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Mark Levinson №53 Reference Monaural Power Amplifier

Technology Background

Overview

Mark Levinson was founded in 1972 to produce the first solid-state electronics that

sonically outperformed the finest tube electronics of the era. In 1993, the Mark Levinson

№33 Reference Monaural Power Amplifier was hailed by audiophiles and music lovers

around the world as the ultimate power amplifier. Now, the Mark Levinson №53 debuts

– the first switching technology amplifier to sonically outperform the finest Class A or AB

amplifiers.

Cosmetically similar to its predecessor, the №53 is the first Mark Levinson Reference

Monaural Amplifier to incorporate multi-stage very high speed switching amplifier

technology, dispensing with the conventional Class AB power output stage in favor of

Interleaved Power Technology (IPT), which features a patented

circuit design that

provides significant advantages over prior switching amplifier topologies.

PWM Limitations

Switching amplifiers aren’t new (the earliest design originated back in 1932 and was

vacuum tube-based), and offer significant advantages over conventional designs in

terms of thermal and power efficiency, and operational stability. However, while they are

popular in industrial electronics and professional sound reinforcement applications,

switching amplifier technology had yet to be refined enough to be on par with the best

conventionally configured audiophile power amplifiers.

Challenges that needed to be addressed include high frequency noise components that

are a result of the PWM process. Analogous to digital audio quantization noise, these

high frequency residual components need to be filtered with a sharp slope brickwall filter,

which can have unwanted consequences such as phase alteration and high frequency

ripple in the audio passband.

In-band distortion can also be higher than desirable, especially compared to reference

class audiophile amplifier designs.

Another area of concern is a limited frequency response range, an important

consideration in the era of modern wideband high resolution audio formats, including

SACD, Dolby TrueHD and DTS-HD Master Audio. These formats support up to 192 kHz

sampling, allowing an audio passband that extends to over four times that of standard

resolution formats such as CD.

Covered under one or more U.S. patents, including #5,657,219, #6,297,975 B1, #6,504,348 B2,

#6,556,053 B2, #6,909,321 B2

Summary of content (7 pages)

PAGE 1
Mark Levinson №53 Reference Monaural Power Amplifier Technology Background Overview Mark Levinson was founded in 1972 to produce the first solid-state electronics that sonically outperformed the finest tube electronics of the era. In 1993, the Mark Levinson №33 Reference Monaural Power Amplifier was hailed by audiophiles and music lovers around the world as the ultimate power amplifier.
PAGE 2
New Class I Interleaved Output Stage Our engineers set out to develop a new PWM output stage design that would overcome these limitations, based on improvements made to earlier designs employed in pro sound reinforcement and automotive audio applications.
PAGE 3
Sample IPT (N=8) with extremely marginal residuals around 800 kHz With Interleaved Power Technology (N=8), the comparably much smaller byproducts of the PWM switching process are easily filtered out using a simple high frequency notch filter, which has no deleterious effect on sound quality, compared to brickwall filter types.
PAGE 4
№53 Six layer modulator PCB contains about 1,500 parts The output stage features multiple high voltage, high current, high frequency vertical MOSFET output devices, as well as eight air core inductors (four on each of the two amplifier boards). As the high current, low inductance coils are air core (as opposed to ferrite core) types, there is virtually no problem with saturation at high current levels, a problem with standard (and less costly) ferrite core inductor types.
PAGE 5
The power supply includes a large capacity toroidal power transformer (pictured at bottom center in the photo above), which carries a raw power capacity rating of 2.8 kVA. For the №53, the power transformer is conservatively de-rated to a more reasonable 1.065 kVA, to ensure long term operational stability and lower thermal operational limits to conform to electrical safety compliance requirements.
PAGE 6
real world operational stability with the widest range of loudspeakers, including models that feature lower than normal impedances over portions of the frequency range. Listen Testing & Evaluation At each stage of the №53’s development, extensive listen testing and thorough measurements ensured that our goal of Mark Levinson Reference Class performance was attained.
PAGE 7
The following decade saw Mark Levinson approach digital audio with the goal of achieving true audiophile reference class performance, with the introduction of the №30 digital audio processor and the №31 digital CD transport. Both of these were “from the ground up” designs, as opposed to numerous competitive offerings at the time that were merely massaged-over models that originated from mass brand products.