Power Amplifier Yamaha M-5000 Silver/Pianoblack

Yamaha M-5000: fully balanced power amplifier with a floating MOSFET output stage

The M-5000 is Yamaha's flagship stereo power amplifier, built around a fully balanced signal path and a perfectly symmetrical layout that separates the left and right channels both physically and electrically. It delivers 100 W + 100 W into 8 ohms and 200 W + 200 W into 4 ohms (20 Hz–20 kHz, 0.07% THD), and 400 W into 8 ohms in bridged mono mode. Together with the GT-5000 turntable and the C-5000 preamplifier, it forms a complete balanced chain from source to loudspeakers.

The key design solution is the floating and balanced power stage with MOSFET transistors, in which the power supply is fed directly to both the positive and negative sides of the output stage instead of the usual connection to ground. Isolating the entire power circuit from ground eliminates the influence of minor voltage fluctuations and ground noise, while creating an ideally symmetrical layout for greater ability to drive low-impedance loudspeakers. The deliberately simple topology shortens both the signal and power supply paths, thereby reducing impedance and energy losses.

Power is supplied by a massive toroidal transformer mounted on a 3 mm pure brass base, which suppresses unwanted vibrations; its low stray flux minimises the effect on surrounding audio circuits. Copper conductors led directly from the windings, thick wiring and screw connections with brass terminals on the block capacitors instead of soldering keep the connections at low impedance. The rigid chassis works with the concept of mechanical grounding – the transformer, block capacitors and heatsink are bolted directly to the structure, so they are fully supported and resistant to vibration.

The result is a high damping factor (300 and above at 8 ohms), a signal-to-noise ratio of 110 dB and a frequency response of 5 Hz–100 kHz (+0/−3 dB), which translates into firm control of the bass range, stable localisation of instruments and clear legibility of quiet details. The front panel features large, precise needle meters with 7 mm thick Asahi glass, displaying the dynamics of the signal. Connection to the loudspeakers is provided by oversized screw terminals machined from a block of pure brass with a 3 mm brass base plate, whose non-magnetic properties contribute to lower distortion. The solid brass feet can be used as spikes or with a protective pad.

Key features

• Power output: 100 W + 100 W (8 Ω), 200 W + 200 W (4 Ω), 400 W mono
• Design: Floating balanced MOSFET power stage
• Symmetry: Separation of the left and right channels
• Power supply: Massive toroid on a brass base
• Specifications: Damping factor 300, S/N ratio 110 dB
• Terminals: Screw binding posts made of pure brass