Rega Solis

Four years of development have led to Rega’s first separate power amplifier since the launch of the Osiris. The Solis draws on four decades of expertise in transistor amplification, from the first Elicit in 1990 to the proven circuits of the Aethos. Its name comes from the Latin word for “sun,” with Mercury (preamplifier) being the planet closest to this energy source.

Dual mono and fully balanced symmetry

The dual mono architecture physically separates the two channels from input to output, each with its own 330 VA toroidal transformer and 40,000 µF of K-Power smoothing capacitors. This independence ensures that the current demands of one channel do not affect the other, preserving stereo image stability in the most demanding passages.

The circuit follows a fully balanced topology with a high-linearity, wide-bandwidth driver stage in common-base configuration. The cascoded differential input stage uses two low-noise current generators referenced by LED. This technical choice allows the voltage swings needed to drive any load with minimal distortion.

Power and control of difficult speakers

Twelve 130 W and 15 A Sanken output transistors (six per channel), high-frequency multi-emitter components, operate in a high-current triple configuration. This current reserve allows the Solis to drive speakers with complex loads or low impedance without flinching.

Power output of 168 W per channel into 8 Ω rises to 305 W into 4 Ω, an almost doubling that demonstrates the quality of the power supply. Fast-recovery rectifier diodes generate less high-frequency switching noise, producing cleaner direct current. The input and driver stages benefit from a regulated balanced power supply with low-noise voltage reference.

Components and signal path

The signal path uses ICEL polypropylene capacitors, HTR non-inductive resistors, and selected relays. Audio-grade Nichicon capacitors are used in decoupling positions, while polyester capacitors bypass the electrolytics to improve high-frequency behavior. Open-loop and closed-loop feedback levels are optimized to produce a controlled soundstage, particularly in the bass.

The separation between audio circuits and power stages reduces interference. Separating the preamplifier and power amplifier into two distinct chassis isolates sensitive low-voltage circuits from high-current circuits, reducing noise and purifying the signal.

Protection and automation

The Solis continuously monitors DC levels at the speaker terminals and the temperature of the output stages. A microcontroller manages the soft start of both transformers to limit inrush current at power-on. This supervisory circuit has its own power supply, galvanically isolated from the audio stages to prevent any contamination of the signal.

Automatic standby in the absence of a signal complies with current energy standards (0.4 W in standby). The 12 V trigger enables synchronized power-on with the Mercury or other devices. The independent Mute function cuts the output without turning off the amplifier.

Connectivity and usage recommendations

For home use, Rega recommends unbalanced RCA connections rather than balanced XLR inputs. The Mercury and Solis circuits fundamentally operate in unbalanced mode; adding balancing circuitry introduces additional noise and distortion, however slight. Balanced connections are justified for long cable runs in professional or studio environments, where their noise rejection capability becomes relevant.

The Solis works with the Mercury preamplifier, but also with the Aethos used in preamp mode via its pre-out output. Combined with the Aura phono stage and the Mercury, it forms a fully balanced and discrete system from source to speakers.

Frequently asked questions

Can the Solis operate without a preamplifier?

No. It is a pure power amplifier, with no volume control or input selection. It requires an upstream preamplifier, such as the Mercury or the Aethos used via its pre-out output.

Why does Rega advise against XLR connections?

The internal circuits of the Mercury and Solis are unbalanced. The XLR inputs and outputs add conversion circuitry that, even if high quality, introduces slight noise compared with a direct RCA connection. The advantage of balanced cables (interference rejection) only really becomes apparent over significant lengths.

What is the difference compared with the Osiris?

The Osiris is an integrated amplifier with passive volume control and input selection. The Solis is a pure power amplifier, more powerful (168 W versus 162 W into 8 Ω), using twelve output transistors versus eight for the Osiris. The Solis is part of a separable pair with the Mercury.

Technical specifications

Amplification and design

• High-end stereo power amplification
• Fully balanced and discrete design
• Dual-mono architecture
• Balanced (XLR) and unbalanced (RCA) inputs
• Automatic standby mode and low power consumption
• 12 V trigger and independent MUTE function
• Comprehensive protection
  • Short circuit
  • Thermal
  • Direct current (DC)

Architecture and power supply

• Dual custom 330 VA low-noise toroidal transformers, designed to minimize mechanical noise and mains interference
• 40000 µF filtering capacity per channel, ensuring stable and instantaneous power delivery even under the most complex loads
• Input and driver stages benefit from a very low-noise regulated power supply, guaranteeing optimal signal purity
• Strict separation between the audio circuits and the power stages, drastically reducing interference for an exceptionally clean signal

Audio performance

• Output power
  • 168 W RMS per channel into 8 Ω
  • 305 W RMS per channel into 4 Ω
• Distortion (THD+N): 0.015% at 1 kHz (100 W / 8 Ω)
• Gain: 33.3 dB
• Frequency response: 15 Hz to 30 kHz (-0.5 dB)

Connectivity and sensitivity

• RCA input (unbalanced): 820 mV / 35 kΩ
• XLR input (balanced): 1.64 V / 26 kΩ

Power supply and consumption

• Power supply: 100 / 120 / 220 / 230 V ±10%
• Power consumption: 500 W (1 / 8 power into 4 Ω)
• Standby power consumption: 0.4 W

Dimensions and weight

• Dimensions (W x H x D): 435 x 140 x 385 mm
• Weight: 24.8 kg

General information

The Solis is a high-end stereo power amplifier based on a fully balanced and discrete dual-mono architecture. Compatible with the Mercury preamplifier and the Rega Aethos amplifier (in preamplifier mode), it is handcrafted in the United Kingdom and comes with a lifetime warranty against any manufacturing defect.