Power Requirements
The 750-LFC loudspeaker design combines advanced loudspeaker technology with equally advanced power capabilities. Understanding power distribution, voltage and current requirements, and electrical safety guidelines is critical to the safe operation of the 750-LFC loudspeaker.
AC Power Distribution
All components in an audio system (self-powered loudspeakers, mixing consoles, and processors) must be properly connected to an AC power distribution system, ensuring that AC line polarity is preserved and that all grounding points are connected to a single node or common point using the same cable gauge (or larger) as the neutral and line cables.
Caution
Make sure the voltage received by the 750-LFC loudspeaker remains within its 90–264 V AC operating range. In addition, the ground line must always be used for safety reasons and the line-to-ground voltage should never exceed 250 V AC (typically 120 V AC from line to ground).
Before applying AC power to any Meyer Sound self-powered loudspeaker, ensure the voltage potential difference between the neutral and earth-ground lines is less than 5 V AC when using single-phase AC wiring.
Note
Improper grounding of connections between loudspeakers and the rest of the audio system may produce noise or hum, or cause serious damage to the input and output stages of the system’s electronic components.
120 V AC, 3-Phase Wye System (Single Line) Line-Neutral-Earth/Ground
The figure below illustrates a basic 120 V AC, 3-phase Wye distribution system with the loudspeaker load distributed across all three phases, with each loudspeaker connected to a single line and common neutral and earth/ground lines. This system delivers 120 V AC to each loudspeaker
120 V AC, 3-Phase Wye System (Single Line to Loudspeakers)
120 V AC, 3-Phase Wye System (Two Lines) Line-Line-Earth/Ground
The figure below illustrates a 120 V AC, 3-phase Wye distribution system with each loudspeaker connected to two lines and a common earth/ground line. This configuration is possible because the 750-LFC loudspeaker tolerates elevated voltages from the ground line and does not require a neutral line. This system delivers 208 V AC to each loudspeaker.
120 V AC, 3-Phase Wye System (Two Lines to Loudspeakers)
Tip
The 120 V AC, 3-phase Wye system with two lines is recommended because it allows loudspeakers to draw less current than with single-line systems, thereby reducing voltage drop due to cable resistance. It also excludes the potential of varying ground to neutral voltages producing an audible hum.
230 V AC, 3-Phase Wye System (Single Line) Line-Neutral-Earth/Ground
The figure below illustrates a basic 230 V AC, 3-phase Wye distribution system with the loudspeaker load distributed across all three phases, with each loudspeaker connected to a single line and common neutral and earth/ground lines. This system delivers 230 V AC to each loudspeaker.
230 V AC, 3-Phase Wye System (Single Line to Loudspeakers)
Caution
For 230 V AC, 3-phase Wye systems, never connect two lines to the AC input of Amie, as the resulting voltage would exceed the upper voltage limit (275 V AC) and will damage the loudspeaker.
AC Connectors
The 750-LFC user panel includes two powerCON 20 connectors, as shown in the figure below, one for AC Input (blue) and one for AC Loop Output (gray).
AC Input (Left) and AC Loop Output (Right) Connectors
AC Input (Blue)
The blue AC Input connector supplies power to the 750-LFC loudspeaker. The 3-conductor powerCON 20 is rated at 20 A and uses a locking connector that prevents accidental disconnections. A 10-foot AC power cable, rated at 15 A, is included with each loudspeaker. If you replace the included AC power cable, make sure to use a cable with the appropriate power plug (on the other end) for the area in which you will operate the loudspeaker. The 750-LFC requires a grounded outlet. To operate safely and effectively, it is extremely important that the entire system be properly grounded.
The AC Input connector also supplies power to any additional loudspeakers connected to the loudspeaker’s gray Loop Output connector.
Caution
When looping AC power for loudspeakers, do not exceed the current capability of the AC Input connector (20 A) or the included AC power cable (15 A). Consider the total current draw for all loudspeakers on the circuit, including the first loudspeaker. See AC Loop Output (Gray) for more information.
