Усилители мощности моно — Pro-Ject Amp Box S3 CI

The Amp Box S3 CI is a micro two-channel amp by Pro-Ject Audio Systems, built on the Amp Box S3 platform and adapted for custom installation work. It adds automatic switching, RS232 control and adjustable tone controls to the small S3 chassis, uses professional-grade connectors, and is housed in a full aluminium case that protects the circuit against interference and vibration. Production is in Europe, and buyers pick a black or a silver version of the aluminium enclosure.

Key specs that matter

Rated output is 2 x 20 W into 8 ohm and 34 W into 4 ohm, with peak power given as 2 x 50 W into 4 ohm. Gain at maximum level is 37 dB and input impedance is 10 kohm. Signal-to-noise ratio is 88 dBV, or 95 dBV A-weighted, and channel separation is 68 dB at 10 kHz. Total harmonic distortion stays under 0.03 percent at 5 W. The bass control spans plus or minus 11 dB and the treble control plus or minus 5 dB. The case measures 103 x 36 x 112 mm and weighs 380 g on its own. Power is supplied by an external 20 V DC adapter rated at 3 A.

Engineering and use context

Three switching functions suit installations where the amplifier is hidden away. Signal Sensing wakes the amplifier once music arrives at the input and shuts it down again when it stops. Auto Power starts the unit as soon as its supply is connected, so it can follow a switched mains circuit. A 12 V DC trigger input and output allow it to switch together with other equipment, and the trigger can be passed on down a chain. For integration with smart home and automation systems the amplifier accepts commands over an RS232 control protocol. Level, bass and treble can be set on the unit, so the output can be matched to the speakers and the source before the installation is closed up. The circuit board follows a low-distortion layout, and the speaker and power sockets are professional types.

Pairing

A stereo RCA input is joined by an RCA loop output, so the same source signal can be passed to a second Amp Box S3 CI or another amplifier to cover more zones or more speakers. The output ratings cover in-wall, in-ceiling and small passive speakers of either impedance, and the trigger and RS232 links let a streamer, preamplifier or control system switch the unit.

Alternatives

For a true single-channel design, Pro-Ject has made the Amp Box RS Mono monoblock.