GENERAL OPERATING INSTRUCTIONS

MAINS LEAD
A mains power lead is supplied with a moulded plug for immediate use. Connections are: Brown = Live, Blue = Neutral, Green/Yellow = Earth. Under no circumstances operate with the Earth disconnected. Voltage: 230V AC, ±10%, 50-60Hz.

MAINS INLET
A standard I.E.C. mains inlet is fitted to all models. The inlet socket contains an inline fuse and a spare. Only use the correct mains voltage and fuse rating as indicated on the panel by the mains inlet. The I.E.C. lead connects between the inlet socket and a suitable mains voltage supply.

SWITCH ON/OFF
Ensure all leads are connected and all volume controls are turned down before switching on and off. If you need to connect leads whilst the unit is on, make sure the volume controls are at minimum. A red LED indicates that the power is on.

INPUT LEVELS
Inputs can be overdriven by excessive signal levels, which will cause distortion and can damage loudspeakers. Some amplifiers are fitted with P.P.I.'s (peak programme indicators), which will illuminate to indicate the onset of an overdriven condition. If this occurs, lower the channel gain and increase the Master Volume, or select a lower sensitivity input if available. If neither of these options is possible, the input signal must be reduced externally. Try to avoid continuous PPI illumination.

TONE CONTROLS
When setting up for the first time, turn all the tone controls to the flat (midway) position. Set the volume to approximately three-quarters of the desired level, and adjust the tone controls for the best sound. Then increase the volume to the required level, and make any minor adjustments to the tone controls. Since all room acoustics are different, and change as the room becomes crowded, check tone settings when the room is full of people. Get a colleague to listen from in front of the speakers.

GRAPHIC EQUALISERS
Graphic Equalisers are effectively narrow-band tone controls centred on the frequency shown below each slider. Each band can be boosted or cut. The centre point is the flat position, i.e. no boost or cut. Experiment starting with all sliders at the centre point, and adjust each slider in turn while listening to the resulting tone change. Then contour your graphic in small steps to optimise the sound, boosting desirable frequencies and cutting unwanted ones like those causing feedback. The Tone Control remarks above also apply.

FEEDBACK
Acoustic feedback is due to sound from the speakers entering a microphone and being re-amplified. This occurs if the microphone gain is too high relative to the position of the speakers. Ensure microphones are as far away from, and if possible behind, the speakers. Reducing the tone control or graphic fader positions at the feedback frequency will enable higher volumes to be used without feedback. Remember that loudspeakers are easily damaged if feedback is allowed to continue (apart from the unpleasant howl), and every effort must be made to stop it.

LIMITERS
Some models are fitted with fixed or switchable limiters to protect speakers and reduce clipping (overload) distortion. We recommend that you keep the limiter switch on at all times. LED's marked "ACL" (active clip limiter) glow when the unit is being driven past the overload point, and indicate that the limiter circuit is automatically taking corrective action by reducing gently the amplifier input gain.

SPEAKERS
Always use speakers with a high enough power rating for your amplifier. Full power is achieved into a 4 ohm load, do NOT connect speakers with a total load below 4 ohms. Two 8 ohm speakers connected in parallel constitute a 4 ohm load. An 8 ohm load will produce about 70% of the maximum amplifier power. If in doubt please ask your dealer for advice about correct speaker rating and impedance matching.

VENTILATION
If your amplifier is fan cooled, ensure that the air inlet and exit vents are unrestricted. Restricting the airflow will result in the unit automatically switching off if the internal temperature gets too high. If the amplifier has a proportional speed fan, the speed will increase as the demands placed on the amp raise the temperature. Convection cooled models - those without a fan - must have good air circulation around the rear heatsink (aluminium 'fins'). It's normal for heatsink temperatures to reach 60-70 degrees Centigrade.

AUXILLIARY SEND AND RETURN SOCKETS
These 3 pole jack sockets enable an external effects unit or sound processor to be used, tip is send and ring is return. All input signals will be routed via the effects unit once it is connected. If the unit is fitted with Aux push switches, they must be pushed on the relevant channel to select the effect.

FOOTSWITCH (F/S) SOCKETS
These will only be found on McGregor amplifiers fitted with an internal effect. A footswitch plugged into this socket will enable the reverb to be muted by foot operation. Footswitch pedals (not included) can be latching or non-latching types.

SLAVE/LINE AND LINK SOCKETS
These jack sockets enable a line level output signal to be fed to an additional power amplifier. They can be either pre or post the master volume control. Some amplifiers are fitted with both pre and post sockets. All sockets are mono unless labelled stereo on the panel.

DIGITAL EFFECTS PROCESSOR
If fitted, this has a bank of 64 selectable effects (4 x 16). The four red leds indicate which bank, A-D, is selected. Pres select to change bank. Each bank has 16 effect variations. Select 1-16 by pressing the up/down keys below the eight dual-colour leds. A level control allows effect mix, and an on/off footswitch can be connected to the F/S socket. The last effect selected is always reloaded by the non-volatile memory when the amplifier is first switched on. Remember to select the effects on the required channels by pressing the switch marked 'rev' on those channels.

DIGITAL DELAY
Press the switch marked 'rev' on the selected channel, then adjust the level control for the amount of delay sound you require. Set the repeat control for the desired number of repeats, and adjust the delay control for the duration between repeats. The F/S socket can be used to mute the effect. A slight delay before the effect works when first switched on is normal, the memory has to reset before use.

SX SERIES POWER AMPS
Crossover: Both channels are full-range, unless the crossover button is pressed. When selected, that channel becomes a high pass channel feeding everything above 135Hz to the output (i.e. the bass is removed), and should be connected to a mid-high loudspeaker. If the 'Low Pass' button is pressed, frequencies from 20Hz to 135Hz are fed to the output (i.e the mid-high is removed), this should be connected to a bass speaker cabinet. The other channel works in exactly the same way, this system removes the need for an external electronic crossover.
LF Enhancer: When selected, this button engages a fast roll-off filter below 38Hz to remove unwanted low frequency rumble, which would waste amplifier and loudspeaker power, resulting in a cleaner and tighter bottom end. It also adds a small boost at 55Hz to enhance the bass response.

CONNECTORS
Mono jack plug: Sleeve= Ground, Tip=Hot. Stereo jack plug: Sleeve=Ground, Tip=Hot, Ring=Negative. Din Plug: Pin 2=Ground, Pin 3+5=Play, Pin 1+4=Rec. XLR output: Pin 1=Ground, Pin 2=Hot, Pin 3=N/C. XLR input (balanced): Pin 1=Ground, Pin 2=Hot, Pin 3=Negative. XLR input (unbalanced): Pin 1=Ground, Pin 2=Hot, Pin 3=Ground (to Pin 1). Speakon: -1=Ground, +1=Hot (push, then twist clockwise to lock and ensure proper connection). Speakon: -2=100v line, +2=100v line (only if the amplifier is fitted with the 100 volt line option).

All the plugs listed above require the wires to be soldered for a reliable connection. If you are not familiar with using a soldering iron, or the plugs mentioned, please refer to your dealer or qualified engineer, or buy pre-made leads from your retailer. Your amplifier has been very thoroughly tested before leaving the factory; if, after following the above guide, your amplifier does not function correctly, please contact the dealer who supplied you. All servicing must only be carried out by a qualified audio and electrical engineer.