Unless otherwise noted, measurements were taken at 120V AC line voltage, at the balanced input, and with the Audio Precision AUX-0025 measurement filter.
- Power output at 1% THD+N: 380.0W @ 8 ohms, 643.0W @ 4 ohms
- Power output at 10% THD+N: 489.0W @ 8 ohms, 841.0W @ 4 ohms
- Input/output polarity: noninverting
- AC line current draw at idle: 25.0W, 0.44A, 0.47PF
- Gain: output voltage divided by input voltage, 8-ohm load
- Unbalanced input: 24.1X, 27.6dB
- Balanced input: 24.1X, 27.6dB
- Input sensitivity for 1W output into 8 ohms
- Unbalanced input: 117.3mV
- Balanced input: 117.3mV
- Output impedance @ 50Hz: 0.0033 ohm
- Input impedance @ 1kHz
- Unbalanced input: 92.5k ohms
- Balanced input: 92.5k ohms
- Output noise, 8-ohm load, unbalanced inputs terminated with 1k ohms
- Wideband: 0.600mV, -73.5dBW
- A weighted: 0.0264mV, -100.6dBW
- Output noise, 8-ohm load, balanced inputs terminated with 600 ohms
- Wideband: 0.597mV, -73.5dBW
- A weighted: 0.026mV, -100.7dBW
- Output noise, 8-ohm load, unbalanced inputs terminated with 1k ohms, without the AP AUX-0025 filter
- Approx. 450kHz: 448.0mV, -16.0dBW
- Output noise, 8-ohm load, balanced inputs terminated with 600 ohms, without the AP AUX-0025 filter
- Approx. 450kHz: 448.0mV, -16.0dBW
The Mola Mola Kaluga is a switching power amplifier that uses the latest Hypex Electronics Ncore technology.
Chart 1 shows the Kaluga’s frequency response with varying loads. One of the interesting aspects of the Ncore technology is its amazing independence from load in the high-frequency region; this is in contrast to many switching-amplifier designs. Here, though, there is a significant anomaly between 50 and 60kHz. Of interest is the regulation of the output -- which, as indicated by the closeness of the three curves, is very good before the anomaly and uniformly poorer after. The output impedance within the audioband is low enough that there was negligible variation with the NHT dummy speaker load.
Chart 2 illustrates how the Kaluga’s total harmonic distortion plus noise (THD+N) vs. power varies for 1kHz and SMPTE intermodulation test signals and amplifier output load for loads of 8 and 4 ohms. The level of distortion is quite low.
Chart 3 plots the Mola Mola’s THD+N as a function of frequency at different power levels. The increase in distortion with frequency is pronounced. Also, the low-frequency region begins to distort more at higher power levels. Still, the levels of distortion are very low through most of the power and frequency ranges.
The Kaluga’s damping factor vs. frequency is shown in Chart 4. The damping factor is very high, and is still about 1000 even at 20kHz. Fantastic! However, as mentioned in the description of Chart 1, things are quite different above the audioband, especially above about 50kHz.
Chart 5 shows the spectrum of the residue of harmonic distortion and noise of a 10W, 1kHz test signal. The AC-line harmonics are very low, and are mostly odd harmonics of 60Hz. The signal harmonics are dominated by the third harmonic, with higher harmonics of rapidly decreasing magnitude.
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 100W to determine lines)
Top line = 4-ohm SMPTE IM distortion
Second line = 8-ohm SMPTE IM distortion
Third line = 4-ohm THD+N
Bottom line = 8-ohm THD+N
Chart 3 - Distortion as a function of power output and frequency
Red line = 1W
Magenta line = 10W
Blue line = 70W
Cyan line = 150W
Yellow line = 300W
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