Mark Levinson No. 534 Power Amplifier
The Mark Levinson No. 534 dual-monaural amplifier features Pure Path circuit design for a high-current, low-feedback amplifier that delivers 250 watts per channel and operates in pure class A for most listening conditions, doubles down into 4 ohms, and remains stable into 2-ohm loads.
- Pure Path discrete, direct coupled, fully balanced, dual-monaural signal path
- Fully differential class-AB architecture, operates in class A for most listening conditions
- 6000-series aluminum chassis, extremely high precision, exceedingly low tolerances
- Expansive, fine imaging, extended low frequency response/pitch, and natural high frequencies
- Rated for 250wpc into 8 ohms, 500wpc into 4 ohms, with 2-ohm stability
- System-integration connectivity: Ethernet, IP, RS-232, triggers, web monitoring and control
- Painstakingly optimized little negative feedback, bandwidth, slewing, and open-loop linearity
- Custom-designed, low noise toroid with separate secondary windings for each output stage
- Designed and handcrafted in the USA
Pure Path Circuit Design
Since 1972, Mark Levinson has been dedicated to the uncompromising art of sound, with the guiding principle of musical purity above all else. To achieve that goal like never before, Mark Levinson engineers scoured company archives, ultimately developing a circuit-design philosophy called Pure Path. On a conceptual level, its hallmark principles include a discrete, direct-coupled, fully balanced, dual-monaural signal path that delivers unrestricted, uncompromised sonic purity. Far from merely arranging high quality components in an intelligent manner, Pure Path is the meeting of science and art: Mark Levinson engineers are tasked to create the best possible measured AND subjective performance. To quote Albert Einstein: “Everything should be made as simple as possible, but not simpler." Pure Path highlights in the No. 523 include Folded Cascodes, an R-2R Ladder volume control, the class-A Pure Phono stage, and class-A Main Drive Headphone amplifier output.
The Folded Cascode
Mark Levinson components are designed around a Pure Path amplifier circuit concept that makes heavy use of a circuit design element called a cascode. Originally created for improving the bandwidth of vacuum tube circuits in radios, Mark Levinson engineers deploy cascodes in Pure Path circuit designs to both improve bandwidth and enhance linearity. A cascode combines two transistors so that they operate as a single composite device that functions like a single transistor, using the wanted characteristics of each component transistor, and rejecting the unwanted characteristics.
Mark Levinson engineers began their design of the gain stage with pairs of JFETs (junction field-effect transistors), chosen for their low noise and high gain. JFETs achieve these characteristics in part by being large, and with their large size comes nonlinear gain – or distortion. To mitigate this, BJTs (bipolar junction transistors) were added to the circuit. The BJTs exhibit very low input impedance and very high output impedance, which translates to excellent bandwidth and linearity. By creating a cascode of the JFETs and BJTs, they created a design with the best characteristics of both sets of devices.
Engineers than connected the output of the cascode to another transistor of the opposite “gender." Current flows through it in the opposite direction to “turn around" the direction of the signal current. This special connection is called a Folded Cascode and it is a hallmark of the Pure Path circuit: high gain with low noise, wide bandwidth, and excellent linearity.
The audio circuitry in the No. 534 has been optimized for the best possible open-loop performance. As a result, very little negative feedback is necessary, and the amount employed could be adjusted to achieve certain subjective or objective results. The open-loop gain and bandwidth of the circuit were painstakingly set using precision resistors and compensation capacitors, and additional precision resistors were employed to compose the feedback network.
Military Grade Components
All Mark Levinson equipment employs electronic components carefully chosen for their specific task. Gain-stage JFET pairs have high gain, low noise, low distortion, and because they are encapsulated in the same package, the two devices operate under nearly identical conditions. Capacitors used in critical filtering locations are film types, noted for their consistent performance regardless of temperature and frequency. Finally, resistors in critical gain-setting and feedback locations use tantalum nitride thin-film elements. An extremely costly material, tantalum nitride typically finds use in sensitive military equipment because it is unusually stable with respect to temperature, exhibits very low noise, and is unaffected by magnetic fields. In fine audio equipment, those characteristics make the sound even more revealing and effortless, free of the low-level nonlinearities caused by lesser resistive materials as they heat and cool under dynamic conditions.
Completing the Signal Path
The No. 534 offers balanced and single-ended inputs for use with virtually any preamplifier or source player with variable output. For connection to loudspeakers without needing tools for a secure link, the No. 534 features four pairs of gold-plated binding posts with Mark Levinson Hurricane terminal knobs to support either standard or bi-wired loudspeaker connections. Speaker cables terminating in banana plugs can be used in the USA and other non-European countries.
|Power Per Channel||250W (8 Ohms)|
|Number of Channels||2|
|THD Stereo||<0.3% THD @ 20 Hz - 20 kHz|
|Signal To Noise Ratio||85 dB|
|Inputs||1 Pair Balanced XLR (L/R), 1 Pair Single-Ended RCA (L/R), 1 Relay Trigger, Ethernet, RS-232, USB-A, Mini USB|
|Number of Outputs||4 Pairs of Hurricane Loudspeaker Outputs (banana-plug sockets), 1 Relay Trigger|
|Power Requirements||100V~, 120V~, 230V~, Factory Set for Destination Country, 1500W|