
6) Headphone/Talkback mic jacks have volume controls.
Mixers offer multi-channel inputs for independent processing (amplification, bass/mid/treble EQ, spatial effects) and adjustable mixing. Outputs include L/R stereo, group, mono mix, monitor, record, and aux sends. Below are key sockets and controls.
(I) Input Section Sockets
1) XLR (MIC): Balanced, low-impedance input (Pin 1=GND, Pin 2=Hot/+, Pin 3=Cold/-). Offers noise immunity. For wired mics.
2) Line Input (1/4" TRS/TS): High-impedance balanced (TRS: Tip=+, Ring=-, Sleeve=GND) or unbalanced (TS) input. For non-mic sources.
3) Insert (INS) (1/4" TRS): Normally closed. Inserting a TRS plug (Tip=Send, Ring=Return, Sleeve=GND) routes the signal out for external processing (e.g., compressor) and back in. Labeled "Send/Return" or "in/out".
4) Pad (-20/-30dB): Attenuates strong line-level signals.
5) Gain: Adjusts input signal amplification. Combined with Pad, optimizes signal level for best SNR/distortion (peak LED barely lighting).
6) Low Cut (100Hz): Filters out low-frequency rumble below 100Hz.
7) EQ: Three-band (HF, MF, LF) for tonal compensation.
a. HF: Shelving at 10kHz (±15dB). Affects clarity.
b. MF: Parametric, center freq 250Hz-8kHz (±15dB). Adjusts brightness (higher center) or punch (lower center).
c. LF: Shelving at 150Hz (±15dB). Affects fullness.
8) Aux Sends (AUX1-4): Control level sent to aux buses. AUX1/AUX2 (Pre-Fader) are pre-fader. AUX3/AUX4 (Post-Fader) are post-fader.
9) Pan (PAN): Controls signal placement in stereo field (Left, Center, Right). Crucial for stereo imaging.
10) Fader: Dual function: 1) Sets channel level in mix. 2) Affects perceived distance (higher level = closer). Combined with PAN for spatial placement.
(II) Input Section Controls
1. PFL (Pre-Fade Listen): Monitors signal pre-fader via headphones.
2. On: Activates channel signal to mix.
3. L-R: Routes signal post-fader/pan to Left/Right bus.
4. 1-2: Routes signal post-fader/pan to Group buses 1 & 2.
5. 3-4: Routes signal post-fader/pan to Group buses 3 & 4.
Note: Each input channel handles one source only to prevent interference/distortion.
(III) Output Section
Key Principles:
1) Number of buses = number of output jacks.
2) Each output has a corresponding level control (fader/knob).
3) Each output control has a nearby listen button (PFL for faders, AFL for knobs).
4) Signals entering via Aux Return/Effect Return jacks have level and pan controls.
5) Main L/R or Group outputs usually feature Insert (INS) jacks for processing. Aux outputs lack INS.
6) Headphone/Talkback mic jacks have volume controls.