Meyer Sound Documentation

MM-10XPs require a Meyer Sound IntelligentDC external power supply. The MPS-488HP single-space 19-inch rack unit receives balanced audio from its XLR female inputs and routes the audio, along with 48 V of DC power, to its channel outputs. The channel outputs—equipped with either Phoenix 5-pin male connectors (MPS-488HPP) or EN3 5-pin female connectors (MPS-488HPE)—can deliver DC power to up to eight MM-10XP subwoofers. The smaller, 1RU,

half-rack MPS-482HP unit provides power and audio to two loudspeakers via its two Phoenix 5-pin male connectors.

Meyer Sound IntelligentDC Power Supply

Cable lengths up to 150 feet for DC power are possible when using 18-AWG wire, with just 1 dB of loss in peak SPL. Longer cable runs are possible for moderate applications that do not drive the subwoofers to maximum output, or for installations with heavier wire gauges.

The use of composite multiconductor cables (such as Belden® 1502) allows a single cable to carry both DC power and balanced audio to the MM-10XPs.

The MM-10XP is powered by a Meyer Sound external 48 V DC power supply, eliminating the need for wiring conduits while still preserving the advantages of self-powered loudspeaker systems. The unit's onboard amplifier and signal-processing circuits were designed to store DC power and tolerate voltage drops, thereby accommodating light-gauge cables and lengthy cable runs.

The MM-10XP subwoofer is available with either a Phoenix 5-pin male or SwitchCraft EN3 5-pin male connector for receiving DC power and balanced audio. The connectors’ five pins include two for DC power (negative and positive) and three for balanced audio (shield, negative, and positive). These pins are clearly labeled on the MM-10XP rear panel. To function properly, the MM-10XP requires 48 V of DC power.

Phoenix 5-Pin Male Connector

EN3 5-Pin Male Connector

Depending on the subwoofer’s connector, the MM-10XP ships with either a single Phoenix cable connector or an EN3-to-pigtail cable for constructing loudspeaker cables.

The Input Polarity switch swaps the polarity of the audio source signal, which is sometimes necessary to acoustically align the subwoofer with other loudspeakers in the system. When the switch is in the up (non-inverting) position, the positive audio pin (+) is hot relative to the negative audio pin (–), resulting in a positive pressure wave when a positive signal is applied to the positive pin. When the switch is in the down (inverting) position, the negative audio pin (–) is hot relative to the positive audio pin (+), resulting in a positive pressure wave when a positive signal is applied to the negative pin.

MM-10XP Input Polarity Switch

The MM-10XP has a three-color Limit LED on its rear panel that changes color to indicate the subwoofer’s status.

MM-10XP Limit LED

Powering On (Green)

When powering up the MM-10XP subwoofer, the following startup events occur and are indicated by the Limit LED:

1. The LED flashes green and then yellow during power-up.

2. The LED turns solid green indicating the subwoofer is ready to reproduce audio.

Caution

• If the Limit LED turns red and stays solid red after powering up and the audio is muted, the subwoofer has encountered a failure and may need to be serviced. Contact Meyer Sound Technical Support.

• If the Limit LED turns solid red and the MM-10XP continues to output audio, though at reduced levels, the subwoofer’s voltage may have dropped below 25 V DC. When these conditions are encountered, operation of the subwoofer should cease and its power supply and cabling should be verified.

Limiting (Yellow)

Limiting activity is indicated when the Limit LED turns yellow. When engaged, the limiter protects the subwoofer’s driver and prevents signal peaks from causing excessive distortion in the subwoofer’s amplifier, thereby preserving headroom and maintaining smooth frequency responses at high levels. When the level returns to normal, below the limiter’s threshold, the LED turns green and limiting ceases.

The MM-10XP performs within its acoustical specifications at normal temperatures when the Limit LED is green, or if the LED turns yellow for two seconds or less and then returns to green for at least one second. If the LED remains yellow for longer than three seconds, the subwoofer enters hard limiting where:

• Increases to the input level have no effect.

• Distortion increases due to clipping and nonlinear driver operation.

• The drivers are subjected to excessive heat and excursion, which will compromise their life span and may eventually lead to damage over time.

Caution

The Limit LED turns yellow when the subwoofer’s signal rises 2 dB above the limiting threshold, and indicates a safe, optimum level has been exceeded. If the MM-10XP subwoofers in a system begin to limit before reaching the desired SPL, consider adding more subwoofers to the system to achieve the desired SPL without exposing the subwoofers to excessive levels and possible overheating.

MM-10XP Temperature and Limiting

The Limit LED turns solid yellow when its heat sink temperature reaches 65° C (145° F), indicating the unit is reaching its maximum heat dissipation and a reduction in SPL is recommended. While the MM-10XP will continue to operate while the LED is yellow, the limiter threshold is lowered to a safe level (causing the output level to be lowered by 6 dB) to prevent the subwoofer from overheating. When the temperature of the heat sink cools to 50°C (122°F), the LED changes from yellow to green and the limiter threshold returns to normal.

Clipping (Red)

The Limit LED flashes red when its input signal causes the amplifier to overload. If the LED flashes red continuously, the subwoofer is severely overloaded and a reduction in the input level is recommended.

Caution

If the Limit LED turns solid red and the subwoofer continues to output audio, though at reduced levels, the subwoofer’s voltage may have dropped below 90 V AC. When these conditions are encountered, operation of the sub-woofer should cease and its power supply and cabling should be verified.

Each MM-10XP subwoofer draws a maximum current of 3.31 A average and 3.45 A peak from the 48 V DC output of the MPS-488HP. The current draw for the MM-10XP is dynamic and fluctuates as operating levels change. The cabling between the MM-10XP and the MPS-488HP adds resistance and hence causes a voltage drop at the subwoofer. Because lower DC voltages compromise amplifier performance (peak SPL), and in some cases frequency response, cable resistance should be kept to a minimum.

Cable Lengths and Cable Gauges for MM-10XPs

When connecting an MM-10XP to an MPS-488HP channel output, you can use cable lengths of up to 150 feet with only 1 dB of peak SPL loss using 18 AWG wire. Longer cable lengths are possible with heavier wire gauges (see the tables below).

Table 1. MM-10XP Loudspeaker Cable Lengths (AWG)

Cable Gauge	Resistance (Ω/ft)	Approximate Max. Length
12 AWG	0.0016	600 ft
14 AWG	0.00253	375 ft
16 AWG	0.00402	237 ft
18 AWG	0.00636	150 ft
20 AWG	0.01008	87 ft

Table 2. MM-10XP Loudspeaker Cable Lengths (European)

Cable Gauge	Resistance (Ω/m)	Approximate Max. Length
2.50 mm2	0.0052	157 m
1.50 mm2	0.01076	87 m
1.00 mm2	0.02087	45 m
0.75 mm2	0.03307	27 m

Note

When connecting an MM-10XP to an MPS-488HP channel output, the total cable resistance should not exceed 2 ohms.

Calculating the Maximum Cable Length

The maximum cable length for an MM-10XP can be calculated with the following formula:

maximum length = 2 Ω / 2 * cable resistance (in Ω/ft)

For example, the maximum length of an 18 AWG cable with a resistance of 0.00636 Ω/ft is 157.2 feet

(2 Ω/ 2 * 0.00636 Ω/ft).

When wiring MM-10XP loudspeaker cables with Belden 1502 or an equivalent cable, use the conventions in Table 3. The red and black wires in the Belden 1502 cable have a thicker gauge than the other three wires and should be used for DC power. The blue, white, and shield wires are shielded together and should be used for audio.

