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Equipment Measurements

June 2003

Anthem PVA 2 Stereo Amplifier: Measurements

All amplifier measurements are performed independently by BHK Labs. Please click to learn more about how we test amplifiers there. All measurement data and graphical information displayed below are the property of SoundStage! and Schneider Publishing Inc. Reproduction in any format is not permitted.

Additional Data
  • Measurements were made with 120V AC line voltage.
  • Power output and distortion plotted with both channels driven.
  • Gain: 28.0x, 28.9dB.
  • Output noise, 8-ohm load, unbalanced input, 1k-ohm input termination: wideband 0.115mV, -87.8dBW; A weighted 0.028mV, -100.1dBW.
  • AC line current draw at idle: 0.41A.
  • Output impedance at 50Hz: 0.02 ohms.
  • This amplifier does not invert polarity.
Measurements Summary

Power output with 1kHz test signal

  • 8-ohm load at 1% THD: 119W

  • 4-ohm load at 1% THD: 193W

General

The Anthem PVA 2 is a solid-state design with low measured distortion, wide frequency response, and very low output impedance

Chart 1 shows the frequency response of the amp with varying loads. As can be seen, this unit has low output impedance as evidenced by the v ery close spacing of the curves for an open circuit down to 4-ohm loading in the audio range. The deviation above the audio range is common and typical due to the usual presence of a series RL network in the output for circuit stability and the decrease in overall negative feedback with increasing frequency. When an amplifier has such low output impedance, it doesn't make any sense to measure the NHT dummy speaker load as we do for many amplifiers because its impedance variation won't show on the chart. Needless to say, the frequency-response variation with varying-impedance speaker loads with this amp will be negligible. Chart 2 illustrates how total harmonic distortion plus noise versus power varies for a 1kHz sine wave, SMPTE IM test signals, and amplifier output load. As can be seen, attainable power is greater for the 4-ohm load, as is usual for most power amplifiers. Total harmonic distortion plus noise as a function of frequency at several different power levels is plotted in Chart 3. Distortion up to about 300Hz is very low, but as is typical with most power amplifiers, it does rise as frequency increases. Damping factor versus frequency is shown in Chart 4 and is very high for this design. A spectrum of the harmonic distortion and noise residue is plotted in Chart 5 for a 10W 1kHz signal into a 4-ohm load. Amount of the signal distortion products is very low, as is the amount of AC line-hum harmonics. Virtually absent is the cluster of AC line harmonics around some of the signal harmonics as has been seen in some other amplifiers measured.

Chart 1 - Frequency Response of Output Voltage as a Function of Output Loading


Red line: open circuit
Magenta line: 8-ohm load
Blue line: 4-ohm load

Chart 2 - Distortion as a Function of Power Output and Output Loading


(line up at 50W to determine lines)
Top line: 4-ohm SMPTE IM
Second line: 8-ohm SMPTE IM
Third line: 4-ohm THD+N
Bottom line: 8-ohm THD+N

Chart 3 - Distortion as a Function of Power Output and Frequency


8-ohm output loading
Red line: 1W
Magenta line: 10W
Blue line: 30W
Cyan line: 100W

Chart 4 - Damping Factor as a Function of Frequency


Damping factor = output impedance divided into 8

Chart 5 - Distortion and Noise Spectrum


1kHz signal at 10W into an 4-ohm load

 

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