9-Channel Amplifier
Transcendental Performance from Flagship Power Amplifier

Rather than simply offering raw power, the PA-MC5501 is engineered to deliver superior dynamic response and outstanding signal purity. Onkyo’s highly efficient push-pull amplification and WRAT suite work to minimize interference, stabilize the voltage, and boost the current across the unit’s electrical system. Components such as the toroidal transformer, large capacitors, and heavy-duty transistors are all designed to handle very high loads. Audiophile-grade parts—such as gold-plated speaker posts and XLR inputs—are used throughout. The result? Instantaneous response to signal gains, extremely low levels of distortion through the dynamic range, and the sort warmth and clarity only a top-shelf analog amplifier can provide. Paired with a matching Onkyo pre-pro unit, the PA-MC5501’s nine channels and bi-amping capability offer extraordinary set-up flexibility to bring you the ultimate in THX® Ultra2™-certified surround sound.

WRAT (Wide Range Amplifier Technology)

The PA-MC5501 employs proprietary Onkyo technologies to ensure optimal audio performance.

Benefit 1: Uncommonly Low Negative-Feedback Design — Get cleaner sounds on program peaks

Although negative feedback (NFB) is a cheap way to reduce noise at lower frequencies, there is a price to pay in terms of audio quality: NFB can severely inhibit an amplifier’s ability both to respond to large signal gains (for example, in a fortissimo passage) and to produce sound at high frequencies. That’s why the PA-MC5501 has a low-NFB design with audiophile-grade, close tolerance components at critical points in the signal path. This design allows it to achieve a frequency response out to 100 kHz for high-resolution formats such as DVD-Audio and Super Audio CD, as well as for regular CDs, DVDs, and other music sources.

Benefit 2: Closed Ground-Loop Circuits — Enjoy greater maximum volume without distortion

If an amplifier’s ground potential (voltage) fluctuates during playback, noise is likely to result. In an open-loop circuit design, where all circuits are connected to the power supply via a single loop (as on many amplifiers), the noise is compounded. To avoid this, the PA-MC5501 employs a sophisticated closed-circuit design in which each circuit has a separate link to the power supply—this helps to cancel individual circuit noise and keep the ground potential free of distortion.

Benefit 3: HICC (High Instantaneous-Current Capability) — Experience audio with greater dynamics

When an amplifier outputs an audio signal, the connected speakers accumulate energy, reflex, and send energy back to the amplifier. The amplifier must then immediately cancel the speakers’ reflex energy and instantaneously send out the next signal. The same high current required to achieve this is also necessary to handle speaker impedance fluctuations, which can force an amplifier to provide four to six times its usual current load. The PA-MC5501’s instantaneous current capability ensures that audio output is not affected by power limitations.

HICC (High Instantaneous-Current Capability)

In order to handle high levels of instantaneous current, the PA-MC5501 incorporates several key design features.

(1) Push-Pull Amplification Design with Three-Stage Inverted Darlington Circuitry

Found only in high-end amplifiers, this ultra-sensitive circuitry reduces distortion by maintaining voltage stability and enhancing transient response.

(2) Improved Board Design

The PA-MC5501 features an improved board design with short signal pathways to reduce electromagnetic interference. The board is also designed to optimize power delivery to the speaker drivers.

(3) Symmetrical Layout

The amplifier design also incorporates a symmetrical alignment of power devices for each channel. With channels built to be identical in terms of electrical, structural, heat-generating, weight, and electromagnetic characteristics, errors in stereophonic playback are minimized.

All-Analog Circuitry Unaffected by Digital Noise

A standard integrated A/V receiver has the dual task of both processing and amplifying audio signals, and is therefore susceptible to noise interference from digital circuitry. As a dedicated power amp with all-analog circuitry, the PA-MC5501 suffers no such interference. When partnered with a high-quality pre-pro, such as Onkyo’s PR-SC5509, the PA-MC5501 offers all the benefits of pure analog amplification: a warm, musical, and full-bodied sound.

THX® Ultra2™ Certified

When a home cinema component receives THX certification, it is your guarantee that it will accurately present movies the way they were mixed by the filmmaker in the studio. In the case of THX Ultra2 certification — the ultimate benchmark for home audio performance—a power amplifier must offer high-quality, high-output performance for multi-channel playback in large rooms. Among the strict criteria that THX uses for judging the quality of a power amplifier are measurements of continuous power output, distortion levels, and heat generation.

Audiophile Design and Components for High-Power Performance

Like any Onkyo amplifier, the PA-MC5501 is designed to deliver ample power to your speakers, regardless of fluctuations in impedance. What makes the PA-MC5501 our top power amp, though, is the extra attention to parts and construction. A massive toroidal transformer; two 22,000 μF capacitors; large, custom-designed transistors; circuit boards with 70 μm thick copper foil; and low impedance copper bus plates all work in concert to enhance the power and fidelity of your audio sources. Housed in a highly rigid, anti-resonant steel-plate chassis, the PA-MC5501 also sports audiophile-grade connections: gold-plated XLR inputs; machine-tooled solid brass RCA inputs; and gold-plated, banana plug-compatible speaker posts. From input to output, signal purity is maintained at every stage.

Discrete Output Stage Circuitry to Inhibit Audio Interference

The current that drives loudspeakers is delivered by transistors in the output stage circuitry. Although adding more transistors to the output stage increases the output currentcapability, these extra transistors put added strain on the power supply and generate more heat. When the output stage is required to deliver more power than it is capable of, the top and bottom parts of the waveform are flattened or “clipped”. This clipping causes noticeable distortion, even if it occurs only infrequently. The PA-MC5501’ s circuit design keeps the transistors separate at the output stage, which means that audio signals are kept free of clipping. Also, with less heat generated, the longevity of the output stage circuitry is enhanced, ensuring that the component stands the test of time.

Technical Details

Features
FEATURES
220 W/Ch at 6 Ω, 1 kHz, 1 %, 1 Channel Driven, IEC
THX® Ultra2™ Certified
WRAT (Wide Range Amplifier Technology)
Push-Pull Amplification Design with Three-Stage Inverted Darlington Circuitry to Remove Distortion
All Discrete Output Stage Circuitry
Massive Toroidal Transformer
Two Large, Customized, 22,000 μF Capacitors for Effective Power Supply
Audio-Tuned Reference Capacitors for Each Channel
Large, Custom-Designed Power Transistors to Drive High Currents
Low-Impedance Copper Bus Plates for Perfect Ground Potential
High-Current, Low-Impedance Circuit Boards with Thick Copper Foil (70 μm)
Separate Anti-Vibration Panels
Flat, High-Rigidity, Anti-Resonant Chassis
Gold-Plated XLR Inputs
Machined Solid Brass RCA Inputs
Gold-Plated, Color-Coded, Banana Plug-Compatible, Transparent Speaker Posts
Multi-Zone Capability (up to Zone 3)*
Bi-Amping Capability*
12 V Trigger Input
Auto Standby Function
Aluminum Front Panel
*Depending on A/V Controller.