USER MANUAL HEADLINES
LAB 300
USER MANUAL
Unpacking 2
Warnings 2
User responsibility 2
1.Speaker damage
2.Speaker output hazard.
3.Radio interference.
Introduction 3
1.Front panel
2.Rear panel
Installation 4
1.Mounting
2.Cooling
3.Operating voltage
4.Grounding
5.Power consumption
6.Input connections
7.Connecting speakers
Operation modes 6
1.Stereo
2.Tandem mono
3.Bridged mono
4.Stereo reverse
Operation 7
1.Operation precautions
2.Input attenuators
3.Gain switch
4.Indicators
Protections 8
1.Clip-limiter
2.Thermal protection
3.VHF protection
4.Short circuit protection
5.D.C. protection
Design features |
9 |
•Safety approvals
•EMC approvals
Specifications |
9 |
•EMC-declaration
Appendix A |
10 |
•Mains voltage selection
Troubleshooting |
10 |
Warranty and disclaimers |
11 |
•General
•International
Technical assistance and services 11
•International
•Factory services
1
Unpacking
Carefully open the shipping carton and check for any noticeable damage. Every LAB.GRUPPEN amplifier is tested and inspected before leaving the factory and should arrive in perfect condition. If found to be damaged, notify the shipping company immediately. Only the consignee may institute a claim with the carrier, for damage incurred during shipping. Be sure to save the carton and packing materials for the carrier's inspection.
It is also advisable, to save the carton and packing material, even if the amplifier is undamaged. Should you ever need to ship the amplifier, use the original packing.
Warnings
Read this before you are operating your amplifier:
•Do not use this amplifier if the power cord is broken or frayed.
•Always operate the unit with the chassis ground wire connected to the electrical safety earth.
•Do not parallel or series connect an amplifier output, with any other amplifier output. Do not connect the amplifier output to any other voltage source, such as battery, mains source, or power supply, regardless of whether the amplifier is turned on or off.
•Do not run the output of any amplifier back into another channel's input.
•Do not block the air intake or exhaust ports. Do not operate the amplifier near heat producing devices such as radiators, stoves etc.
•Do not spill water or other liquids into or on the unit. Do not operate the amplifier if suspected or standing in liquid.
•Do not remove top or bottom covers. Removal of the cover will expose hazardous voltages. There is no serviceable parts inside and removal may void warranty.
•Keep this manual for future reference.
User responsibility
1.Speaker damage
Your amplifier is very powerful and can be potentially dangerous to both loudspeakers and humans alike. Many loudspeakers can be easily damaged or destroyed by overpowering, especially with the high power available from a bridged amplifier. Always check the speakers continuous and peak power capabilities.
Even if the gain is reduced by using the amplifier's front panel attenuator, it is still possible to reach full output power, if the input signal level is high enough.
2.Speaker output hazard
Power amplifiers are capable of producing hazardous output voltages. To avoid electrical shock, do not touch any exposed speaker wiring, while the amplifier is operating. See page 6 about outputs for proper connection of speakers.
3.Radio interference
This product has been tested, and complies with the limits for the European Electro Magnetic Compatibility (EMC) directive. These limits are designed to provide reasonable protection against harmful interference between electrical equipment. However, there is no guarantee for no interference even if the amplifier is EMC approved.
If the amplifier cause interference, which can be easily determined by turning the amplifier on and off, the user can correct the interference by one or more of the following steps:
1.Increase the proximity between the equipment.
2.Connect the AC cord to an outlet on a different circuit from that to which the affected unit is connected.
3.If a radio receiver is interfered (normally amplitude modulation); reorient the antenna.
4.Check if the affected unit complies with the EMC limits for immunity, (CE-labelled).
If not, address the problem with the manufacturer or supplier. All electrical products sold in the EC must be approved for immunity against electromagnetic fields, high voltage flashes, and radio interference.
2
Introduction
Thank you for purchasing a LAB.GRUPPEN power amplifier. This manual contains important information on operating your amplifier correctly and safely. Please take some time and read this manual to familiarize yourself with the amplifier.
The front panel
Figure 1. Front panel
1.Carry/protection handle
Both handles can be used to carry the amplifier, they also act as protection for the front panel. If so desired they can be removed (by removing the screws behind the front panel and replacing the handles with nuts) for fixed installations, or racks where the front covers are to shallow.
