November 2006

Flying Mole CA-S10 Integrated 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, including graphical information displayed below, is the property of SoundStage! and Schneider Publishing Inc. Reproduction in any format is not permitted.

• Measurements were made at 120V AC line voltage with both channels being driven; measurements made on left channel unless otherwise noted; an Audio Precision AUX-0025 low-pass filter was used unless otherwise noted.
• This integrated amplifier does not invert polarity.
• AC line current draw at idle: 0.26A
• Input sensitivity for 1W output into 8 ohms, volume at maximum, Lch/Rch:
  14.1mV/14.8mV
• Input impedance @ 1kHz: 9.85k ohms
• Output impedance at 50Hz: 0.09 ohms
• Gain, output voltage divided by input voltage, volume at maximum, Lch/Rch:
  200.2X, 46.0dB/190.6X, 45.6dB
• Output noise, 8-ohm load, 1k-ohm input termination, Lch/Rch
  • Volume control at reference position
    • wideband without AUX-0025 filter: 197.4 mV, -23.1dBW / 224.4mV, -22.0 dBW
    • wideband: 1.97mV, -63.1dBW / 2.23mV, -62.1dBW
    • A weighted: 0.30mV, -79.5dBW / 0.26mV, -80.7dBW
  • Volume control at maximum
    • wideband: 49.7mV, -35.1dBW / 7.0mV, -52.1 dBW
    • A weighted: 2.4mV, -61.4dBW / 1.5mV, -65.5dBW
  • Volume control at minimum
    • wideband: 1.9mV, -63.4dBW / 2.2mV, -62.2 dBW
    • A weighted: 0.25mV, -81.1dBW / 0.24mV, -81.4dBW

Power output with 1kHz test signal

• 8-ohm load at 1% THD: 90W
• 8-ohm load at 10% THD: 113.1W
  
  
• 4-ohm load at 1% THD: 135.3W
• 4-ohm load at 10% THD: 173.3W

General

The Flying Mole CA-S10 is a medium-power solid-state integrated amplifier using their proprietary switching-amp technology. Overall gain of this unit is on the high side for an integrated amplifier of the type so popular these days -– the kind with a passive selector switch and volume control preceding a power amplifier. The CA-S10 has a active line-level preamp stage within, and with this in mind, the overall gain is appropriate for this topology.

Chart 1 shows the frequency response of the amp with varying loads. This data was taken without the Audio Precision AUX-0025 low pass filter to show the true frequency response of the unit. As is typical of most switching-amp designs, the high-frequency response is a strong function of load impedance. Output impedance as judged by the closeness of spacing between the curves of open-circuit, 8-ohm, and 4-ohm loading, is reasonably low below about 1kHz. The impedance variations of the NHT dummy-speaker load start to show above about 1kHz as the output impedance rises with increasing frequency. Still, the variation with the NHT load is a reasonable +/-0.5 dB over the audio range. The frequency response was quite independent of volume control setting with volume control tracking within 0.5dB or less from full volume down to 60dB.

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 reasonably low and power into the 4-ohm load is, as typical, higher than for the 8-ohm load.

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 moderately low.

Damping factor vs. frequency is shown in Chart 4 and is of a value and nature typical of many solid-state amplifiers, being high up to several hundred Hz and then rolling off with frequency.

A spectrum of the harmonic distortion and noise residue of a 10W 1kHz test signal is plotted in Chart 5. The magnitudes of the AC-line harmonics are low and simple, and intermodulation components of AC-line harmonics with signal harmonics are also low. Signal harmonics consist of a dominant second, a continuous spectra of higher components, and a rising noise floor starting at about 7kHz.

Red line: open circuit
Magenta line: 8-ohm load
Blue line: 4-ohm load
Cyan line: NHT dummy-speaker load

(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

8-ohm output loading
Cyan line: 80W
Blue line: 30W
Magenta line: 10W
Red line: 1W

Damping factor = output impedance divided into 8

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

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