AC Loop Output (Gray)
The gray AC Loop Output connector allows multiple 750-LFC loudspeakers to be looped and powered from a single power source. The 3-conductor powerCON 20 is rated at 20 A and uses a locking connector that prevents accidental disconnections. For applications that require multiple 750-LFC loudspeakers, connect the AC Loop Output of the first loudspeaker to the AC Input of the second loudspeaker, and so forth.
The maximum number of loudspeakers that can be looped from the AC Loop Output connector is determined by the voltage of the power source, the current draw of the looped loudspeakers, the circuit breaker rating, and the rating of the AC power cable connected to the first 750-LFC loudspeaker, as shown in the table below.
Circuit Breaker/ Connector Rating | 115 V AC | 230 V AC | 100 V AC |
|---|---|---|---|
15 A / 16 A | 1 looped (2 total) | 4 looped (5 total) | 1 looped (2 total) |
20 A | 2 looped (3 total) | 6 looped (7 total) | 2 looped (3 total) |
Note
Current draw for the 750-LFC loudspeaker is dynamic and fluctuates as operating levels change. The indicated number of loudspeakers that can be looped assumes that operating levels are normal and not such that loudspeakers are constantly limiting.
The 750-LFC loudspeaker ships with a gray powerCON 20 cable mount connector, rated at 20 A, for assembling AC looping cables. Assembled AC looping cables are also available from Meyer Sound [PN 28.115.032.03: 3.2 ft (1 m), 13 AWG (2.5 mm2)].
Wiring AC Power Cables
The pins on the powerCON 20 cable mount connector are labeled as follows:
L (Line)
• N (Neutral)
PE (Protective Earth or Ground)
powerCON 20 Cable Mount Connector
How AC power cables are wired is determined by the type of AC power distribution system used (see AC Power Distribution). When wiring AC power cables for single-line systems, use one of the following wiring schemes:
Wire Color | Attach to the Following Terminal | |
|---|---|---|
U.S. / Canada 60 Hz | European 50 Hz | |
Black | Brown | Hot or live (L |
White | Blue | Neutral (N) |
Green | Green or Yellow | Protective earth / ground (E or PE) |
Caution
When wiring AC power cables and distribution systems, it is important to preserve AC line polarity and connect the earth ground on both ends of the cable. The 750-LFC loudspeaker requires a grounded connection. Always use a grounded outlet and plug. It is extremely important that the system be properly grounded to operate safely and properly. Do not ground-lift the AC cable.
750-LFC Voltage Requirements
The 750-LFC loudspeaker operates as intended when receiving AC voltage within the following range:
90–264 V AC, 50–60 Hz
If the voltage drops below 90 V, the loudspeaker uses stored power to continue operating temporarily; the loudspeaker powers off if the voltage does not return to its operating range.
If the voltage rises above 275 V, the power supply could become damaged.
Caution
The power source for the 750-LFC loudspeaker should always operate within the required operating range, at least a few volts from the upper and lower limits. This ensures that AC voltage variations from the service entry — or peak voltage drops due to cable runs — will not cause the loudspeaker’s amplifier to cycle on and off or cause damage to the power supply.
750-LFC Current Requirements
Current draw for loudspeakers is dynamic and fluctuates as operating levels change. Because different cables and circuit breakers heat up at varying rates, it is important to understand the following types of current ratings and how they affect circuit breaker and cable specifications.
Idle Current — The maximum rms current during idle periods.
Maximum Long-Term Continuous Current — The maximum rms current during a period of at least 10 seconds. The maximum long-term continuous current is used to calculate temperature increases for cables to ensure that the size and gauge of the cables conform to electrical code standards. The current rating is also used to select appropriately rated, slow-reacting thermal breakers, which are recommended for loudspeaker power distribution. In addition, the maximum long-term continuous current can be used to calculate the AC looping capability for 750-LFC loudspeakers.
Burst Current — The maximum rms current during a period of around 1 second. The burst current is used as a rating for magnetic breakers. It is also used for calcuating the peak voltage drop in long AC cable runs according to the following formula:
V pk (drop) = I pk x R (cable total)
Maximum Instantaneous Peak Current — A rating for fast-reacting magnetic breakers.
