Power Amplifiers

Mark Levinson No533H Three Channel Power Amplifier


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.