L-Acoustics LA48A, Руководство пользователя

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L-ACOUSTICS LA48a Manual V1.0 27/01/2003 13
5.6 HEAT POWER CALCULATION
The heat power can be calculated according to the following example:
Consider headroom of at least 9 dB (1/8 of full power) and a 4 ohm load on an amplifier producing
2300 watts per channel. The 1/8 power per channel is then: 2300 / 8 = 287.5 watts; and the total
output power is : 2 x 287.5 = 575 watts.
The power consumption according to Table 4 is 900 watts (Table 4 gives the active power
consumption of the amplifier for different loads and power levels).
The
heat power produced is the difference between the power consumption and the output power:
900 - 575 = 325 watts per amplifier.
5.7 GAIN AND SENSITIVITY
As standard, the LA48a is delivered with 32 dB gain. For most professional applications, mixing consoles
operate at a nominal level of +4 to +6 dBu, therefore the 32 dB position provides optimal gain
structure with plenty of fader movement. In addition, all L-ACOUSTICS LLC analog controllers and
OEM factory presets for approved digital processors are optimized for use with 32 dB gain amplifiers.
Sensitivity is defined as how many volts (rms) or dBu (referred to 0.775Vrms) are required at the
amplifier input to obtain full output power. 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.
For the LA48a, the input sensitivity will depend on the specific MLS switch setting. Input sensitivity is
summarized below in Table 5.
Table 5: LA48a Output Power and Input Sensitivity versus MLS Switch Setting (32 dB gain)
LA48a
MLS SWITCH SETTING
LOAD CONFIGURATION -5 dB -4 dB -2 dB 0 dB
16 ohms Stereo (2 channel) 220 W 260 W 410 W 650 W
(5.7 dBu) (6.4 dBu) (8.4 dBu) (10.4 dBu)
8 ohms Stereo (2 channel) 430 W 520 W 820 W 1300 W
(5.6 dBu) (6.4 dBu) (8.4 dBu) (10.4 dBu)
4 ohms Stereo (2 channel) 830 W 1000 W 1600 W 2300 W
(5.4 dBu) (6.2 dBu) (8.3 dBu) (9.9 dBu)
2 ohms Stereo (2 channel) 1660 W 2000 W 2400 W 2900 W
(5.4 dBu) (6.2 dBu) (7.0 dBu) (7.8 dBu)
16 ohms Bridged mono 860 W 1040 W 1640 W 2600 W
(5.6 dBu) (6.4 dBu) (8.4 dBu) (10.4 dBu)
8 ohms Bridged mono 1660 W 2000 W 3200 W 4600 W
(5.4 dBu) (6.2 dBu) (8.3 dBu) (9.9 dBu)
4 ohms Bridged mono 3400 W 4000 W 4800 W 5800 W
(5.4 dBu) (6.2 dBu) (7.0 dBu) (7.8 dBu)
[1] Component tolerance
dependent
Power in watts (EIA 1 kHz, 1%
THD)