d&b audiotechnik M2

Prepare a compatible d&b amplifier with the M2 setup and 2-Way Active mode. The M2's low- and high-frequency sections are separated in the amplifier, using two channels to drive one cabinet. Choosing a replacement by power and impedance alone does not ensure the processing the monitor requires. d&b warns that incorrect configuration can damage its components.

M2 manual 5.3 en recommends D80, D12 and 30D. It permits up to two M2 cabinets per channel pair on D80/D12 and one per pair on 30D. The table refers to a pair of channels, not each channel. On D80 the mode is assigned to A/B or C/D. On D12 it occupies A/B, with channel A's settings and input linked to B.

1. Before the event, record amplifier model and firmware, channel pair, input, M2 setup, 2-Way Active mode, cabinet count and connectors. Preserve the intended level, EQ, delay, CUT and CPL settings as well.
2. Check the spare through the same signal path and cabling at an agreed test level. Verify that both frequency sections work and that settings match before adding it to the system. If the M2 setup is missing, check amplifier mode and compatibility; do not choose another cabinet's preset.
3. To replace the unit, remove its input signal and switch off amplification before disconnecting speaker cables. Reconnect according to the verified patch and test gradually. If you intend to restore settings over the network, check that procedure during preparation.

Trace LF and HF separately, starting with mode, setup and cable. On an M2 with NLT4 F/M, LF uses 1+/1− and HF uses 2+/2−. A cable carrying only the first pair leaves the high-frequency section disconnected even though bass is still audible.

The table on this page retains the M2 pin assignments for NLT4, EP5 and NL8. The connector alone does not identify the circuit: trace the amplifier output and any rack panel or adapter too. In D12 2-Way Active mode, both sections reach OUT A and OUT B; on D80 they reach the outputs of the configured pair. The pair's input and settings are linked; they are not two independent mixes.

For LF SenseDrive with D12, the M2 manual text specifies EP5, five-conductor cabling and connection to OUT A. With two cabinets, link them together locally and then to OUT A. The tables also show a SenseDrive contact for NL8, but the cited text does not resolve that variant. Confirm it with d&b before treating that path as validated.

1. Preserve the initial state and check input, mute, 2-Way Active mode and M2 setup. If all signal is missing, start with the input path. If only HF is missing, do not try to recover it by raising high-frequency EQ or level.
2. With the amplifier off and the cable disconnected at both ends, check continuity and crossed conductors. Test cable, panel and adapters separately. Use the pinout for the actual connector; do not carry the 2+/2− assignment over to NL8.
3. Compare with a cable whose path has already been checked, then with another identified M2, keeping everything else unchanged. If the HF loss follows the cable, remove it for repair. If it follows the cabinet, set that cabinet aside for inspection. If it remains at the same output with a checked cable and cabinet, review amplification and configuration with the responsible technician. Do not connect the HF driver directly to a full-range output.

Check CPL to compensate for coupling between nearby cabinets. CUT addresses a different condition: it inserts a 110 Hz high-pass filter when the M2 is used with actively driven d&b subwoofers. Using it to reduce the buildup from two monitors also changes their low-frequency extension and can mask the cause.

According to the manual, CPL starts acting gradually around 1 kHz, with its greatest attenuation below 400 Hz. It allows attenuation from 0 to −9 dB; positive values from 0 to +5 dB boost bass around 65 Hz. The manufacturer relates CPL 0 dB to Floor, +3 dB to Free and −3 dB to Pair on the A1's M2 module. These are documented comparison points, not settings confirmed for every stage.

On A1 those names belong to the M2 module's LF Coupling control: FLOOR is for one cabinet on the floor, PAIR reduces bass and low mids in a pair, and FREE adds bass when there is no floor coupling. Do not look for an identically named control on D12/D80; use the functions of the actual amplifier.

1. Record whether both cabinets receive the same mix, their position, spacing and orientation, and the initial CPL and CUT settings. If the signals differ, account for that before attributing the balance to coupling.
2. Listen to each cabinet and then the pair from the performer's working positions, using the same signal and input level. Compare one CPL change at a time and note where it improves or worsens the balance. The Pair reference of −3 dB can be useful for a paired-monitor rehearsal, without making it a compulsory final setting.
3. If the problem is microphone feedback, also record microphone, position, mix and frequency. Cabinet tonal balance alone does not identify the cause. If a subwoofer is present, identify its model and processing before comparing CUT.