Belden 1502 Composite Cable

Wiring EN3-to-Pigtail Cables

MM-10XPs equipped with EN3 connectors are shipped with one 10-foot EN3 5-pin female-to-pigtail cable. The EN3 end of the cable connects directly to the MM-10XP input connector. The pigtail end of the cable can be equipped with either an EN3 5-pin male connector for connecting to the MPS-488HPE power supply, or a Phoenix 5-pin female connector for connecting to the MPS-488HPP power supply. The pigtail can also be spliced to a longer loudspeaker cable or to a junction box. The included EN3-to-pigtail cable uses a multiconductor cable, which can be wired for both DC power and balanced audio. The EN3- to-pigtail cable is available in plenum or regular (non-plenum) versions.

Note

For a complete list of cables and cable connectors available from Meyer Sound that can be used with the MM-10XP subwoofer and MPS-488HP power supply, see MM-10 Accessories.

The MM-10AC subwoofer combines advanced loudspeaker technology with equally advanced power capabilities.

Understanding voltage and current requirements, as well as electrical safety issues, is critical to the safe operation of the MM-10AC. The MM-10AC rear user panel includes the following PowerCON AC connectors:

MM-10AC AC Input (Left) and AC Loop Output (Right) Connectors

AC Input Connector (Blue)

The blue AC Input connector supplies power to the MM-10AC. The input is rated at 20 amps and uses a PowerCON AC mains locking connector that prevents accidental disconnections. A 10-foot AC power cable, rated at 15 amps, is included with each MM-10AC. 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 region in which you will operate the unit.

The AC Input connector also supplies power to any additional subwoofers connected to the MM-10AC’s gray AC Loop Output connector. Each MM-10AC requires approximately 0.9 A rms maximum at 115 V AC and 0.4 A rms maximum at 230 V AC.

Caution

When using the included AC power cable, do not loop more than 15 additional MM-10ACs from the AC Loop Output connector at 115 V (16 total for the circuit), and not more than 36 at 230 V (37 total for the circuit).

AC Loop Output Connector (Gray)

The gray AC Loop Output connector allows multiple

MM-10AC subwoofers to be looped and powered from a single power source. Connect the AC Loop Output of the first MM-10AC to the AC Input of the second MM-10AC, and so forth. The AC Loop Output uses a PowerCON AC mains locking connector that prevents accidental disconnections.

The maximum number of subwoofers 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 subwoofers, the circuit breaker rating, and the rating of the AC power cable connected to the MM-10AC.

Table 4. Number of MM-10ACs that Can Be Looped

Circuit Breaker/ Connector Rating	115 V AC	230 V AC	100 V AC
15 amps	15 looped (16 total)	36 looped (37 total)	12 looped (13 total)

Note

The current draw for the MM-10AC is dynamic and fluctuates as operating levels change. The numbers in Table 4 assume that operating levels are normal and not such that the subwoofers are constantly limiting.

Each MM-10AC ships with one AC looping connector for making AC looping cables. Assembled AC looping cables are available from Meyer Sound.

Caution

Do not exceed the current capability of the 20-amp Input connector for the MM-10AC. When looping MM-10ACs, consider the total current draw for all units on the circuit, including the first.

The MM-10AC requires a grounded outlet. To operate safely and effectively, it is extremely important that the entire system be properly grounded.

AC Cable Wiring Scheme

When wiring international or special-purpose power connectors:

The MM-10AC operates safely and continuously when the AC voltage stays within 100–240 V AC at 50 or 60 Hz. The subwoofer allows any combination of voltage to GND (neutral-line-ground or line-line-ground).

If the voltage drops below 90 V (brownout), the MM-10AC uses stored power to continue operating temporarily; the subwoofer will shut down if the voltage does not rise above the low boundary before the stored power is used.

If the voltage rises above 264 V, the power supply could become damaged.

The current draw for the MM-10AC is dynamic and fluctuates as operating levels change. Since 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.

You can use the following table as a guide for selecting cable gauges and circuit breaker ratings for the system’s operating voltage.

