Onkyo model 931
Solid State Stereo Power Amplifier
Model 931 is an independent power amplifier that is so versatile that it can fit into any system.
It was designed so that all distortion is reduced to a minimum. Some of the factors that assure less distortion are quasi complementary SEPP, direct coupled and differential circuitry.
The power amplifier circuitry was analysed by a computer but this analysis was not restricted to the audible range alone. Onkyo found that the very low frequencies have a very important bearing on the music even though inaudible. Since these low frequencies are not taken into account when ordinary amplifiers are designed they cause very much distortion. This distortion in the very low frequencies causes IM distortion.
This model is rated at 22 watts per channel at 8 ohms. The THD of model 931 is rated at less than 0.05%. Whether the amplifier is used at full or very low power this distortion rate does not vary.
Added stability is gained because a differential amplifier is used. Instability in an amplifier will put DC voltage on the loudspeaker terminals and this will lead to distortion. The differential amplifier also takes care of any distortion that could come from fluctuations in the power supply voltage and temperature.
The OCL circuitry is an added factor why model 931 has less distortion, a flatter response over the whole frequency range and especially good damping in the lower frequency range.
The input sensitivity of model 931 is variable so that it can be matched perfectly to any preamplifier. An integrated attenuator for both channels is installed in model 931. This makes attenuation of both channels very easy. With this added feature incorporated into its design model 931 fits very easily into any 4 channel system.
Power output: 22 watts per channel into 8Ω (stereo)
Frequency response: 10Hz to 80kHz
Total harmonic distortion: 0.1%
Damping factor: 60
Gain: 22 dB
Input sensitivity: 1V
Signal to noise ratio: 100dB
Speaker load impedance: 4Ω to 16Ω
Dimensions: 130 x 352 x 135mm
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