Class AB output stages with identical N-channel MOSFETs, local control loops on AAB models, input matching via DIP switch

The MOSCONI PRO EVO series comprises nine amplifiers, from the PRO 1|10 EVO monoblock with 900 W into 4 Ω to the eight-channel PRO 8|30 DSP EVO with a 12-channel DSP. Technically, the models differ mainly in their output stage: Class D, Class AB with two identical N-channel MOSFETs, or AAB with a dedicated control loop for each output MOSFET.

The quasi-complementary Class AB output stage of the PRO 2|10 EVO, PRO 4|10 EVO, PRO 5|30 EVO and PRO 8|30 DSP EVO uses two identical N-channel MOSFETs instead of an N/P pair. N-channel devices have a lower on-resistance R_DS(on) and lower gate capacitance than comparable P-channel devices. With identical parts, switching times and parasitic capacitances are the same for both half-waves. A bootstrap drive circuit supplies the gate voltage above the supply rail that the high-side MOSFET requires.

On the PRO 2|10 AAB EVO, PRO 4|10 AAB EVO and PRO 4|30 AAB EVO, AAB control adds a local control loop for each output MOSFET to the Class AB circuit. The dynamically tracked bias current keeps the operating point and bias stable over temperature, improves behavior with reactive speaker loads and provides progressive clipping. Class A output is 2 x 30 W RMS into 4 Ω (PRO 2|10 AAB EVO), 4 x 20 W (PRO 4|10 AAB EVO) and 4 x 30 W (PRO 4|30 AAB EVO). Total output into 4 Ω is, in the same order, 2 x 240 W, 4 x 80 W and 4 x 150 W. The PRO 2|10 AAB EVO achieves THD below 0.05 % into 4 Ω and 2 Ω (1 kHz, 90 % of rated power) and a signal-to-noise ratio of 101 dB(A) referenced to rated power.

The Class D amplifiers PRO 1|10 EVO and PRO 2|30 EVO cover the low-frequency range. The PRO 1|10 EVO delivers 900 W into 4 Ω, 1600 W into 2 Ω and, with music signals only, 3000 W into 1 Ω. Its signal-to-noise ratio is 108 dB(A) referenced to 600 W. The output stage of the PRO 2|30 EVO switches at 500 kHz. It delivers 2 x 550 W into 4 Ω, 2 x 825 W into 2 Ω or 1650 W bridged into 4 Ω, and reaches an efficiency of 81 % in stereo operation into 4 Ω.

The PRO 5|30 EVO combines four Class AB channels with 2 x 95 W and 2 x 185 W and a Class D subwoofer channel with 660 W, each into 4 Ω. Bandwidth of the Class AB channels extends from below 5 Hz to 135 kHz and 145 kHz respectively (−3 dB); the subwoofer channel extends to 1.75 kHz.

The PRO 8|30 DSP EVO combines amplifier channels with 4 x 90 W and 4 x 170 W into 4 Ω with a 32-bit 12-channel DSP. Signals enter through high-level inputs with autosense, RCA, the optical input or the EXT_CARD connector. Four DSP outputs with 2 V RMS drive additional amplifiers. Tuning is done on a PC via the USB port; four presets can be stored.

An unregulated push-pull switching power supply running at 50 kHz powers all models at an operating voltage of 10 to 16 V. On models without DSP, input sensitivity is set reproducibly from 1 to 8.75 V in 32 steps via DIP switch, independently for each channel on the multi-channel models. During a voltage dip to 7.5 V the amplifiers keep operating for up to 300 ms, which makes them suitable for start-stop vehicles. The damping factor into 4 Ω is above 100 to above 105, depending on the model. Power and speaker terminals are gold-plated.

Model	Channels	Technology	RMS power into 4 Ω	Class A share
PRO 1\|10 EVO	1	Class D	1 x 900 W	–
PRO 2\|10 EVO	2	Class AB	2 x 240 W	–
PRO 2\|10 AAB EVO	2	Class AB, AAB	2 x 240 W	2 x 30 W
PRO 2\|30 EVO	2	Class D	2 x 550 W	–
PRO 4\|10 EVO	4	Class AB	4 x 120 W	–
PRO 4\|10 AAB EVO	4	Class AB, AAB	4 x 80 W	4 x 20 W
PRO 4\|30 AAB EVO	4	Class AB, AAB	4 x 150 W	4 x 30 W
PRO 5\|30 EVO	5	Class AB + Class D	2 x 95 W + 2 x 185 W + 1 x 660 W	–
PRO 8\|30 DSP EVO	8	Class AB, 12-channel DSP	4 x 90 W + 4 x 170 W	–