Introduction

The GR4 is a 1U rack-mounting or desktop audio mixer, providing simple yet comprehensive control of background music and paging in bars, restaurants, stores and other leisure / retail environments. Standout features include optional remote wall plates, a mic input on the front panel, plus a 3.5mm jack on the front for portable music sources.

Packed Contents

The following items are included in the box when the GR4 is shipped.

1 x GR4 Zone Mixer

1 x Mains Cable (IEC C13 to local mains connector)

19 x Blanking Bung

1 x Set of Rack ears

2 x Header Plug Euroblock 2-Pole

4 x M3 X 6mm Countersunk Pozi screws

2 x Header Plug Euroblock 4-Pole

10 x Header Plug Euroblock 3-Pole                  

1 x ROHS Addendum Notes (AP7014).

1 x Safety Instructions (AP9240/CL1-1) - PLEASE READ BEFORE CONTINUING WITH THIS MANUAL.

Front Panel

Input Section

1. MIC SELECT
   A user selectable switch for MIC 1 input. MIC 1 signal can either be derived from the rear mount Euroblock or front mount XLR connectors. Use pointed object to select switch.
2. MIC 1 INPUT
   Front mount XLR receptacle for MIC 1 input.
3. MIC LEVEL
   Adjustable rotary level control for MIC inputs 1-4. Mic level control of Off to +6dB.
4. ST LEVEL
   Adjustable rotary level control for LINE inputs 1-4. Line level control of Off to +6dB.
5. Hi LEV LED
   LED level indicator which illuminates when signal to MIC 1-4 and ST 1 to 4 is approaching clip level. The Hi Level LED illuminates when one or more inputs are at 3dB before clip level.
6. Z1 SELECTION INDICATOR
   LED indicator showing input selection to ZONE 1 mix bus.
7. Z2 SELECTION INDICATOR
   LED indicator showing input selection to ZONE 2 mix bus.

8. AUX INPUT
   Auxiliary input on 3.5mm jack socket.

   ⓘ This input will override any input connected to ST4 on the rear Euroblock connector.

Output Section

1. Z1 MIC MIX OUTPUT LEVEL
   Adjustable rotary level control for MIC Mix to Zone 1. Output level control Off to +6dB.
2. Z1 MIC SELECT SWITCH
   Output Zone Mic selection switch used to add/remove mic sources to/from the output Zone 1 mix signal. The following combinations are supported: Mic 1 only/Mics 2-4 only/All Mics
3. Z1 OUTPUT METER
   Three-segment LED meter showing L & R output level of Z1 Mix. Illumination will occur at -18, +3 and +17dB.
4. Z1 MUSIC OUTPUT LEVEL
   Adjustable rotary level control of Stereo sources to Zone 1. Output level control Off to +6dB.
5. Z1 MUSIC SELECT SWITCH
   Output Zone Music selection switch used to select Stereo sources to output Zone 1 mix.
6. Z1 OUTPUT EQ
   LF control of Zone 1 output signal. Shelving EQ with +/-15dB with cut-off frequency at 80Hz.
7. Z1 OUTPUT EQ
   HF control of Zone 1 output signal. Shelving EQ with +/-15dB with cut-off frequency at 8kHz.
8. Z2 MIC MIX OUTPUT LEVEL
   Adjustable rotary level control for MIC Mix to Zone 2. Output level control Off to +6dB.
9. Z2 MIC SELECT SWITCH
   Output Zone Mic selection switch used to add/remove mic sources to/from the output Zone 2 mix signal. The following combinations are supported: Mic 1 only/Mics 2-4 only/All Mics.
10. Z2 OUTPUT METER
    Three-segment LED meter showing L & R output level of Zone 2 Mix. Illumination will occur at -18, +3 and +17dB.
11. Z2 MUSIC OUTPUT LEVEL
    Adjustable rotary level control of Stereo sources to Zone 2. Output level control Off to +6dB.
12. Z2 MUSIC SELECT SWITCH
    Output Zone Music selection switch used to select Stereo sources to output Zone 2 mix
13. Z2 OUTPUT EQ
    LF control of Zone 2 output signal. Shelving EQ with +/-15dB with cut-off frequency at 80Hz.
14. Z2 OUTPUT EQ
    HF control of Zone 2 output signal. Shelving EQ with +/-15dB with cut-off frequency at 8kHz.
15. Z3 MIX OUTPUT LEVEL
    Adjustable rotary level control of Mix to Zone 3. Output level control Off to +6dB.
16. Z3 OUTPUT METER
    Three-segment LED meter showing mono output level of Zone 3 Mix. Illumination will occur at -18, +3 and +17dB.
17. Z4 MIX OUTPUT LEVEL
    Adjustable rotary level control of Mix to Zone 4. Output level control Off to +6dB.
18. Z4 OUTPUT METER
    Three-segment LED meter showing mono output level of Zone 4 Mix. Illumination will occur at -18, +3 and +17dB.

