[SoundStage!]Home Audio
Equipment Measurements

July 2008

Luxman B-1000F Mono Amplifiers: 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 at 120V AC line voltage and using the balanced inputs unless otherwise noted.
  • Input/output polarity:
    • Unbalanced inputs: non-inverting
    • Balanced inputs: switchable; default is inverting (relative to pin 2 hot)
  • AC line current draw at idle: 3.2A
  • Input impedance @ 1kHz:
    • Unbalanced input: 52.5k ohms
    • Balanced input: 40.0k ohms
  • Output impedance at 50Hz: 0.0039 ohms
  • Input sensitivity for 1W output into 8 ohms:
    • Unbalanced input: 64.3mV
    • Balanced input: 64.7mV
  • Gain, output voltage divided by input voltage:
    • Unbalanced input: 44.0X, 32.8dB
    • Balanced input: 43.7X, 32.8dB
  • Output noise, 8-ohm load, unbalanced input, 1k-ohm input termination:
    • Wideband: 0.28mV, -80.1dBW
    • A weighted: 0.071mV, -92.0dBW
  • Output noise, 8-ohm load, balanced input, 600-ohm input termination:
    • Wideband: 0.96mV, -69.3dBW
    • A weighted: 0.29mV, -79.8dBW
Measurements Summary

Power output with 1kHz test signal

  • 8-ohm load at 1% THD: 312W
  • 8-ohm load at 10% THD: 427W

  • 4-ohm load at 1% THD: 632W
  • 4-ohm load at 10% THD: 844W

General

The Luxman B-1000f is a high-power solid-state mono power amplifier and the flagship of the Luxman line.

Chart 1 shows the frequency response of the amp with varying loads. The high-frequency response is moderately wide with an approximate -3dB point of about 90kHz. Output impedance, as judged by the closeness of spacing between the curves of open-circuit, 8-ohm, and 4-ohm loading, is very low in the audio band and beyond. The usual NHT dummy-load curve is not shown, as the variations in the response would not show.

Chart 2 illustrates how total harmonic distortion plus noise vs. power varies for 1kHz and SMPTE IM test signals and amplifier output load. Amount of distortion is low right up to clipping -- the behavior of most solid-state power amplifiers. This particular design has an enormous power supply and super-beefy output stage and is said to put out 2kW into 1-ohm loads. I have no doubt that it can.

Total harmonic distortion plus noise as a function of frequency at several different power levels is plotted in Chart 3 for 4-ohm loading. As is usual for all but a very few amplifiers, the distortion does rise at high frequencies, above around 500Hz.

Damping factor vs. frequency is shown in Chart 4 and is of a very high value at low frequencies and typical of many solid-state amplifiers, being high at low frequencies and rolling off with increasing frequency starting at some 200Hz. Still, for this amplifier, the damping factor is greater than 100 at 20kHz.

The spectrum of AC-line and test signal-harmonics shown in Chart 5 for a 10W 1kHz test signal into 4 ohms has low amounts of AC-line harmonics. Signal harmonics of second, third, fourth, and fifth order are visible at very low magnitudes, the second being the highest at only 0.001%.

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 70W to determine lines)
Top line: 4-ohm SMPTE IM
Second line: 4-ohm THD+N
Third line: 8-ohm THD+N
Bottom line: 8-ohm SMPTE IM

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


4-ohm output loading
Green line: 500W
Cyan line: 200W
Blue line: 70W
Magenta line: 10W
Red line: 1W

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 a 4-ohm load

 

[SoundStage!]All Contents
Copyright 2008 Schneider Publishing Inc.
All Rights Reserved