HiFi Rose - RA180 Integrated Amplifier

Four independent GaN FET amplifier modules, a switchable MM/MC phono stage with selectable historic EQ curves, and analog meters — HiFi Rose’s flagship integrated.

The RA180 carries a lower model number than the RA280 but it is the more ambitious product, and it remains HiFi Rose’s flagship integrated amplifier. The defining choice is four independent gallium nitride Class-D amplifier modules rather than the usual two, arranged as a pair per channel and fed from an 800W switch-mode supply built around silicon carbide FETs with an in-house power factor correction stage.

That architecture is why the power figures need reading carefully. Each module makes 200W into 8 or 4 ohms. Run conventionally you have 200W per channel; bi-amp and all four modules work, 200W each; bridge them in BTL mode and you get 400W into a single pair of speakers. The 800W often quoted is the arithmetic sum of the four modules, not a figure any one speaker ever sees. Sixteen binding posts in two rows of eight make that flexibility physically available, with A/B speaker switching.

Gallium nitride is the reason Class D behaves here. A switching output stage is theoretically capable of perfect linearity at zero distortion, but only if the switching is fast and clean enough; silicon FETs need a dead-time margin between devices turning off and on that smears the waveform. GaN switches fast enough to shrink that dead time toward nothing, which is what lets the topology sound closer to an analog amplifier than earlier Class D did.

The phono stage is the other unusual element and the one vinyl collectors care about. MM and MC are both on board, switch-selected, and instead of a fixed RIAA curve the RA180 offers five turnover settings and six roll-off settings built from 0.1%-tolerance parts. That means pre-1955 Columbia, Decca FFRR and other historic equalisation curves can be dialled in correctly rather than approximated — a facility almost nothing else at any price provides inside an integrated amplifier.

Around all that sit a switchable 50Hz subsonic filter, switchable bass and treble at ±15dB, a switchable 600Hz–6kHz high-pass crossover for use with a subwoofer or horn, and a bypass power-amp mode. The presentation is deliberate: high-purity aluminium, sliders, toggle switches and dimmable illuminated meters.

Features

• Four independent GaN FET Class-D amplifier modules, two per channel
• 200W into 8Ω or 4Ω per module — 200W x 4 for bi-amping, or 400W x 2 bridged in BTL mode
• Sixteen binding posts in two rows of eight, with A/B speaker switching
• MM and MC phono stage, switch-selected
• Selectable phono EQ curves — five turnover and six roll-off settings from 0.1%-tolerance parts, for historic non-RIAA pressings
• Switchable 50Hz subsonic filter
• Switchable 600Hz–6kHz high-pass crossover for subwoofer or horn integration
• Bass and treble at ±15dB with bypass switch
• Bypass power-amp mode
• 800W switch-mode supply using silicon carbide FETs with power factor correction
• Dimmable illuminated analog level meters
• Balanced XLR, three RCA line inputs, coaxial and USB audio inputs

Specifications

• Type: Integrated amplifier, GaN FET Class-D
• Amplifier Modules: Four independent modules, two per channel
• Power Output: 200W x 4 channels into 8Ω; 200W x 4 channels into 4Ω; 400W x 2 channels into 8Ω bridged (BTL)
• FTC Power Rating: 200W x 2 channels (8Ω, 20Hz–20kHz, THD 0.1%)
• Operating Modes: Stereo A, Stereo B, and BTL bridged. Bi-amping supported
• Frequency Response: Nominally flat 20Hz–50kHz, −3dB at 100kHz, −6dB at 200kHz
• Load Impedance: 8Ω nominal; 4Ω supported at the same rating
• Damping Factor: Greater than 150 at the speaker output
• Output Impedance: 53 mΩ at the speaker output
• Signal to Noise Ratio: 107dB / 105dB line; 80dB phono MM; 60dB phono MC
• Input Sensitivity: Balanced 2V, unbalanced 1V for maximum output; phono 5mV (MM), 0.5mV (MC)
• Input Impedance: 44kΩ balanced; 47kΩ unbalanced and phono
• Audio Inputs: Balanced XLR x1, unbalanced RCA line x3, MM/MC switchable phono x1 with ground posts, coaxial x1, USB audio x1
• Audio Outputs: Sixteen speaker binding posts (eight pairs, A/B switchable); subwoofer out RCA x1
• Headphone Output: Not fitted
• Phono Turnover Settings: Flat; 300Hz (+7.7dB at 100Hz); 400Hz (+11.7dB); 500Hz (+13dB); 700Hz (+14.5dB)
• Phono Roll-Off Settings: Flat; 1.6kHz (−16dB at 10kHz); 2.1kHz (−13.7dB); 3.18kHz (−11dB); 3.4kHz (−8dB); 6.36kHz (−5dB)
• Subsonic Filter: −3dB at 50Hz, switchable
• Tone Control: Bass (100Hz) and treble (10kHz), ±15dB, switchable
• Crossover: High-pass filter, −3dB, adjustable 600Hz–6kHz, switchable
• Power Supply: 800W switch-mode, silicon carbide FETs with power factor correction
• Mains Input: AC 100–230V, 50/60Hz
• Trigger: Input, 3.3V–12V. No trigger output
• Remote Control: 38kHz infrared, within 10 m
• Finish: High purity aluminium, silver only
• Dimensions (W x D x H): 16.9″ x 13.7″ x 4.3″ chassis; 5.1″ high including feet
• Weight: 36.8 lbs (16.7 kg)
• Warranty: Two years. US warranty and service are administered by HiFi Rose USA
• Note: HiFi Rose publishes no channel separation figure and no idle power consumption. Its published THD row references 250W, a level this model is not rated for, and appears to be carried over from the RA280 — we have omitted it rather than reprint it