W-6 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.
- Measurements were made with 120V AC line voltage.
- Gain: 71.2x, 37dB.
- Output noise, 8-ohm load, unbalanced input, 1k-ohm input
termination: wideband 0.309mV, -79.2dBW; A weighted 0.084mV, -90.4dBW.
- Output noise, 8-ohm load, balanced input, 600-ohm input
termination: wideband 0.288mV, -79.8dBW; A weighted 0.087mV, -90.2dBW.
- AC line current draw at idle: 0.46A.
- Output impedance at 50Hz: 0.0014 ohms.
- This amplifier does not invert polarity.
Power output with 1kHz test signal
- 8-ohm load at 1% THD: 440W
- 4-ohm load at 1% THD: 770W
The Moon W-6 is a high-power solid-state design with
typically wide bandwidth and very low output impedance.
Chart 1 shows the frequency response of the amp with
varying loads. As can be seen, the output impedance, as judged by the closeness of spacing
between the curves of open circuit, 8-ohm, and 4-ohm loading, is quite low. The variation
with the NHT dummy load would be absolutely negligible. Chart 2 illustrates how total
harmonic distortion plus noise versus power varies for 1kHz and 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. Amount of rise in
distortion at high frequencies is typical of most modern solid-state power amplifiers.
Note how the amount of distortion here is fairly constant with power level over much of
the frequency range. Damping factor versus frequency is shown in Chart 4. Unusual is how
high the damping factor is at low frequencies. A spectrum of the harmonic distortion and
noise residue is plotted in Chart 5. The AC-line harmonics are quite low for this
amplifier. The test-signal harmonics are dominantly odd harmonic with a slow falloff of
magnitude with harmonic order.
- 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 10W 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
Green lin: 400W
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
1kHz signal at 10W into an 8-ohm load