Arcam Alpha 9
The Arcam Alpha 9 is a high-quality integrated stereo amplifier from the late 1990s. It was one of the higher-end models in Arcam's Alpha series at the time.
The power supply features a substantial toroidal transformer and 10,000µF power supply capacitors. The output stage uses four IRFP240 MOSFET transistors in a quasi-complementary configuration. Two pairs of loudspeakers can be connected, with separate protection relays for each speaker pair.
The amplifier features motorized volume control and a motorized input selector, providing convenient remote operation. Additional features include a Direct function for a shorter signal path and an optional phono section. The internal construction is well organized, with good accessibility for servicing and maintenance.
The soundstage is accurate and pleasant, with a slight reduction in bass at very low frequencies.
General Specifications
Maximum power (8Ω): 70WPower bandwidth (0.5%THD): 20Hz-20kHz
THD (1kHz): 0.02%
Signal to noise ratio (Line): 98dB
Signal to noise ratio (MM): 79dB
Signal to noise ratio (MC): 73dB
Crosstalk attenuation: 65dB
Input sensitivity (Line): 160mV
Input sensitivity (MM): 2.6mV
Input sensitivity (MC): 260µV
Speaker load impedance: 4Ω-16Ω
Dimensions (WHD): 430×110×330mm
Weight: 6.1kg
Produced: 1996-1999
Initial price: £500
Measured Values
Maximum power (8Ω): 67WFrequency response (20Hz-20kHz): <1.0dB
Channel imbalance: <1.0dB
THD (1kHz, 1W): 0.012%
THD+N (1kHz, 1W): 0.028%
THD (1kHz, 20W): 0.012%
THD+N (1kHz, 20W): 0.018%
IMD (70Hz, 5kHz, 1W): 0.078%
Noise: -59.2dB
Amplification: 136.3
DC offset L: -7.7mV
DC offset R: -6.8mV
Factory Specification Sheet
Factory specification images are sourced directly from the device's original service manual or user manual. These documents are produced by the manufacturer and provide authoritative information on the product's specifications.
Maximum Power
Maximum power is measured using 8Ω resistors on both channels. A 1kHz sine wave input signal is applied and gradually increased until higher harmonics rise significantly. Typically, this is the point at which output clipping occurs.
Frequency Response
Frequency response is measured using several equilizer settings. 'Flat' indicates the tone controls are either turned off or set to their neutral position. 'Max' and 'Min' refer to the maximum and minimum tone control positions, respectively. In the phono section, the expected response follows the RIAA equalization curve.
Residual Noise
These graphs display the noise levels at various volume positions. To eliminate any interference from the input signal, the input lines are shorted during the measurement. Generally, the noise is highest at the mid-point of the volume range (50%)
Distorsion
Total harmonic distortion (THD) is measured using a 1kHz sine wave input, with the output level adjusted to meet different conditions. Intermodulation distortion (IMD) is measured using 'two sine' input signal. THD versus voltage is measured with a 1kHz sine wave input, while THD versus frequency is measured at various output levels.