General

1. POWER INDICATOR
   LED indicator showing the unit has power. Also used to indicate when unit is in ‘Programming’ mode (see section 6.4).

2. MAINS SWITCH
   Switch to power the unit ON/OFF.

   ⓘ The mains button can be removed and replaced with a blanking bung to avoid accidental powering off of the unit.

Rear Panel

General

1. AC POWER
   IEC receptacle to connect mains power cable (included). 100V to 240V accepted.
2. KENSINGTON LOCK
   Kensington lock cut-out for securing unit.

Control Section

1. DIP SWITCHES
   Dip switches used to control priority settings, zone lock, remote operation and contact closure configuration.
2. ALARM INPUT
   Contact closure (DIP switch option for Normally Open/Closed) for emergency input detect. On activation all inputs will fade to the pre-set level except for Mic 1 and Z1 &Z2 LED’s will flash quickly. Normal operation will resume once contact is reset to original state.
3. PAGE INPUT
   Contact closure (DIP switch option for Normally Open/Closed) for paging announcements. On activation all inputs will fade to the pre-set level except for Mic 1 and Z1 & Z2 LED’s will flash slowly. Normal operation will resume once contact is reset to original state.
4. ANALOGUE ZONE REMOTE
   4-pole Euroblock connector for connection of custom or 3^rd party volume and/or source selection panels.
5. DIGITAL ZONE REMOTE
   RJ45 connector for use with the Allen & Heath PL-14 remote controller.

Output Section

1. Z3 & Z4 OUTPUTS
   Mono, balanced zone outputs on Euroblock connector.
2. Z1 & Z2 OUTPUTS
   Stereo (mono configurable via internal jumpers) balanced outputs on Euroblock connector.

Input Section

1. STEREO INPUTS
   Line level inputs 1 to 4 on unbalanced phono connectors.

   ⓘ Unloaded Phono connectors can induce noise on the output if the input level is not on the fully off position. Either ensure unused channels have Zero Gain/Level or use termination connectors on unused inputs.

2. MIC INPUTS
   Microphone input on balanced Euroblock connector.

   ⓘ Mic 1 is selectable between rear Euroblock and front mount XLR via front mount switch.

3. MIC INPUT ADJUSTMENT
   Microphone gain, Lo and Hi EQ trim pots used to adjust the input sensitivity of the pre-amplifier channel* and to adjust the EQ setting of the MIC channel.

Setting the channel gain

1. Connect the microphone to be used with the associated input.
2. Speak into the microphone whilst adjusting the gain trim with a small flat blade screwdriver.
3. Adjust the trim until the Hi Lev LED illuminates and then trim back the level slightly so it no longer illuminates.
4. Further adjustments may be required to suit the dynamics of the users’ normal range.

Installing GR4

Mounting the unit

The GR4 can be used as a stand-alone unit and placed on a hard surface or rack-mounted in a standard 1U 19” profile.

