Allen & Heath ZED-6FX 6-Channel Mixer

1.1 Mono Input Channels (M)

1. Mic Input Socket: Uses a standard 3-pin XLR connector for dynamic or condenser microphones.

2. Line / Inst Input Socket: Uses a standard 1/4" (6.25mm) jack for balanced or unbalanced signals, such as guitars and other instruments.

3. Gain Control: Adjusts the input preamp gain to control the source signal level. Gain ranges from 5dB to 60dB.

4. Instrument: Activates the Line / Inst input circuit for electro-acoustic and electric guitars, basses, and other Direct Input instruments. When active, the Mic Input socket is disabled.

5. Lo-cut (Hi-Pass Filter): Used to reduce low-frequency noise such as handling noise, pops, rumble, and proximity effect in microphone signals.

6. HF EQ (High Frequency): Adjusts high frequencies in the signal to add "brightness" and "clarity" or to reduce "hiss" and "harshness".

7. LF EQ (Low Frequency): Adjusts low frequencies in the signal.

8. FX Send: Controls the amount of signal sent from the channel to the FX bus and FX output. The signal is post-fader (MIX), meaning it is affected by the MIX fader, so it remains proportional to the signal going into the MAIN MIX. There is no master level control for FX OUT.

9. PAN: Balances the signal from the mono input channel between the left and right buses and subsequently the main outputs.

10. MIX: The fader controls the amount of signal for the left and right buses.

11. Pre-Fade Listen (PFL): Sends the channel's input signal to the headphones for monitoring before adding it to the Mix. The PFL signal is taken after the EQ but before the MIX fader. LR meters display the channel input level when the PFL switch is activated.

1.2 Stereo Input Channels (ST)

ST1 and ST2 use standard 1/4" (6.25mm) jacks for balanced or unbalanced line stereo sources, such as professional keyboards, drum machines, and other professional audio equipment.

ST1 and ST2 Gain Control: Adjusts the input signal level for the channel.

HF and LF EQ: Are the same for ST1 and ST2 as for M1 and M2, and are set at identical frequencies.

BAL: Adjusts the relative level between the left and right stereo signals when they are sent to the left and right buses, and then to the main outputs.

1.3 Master Section

1. MAIN OUT L & R: Are line outputs for the main stereo mix, using standard XLR output connectors and are impedance balanced to prevent unwanted interference.

2. 48V: Switches standard 48V (phantom power) to all microphone inputs for use with condenser microphones and active DI boxes requiring +48V.

3. POWER LED: Indicates that the mixer is powered on.

4. LR meters: Display the MAIN MIX level or a mono PFL signal, if activated by any of the PFL switches.

5. MAIN MIX fader: Is the main volume control for the main stereo mix.

6. PFL (Pre-Fade Listen) LED: Indicates when a channel's PFL switch has been pressed.

7. PHONES control: Adjusts the volume of the signal to the PHONES output. Warning! To avoid hearing damage, do not use headphones or audio system at too high a volume. Prolonged exposure to high volume sound can lead to hearing loss!

8. PHONES output: Uses a standard 1/4" (6.25mm) jack.

2.1 "Zeroing" (Setup Procedure)

It is recommended to "zero" the mixer and mute relevant channels before connecting any equipment, as this prevents potential damage to speakers or other equipment.

Setup Steps:

1. Ensure the power switch on the rear panel of the mixer is set to the "OFF" position.
2. Connect the AC power cord to the AC MAINS IN socket on the rear panel. Ensure the correct mains plug for your country is fitted, and connect the AC power cord to a standard wall outlet.
3. Turn the Gain controls fully down (fully left).
4. Ensure the Instrument, HPF, PFL, and 48V switches are not pressed.
5. Set all EQ and PAN controls to the center position marked "▼".
6. Turn all FX send, AUX send, and MIX controls down (fully left).
7. Lower the MAIN MIX fader to the "0" position.
8. Reduce the PHONES level.
9. Double-check that speakers or amplifiers are OFF!
10. Connect speakers, instruments, and other equipment.
11. Turn on instruments and other equipment, then the mixer, then the speakers!

3.1 Connecting Microphones

Dynamic or condenser microphones and DI boxes should be connected to the Mic Input socket using a balanced XLR microphone cable. If you are using a condenser microphone, it will require 48V phantom power to operate. Some active DI boxes may also require phantom power.

Avoid "hot plugging" when connecting any equipment and ensure that the AUX MASTER and MAIN MIX controls are turned down before engaging 48V, as this can cause loud thumps and pops!

3.2 Connecting Instruments and Line Equipment

High impedance (Hi-Z) instruments, such as electro-acoustic guitars, basses, and other instruments with a direct input, should be connected to the line inputs on channels M1 and M2 using a jack-to-jack cable and do not require an additional DI box or preamp. The Instrument switch should be activated to match very high impedance (10MΩ) signals.

Line level instruments, such as keyboards, synthesizers, drum machines, or equipment such as external effects processors, can be connected to the Line / Inst inputs on channels M1 and M2, and the LINE inputs on M3 and M4 for mono sources or ST1 and ST2 for stereo sources. For channels M3 and M4, the LINE / PAD switch should be activated.

4.1 Gain Structure

Setting input levels is important before you can mix signals together. Gain structure is important for achieving maximum signal level without unwanted distortion. Correct gain staging helps optimize signal quality and ensure the lowest possible signal-to-noise ratio.

