MastersounD Gemini

MastersounD Gemini – KT150 push-pull Class A integrated amplifier with triode/pentode switching

The most powerful integrated in the MastersounD range

The MastersounD Gemini uses four KT150 output valves in a push-pull Class A circuit, consequently delivering 2× 50 W. Since a triode/pentode switch is built in, two distinct characters are available: 2× 25 W in triode mode for maximum musicality, or 2× 50 W in pentode mode for greater grip and dynamic range. The Gemini is therefore the most versatile amplifier in the MastersounD lineup — above all, it suits listeners who need more power than a single-ended design can offer, without sacrificing the musical openness of valve amplification.

Push-pull — a deliberate departure from single-ended

By contrast with every other MastersounD integrated amplifier, the Gemini uses a push-pull topology. As a result, output power is considerably higher and the amplifier drives a wider range of loudspeakers. Since MastersounD's hand-wound output transformers are sufficiently refined, zero negative feedback is maintained throughout — thereby preserving the direct, uncoloured house sound that defines the brand.

Built-in phono stage and flexible connectivity

The Gemini includes a built-in MM phono stage, so a turntable connects directly without an external stage. Furthermore, inputs cover one balanced XLR line input, three single-ended RCA line inputs and one direct RCA input. Two outputs — one preamplified and one fixed line — moreover allow flexible integration into a larger system. Automatic bias keeps all four KT150 valves at their optimal operating point at all times.

The KT150 — the most powerful valve in the KT88 family

The KT150 is the most powerful pentode in the KT88/6550 family, developed specifically for hi-fi use. Since MastersounD builds every Gemini by hand in Arcugnano, Vicenza, each unit is individually assembled and tested before leaving the factory. The result is a push-pull amplifier that retains the warmth and directness that valve amplification is known for.

Specifications

• Type: push-pull Class A integrated amplifier, switchable pentode/triode
• Output power pentode: 2× 50 W Class A
• Output power triode: 2× 25 W Class A
• Valves: 4× KT150, 4× ECC802
• Input XLR: 1× line
• Inputs RCA: 1× phono MM, 3× line, 1× direct
• Outputs: 1× preamplified, 1× line
• Load impedance: 4–8 ohm
• Bandwidth: 12 Hz–38 kHz, 0 dB
• Output transformer: bespoke MastersounD, hand-wound
• Bias: automatic
• Negative feedback: 0 dB
• Remote control: included
• Dimensions: 460×415×275 mm
• Weight: 31 kg
• Origin: hand-built in Italy

Frequently asked questions about the MastersounD Gemini

What is the difference between pentode and triode mode?

In pentode mode the Gemini delivers 2× 50 W — more grip, more dynamics, and suitable for less sensitive loudspeakers. In triode mode output drops to 2× 25 W, but the sound becomes softer and more intimate. Since both modes are available via a single switch, the Gemini consequently offers two amplifiers in one chassis.

Why does MastersounD use push-pull rather than single-ended in the Gemini?

Push-pull allows considerably higher output power from the same valve type. Since MastersounD's output transformers are refined enough to eliminate negative feedback entirely, the musical openness of the brand's house sound is thereby fully preserved.

Is the MastersounD Gemini suitable for vinyl?

Yes — the built-in MM phono stage accepts a turntable directly. Since no external phono stage is required, the Gemini therefore works as a complete integrated solution for both streaming and vinyl sources.