2.Input level attenuators
These controls are used to alter the signal level entering the amplifier. They are calibrated in dB to help set up active loudspeaker systems or cut down unwanted noise from the input signal.
(See page 7).
3. Protect indicator (Temperature and VHF)
This indicator is lit if the amplifier tries to operate above its maximum operating temperature (90oC). The indicator first comes on as a warning, to either turn down the input level, or check the cooling arrangements after what point
the amplifier will mute the input signal. When the cooling has returned the output heat sinks to the normal operating temperature, the input signal is unmuted.
This indicator also lights when constant signals, above 20 kHz at full power, are present at the output terminals. When this happens the input signal is muted and the process cycles until the VHF signal is no longer present. (See page 8).
4.Clip/limit indicator
This indicator tells when the amplifier output is clipping or limiting. The two different states can be told apart:
•When the clip limiter is engaged it flickers briefly. (See page 8).
•When the clip limiter is not engaged it lights for a longer period.
5.Power actuator
This is used to start the amplifier. (See page 4 and 7).
The rear panel
Figure 2. Rear panel
3
Please refer to diagram on page 3
1.Speaker connector
This type of speaker connector may be unfamiliar to some users. A full description is found in the operation section. (See page 6).
2.AC line cord (See page 5).
3.Clip limiter switch
Turns the clip limiter on and off. (See page 8).
4.Input jack
Alternative to using input XLR or for linking inputs with other amplifiers. (See page 5).
5.Input signal XLR (See page 5).
6.Phase reverse switch for channel B
For reversing the input signal phase of channel B to allow bridged operation. (See page 7).
7.Link switch
Allows a single input to drive both channels simultaneously. (See page 6).
8.Gain select switch
Allows amplifier gain to be switched between 23dB and its normal gain at 0.775mV input sensitivity. (See page 7).
Installation
1.Mounting
The amplifier is one rack unit high (1U) and will mount in a standard EIA 19 inch rack. Amplifiers may be stacked directly on top of each other. There is no need for spacing between units. If it is the intention to fill a rack with amplifiers, we recommend racking is started from the bottom of the rack. It is also recommended that rear supports are used for amplifiers mounted in the middle of the rack, especially if used as part of a portable system.
2. Cooling
Should a heat sink get too hot, its sensing circuit will mute the hot channel. If the power supply overheats, another sensing circuit will mute both output channels, until it cools down to a safe operation temperature.
Make sure that there is adequate air supply in the rack and that the space at the rear allows the exhaust to escape.
For fixed installations with a central cooling system, usually found in fixed installations with a dedicated rack room, it may be necessary to calculate the maximum heat emission. Refer to Power consumption on page 5.
3. Operating voltage
A label just below the mains cable on the rear of the amplifier indicates the AC mains voltage, for which the amplifier is wired. Connect the power cable only to the AC source referred to on the label. The warranty will not cover damage caused by connecting to the wrong type of AC mains.
For converting a 230 volt amplifier to 115 volt or vice-versa, see Appendix A.
The amplifier is supplied with an approved European AC line connector. If this connector is not appropriate for your country, it can be cut off and wired to a suitable connector in the following way :
BROWN |
LIVE |
BLUE |
NEUTRAL |
GREEN/YELLOW |
EARTH |
Once the AC connector is connected to a suitable AC supply, the amplifier can be started with the AC actuator.
4. Grounding
There is no ground lift switch or terminal on this amplifier. The signal ground is always floating via a resistor to chassis and the grounding system is automatic. If a potential above 0.6V presents itself between signal ground and chassis ground, a short circuit is introduced between the two, thereby enabling electrical protection. If a unit in the system is faulty, its mains fuse will blow, due to this automatic ground system.
If however you wish to tie the signal ground to chassis, connect the XLR-connector’s shell lug to pin 1. In the interest of safety never disconnect the earth pin on the AC cord.
For all units that are EMC approved (radio interference), there is an AC mains filter. This filter needs the chassis ground for reference, otherwise a current loop is formed via the signal ground.
Use the balanced input to avoid hum and interference.
5. Power consumption
There are three ways to determine the power/current consumption of the amplifier:
First, the peak current draw at full output power. Under this condition the power will trip the
4
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