The minimum electrical service amperage required by an MM-10AC subwoofer system is the sum of the Maximum Long-Term Continuous Current for each unit. An additional 30 percent above the minimum amperage is recommended to prevent peak voltage drops at the service entry.

Pay close attention to these important electrical and safety issues.

The MM-10AC includes an XLR female Audio In connector and XLR male Audio Loop Out connector.

MM-10AC Audio In and Audio Loop Out Connectors

Audio In Connector

The XLR female Audio In connector accepts balanced audio signals with an input impedance of 10 kOhm. The connector uses the following wiring:

• Pin 1 — 220 kOhm to chassis and earth ground (ESD clamped)

• Pin 2 — Signal (+)

• Pin 3 — Signal (–)

• Case — Earth (AC) ground and chassis

Pins 2 and 3 carry the input as a differential signal. Pin 1 is connected to earth through a 220 kOhm, 1000 pF, 15 V clamped network. This circuitry provides virtual ground lift for audio frequencies while allowing unwanted signals to bleed to ground. Make sure to use standard, balanced XLR audio cables with all three pins connected on both ends.

Telescopic grounding is not recommended, and shorting an input connector pin to the case may cause a ground loop, resulting in hum.

Tip

If unwanted noise or hiss is produced by the subwoofer, disconnect its input cable. If the noise stops, there is most likely nothing wrong with the subwoofer. To locate the source of the noise, check the audio cable, source audio, and AC power.

Audio Loop Out Connector

The XLR male Audio Loop Out connector allows multiple MM-10AC subwoofers to be looped from a single audio source. For applications that require multiple MM-10ACs, connect the Audio Loop Out of the first unit to the Audio In of the second, and so forth.

Note

The order in which subwoofers are connected when looping audio signals is unimportant. The Audio Loop Out connector is wired in parallel to the Audio In connector and transmits the unbuffered source signal even when the MM-10AC is powered off.

To avoid distortion when looping multiple MM-10ACs, make sure the source device can drive the total load impedance of the looped subwoofers. In addition, the source device must be capable of delivering approximately 20 dBV (10 V rms into 600 ohms) to yield the maximum peak SPL over the entire operating bandwidth of the subwoofers. Most professional audio equipment can transmit these source levels.

To calculate the load impedance for the looped subwoofers, divide 10 kOhms (the input impedance for a single MM-10AC) by the number of looped subwoofers. For example, the load impedance for 10 MM-10AC subwoofers is 1000 ohms (10 kOhms / 10). To drive this number of looped subwoofers, the source device should have an output impedance of 100 ohms or less. This same rule applies when looping MM-10AC subwoofers with other self-powered Meyer Sound loudspeakers.

Note

Most source devices are capable of driving loads no smaller than 10 times their output impedance.

Caution

Make sure that all cabling for looped subwoofers is wired correctly (Pin 1 to Pin 1, Pin 2 to Pin 2, and so forth) to prevent the polarity from being reversed. If one or more subwoofers in a system have reversed polarity, frequency response and coverage will be significantly degraded.

The Input Polarity switch swaps the polarity of the audio source signal, which is sometimes necessary to acoustically align the subwoofer with other loudspeakers in the system. When the switch is in the up (+), non-inverting position, pin 2 is hot relative to pin 3, resulting in a positive pressure wave when a positive signal is applied to pin 2. When the switch is in the down (–), inverting position, pin 3 is hot relative to pin 2, resulting in a positive pressure wave when a positive signal is applied to pin 3.

MM-10AC Input Polarity Switch

The MM-10AC has a three-color Limit LED on its rear panel that changes color to indicate the subwoofer’s status.

