Power Amplifiers

Mark Levinson No533H Three Channel Power Amplifier

ARTICLE INDEX

Mark Levinson No533H Three Channel Power Amplifier On the Bench

The Mark Levinson No533H was tested using SpectraPlus software and a LynxTwo soundcard with either 4 ohms or 8 ohms of resistance. Two channels were driven while one was measured.

With a 1 kHz test tone, the No533H measured higher than expected with 0.02%-0.04% THD+N at 4 ohms and similar measurements at 8 ohms. There is typically around 85dB of headroom available with a 2V output, though with the 5V test there it a large spike in the 3rd harmonic that drops headroom down to around 65dB. The main noise floor is a good 110dB below the fundamental, but those third and fifth harmonic spikes are a bit high.

On the IMD testing the 60 Hz and 7 kHz tone tests show around 70 dB of range above the harmonics, though looking at the numbers those 0.09% readings are much higher than I would have expected to see from this amplifier.

The 19 kHz + 20 kHz graphs show similar performance with around 70-75 dB of dynamic range available and harmonics that extend out the full range of the bandwidth.

Frequency response on the No533H is very flat over the first 30 kHz, with a gentle roll off out to around 80 kHz where the angle becomes steeper. The THD+N vs. Frequency graphs show that the level of THD+N is a consistent 0.02% or so across the whole spectrum.

Overall the No533H was a decent but not spectacular performer on the bench tests. There were no massive issues that would be readily apparent and cause obvious issues, but the THD+N levels and IMD levels were higher than I expected them to be for an amplifier of this class.