Subwoofers — Monitor Audio Radius 380

The Radius 380 is the smaller of the two active subwoofers in Monitor Audio's third-generation Radius Series, launched in 2013. It combines a 200 mm C-CAM long-throw driver with a 200 mm Auxiliary Bass Radiator in a compact cabinet and was priced at USD 875 or GBP 678.50. Finishes include gloss black and satin white.

Key specs that matter

System format is an active subwoofer with ABR (Auxiliary Bass Radiator) loading in an 18 mm MDF cabinet. Low frequency limit is 30 Hz (-6 dB), and the upper frequency limit is variable from 40 to 120 Hz at 24 dB/octave. A Class D amplifier with a switch mode power supply (SMPSU) is rated at 140 W at below 1% THD+N. Connections are stereo RCA in, LFE in and a 12 V trigger input on a 3.5 mm mono mini-jack that accepts 5 - 12 V, and input impedance is above 20 kohms. Power consumption is below 0.5 W in standby, below 10 W at typical idle and 200 W maximum rated. Dimensions including amplifier and feet are 308 x 290 x 305 mm (H x W x D), and weight is 10.16 kg.

Engineering and use context

A three-position bass EQ switch selects Music, Movie or Impact. Monitor Audio specifies a relatively flat response down to 35 Hz in Movie mode, while Music mode sits 2 dB lower and extends to 30 Hz, and Impact mode is 3 dB higher and goes down to 40 Hz. Its phase switch has 0 and 180 degree positions.

With the power mode switch set to On the subwoofer stays permanently active. In Auto it switches on when the input signal exceeds 3.5 mV and returns to standby after about 15 minutes without signal, and an LED on top glows red in standby and green in operation. A 12 V trigger lead is supplied, and with the trigger connected the mode switch can be in any position.

The crossover dial works only with the stereo RCA inputs. On the LFE input the low-pass point is set by the AV amplifier or processor. Mains voltage is preset at the factory for the region, either 110 - 120 V or 220 - 240 V, and the IEC inlet carries an external fuse.

Pairing

The stereo RCA inputs connect to the pre-out of a stereo amplifier, and the LFE input connects to an AV receiver or processor. With Radius Series speakers Monitor Audio suggests a crossover setting of around 80 Hz.

Alternatives

The Radius 390 is the larger Radius 3G subwoofer, with a 250 mm long-throw driver, a 250 mm ABR, a 200 W amplifier and a weight of 13.76 kg.