MM-10AC Limit LED

Powering On (Green)

When powering up the MM-10AC subwoofer, the following startup events occur and are indicated by the Limit LED:

1. The LED flashes green and then yellow during power-up.

2. The LED turns solid green indicating the subwoofer is ready to reproduce audio.

Caution

• If the Limit LED turns red and stays solid red after powering up and the audio is muted, the subwoofer has encountered a failure and may need to be serviced. Contact Meyer Sound Technical Support.

• If the Limit LED turns solid red and the MM-10AC continues to output audio, though at reduced levels, the subwoofer’s voltage may have dropped below 25 V DC. When these conditions are encountered, operation of the subwoofer should cease and its power supply and cabling should be verified.

Limiting (Yellow)

Limiting activity is indicated when the Limit LED turns yellow. When engaged, the limiter protects the subwoofer’s driver and prevents signal peaks from causing excessive distortion in the subwoofer’s amplifier, thereby preserving headroom and maintaining smooth frequency responses at high levels. When the level returns to normal, below the limiter’s threshold, the LED turns green and limiting ceases.

The MM-10AC performs within its acoustical specifications at normal temperatures when the Limit LED is green, or if the LED turns yellow for two seconds or less and then returns to green for at least one second. If the LED remains yellow for longer than three seconds, the subwoofer enters hard limiting where:

• Increases to the input level have no effect.

• Distortion increases due to clipping and nonlinear driver operation.

• The drivers are subjected to excessive heat and excursion, which will compromise their life span and may eventually lead to damage over time.

Caution

The Limit LED turns yellow when the subwoofer’s signal rises 2 dB above the limiting threshold, and indicates a safe, optimum level has been exceeded. If the MM-10AC subwoofers in a system begin to limit before reaching the desired SPL, consider adding more subwoofers to the system to achieve the desired SPL without exposing the subwoofers to excessive levels and possible overheating.

MM-10AC Temperature and Limiting

The Limit LED turns solid yellow when its heat sink temperature reaches 65° C (145° F), indicating the unit is reaching its maximum heat dissipation and a reduction in SPL is recommended. While the MM-10AC will continue to operate while the LED is yellow, the limiter threshold is lowered to a safe level (causing the output level to be lowered by 6 dB) to prevent the subwoofer from overheating. When the temperature of the heat sink cools to 50°C (122°F), the LED changes from yellow to green and the limiter threshold returns to normal.

Clipping (Red)

The Limit LED flashes red when its input signal causes the amplifier to overload. If the LED flashes red continuously, the subwoofer is severely overloaded and a reduction in the input level is recommended.

Caution

If the Limit LED turns solid red and the subwoofer continues to output audio, though at reduced levels, the subwoofer’s voltage may have dropped below 90 V AC. When these conditions are encountered, operation of the subwoofer should cease and its power supply and cabling should be verified.

The MM-10ACX subwoofer combines advanced loudspeaker technology with equally advanced power capabilities. Understanding voltage and current requirements, as well as electrical safety issues, is critical to the safe operation of the MM-10ACX. The MM-10ACX rear user panel includes the following PowerCON AC connectors:

MM-10ACX AC Input (Left) and AC Loop Output (Right) Connectors

AC Input Connector (Blue)

The blue AC Input connector supplies power to the MM-10ACX. The input is rated at 20 amps and uses a PowerCON AC mains locking connector that prevents accidental disconnections. A 10-foot AC power cable, rated at 15 amps, is included with each MM-10ACX. 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 region in which you will operate the unit

The AC Input connector also supplies power to any additional subwoofers connected to the MM-10ACX’s gray AC Loop Output connector, as well as any loudspeakers connected to the Satellite Out connectors. Each MM-10ACX requires approximately 3 A rms maximum at 115 V AC and 1.5 A rms maximum at 230 V AC.

Caution

When using the included AC power cable, do not loop more than five additional MM-10ACXs from the AC Loop Output connector at 115 V (six total for the circuit), and not more than 10 at 230 V (11 total for the circuit).