Steps to set gain:

1. Connect instruments and equipment. Set input levels.
2. Ensure the microphone is positioned at an appropriate distance from the sound source.
3. Press the PFL switch on the relevant channel. This allows you to hear the pre-fader input signal and shows the signal level on the LR meters.
4. Sing, speak, or play your instrument at a typical volume.
5. Slowly raise the Gain control on the relevant channel until you see a good signal level on the LR meters. Maximum peaks between "0" and "+6" on the meters are a good indicator.
6. Connect professional headphones to the Phones output and increase the PHONES level to a safe listening volume.
7. If the sound is undesirably distorted at low signal levels, engage any pad switch on the microphone or move the microphone further away from the source and repeat the process.

Once you are satisfied with the input signal level, you can use the lo-cut (Hi-pass Filter) and EQ to improve intelligibility or remove unwanted frequencies, and enhance the original sound's tonal balance, so keep the channel PFL switch engaged!

4.2 Sound Shaping (EQ)

The equalizer filters the sound passing through it and allows you to "cut" (reduce) or "boost" (increase) selected frequencies. "Boosting" too much of a frequency can cause clipping or distortion. "Cutting" a frequency will reduce the signal level. Excessive use of EQ can make sound unnatural. Understanding the frequency characteristics of different instruments and how they may overlap will help you make correct decisions about how to EQ musically.

1. Lo-cut (Hi-pass Filter): Removes unwanted low-frequency noise, such as rumble, handling noise, plosives, and proximity effect, and helps maintain signal clarity. Lo-Cut affects Mic and Line / Inst inputs. The corner frequency is set at 100 Hz.

2. HF EQ (High Frequency): Affects high frequencies in the signal. The corner frequency is 12 kHz for adding "brightness" and "clarity" to guitars or for reducing "hiss" in vocals and "harshness" in cymbals.

3. LF EQ (Low Frequency): Affects low frequencies in the signal. The corner frequency is 80 Hz for adding "warmth" and "sub-bass" to bass guitar or kick drum, or for removing "boom" from toms.

When you are satisfied with the input signal level and tone, you can disengage the channel PFL switch and consider how to mix all these sounds together!

4.3 Balancing the Mix

After you have set the input gain levels and applied EQ to the source signals, you can start mixing all your channels to the outputs. Consider the importance of each instrument and how they should be heard in the mix.

Steps to balance the mix:

1. Ensure all PFL switches on the mixer are disengaged to view the MAIN MIX level on the LR Meters.
2. Slowly raise the MAIN MIX fader to approximately "0".
3. Turn up the channel MIX controls to send their signal to the main mix.
4. You will see the signal level displayed on the LR meters.
5. As you mix signals together, you will see the combined level rise. Avoid clipping and leave headroom for any loud moments in the program material. Average peaks around "0" on the meters are a good indicator.
6. Maintain a natural balance between voices and instruments, i.e. which instruments should be heard more clearly compared to others.
7. If you find that the MIX controls are set very high and the signal level is still low, or the MIX level is very low but the signal is too high, readjust the gain and EQ controls to improve the gain structure and tone (See Section 6.1).

Use the PAN and BAL controls to position sounds and give instruments space in the mix or a realistic representation of where they might be in the stereo image. Ideally, high-energy low-frequency sounds, such as kick drums, should be centered to distribute them evenly and balance the load between speakers.

Once you are satisfied with the sound, disengage all PFL switches. Slowly set the FX MIX control to "0" to add the effects signal to the MAIN MIX. Readjust channel FX send controls if necessary.

5.1 FX Section

Effects such as reverb and delay are commonly used to add "natural sound" and a sense of space to a mix, but can also be used to add interesting repeats in time with the music. Modulation effects can be used to harmonically enhance sound or add depth and movement.

1. FX OUT / MUTE: Is a line level output from the FX bus, using a standard 1/4" (6.25mm) jack. Stereo signals from external effects processors should be returned to ST1 or ST2 inputs. A latching footswitch can be connected to the FX OUT jack to mute the ZED FX Multi Model processor. The footswitch should be connected between Tip and Sleeve. The FX OUT can be monitored by connecting it to a speaker input, however the signal is post-fader (MIX), meaning it will be affected by the FX send and MIX controls.

2. ZED FX Multi-Model Processor: Is a high-quality built-in effects unit that is powered by a mono signal from the FX bus. The output signal from the processor to the MAIN MIX is stereo.

3. FX Select / Parameter control: Is used to scroll through effect presets and make changes to editable parameters.

4. TAP TEMPO button: Can be used to set the rate or tempo of delay effects that include the Tap Tempo parameter. If a delay effect is selected, you will see a flashing decimal point on the right side of the preset display. Change effect parameters by pressing and holding the TAP TEMPO button while turning the FX Select / Parameter control. The display will show parameter values from P0 to P9. Disable internal effects by setting the ZED FX Multi Model preset to "00". Reset editable parameters to factory defaults by holding down the FX Select / Parameter control and the TAP TEMPO button simultaneously while powering on.

5. MIX fader: Controls the level of the effects ("wet") signal in the MAIN MIX.

5.2 Applying Effects in the Mix

Before adding effects, consider whether you want them to sound as if the voice or instruments are in a particular performance space, want to add repeat effects such as echo (delay), or want them to sound like a classic album. Using too much effect can mean losing clarity or intelligibility of the original sound!

Steps to apply effects:

1. Select the desired effect preset and turn the FX Select / Parameter control.
2. Press PFL on the channel and on the effects section to monitor the channel's (dry) signal and the effect's (wet) return via the PHONES output before adding it to the MAIN MIX.
3. If you have selected a delay effect and the preset display shows a flashing decimal point, use the TAP TEMPO button to time the effect with the program material.
4. Turn up the FX send on the channel until you hear the desired effect. The channel MIX control must be turned up because the FX send is post-fader.
5. Repeat this for any additional channels.
6. Once you are satisfied with the sound, disengage all PFL switches.
7. Slowly set the FX MIX control to "0" to add the effects signal to the MAIN MIX.
8. Readjust channel FX send controls if necessary.