Усилители мощности моно — Pro-Ject Amp Box DS2 Mono

The Amp Box DS2 Mono is a monoblock in the small Box Design format of Pro-Ject Audio Systems, the Austrian electronics and turntable maker. A stereo setup therefore calls for a matched pair. Pro-Ject listed it at EUR 499 including VAT in black or silver aluminium, and at EUR 559 with matt real wood side panels in eucalyptus, rosewood or walnut.

Key specs that matter

Rated output is 120 W into 8 ohm and 205 W into 4 ohm at under 1% THD, and distortion stays below 0.1% at 90 W. Bandwidth reaches from 10 Hz to 50 kHz at the minus 3 dB points. Gain is 31 dB, and 550 mV at the input drives the module to 100 W into 4 ohm. The noise floor is given as better than 90 dB. The aluminium version is 206 mm wide, 68 mm high and 194 mm deep at 1,450 g, while side panels widen the case to 240 mm and raise the weight to 1,900 g. Power comes from an external 48 V, 2.5 A DC brick that accepts 100 to 240 V mains, and standby consumption stays under 1 W.

Engineering and use context

At the core sits a Class D module working with pulse width modulation, chosen by Pro-Ject for high efficiency and a frequency response that does not vary with the connected load. The company also cites low output impedance and distortion that stays nearly constant across the audio band. A four-layer circuit board shortens signal paths compared with the earlier Amp Box DS Mono. The signal enters through one RCA socket, and a second RCA socket loops it out, so a subwoofer or another amplifier can be fed from the same source cable. Isolated speaker outputs accept 4 mm banana plugs, spades or bare wire. A 12 V trigger input and a trigger loop output on 2.5 mm jacks let a preamplifier wake the amplifiers, and as long as the 12 V signal stays on, pressing the front switch will not send the amplifier to standby. Pro-Ject forbids stacking the units, so each monoblock needs free air around it. An optional Power Box DS Amp linear supply was offered as an upgrade path.

Pairing

Pro-Ject allows only one loudspeaker per amplifier with an impedance of at least 4 ohm, which rules out parallel speaker pairs. Any preamplifier or AV processor with RCA outputs can drive it, and the same trigger lead can be daisy-chained from the first monoblock to the second. Because each channel has a separate amplifier and a separate adaptor, the left and right speakers do not share a power supply.

Alternatives

The Pro-Ject Amp Box RS Mono is the higher mono model, adding XLR inputs, 2 ohm drive and an ECC88 valve buffer at an MSRP of EUR 799.