AC Loop Output Connector (Gray)

The gray AC Loop Output connector allows multiple

The gray AC Loop Output connector allows multiple MM-10ACX subwoofers to be looped and powered from a single power source. Connect the AC Loop Output of the first MM-10ACX to the AC Input of the second MM-10ACX, and so forth. The AC Loop Output uses a PowerCON AC mains locking connector that prevents accidental disconnections.

The maximum number of subwoofers 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 subwoofers and any connected satellite loudspeakers, the circuit breaker rating, and the rating of the AC power cable connected to the MM-10ACX.

Table 6. Number of MM-10ACXs that Can Be Looped (with Two MM-4XP Satellite Loudspeakers Attached to Each MM-10ACX)

Circuit Breaker/ Connector Rating	115 V AC	230 V AC	100 V AC
15 amps	5 looped (6 total)	10 looped (11 total)	4 looped (5 total)

Note

The current draw for the MM-10ACX is dynamic and fluctuates as operating levels change. The numbers in Table 5 assume that operating levels are normal and not such that the subwoofers and satellite loudspeakers are constantly limiting.

Each MM-10ACX ships with one AC looping connector for making AC looping cables. Assembled AC looping cables are available from Meyer Sound.

Caution

Do not exceed the current capability of the 20-amp Input connector for the MM-10ACX. When looping MM-10ACXs, consider the total current draw for all subwoofers and satellite loudspeakers on the circuit.

The MM-10ACX requires a grounded outlet. To operate safely and effectively, it is extremely important that the entire system be properly grounded.

AC Cable Wiring Scheme

When wiring international or special-purpose power connectors:

The MM-10ACX operates safely and continuously when the AC voltage stays within 100–240 V AC at 50 or 60 Hz. The subwoofer allows any combination of voltage to GND (neutral-line-ground or line-line-ground).

If the voltage drops below 90 V (brownout), the MM-10ACX uses stored power to continue operating temporarily; the subwoofer will shut down if the voltage does not rise above the low boundary before the stored power is used.

If the voltage rises above 264 V, the power supply could become damaged.

The current draw for the MM-10ACX is dynamic and fluctuates as operating levels change. Since 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.

You can use the following table as a guide for selecting cable gauges and circuit breaker ratings for the system’s operating voltage.

The minimum electrical service amperage required by an MM-10ACX subwoofer system is the sum of the Maximum Long-Term Continuous Current for each unit. An additional 30 percent above the minimum amperage is recommended to prevent peak voltage drops at the service entry

Pay close attention to these important electrical and safety issues.

The MM-10ACX includes an XLR female Audio In connector and XLR male Audio Loop Out connector.

MM-10ACX Audio In Connectors: Satellite 1, Satellite 2, and Subwoofer

The XLR female Audio In connectors accept balanced audio signals with an input impedance of 10 kOhm. The connectors use the following wiring:

Pins 2 and 3 carry the input as a differential signal. Pin 1 is connected to earth through a 220 kOhm, 1000 pF, 15 V clamped network. This circuitry provides virtual ground lift for audio frequencies while allowing unwanted signals to bleed to ground. Make sure to use standard, balanced XLR audio cables with all three pins connected on both ends. Telescopic grounding is not recommended, and shorting an input connector pin to the case may cause a ground loop, resulting in hum.

The Satellite Out connectors deliver DC power (48 V DC) and balanced audio to up to two MM-4XPs. The source audio for the satellite loudspeakers is received from the MM-10ACX’s Audio 1 In and Audio 2 In connectors. The DC power for the satellite loudspeakers is generated by the MM-10ACX’s onboard DC power capabilities.

The Satellite Outs can be equipped with either Phoenix 5-pin male connectors or EN3 5-pin female connectors.

Phoenix Outputs

The MM-10ACX Satellite Outs are available as Phoenix 5-pin male connectors with three pins for balanced audio (positive, negative, and shield) and two pins for DC Power (positive and negative). These pins are clearly labeled on the MM-10ACX rear panel. A single composite cable (such as Belden 1502) wired for both DC power and balanced audio can be used to connect to each satellite loudspeaker.

