Scale: Watts / 8 Ohm
|Form Factor||Standard Width|
|Signal Path||Analog Hardware|
| Dimensions |
(H × W × D)
|Frequency Response||10 Hz - 100 Khz (8 Ohm, 50 W, 0.02% THD)|
|Notes||A smaller and less powerful followup design to the M-2 introduced earlier. The Japanese version is called the B-2 and is sufficiently different from the M-4 to not be included here. This is a class AB transistor design conservatively rated at 170 Watts per channel into 4 ohms and capable of driving most loudspeakers, including inefficient designs and those with difficult impedance curves. It has Yamaha's typical refined sound for the period. Some M-4 amplifiers include a voltage selector switch. The original sale price was ¥250,000 in 1979. |
• Gold-plated RCA inputs
• Gold-plated speaker outputs
• 2.5 mm pure copper bus
• Phase-corrected polystyrene caps
• Ground termination
• AC-DC input coupling selector
Excerpt from the owner's manual:
"The voltage amplifying stage employs a cascode-connected differential two-stage circuit throughout.
The use of a Dual FET input and a new cascode bootstrap circuit in the first stage and a cascode-connection, current-mirror and push-pull output in the pre-driver stage ensures a high degree of stability, low distortion and improved high-frequency characteristics.
In the driver and the power amplifier, a three-stage emitter follower is paralleled with pure complementary OCL SEPP circuitry using high-fT transistors. This accounts for wide bandwidth, high output and low distortion.
Two extremely large 15,000µF capacitors, two separate constant-voltage power supplies for the voltage amplifying stage, and the use of a pure copper plate earth line for ultra-low impedance guarantee greatly reduced intermodulation distortion, improved separation and absolutely stable operation.
Except for the chemical capacitors in the power supply section, mylar and styrol capacitors are employed throughout ; layout of parts, wiring, earth line as well as many other aspects have been given due consideration."
|Rated Power 8 Ohm||100 W/ch||20 Hz - 30 Khz, 0.005% THD @ 8 Ohms|
|Rated Power 4 Ohm||170 W/ch||20 Hz - 30 Khz, 0.005% THD @ 4 Ohms|
|Intermodulation Distortion||<0.002% @ half rated power|
|Bandwidth||DC - 100 KHz (-0.7 / +0.5 dB)|
|Damping Factor 8 Ohm||200|
|Damping Factor 4 Ohm||100|
|Stereo Separation||118 dB (IHF-A)||90 dB @ 1 Khz 70 dB @ 20 Khz|
|Max Power Consumption||900 W|