Use the information provided in the table below as a guide for selecting the gauge of cables and the circuit breaker ratings for the system’s operating voltage.
Current Draw | 115 V AC | 230 V AC | 100 V AC |
|---|---|---|---|
Idle | 0.39 A rms | 0.38 A rms | 0.42 A rms |
Maximum Long- Term Continuous | 5.3 A rms | 2.7 A rms | 6.2 A rms |
Burst | 9.2 A rms | 4.4 A rms | 10.7 A rms |
Maximum Instantaneous Peak | 15.3 A peak | 7.8 A peak | 18.0 A peak |
The minimum electrical service amperage required by a loudspeaker system is the sum of the maximum long-term continuous current for all loudspeakers. An additional 30 percent above the combined Maximum Long-Term Continuous amperages is recommended to prevent peak voltage drops at the service entry.
Note
For best performance, the AC cable voltage drop should not exceed 10 V (10 percent at 115 V and 5 percent at 230 V). This ensures that the AC voltage variations from the service entry—or peak voltage drops due to longer cable runs—do not cause the amplifier to cycle on and off.
Intelligent AC Power Supply
The 750-LFC loudspeaker’s Intelligent AC™ power supply automatically:
Selects the correct operating voltage, allowing for international use without manually setting voltage switches
Eliminates high inrush currents with soft-start power up
Suppresses high-voltage transients up to several kilovolts
Filters common mode and differential mode radio frequencies (EMI)
Sustains operation temporarily during low-voltage periods
Powering on the 750-LFC Loudspeaker
When powering on the 750-LFC loudspeaker, the following startup events take place over several seconds.
Audio output is muted.
Voltage is detected and the power supply mode is automatically adjusted as necessary.
The power supply ramps up.
On the user panel, the Active/Status LED flashes multiple colors successively.
The Active/Status LED turns solid green, indicating the loudspeaker is unmuted and ready to output audio.
Caution
If the Active/Status LED does not turn solid green, or the 750-LFC loudspeaker does not output audio after 10 seconds, remove AC power immediately and verify that the voltage is within the required range. If the problem persists, contact Meyer Sound Technical Support.
Electrical Safety Guidelines
Make sure to observe the following important electrical and safety guidelines.
The powerCON 20 connector should not be engaged or disengaged when under load or energized. Either de-energize- energize or disconnect the other end of the cable.
The 750-LFC loudspeaker requires a grounded outlet. Always use a grounded outlet and plug.
Do not use a ground-lifting adapter or cut the AC cable ground pin.
Do not exceed the current capability of the 20 A AC Input connector for the loudspeaker. When looping loudspeakers, consider the total current draw for all loudspeakers on the circuit, including the first loudspeaker.
Make sure the AC power cable for the loudspeaker has the appropriate power plug (on the other end) for the area in which you will operate the loudspeaker. In addition, the AC power cable must be rated for the total current draw of all loudspeakers looped from the power source.
Do not operate the loudspeaker if the power cable is frayed or broken.
Keep all liquids away from LINA loudspeakers to avoid hazards from electrical shock.
Use the cable rings (see Cable Rings) on the rear of the 750-LFC cabinet to reduce strain on the AC power cable (and audio cables). Do not use the cable rings for any other purpose.
MDM-832 Distribution Module
The optional MDM-832 Distribution Module simplifies installation by using regular or composite cables to route AC power, balanced audio, and RMS to multiple LINA and 750-LFC units. This approach reduces setup and tear-down time for portable systems, and cable clutter for fixed installations.
Meyer Sound offers the MDM Load Calculator program that estimates AC power and AC load. This program helps users design the AC distribution system using the MDM-832 (or the larger MDM-5000) distribution modules.
The MDM Load Calculator program and the MDM-832 Operating Instructions (which includes information for the MDM-832 and MDM-5000) are available for download on the Meyer Sound website: meyersound.com/product/mdm/#software