MM-10ACX Satellite Outs, Phoenix

When equipped with Phoenix Satellite Outs, the MM-10ACX comes with Phoenix 5-pin female cable connectors for assembling loudspeaker cables. For information on cable requirements for a satellite loudspeaker, refer to its operating instructions.

EN3 Outputs

The MM-10ACX Satellite Outs are available as EN3 5-pin female connectors with three pins for balanced audio (positive, negative, and shield) and two pins for DC Power (positive and negative). These pins are clearly labeled on the MM-10ACX rear panel. A single composite cable (such as Belden 1502) wired for both DC power and balanced audio can be used to connect to each satellite loudspeaker.

MM-10ACX Satellite Outs, EN3

When equipped with EN3 Satellite Outs, the MM-10ACX comes with EN3 5-pin male cable connectors for assembling loudspeaker cables. For information on cable requirements for a satellite loudspeaker, refer to its operating instructions.

Note

For information on cables and cable accessories available from Meyer Sound, see MM-10 Accessories. For information on cable assembly, see Assembling Loudspeaker Cables

The Input Select switch determines the audio source signal for the subwoofer. When the switch is in the down position (SUB CH), the source signal is received from the Subwoofer Audio In connector. When the switch is in the up position (SUM CH 1 + 2), the source signal is received from the Satellite 1 and Satellite 2 Audio In connectors and is summed.

MM-10ACX Input Select Switch

Input Select Switch and Summing

When the Input Select switch is in the up position (SUM CH 1 + 2), the source signal that is routed to the subwoofer from the Satellite Audio Ins is attenuated.

• If audio signals are present at both Satellite Audio Ins, the signal is summed and attenuated by 6 dB, resulting in a net gain of 0 dB.

• If only a single audio signal is present at one of the Satellite Audio Ins, the signal is also attenuated by 6 dB. But this time the result is a net gain of -6 dB.

The Gain knob adjust the subwoofer signal from completely attenuated to +10 dB and can be used to the balanced the subwoofer output with that of the satellite loudspeakers.

The Gain knob is always active, regardless of the Input Select switch setting.

MM-10ACX Gain Knob

The Input Polarity switch swaps the polarity of the audio source signal, which is sometimes necessary to acoustically align the subwoofer with other loudspeakers in the system. When the switch is in the up (+) position, pin 2 is hot relative to pin 3, resulting in a positive pressure wave when a positive signal is applied to pin 2. When the switch is in the down (–) position, pin 3 is hot relative to pin 2, resulting in a positive pressure wave when a positive signal is applied to pin 3.

MM-10ACX Input Polarity Switch

The MM-10ACX has a three-color Limit LED on its rear panel that changes color to indicate the subwoofer’s status.

MM-10ACX Limit LED

USM-1P — Extended Range Narrow Coverage Stage Monitor

When powering up the MM-10XP subwoofer, the following startup events occur and are indicated by the Limit LED:

1. The LED flashes green and then yellow during power-up.

2. The LED turns solid green indicating the subwoofer is ready to reproduce audio.

Caution

• If the Limit LED turns red and stays solid red after powering up and the audio is muted, the subwoofer has encountered a failure and may need to be serviced. Contact Meyer Sound Technical Support.

• If the Limit LED turns solid red and the MM-10ACX continues to output audio, though at reduced levels, the subwoofer’s voltage may have dropped below 90 V AC. When these conditions are encountered, operation of the subwoofer should cease and its power supply and cabling should be verified.

Limiting (Yellow)

Limiting activity is indicated when the Limit LED turns yellow. When engaged, the limiter protects the subwoofer’s driver and prevents signal peaks from causing excessive distortion in the subwoofer’s amplifier, thereby preserving headroom and maintaining smooth frequency responses at high levels. When the level returns to normal, below the limiter’s threshold, the LED turns green and limiting ceases.

