Unfortunately I have not yet heard this amp. It is clearly a sign of the growing maturity of class D amplification if yet one more major manufacturer creates a statement product around switching amplification technology. There is a good info page at:
http://www.marklevinson.com/products/details.asp?prod=no53
It appears that ML is not using third party modules, but has created its own proprietary class D switching technology. From the page, here are a few interesting paragraphs:
"The Nº53 removes switching noise without affecting the audio with the introduction of the new patented and proprietary Interleaved Power Technology (IPT), which, among other things, raises the switching frequency of the Nº53 to an extremely high 2MHz. The advantages of this are twofold: first, it pushes the fundamental switching noise and its harmonics far above the limit of human hearing, so that they have no direct affect whatsoever on sound quality; second, it allows for easier removal of the switching noise from the signal by using much gentler filters, having no negative effect in the crucial audio band (the result is a frequency response that is ruler flat across the entire audio spectrum and is only a few dB down at 100kHz impressive for any power amplifier, but staggering for a switching design).
The Nº53 has also overcome the dead band problem. Dead bands are silent gaps in the audio output, created when the output devices driving the positive half of the signal and the negative half of the signal are both turned off. This generally occurs at every zero crossing point, whenever the audio waveform crosses over from positive amplitude to negative amplitude or vice versa. This is a constant phenomenon in a 20kHz audio signal, this point occurs 40,000 times per second. It becomes a problem, however, because even the best output devices are not able to turn on and off instantaneously, so the result is a number of dead bands of signal every second. Obviously, the larger the gap, the more detrimental to the audio signal. Many designs minimize dead bands by ensuring that the time both sets of output devices are off is kept as short as possible, which unfortunately increases the potential for the output devices to be on simultaneously, which can damage or destroy them. The Nº53, on the other hand, was designed using a patented technology that allows both sets of output devices to be on simultaneously for short periods of time, to completely eliminate dead bands without damaging the output devices or reducing their life expectancy. In other words, this completely eliminates the dead band problem and maintains the Nº53s long-term reliability.
Power amplifiers challenge and goal is to amplify the incoming audio signal without distorting it and effortlessly drive a wide range of loudspeaker impedances at any volume level with the forcefulness and grace that reference-quality sound reproduction demands. The Nº53 is designed toward that end. The chassis is a compact vertical design consisting of three separate internal compartments to provide shielding and isolation of the different circuitry the power supply in the bottom, the four amplifiers in the middle and the control circuitry in the top. The power supply is completely isolated and shielded from the rest of the amplifier to reduce interference from magnetic fields and high current devices. The extremely low-noise toroidal transformer features an oversized 2.8kVA transformer with four 47,000µF low-ESR capacitors. The middle sections four amplifiers, featuring a pair of coils each, are arranged symmetrically and mirror-imaged to maintain separation. Working together, the four amplifiers raise the effective switching frequency from 500kHz to 2MHz to produce the best sound quality known from a switching amplifier. The control circuitry has its own independent regulated power supply and is shielded from the rest of the amplifier to keep it from interfering with the audio circuits."
G.
http://www.marklevinson.com/products/details.asp?prod=no53
It appears that ML is not using third party modules, but has created its own proprietary class D switching technology. From the page, here are a few interesting paragraphs:
"The Nº53 removes switching noise without affecting the audio with the introduction of the new patented and proprietary Interleaved Power Technology (IPT), which, among other things, raises the switching frequency of the Nº53 to an extremely high 2MHz. The advantages of this are twofold: first, it pushes the fundamental switching noise and its harmonics far above the limit of human hearing, so that they have no direct affect whatsoever on sound quality; second, it allows for easier removal of the switching noise from the signal by using much gentler filters, having no negative effect in the crucial audio band (the result is a frequency response that is ruler flat across the entire audio spectrum and is only a few dB down at 100kHz impressive for any power amplifier, but staggering for a switching design).
The Nº53 has also overcome the dead band problem. Dead bands are silent gaps in the audio output, created when the output devices driving the positive half of the signal and the negative half of the signal are both turned off. This generally occurs at every zero crossing point, whenever the audio waveform crosses over from positive amplitude to negative amplitude or vice versa. This is a constant phenomenon in a 20kHz audio signal, this point occurs 40,000 times per second. It becomes a problem, however, because even the best output devices are not able to turn on and off instantaneously, so the result is a number of dead bands of signal every second. Obviously, the larger the gap, the more detrimental to the audio signal. Many designs minimize dead bands by ensuring that the time both sets of output devices are off is kept as short as possible, which unfortunately increases the potential for the output devices to be on simultaneously, which can damage or destroy them. The Nº53, on the other hand, was designed using a patented technology that allows both sets of output devices to be on simultaneously for short periods of time, to completely eliminate dead bands without damaging the output devices or reducing their life expectancy. In other words, this completely eliminates the dead band problem and maintains the Nº53s long-term reliability.
Power amplifiers challenge and goal is to amplify the incoming audio signal without distorting it and effortlessly drive a wide range of loudspeaker impedances at any volume level with the forcefulness and grace that reference-quality sound reproduction demands. The Nº53 is designed toward that end. The chassis is a compact vertical design consisting of three separate internal compartments to provide shielding and isolation of the different circuitry the power supply in the bottom, the four amplifiers in the middle and the control circuitry in the top. The power supply is completely isolated and shielded from the rest of the amplifier to reduce interference from magnetic fields and high current devices. The extremely low-noise toroidal transformer features an oversized 2.8kVA transformer with four 47,000µF low-ESR capacitors. The middle sections four amplifiers, featuring a pair of coils each, are arranged symmetrically and mirror-imaged to maintain separation. Working together, the four amplifiers raise the effective switching frequency from 500kHz to 2MHz to produce the best sound quality known from a switching amplifier. The control circuitry has its own independent regulated power supply and is shielded from the rest of the amplifier to keep it from interfering with the audio circuits."
G.