Усилители мощности стерео — Emotiva BasX A4

The BasX A4 from Emotiva is a multichannel amplifier with four channels from the second generation BasX range introduced in 2021, where it launched at USD 499 next to the A2, A3, A5 and A7. Emotiva intends it for Dolby Atmos and DTS:X height channels, for surround speakers when a more powerful amplifier already drives the front stage, or for pairs of zone speakers. Emotiva has since marked it as discontinued, and its last listed price was USD 619 with a sale figure of USD 479.

Key specs that matter

With all four channels driven the A4 gives 100 W RMS per channel into 8 ohms from 20 Hz to 20 kHz at under 0.1 percent THD, and 130 W RMS into 4 ohms at 1 kHz at under 1 percent. With only two channels working the 4 ohm figure rises to 175 W. The power bandwidth is 20 Hz to 20 kHz within 0.02 dB, and the broad band response reaches from 10 Hz to 80 kHz within plus 0 and minus 1.8 dB. The A4 keeps THD plus noise under 0.02 percent A-weighted and its S/N rating above 115 dB, and the damping factor at 8 ohms exceeds 500. Input sensitivity is 1.2 V for rated power, gain is 29 dB and input impedance is 27 kOhms. Minimum load is 4 ohms per channel.

Engineering and use context

A Class A/B output stage runs from a heavy-duty linear power supply with an oversized toroidal transformer. The chassis is heavy steel with a milled aluminium faceplate, and it measures about 432 mm wide, 102 mm high and 394 mm deep, weighing about 11.8 kg unboxed. Each channel has its own unbalanced RCA input and audiophile grade five-way binding posts. Protection covers overheating, short circuits and ground faults. A trigger input accepts 5 to 12 V, and the trigger output supplies 12 VDC at up to 120 mA. The mains input selects 115 or 230 VAC at 50 or 60 Hz automatically, and Emotiva gives three years of warranty cover.

Pairing

In an Atmos system the A4 can take the four height channels from the preamplifier outputs of a surround processor, while another amplifier covers the front speakers. The trigger link lets it switch on together with that processor. A second option is to run two pairs of speakers in different rooms, each pair from its own two channels. The boxed unit measures about 546 x 203 x 533 mm and weighs about 14.5 kg.

Alternatives

The Emotiva BasX A2 is the two channel power amplifier from the same BasX generation, rated at 160 W per channel.