The MM-10ACX performs within its acoustical specifications at normal temperatures when the Limit LED is green, or if the LED turns yellow for two seconds or less and then returns to green for at least one second. If the LED remains yellow for longer than three seconds, the subwoofer enters hard limiting where:

• Increases to the input level have no effect.

• Distortion increases due to clipping and nonlinear driver operation.

• The drivers are subjected to excessive heat and excursion, which will compromise their life span and may eventually lead to damage over time.

Caution

The Limit LED turns yellow when the subwoofer’s signal rises 2 dB above the limiting threshold, and indicates a safe, optimum level has been exceeded. If the MM-10ACX subwoofers in a system begin to limit before reaching the desired SPL, consider adding more subwoofers to the system to achieve the desired SPL without exposing the subwoofers to excessive levels and possible overheating.

MM-10ACX Temperature and Limiting

The Limit LED turns solid yellow when its heat sink temperature reaches 65° C (145° F), indicating the unit is reaching its maximum heat dissipation and a reduction in SPL is recommended. While the MM-10ACX will continue to operate while the LED is yellow, the limiter threshold is lowered to a safe level (causing the output level to be lowered by 6 dB) to prevent the subwoofer from overheating. When the temperature of the heat sink cools to 50°C (122°F), the LED changes from yellow to green and the limiter threshold returns to normal.

Clipping (Red)

The Limit LED flashes red when its input signal causes the amplifier to overload. If the LED flashes red continuously, the subwoofer is severely overloaded and a reduction in the input level is recommended.

Caution

If the Limit LED turns solid red and the subwoofer continues to output audio, though at reduced levels, the subwoofer’s voltage may have dropped below 90 V AC. When these conditions are encountered, operation of the subwoofer should cease and its power supply and cabling should be verified.

When installing Meyer Sound loudspeakers, the following precautions should always be observed:

The MUB-MM10 U-bracket mounts the MM-10 on ceilings and walls at adjustable angles. The U-bracket’s adjustment slot lets you adjust how close the MM-10 is located to the mounting surface and at what angle the subwoofer will be positioned. The MUB-MM10 is available in two kits with either 3/8-inch-16 hardware (PN 40.199.060.01) or M10 hardware (PN 40.199.060.02)

MUB-MM10 U-Bracket

The MM-10 can be mounted on a ceiling or underbalcony area with the MUB-MM10 U-bracket.

MUB-MM10 U-Bracket

The MUB-MM10 U-bracket lets you mount the MM-10 either vertically or horizontally on a wall.

MUB-MM10, Horizontal Wall Mount

The following Phoenix and EN3 cable connectors and adapters are available from Meyer Sound.

The following Phoenix and EN3 cables are available from Meyer Sound and can be used to connect MM-10XPs to MPS-488HPs and MPS-482HPs, as well as to connect MM-10ACXs to satellite loudspeakers.

When connecting loudspeakers equipped with Phoenix connectors to the MPS-488HPp power supply, you need a Phoenix 5-pin female to Phoenix 5-pin female cable. The following procedure documents how to assemble this cable.

Assembled Phoenix-to-Phoenix Cable

When connecting loudspeakers equipped with EN3 connectors to power supplies equipped with Phoenix connectors, a Phoenix 5-pin female to EN3 5-pin female cable is required. The following procedure documents how to assemble this cable. If starting with an EN3-to-pigtail cable, skip steps 4–7 in this procedure.

Assembled Phoenix-to-EN3 Cable

To connect the MM-4XP loudspeaker directly to the MPS-488E power supply, you need an EN3 5-pin female to EN3 5-pin male cable. The following procedure documents how to assemble this cable. If you are starting with an EN3-to-pigtail cable (included with the MM-4XP), you can disregard step 5 in the procedure.

Assembled EN3-to-EN3 Cable