YAMAHA A-950

Commentary

Pre-main amplifier equipped with Pure A Class with ZDR power stage.

Yamaha's original Pure A class with ZDR circuit is used to achieve both the sound quality and high power of a class A amplifier.
This circuit is equipped with Yamaha's original ZDR (Zero Distortion Rule) circuit to reduce distortion and nonlinear components caused by non-linearity and bias and bias value of the power stage element. When the volume exceeds the normal pure A class, the circuit switches so that high power can be obtained automatically. Thus, both high sound quality and high power are achieved.

The power supply section is equipped with large-capacity electrolytic capacitors (33,000 μ Fx2, 22,000 μ Fx2) designed for higher sound quality by adopting a hyperfractionation multi-terminal structure.

Yamaha GF (Ground Fixed One Point Earth Circuit) is installed to solve the problem of the earth circuit.
In this system, not only the ground around the power stage and power supply, but also the ground of each circuit of the preamplifier, predrive, heat sink and transformer is completely separated, and the ground of each circuit is made to be one point ground which drops radially in one place, so that common impedance is 0.
This prevents the charge current from flowing from the transformer at a low frequency signal output when there is a common impedance and the output signal is modulated.

A DC servo real-time equalizer is used in the preamplifier section.
With this circuit, an accurate RIAA curve can be generated up to 100 kHz. In addition, the phase shift problem is cancelled out by the CR low-pass filter as the phase goes to the higher frequency region, so that no phase shift occurs as a result.

Equipped with a MM/MC switchable phono selector.

Equipped with a continuously variable loudness control that can compensate for low frequencies at low volume.

Equipped with a subsonic filter.

Model Rating

Type	Pre-main amplifier
Rated Output (20 Hz ~ 20 kHz)	160W + 160W (4 Ω, 0.02%) 140W + 140W (6 ohm, 0.005%) 120W + 120W (8 Ω, 0.003%)
Input Sensitivity / Impedance	Phono MC : 160 μ V/100 Ω, 10k Ω Phono MC : 2.5mV/47k Ω, 220 pf, 330 pf, 100 Ω
Maximum Allowable Input (1 kHz, 0.01%)	MC:10mV MM:165mV
Frequency characteristic	20 Hz to 20 kHz + 0 -0.5 dB (Aux, DAD)
RIAA deviation	Phono MC : 20 Hz to 20 kHz ± 0.3 dB Phono MM : 20 Hz to 20 kHz ± 0.2 dB
Total harmonic distortion factor (20 Hz to 20 kHz, 3 V)	Phono MC - Rec out:0.005% Phono MM - Rec out:0.003%
Signal-to-noise ratio (IHF-A network)	Phono MC : 74 dB (equivalent to 250 μ V) Phono MM : 88 dB (converted to 2.5 mV)
Subsonic filter	15 Hz, 12dB/oct.
High filter	10 kHz, 12dB/oct.
Loudness	Continuus
Power supply voltage	100 VAC, 50Hz/60Hz
Rated power consumption	250W
External dimensions	Width 435x Height 146x Depth 424.5 mm
Weight	13.0kg