2-in / 4-out DSP processor

The miniDSP Flex is the third generation of miniDSP's 2x4 line: a compact DSP processor that handles equalisation, active filtering and room correction for a stereo or multi-way system. It sits between your sources and your amplifiers to align speakers and subwoofer, correct room issues and manage volume from a single box. Three connectivity versions are available: unbalanced RCA, balanced TRS jack, and a digital-output version.

Three connectivity versions

The RCA version offers 2 unbalanced inputs and 4 unbalanced outputs (100 kΩ input, 200 Ω output, 2 V RMS maximum), suited to a conventional home hi-fi setup. The balanced version uses 6.35 mm TRS jacks wired like XLRs, with 4 V RMS maximum output and a 200 kΩ input impedance, for studio active monitors and long cable runs. The digital version keeps 2 analogue RCA inputs and delivers 4 channels over duplicated S/PDIF and Toslink outputs, so you can stay in the digital domain right up to your converters or amplifiers.

Digital inputs and USB interface

All versions share the same digital section: one S/PDIF input on RCA, one Toslink optical input, one stereo USB audio input and Bluetooth reception supporting LDAC, aptX HD, aptX, AAC and SBC, with sample rates from 20 to 216 kHz. The multi-core XMOS USB audio processor runs bidirectional UAC2: ASIO driver supplied for Windows, plug and play on Mac and Linux. The 4 processed channels are also sent back to the computer over USB, which lets you digitise a vinyl record after processing, for example.

Audio processing and Dirac Live

The Analog Devices SHARC ADSP21489 32-bit floating-point DSP running at 400 MHz delivers 32-bit / 96 kHz processing: parametric EQ, IIR and FIR filters, crossover filters for an active crossover, advanced biquad programming and independent delay on each output. Four presets can be stored. The optional upgrade to Dirac Live 3.x adds full-bandwidth room correction from 20 Hz to 20 kHz; note that in this mode the DSP engine runs at 48 kHz, whereas the SHD models keep 96 kHz with Dirac.

Day-to-day use

The front panel combines an OLED display (white or black), a volume encoder and an infrared receiver; the IR v2 remote is included. The Flex is also compatible with the KD-1 rotary remote over Bluetooth LE for volume, mute and source or preset selection. All configuration is done from the miniDSP Device Console software. It works equally well as a compact digital stereo preamplifier or as a processor for one or several subwoofers, 2-way active speakers, a home theatre or a recording studio.

Technical specifications

• Analog Devices SHARC ADSP21489 DSP, 32-bit floating point, 400 MHz
• Processing resolution: 32-bit / 96 kHz (32-bit / 48 kHz with Dirac Live licence)
• Processing: parametric EQ, IIR and FIR filters, crossover filters, advanced biquad programming, delay per output channel
• Up to 4 DSP presets
• Optional Dirac Live 3.x upgrade, room correction 20 Hz - 20 kHz
• Digital inputs (all versions): 1 x S/PDIF RCA, 1 x Toslink optical, 1 x stereo USB audio, 1 x Bluetooth (LDAC, aptX HD, aptX, AAC, SBC), 20 to 216 kHz
• USB interface: multi-core XMOS processor, bidirectional UAC2, ASIO driver on Windows, plug & play on Mac and Linux
• USB audio output: 4 post-DSP channels returned to the computer
• RCA version: 2 unbalanced inputs / 4 unbalanced outputs, 100 kΩ input, 200 Ω output, 2 V RMS max, SNR 120 dB(A), THD+N -110 dB (0.0003 %), crosstalk -120 dB, response 20 Hz - 20 kHz ±0.1 dB
• Balanced jack version: 2 inputs / 4 outputs on 6.35 mm TRS (XLR-style wiring), 200 kΩ input, 200 Ω output, 4 V RMS max, SNR 121 dB(A), THD+N -112 dB (0.00025 %), crosstalk -128 dB
• Digital version: 2 analogue RCA inputs, 4 channels on duplicated S/PDIF and Toslink outputs, response ±0.01 dB, digital-to-digital SNR 137 dB(A), THD+N -130 dB (0.00003 %), crosstalk -165 dB
• Front panel: white or black OLED display, volume encoder, infrared control
• IR v2 remote included, compatible with the KD-1 rotary remote over Bluetooth LE
• Configuration via the miniDSP Device Console software
• Dimensions: 150 x 180 x 41 mm
• External 12 V / 1.6 A power supply included (US, UK, EU, AU plugs)
• Power consumption: 9 W idle and 2.5 W standby (10.3 W / 3.1 W on the TRS version; 7.5 W / 2.5 W on the digital version)
• Supplied with: processor, IR v2 remote, universal 12 V power supply, USB cable