Meyer Sound Documentation

The UPQ-D Series loudspeakers are available with XLR 3-pin, as shown in the first figure below, or 5-pin connectors, as shown in the second figure below, for audio Input and audio Loop output. XLR 5-pin connectors accommodate both balanced audio and RMS signals.

XLR 3-Pin Audio Connectors, Input and Loop Output

XLR 5-Pin Audio Connectors, Input and Loop Output

The XLR 3-pin or 5-pin female Input connector accepts balanced audio signals with an input impedance of 10 kΩ. The connector uses the following wiring scheme:

Pins 2 and 3 carry the input as a differential signal. Pin 1 is connected to earth through a 1 kΩ, 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 balanced XLR audio cables with pins 1–3 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 XLR 3-pin or 5-pin male Loop output connector allows multiple loudspeakers to be looped from a single audio source. The Loop output connector uses the same wiring scheme as the Input connector (see Audio Input (XLR 3-Pin or 5-Pin Female)).For applications that require multiple UPQ-D Series loudspeakers, connect the Loop output of the first loudspeaker to the Input of the second loudspeaker and so forth.

Calculating Load Impedance for Looped Audio Signals

To avoid distortion when looping multiple loudspeakers, make sure the source device can drive the total load impedance of the looped loudspeakers. In addition, the source device must be capable of delivering approximately 20 dBV (10 V rms into 600 Ω) to yield the maximum SPL over the operating bandwidth of the loudspeakers.

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

Note

Most source devices are capable of driving loads no less than 10 times their output image6.pngimpedance.

Tip

Audio outputs from Meyer Sound’s Galileo GALAXY Network Platform have an output impedance of 50 ohms. Each output can drive up to 20 Meyer Sound (10 kΩ) loudspeakers without distortion.

Caution

Make sure that all cables for looped loudspeakers are 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 loudspeakers in a system have reversed polarity, frequency response and coverage will be significantly degraded.

The UPQ-D Series loudspeakers employ Meyer Sound’s advanced TruPower® limiting. Conventional limiters assume a constant driver impedance and set the limiting threshold by measuring voltage alone. This method is inaccurate, because driver impedances change as frequency content in the source material changes, and as thermal values for the loudspeaker’s voice coil and magnet vary. Consequently, conventional limiters often begin limiting prematurely, which reduces system headroom and dynamic range.

In contrast, TruPower limiting anticipates varying driver impedances by measuring both current and voltage to compute the actual power dissipation in the voice coil. This approach improves performance, both before and during limiting, by allowing the driver to produce the maximum SPL across its entire frequency range while also retaining signal peaks. TruPower limiting also eliminates power compression at high levels over lengthy periods, which helps regulate voice coil temperatures, thereby extending the life of the driver.

HF and LF Limit LEDs

The low- and high-frequency drivers for UPQ-D Series loudspeakers are powered by separate amplifier channels, each with their own limiter. Limiting activity is indicated with two Limit LEDs on the user panel. The top Limit LED, shown in the figure below, indicates limiting for the high-frequency channel and the bottom Limit LED indicates limiting for the low-frequency channel.

UPQ-D1/2/3 Limit LEDs

When engaged, the limiters not only protect the drivers but also prevent signal peaks from causing excessive distortion in the amplifier channels, thereby preserving headroom and maintaining smooth frequency response at high levels. When levels return to normal, below the limiter thresholds, limiting ceases.

A UPQ-D Series loudspeaker performs within its acoustical specifications at normal temperatures when the Limit LEDs are unlit, or when the LEDs are lit for 2 seconds or less and then turn off for at least 1 second. If the LEDs remain lit for longer than 3 seconds, the loudspeaker enters hard limiting where:

• Increases to the input level have no effect

• Distortion increases due to clipping

• Drivers are subjected to excessive heat and excursion, thereby compromising their lifespan

Caution

The Limit LEDs indicate when a safe, optimum level is exceeded. If a UPQ-D Series loudspeaker system begins to limit before reaching the desired SPL, consider adding more units to the system.

During normal operation, when a UPQ-D Series loudspeaker is powered on, the On/Status LED is solid green. If the loudspeaker encounters a hardware fault, or the unit begins to overheat, the LED flashes red. In some instances, the loudspeaker will continue to output audio while the LED flashes red, though with a reduction in the limiter threshold and acoustic output to protect the loudspeaker.

If a loudspeaker is overheating (for RMS-equipped loudspeakers, one can verify this situation in Compass RMS), a reduction in SPL may be necessary. If after a reduction in SPL and an appropriate cooling period the Active/Status LED continues to flash red (does not return to solid green), contact Meyer Sound Technical Support.

If the Active/Status LED flashes red and the loudspeaker does not output audio, contact Meyer Sound Technical Support immediately.

The UPQ-D Series loudspeaker is convection cooled. The amplifier’s heat sink provides natural convection cooling from the air flowing near its fins.

A UPQ-D Series loudspeaker system can be deployed with Meyer Sound self-powered low frequency control elements (see [→ _bookmark36]Table 3).These subwoofers achieve very low frequency responses and extend the system response appreciably, increasing the overall acoustic power of the system in the lowest frequencies.

The ideal ratio of UPQ-D Series loudspeakers to low frequency control element depends on the following variables: