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Summary of Contents for L-Acoustics LA48A
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Page 1: Owners Manual
Version 1.0 January 2003 LA48a OWNERS MANUAL... -
Page 3: Table Of Contents
8. PROTECTION FEATURES....................... 19 8.1 Clip Limiter..........................19 8.2 Thermal Protection ........................19 8.3 VHF Protection..........................19 8.4 Short Circuit Protection ......................19 8.5 Automatic Fuse Saver, AFS -Limiter ..................20 8.6 AC Mains Voltage Protection ...................... 20 L-ACOUSTICS LA48a Manual V1.0 27/01/2003... -
Page 4: List Of Figures
Table 4: LA48a Maximum Output Power versus Mains Input Power ..........12 Table 5: LA48a Output Power and Input Sensitivity versus MLS Switch Setting (32 dB gain)....13 Table 6: Maximum Recommended Length for Damping Factor > 20 ..........16 L-ACOUSTICS LA48a Manual V1.0... -
Page 5: Approvals
The third prong is provided for your safety. If the provided plug does not fit into your outlet, consult an electrician for replacement of the obsolete outlet. 9. Connect only to AC power outlets rated 230-240 V, 50-60 Hz. L-ACOUSTICS LA48a Manual V1.0 27/01/2003... -
Page 6: User Responsibility
However, there is no guarantee that interference will not occur in a particular installation. L-ACOUSTICS LA48a Manual V1.0 27/01/2003... - Page 7 All electrical products sold in the EC must be approved for immunity against electromagnetic fields, high voltage flashes, and radio interference. • Consult the dealer or an experienced radio/TV technician for further assistance. L-ACOUSTICS LA48a Manual V1.0 27/01/2003...
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Page 8: Introduction
3. INTRODUCTION Thank you for purchasing the L-ACOUSTICS LA48a power amplifier. This manual contains important information on operating your power amplifier correctly and safely. Please take time to read this manual in order to familiarize yourself with the many advanced features of this amplifier. -
Page 9: Rear Panel
Indicates if the AFS™ (Automatic Fuse Saver) current limiter is activated. 3.3 REAR PANEL Gain=32dB Figure 2: LA48a Rear Panel 1. Output Speaker Connector The Neutrik® Speakon connector may be unfamiliar to some users. A full description is found in Section 6.2. -
Page 10: Rear Panel Features
MLS positions when connected to lower speaker impedances and as can be seen in Table 1, the LA48a can produce output power in excess of 2000 watts. Essentially, the LA48a amplifier is a power converter and by selecting MLS positions you are allocating a portion of the available 5800 watts power. -
Page 11: Mls Technology Background
MLS positions can be different for each channel and a variety of combinations can be selected as seen in Table 2. There is no risk for amplifier damage since the LA48a is very well protected (even down to 0.3 ohms). However, if uncertain or where time does not allow, use the default position (MLS = 0 dB). -
Page 12: Installation
5. INSTALLATION 5.1 MOUNTING The LA48a is two rack units high (2U) and will mount in an EIA-standard 19'' rack. Four mount points are provided on the front panel of the amplifier for rack mounting. For permanent installation, the amplifier can be mounted using standard 19'' rack mount rails and/or slides within the amplifier rack using the four front mount points. -
Page 13: Operating Voltage
National deviation concerning installation of the LA48a: Danish safety regulations stipulate the use of an 8 A mains fuse. Since the LA48a uses an internal primary mains fuse of 15A, the LA48a must be equipped with an industrial mains connector rated for 16 A or, alternatively, be installed to a fixed 16A circuit. -
Page 14: Power Consumption
However, if the amplifier is operated at sustained full power (using a sine wave signal) into low impedances, the LA48a has a mains current limiter called AFS (Automatic Fuse Saver), which will limit the long-term current draw. Please see Section 8.5 for more detail concerning the AFS-limiter. -
Page 15: Heat Power Calculation
Since the output power delivered varies with the load impedance, 4 ohms is generally taken as the reference. For the LA48a, full output power into 4 ohms is 2300 W (MLS switch = 0 dB) and standard gain is 32 dB. This corresponds to an input sensitivity of 2.4 Vrms or 9.9 dBu. -
Page 16: Connections
To daisy chain amplifiers, use the XLR-male connector, labeled Link, provided on each channel. This connector is wired in parallel with the Neutrik® Combo jack on each input. Gain=32dB Figure 7: LA48a Rear Panel Detail L-ACOUSTICS LA48a Manual V1.0 27/01/2003... -
Page 17: Unbalanced Inputs
Speaker connections are made via the two Neutrik® NL4FC Speakon connectors. The Speakon connector is designed for high power speaker connections and assures correct polarity, locks securely in place and prevents from shock hazard. The LA48a power amplifier Speakon connectors are wired in the following manner: Channel A Channel B... -
Page 18: Operation
Note: Formerly, this was referred to as reverse stereo operation for the LA48. For this reason, be sure to use balanced inputs on all measurement equipment (also oscilloscope probes) if you are bench testing. Figure 11: Reverse polarity operation for Channel B L-ACOUSTICS LA48a Manual V1.0 27/01/2003... -
Page 19: Tandem Mode
4 ohm part of the load and the other channel shares the other 4 ohm part. The power into 4 ohms from an LA48a (MLS at 0 dB) is 2300 W. Therefore, the total bridged power into the 8 ohm load will be 2 x 2300 = 4600W. -
Page 20: Powering Up - Soft Start
In bridged mode, both controls must be in the same position so that the speaker load will be shared equally between the channels. 7.5 INDICATORS Figure 13: LA48a Front Panel Detail The two bottom green ”ON” LED’s indicate that the output circuits are receiving the correct rail voltage. -
Page 21: Protection Features
Under normal operation, clip limiting is inaudible. The limiter can be turned On or Off by depressing or pressing the relevant rear panel clip limit switch. L-ACOUSTICS recommends leaving the clip limiters switched ON at all times (Channel A, B rear panel clip limiter buttons depressed in the “IN” position). -
Page 22: Automatic Fuse Saver, Afs Tm -Limiter
During bench test procedures, if the average current draw exceeds what the mains breaker can take the output power is reduced by 2 dB. Effectively, this is the same as an LA48a being reduced to the power of an LA24a (but again, not a single user has reported that the AFS has been activated). In... -
Page 23: Maintenance
In the unlikely event of a non-user rectifiable fault, return the amplifier to your supplier or an approved service centre (see Section 11). L-ACOUSTICS cannot be held responsible for damage or injury as a result of the top or bottom covers being removed. -
Page 24: Warranty
This warranty shall be null and void, if the product is subjected to: 1) Repair work or alteration by persons other than those authorised by L-ACOUSTICS or its agents. 2) Shipping accidents, war, civil insurrection, misuse, abuse, operation with incorrect AC voltage, operation with faulty associated equipment, exposure to inclement weather conditions and normal wear and tear.
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