You will need the following items;

• T8 Torx screwdriver
• Small flat blade screwdriver
• Rack ears (supplied)
• 4 x M3 Torx screws (supplied)
• Posi Screwdriver
• 4 x M6 Screws

To rack-mount the unit follow the below procedure;

1. Using the supplied rack ears and M3 Torx screws fit to the unit as in the below diagram.

Be sure to use the supplied screws or exact replacements (damage to internal PCB’s can result when using longer screws).

2. Using the small flat bladed screwdriver gently remove the four rubberized feet on the base of the unit.

Gently prize the central plastic grommet away from the unit. Once removed the rubberized feet can be strored safely for future use.

To reinstate simply push the grommet into place.

3. Install within the 19” rack making sure the unit is secure.

Please ensure you have enough depth within the rack to accommodate the GR4 together with sufficient cable bending radius (the GR4 is 220mm deep).

ⓘ Please ensure adequate ventilation is provided and the sides of the unit are not obstructed to maintain adequate airflow.

Connecting to GR4

Microphone Inputs

Microphone inputs are balanced connections on Euroblock type connectors.

Pin assignments are screen printed above the connector or alternatively use the below wiring diagram.

XLR to Euroblock (Balanced to Balanced)

0 = Screen (Pin 1)

+ = Hot (Pin 2)

- = Cold (Pin 3)

Balanced microphone input wiring example.

Stereo Inputs

Line level stereo inputs are unbalanced on RCA connectors.

RCA to RCA (Unbalanced to Unbalanced)

Tip = Tip

Sleeve = Sleeve

Unbalanced line input wiring example.

XLR/Euroblock (Transformer or Cross-Coupled Output) to RCA

Screen (Pin 1) = Link to Pin 3

Hot (Pin 2) = Tip

Cold (Pin 3) = Sleeve

Balanced to Unbalanced input wiring example.

Zone Outputs

Zone outputs are balanced connections on Euroblock type connectors.

Pin assignments are screen printed above the connector or alternatively use the below wiring diagrams.

Euroblock to XLR (Balanced to Balanced)

0 = Screen

+ = Hot

- = Cold

Balanced line output (XLR) wiring example.

Euroblock to TRS (Balanced to Balanced)

0 = Sleeve

+ = Tip

- = Ring

Balanced line output (TRS) wiring example.

Euroblock to RCA (Balanced to Unbalanced)

0 = Link to Negative

+ = Tip

- = Sleeve

Balanced line output (Phono) wiring example.

Alarm Input

The Alarm input is a 2-pole connection on Euroblock type connector and is typically configured to the Normally Closed contacts.

Pin assignments are screen printed above the connector or alternatively use the below wiring diagrams.

2-Wire Alarm Contact Closure

0 = COM

+ = N/O (or N/C)

2-wire contact example.

Page Input

The Page input is a 2-pole connection on Euroblock type connector and is typically configured to the Normally Open contacts.

Pin assignments are screen printed above the connector or alternatively use the below wiring diagrams.

2-Wire Paging Switch

0 = COM

+ = N/O (or N/C)

2-wire switch example.

Remote Connection

There are two methods for connecting a remote control to the GR4. Remote control is enabled via the rear mount dip switches.

Digital Remote Connection

The RJ45 “ZONE REMOTE” port allows for the connection of the Allen & Heath PL-14 remote controllers. A maximum of two PL-14’s can be connected in daisy-chain wiring with various control options depending on installation requirements (see PL-14 manual for additional details regarding cable types and length).

⚠ Do not connect remote port to anything other than the designated remote controller.

Digital Remote (RJ45 to RJ45)

1 = White/Orange

2 = Orange

3 = White/Green

4 = Blue

5 = White/Blue

6 = Green

7 = White/Brown

8 = Brown

RJ45 Wiring Example using TIA/EIA 568B standard.

