MastersounD Compact 845

MastersounD Compact 845 – a pure triode single-ended Class A amplifier built around the 845 valve

Twice the power of the 300B, the same design philosophy

Built around two 845 output valves, two ECC802 and two 6SN7, the MastersounD Compact 845 delivers 2× 30 W of pure Class A power with zero negative feedback. Since the 845 is one of the most powerful triodes suitable for audio use, the Compact 845 combines the fluid, direct character of single-ended triode amplification with enough power to drive a wider range of loudspeakers than its smaller sibling, the Compact 300B. Consequently, it suits both high-sensitivity monitors and speakers of more modest efficiency. Every unit is hand-built at MastersounD's factory in Arcugnano, Vicenza.

Hand-wound output transformers — MastersounD's defining advantage

The company's own hand-wound output transformers are the heart of every MastersounD amplifier. Wound one at a time on a mechanical winding machine, they are based on the research of founder Cesare Sanavio and further developed by his son Luciano, who introduced a unique construction technique that extends bandwidth to 8 Hz–40 kHz at 0 dB. Furthermore, automatic bias adjustment keeps the 845 valves at their optimal operating point at all times. As a result, no manual adjustments are needed during normal operation — only when valves are replaced by a qualified technician.

Flexible inputs and Italian craftsmanship

Connectivity covers two balanced XLR inputs — one line and one direct — and four single-ended RCA inputs. Since the direct inputs bypass the preamplifier stage and volume control, the Compact 845 can also be used as a pure power amplifier driven by an external preamplifier. All valves are run in and tested for 48 hours before the amplifier leaves the factory. Moreover, the five-year warranty — one year for valves — reflects MastersounD's confidence in its own build quality. The chassis combines steel with Italian walnut veneer, finished to a standard that makes the amplifier as much a piece of furniture as a piece of audio equipment.

845 versus 300B — which to choose

Above all, both the Compact 845 and the Compact 300B share the same pure single-ended Class A approach with zero feedback. The 300B excels in intimate, vocal-led music with high-sensitivity speakers. By contrast, the 845 offers greater dynamic range and more headroom for complex recordings — making the Compact 845 the more versatile choice for a wider range of loudspeakers and room sizes.

Specifications

• Type: pure triode single-ended Class A integrated amplifier
• Output power: 2× 30 W Class A
• Valves: 2× 845, 2× ECC802, 2× 6SN7
• Inputs XLR: 1× line + 1× direct
• Inputs RCA: 3× line + 1× direct
• Input impedance: 50 kΩ
• Bandwidth: 8 Hz–40 kHz, 0 dB
• Output transformer: bespoke MastersounD, hand-wound
• Bias: automatic
• Load impedance: 4–8 ohm
• Negative feedback: 0 dB
• Remote control: included
• Warranty: 5 years (valves 1 year)
• Dimensions: 460×275×415 mm
• Weight: 35 kg
• Origin: hand-built in Italy

Frequently asked questions about the MastersounD Compact 845

How does the 845 valve differ from the 300B?

The 845 is a more powerful triode than the 300B — consequently the Compact 845 delivers twice the output power of the Compact 300B. Both share the same fluid, direct character of single-ended triode amplification, but the 845 offers greater headroom and suits a wider range of loudspeakers.

Do the valves need regular adjustment?

No — automatic bias keeps the 845 valves at their optimal operating point throughout their life. Since adjustment is only needed when valves are replaced, day-to-day use requires no technical intervention.

Which loudspeakers suit the Compact 845?

With 2× 30 W Class A, the Compact 845 works well with loudspeakers of 87 dB sensitivity or above and a stable impedance. Furthermore, its wider power range compared to the Compact 300B makes it suitable for medium to larger listening rooms.