Power amplifier with 2 and 4 channels Audac SMA and SMQ – a test series published in soundlightup.de

The SM Series Class D amplifiers from the Belgian brand Audac, introduced at the beginning of the year and at the stand of AVDis* on the JTSE (25-26 November 2014), offers six models with two or four channels, with an integrated DSP WaveDyamics TM processor. SMA350 (2 x 350 W RMS), SMQ 350 (4 x 350 W), SMQ750 (4 x 750 W), etc. The interface reminds me of a 2.5″ LCD screen, with rotary encoders and retractable buttons either locally or at the RS232 port, which is reachable on the back.

The acoustic setting is straightforward via the control panel with a library of presets, which can be done via USB key or manually, if you have administrator privileges. The filter algorithms can be selected from the Butterworth, Bessel and Linkwitz-Riley frequency responses with different high-pass, low-pass and band-pass filters.

The DSP also provides a 7-band EQ with variable frequency and Q-factor on each channel, as well as the delays and the use of a physiological control, “Dynamic Bass Boost”, depending on the level. It also controls the protection circuitry (DC, short circuit, overheating, overload) and a programmable limiter, which is available on each channel.

The signal inputs either come via XLR jack or via a terminal block and a control setting between -30 and +5 dB. The outputs are designed accordingly for “Speakon” connectors or a terminal block. These amplifiers are suitable for a fixed installation, as well as for mobile operation.

The outputs can be bridged in the models with two as well as with four channels. The latter can also accommodate two full-range speakers and a bridged subwoofer, for example. All settings are possible.

The switching power supply technology used does not convert any PFC (power factor improvement) and is confined to the mains with 230 V. These amplifiers in the 19″, 2U rack are therefore very lightweight; the most powerful model, the SMQ750 (4 x 750 W RMS at 4 Ohms) weighs just 11.5 kilograms. The models with two channels consume 25 W in stand-by regardless of the performance, and the models with four channels 35 W.

Some common features (SMA350 with 750 W and SMQ 350 with 750 W):
– Signal Noise Ratio: > 95 dB
– THD + Noise on the Audio Band: < 0.05 %
– Interference Suppression Ratio: > 70 dB (Input Impedance: 10 kΩ balanced)
– Diaphonie: > 70 dB

RMS max. performance (up to THD = 1%):
– SMA/SMQ 350: 2 x 350 W RMS @4 Ohm or 4 x 350 W RMS (bridged 700 W, 8 Ohm)
– SMA/SMQ 500: 2 x 500 W RMS @4 Ohm or 4 x 500 W RMS (bridged 1 kW, 8 Ohm)
– SMA/SMQ 750: 2 x 750 W RMS or 4 x 750 W RMS (bridged 1.5 kW, 8 Ohm)

The prices range between 630 euros net (for the SMA350) and 1277 euros net (SMQ750).


Source: soundlightup.de, November 2014:

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