Analogue Remote Connection

The analogue inputs are 4-pole Euroblock type connectors for Zone 1 & Zone 2 control. These are 0-10V inputs and are typically used as a variable resistance and stepped voltage control for analogue volume control and source selection.

Pin assignments are screen printed above the connector or alternatively use the below wiring diagrams.

4-Wire Analogue Remote

0 = 0V

L = Level

S = Source

+ = 10V

Analogue remote connection example.

Setting up GR4

Operating Features

The GR4 is a feature rich analogue zone mixer. Multiple configurations are possible by means of internal jumpers, external dip switches and also via digital programmable pre-sets.

The below gives an overview of the various Modes that the GR4 enters when signal is sensed on various input connectors.

Primary Mic Mode: When audio sensed on Mic 1 channel and/or PAGE contact closure is sensed then music is faded to pre-set level and Mic 2 muted for the duration of the announcement. Mic 1 zone select LEDs flash slowly when in primary mic mode.

Secondary Mic Mode: When audio is sensed on Mic 2, then music is faded to pre-set level for the duration of the announcement. Mic 2 zone select LEDs flash slowly when in secondary mic mode.

Emergency Mic Mode: When ALARM contact is activated all zone feeds are muted and Mic 1 is fed direct to all zones. All select LEDs except Mic 1 LED are switched off for the duration. Mic 1 LED will flash quickly.

Juke Box Mode: Is a priority Music feed. When in Jukebox mode and audio is sensed on ST3 the current music feed will ‘duck’* to the pre-set level. If ST3 is silent for the pre-set period, the previous Music selection will resume. Mic volume is not affected by Jukebox priority.

*Pre-set levels for the above modes are achieved via a side-chain compressor or ‘ducker’. A ducker is dynamic control of Input x by input y which has a higher priority. If audio is detected at Input y then Input x will be ‘Ducked’ by a predetermined level which can be set by the user (see Table 1 6.4 for user definable parameters). In addition to the amount of attenuation is applied to the ‘Ducked’ signal the user can also control the hold time and release time of the compressor to suit the application.

Internal Jumper Settings

⚠ Please ensure that unit is switched off before changing any jumper settings. Ensure necessary precautions have been taken prior to removal of cover. If in doubt call an experienced engineer.

Warning: Do not remove PSU cover.

Zone 3 & 4 are mixed from a matrix on internal jumpers. The unit is shipped with the below settings as default but both zones can have any number of jumpers applied to suit the application.

Zone 3 & 4 Matrix Mix Default Positions

ⓘ Spare jumpers are available in a ‘parking bay’ connector labelled CN9 on the input PCB.

Dip Switch Settings

There are 16 Rear mounted DIP switches for selecting various options.

DIP switch settings Up = ON. Factory default = all switches down (OFF).

*Phantom Power for individual mics can be disconnected via an internal link (as shown in internal jumper diagram)

Please ensure mic levels are fully attenuated prior to engaging phantom power.

Programming Parameters

The GR4 has a total of 7 parameters (shown in Table 1) which are configurable by the installer/user.

Each parameter has four pre-defined values which can be stepped through and set as required.

Changing a Parameter Step by Step Guide- Ensure amplifiers/powered speakers are switched off prior to powering the unit up or down.

To enter Programming Mode;

1. Press and hold Z1 Mic & Music “SEL” switches whilst powering on the GR4
2. Power LED  will flash continuously whilst in Programming Mode.

Changing a parameter;

1. Use Z2 Mic & Music “SEL” switches to toggle through the parameter to change as shown in Table 1.
2. Use Z1 Mic & Music “SEL” switches  to toggle through the value required  as shown in Table 1.
3. The new parameter value is stored automatically. The parameter LED will flash quickly during the save procedure.

Exit Programming Mode;

1. Power cycle the unit to return to normal operation, LED will remain solid 

Table 1 – Showing Parameter/Value/LED State matrix. (Factory settings highlighted)