Wednesday, November 22, 2017

Sponsors

All amplifier measurements are performed independently by BHK Labs. All measurement data and graphical information displayed below are the property of the SoundStage! Network and Schneider Publishing Inc. Reproduction in any format is not permitted.

Note: Unless otherwise noted, measurements were taken on the left-channel balanced input at 120V AC line voltage.

Power output (stereo mode)

  • Power output at 1% THD+N: 130.0W @ 8 ohms, 195.9W @ 4 ohms
  • Power output at 10% THD+N: 157.1W @ 8 ohms, 241.0W @ 4 ohms

Power output (mono mode)

  • Power output at 1% THD+N: 405.0W @ 8 ohms
  • Power output at 10% THD+N: 480.0W @ 8 ohms

Additional data

  • Input/output polarity: noninverting
  • AC-line current draw at idle: 31.0W, 0.53A, 0.48PF
  • Gain: output voltage divided by input voltage, 8-ohm load (balanced/unbalanced inputs)
    •      Stereo mode: 32.2X, 30.2dB
    •      Mono mode: 64.5X, 36.2dB
  • Input sensitivity for 1W output into 8 ohms (balanced/unbalanced inputs)
    •      Stereo mode: 87.7mV
    •      Mono mode: 43.8mV
  • Output impedance @ 50Hz
    •      Stereo mode: 0.003 ohm
    •      Mono mode: 0.0035 ohm
  • Input impedance @ 1kHz (stereo/mono modes)
    •      Balanced input: 90.0k ohms
    •      Unbalanced input: 45.0k ohms
  • Output noise (stereo mode), 8-ohm load, balanced inputs terminated with 600 ohms, Lch/Rch
    •      Wideband: 0.15mV/0.15mV, -85.6dBW/-85.8dBW
    •      A weighted: 0.069mV/0.060mV, -92.3dBW/-93.5dBW
  • Output noise (stereo mode), 8-ohm load, unbalanced inputs terminated with 1k ohms, Lch/Rch
    •      Wideband: 0.18mV/0.15mV, -83.9dBW/-85.5dBW
    •      A weighted: 0.12mV/0.062mV, -87.4dBW/-93.1dBW
  • Output noise (mono mode), 8-ohm load, balanced inputs terminated with 600 ohms
    •      Wideband: 0.20mV, -82.9dBW
    •      A weighted: 0.083mV, -90.7dBW
  • Output noise (mono mode), 8-ohm load, unbalanced inputs terminated with 1k ohms
    •      Wideband: 0.23mV, -81.9dBW
    •      A weighted: 0.13mV, -84.0dBW

Measurements summary

The Simaudio Moon Neo 330A is a medium-power stereo amplifier with a conventional linear power supply and bipolar output devices. It can be bridged to function as a mono power amp by using Simaudio’s special balanced bridge cable, which reverses the signal phase of the left channel to make the outputs of the two stereo channels out of phase. As usual in mono mode, the load is connected between the two plus outputs of the stereo channel outputs.

Chart 1 shows the frequency response of the Moon Neo 330A with varying loads. The output impedance is low enough that there was negligible variation with the NHT dummy speaker load.

Chart 2A illustrates how total harmonic distortion plus noise (THD+N) vs. power varies for 1kHz and SMPTE intermodulation (IM) test signals and amplifier output load for loads of 8 and 4 ohms. The output power is a bit shy of specification into 4 ohms. In contrast to most amplifier measurements at the lower levels that are noise dominated, the Moon Neo 330A has actual distortion at 100mW that remains reasonably constant over most of the power range.

Chart 2B is a plot of THD+N for 1kHz and SMPTE IM test signals into 8 ohms. The Moon Neo 330A was not measured into 4 ohms in mono mode, as the load per channel would have been 2 ohms. This surely would have triggered its protection circuit, and the stock 5A, normal-blow AC line fuse would likely have blown.

THD+N as a function of frequency at several different power levels is plotted in Chart 3. The amount of increase in distortion with frequency is typical of many amplifiers. Also, the low-frequency region begins to be more distorted at the higher power levels. The protection circuit was triggered at the points on the graph at the low-frequency area where the trace stops shy of reaching 10Hz -- these sweeps begin at the high-frequency end and end up at 10Hz.

The Moon Neo 330A’s damping factor vs. frequency (Chart 4A) is of a shape typical of most power amplifiers. Measured in mono mode, the shape was quite a bit different for reasons I don’t understand (Chart 4B).

A spectrum of the harmonic distortion and noise residue of a 10W, 1kHz test signal is plotted in Chart 5. The AC line harmonics are a bit high and complex. The right channel (not shown) was quite a bit better. Signal harmonics are dominated by the second, third, fourth, and fifth harmonics, with higher harmonics of decreasing magnitude.

Chart 1 - Frequency response of output voltage as a function of output loading

Chart 1

Stereo mode
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

Chart 2A

Chart 2A

Stereo mode
(Line up at 100W to determine lines)
Top line = 8-ohm SMPTE IM distortion
Second line = 8-ohm SMPTE IM distortion
Third line = 8-ohm THD+N
Bottom line = 4-ohm THD+N

Chart 2B

Chart 2B

Mono mode
(Line up at 100W to determine lines)
Top line = 8-ohm SMPTE IM distortion
Second line = 8-ohm THD+N

Chart 3 - Distortion as a function of power output and frequency

Chart 3

Stereo mode
(4-ohm loading)
Red line = 1W
Magenta line = 30W
Blue line = 75W
Cyan line = 150W
Yellow line = 200W

Chart 4 - Damping factor as a function of frequency

Chart 4A

Chart 4A

Stereo mode
Damping factor = output impedance divided into 8

Chart 4B

Chart 4B

Mono mode
Damping factor = output impedance divided into 8

Chart 5 - Distortion and noise spectrum

Chart 5

Stereo mode
1kHz signal at 10W into an 8-ohm load

This site is the main portal for
SoundStage!

All contents available on this website are copyrighted by SoundStage!® and Schneider Publishing Inc., unless otherwise noted. All rights reserved.

This site was designed by Rocket Theme, Karen Fanas, and The SoundStage! Network.
To contact us, please e-mail info@soundstagenetwork.com

SoundStageNetwork.com | SoundStage.com