Onkyo Returns to its Stereo Roots to Debut New Digital Amplifier Technology

Onkyo A-9555 integrated amplifier. Additional images at the end of this release.
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LOS ANGELES (June 1, 2006) – Onkyo introduced the A-9555 stereo integrated amplifier to enthusiasts and press at the Home Entertainment show here today, showcasing the company's new VL digital amplifier technology. This high quality audio component marks a return to the classic style, simplicity, and elegance of the heyday of two-channel equipment coupled with a unique implementation of hybrid class 'D' amplification. Because of the extremely high efficiency of this design, the amplifier effortlessly delivers a continuous 100 watts per channel into 8 ohms, and 200 watts into 4 ohms with remarkably little heat production or distortion.

"Nearly a decade ago, Onkyo introduced the acclaimed WRAT (Wide Range Amplifier Technology) that has become a staple technology of nearly all of our amplifiers," said Paul Wasek, Onkyo national marketing manager. "Since Onkyo earned its reputation for high value, extremely musical audio components thanks to its acclaimed two-channel audio designs, we see no better arena to introduce our exclusive VL Digital amplifier technology, the next generation of Onkyo amplification. Over the coming years, VL Digital amplifiers will find their way through the rest of our home theater and audio amplifier lines."

The A-9555 faceplate is dominated by a large, precision motor-driven volume control and seven position input selector. There is a speaker selection switch, defeatable analog tone controls (bass, treble, and loudness,) and a high quality headphone jack for personal listening. The rear panel features two pairs of heavy-duty speaker binding posts, six gold plated line-level audio inputs, including two loops for tape/MD players, a phono input, and a heavy-duty removable power cord.

The A-9555 also features the company's exclusive RI (Remote Interactive) control system, allowing it to control other RI-equipped components through the rear panel RI jacks. It is also compatible with the company's DS-A1iPod dock, allowing users to listen to their iPod through the stereo system, and to control basic functions using the A-9555's included IR remote control. Additionally, the DS-A1 dock charges the iPod while it is being played.

VL Digital Amplifier Technology
The A-9555 is the first Onkyo product to feature the company's third generation VL digital amplification technology. This advanced PWM (Pulse Width Modulation) design offers extremely high efficiency without the high distortion that plagues most conventional PWM designs.

VL Digital employs a high speed switching power supply that is modulated with an analog input signal, then amplified in the digital domain. Conventional PWM designs typically employ a simple comparator circuit to accomplish the critical modulation, which leaves them susceptible to the small instantaneous transients caused by variations in the power supply voltage. These transients lead to jitter-based errors in the digital signal, which in turn lead to high distortion, particularly in the upper frequency ranges.

Onkyo has corrected this flaw in traditional PWM designs through an ingenious implementation of its VL (Vector Linear) circuitry, which modulates signals based on an integration circuit rather than a comparator. This leads to a 'canceling' of the positive and negative pulses of transient distortions, effectively smoothing the analog modulation and removing the error. The end result is a remarkable decrease in jitter, and a .08% THD at 1 kHz, comparable to most class AB analog amplifiers.

Optimum Gain Volume Control
The inclusion of Onkyo's Optimum Gain Volume circuitry also enhances the performance of the A-9555, particularly at lower volumes. In conventional designs, low volume listening is accomplished by attenuating the output signal while the gain of the amplifier remains constant. This leads to an output signal that is operating uncomfortably close to the amplifier's noise floor, and often makes low level listening unpleasant and fatiguing. Onkyo's Optimum Gain Volume Control employs an intermediate, variable gain stage to maintain the audio signal remains well above the noise floor for significant improvements in S/N ratio and output clarity, especially at low listening levels.

Discrete Phono Equalizer Circuitry
Traditionally, there have been two major types of phono stage equalization employed to meet RIAA specifications, CR-type and NF-type. The more common NF (Negative Feedback) designs provide better S/N ration and dynamic range capability through the application of negative feedback. Unfortunately, this implementation requires variation in the amount of feedback applied across the frequency range, which leads to reduced fidelity, especially with regards to transient response characteristics. On the other hand, most CR type phono equalizers are superior in terms of transient response, but suffer from inferior S/N ratio and dynamic range.

Onkyo's A-9555 employs the company's Discrete Phono Equalizer circuitry, which combines the advantages of both NF and CR type equalization circuits for excellent sound quality throughout the frequency range. In the A-9555, negative feedback is applied equally at all frequencies by applying it through an RIAA equalization element at the current output stage of the amplifier. This gives it excellent S/N performance and dynamic range without sacrificing the preamplifier's transient response characteristics.

Onkyo's A-9555 will ship in August at a suggested retail price of $699.99 and be available in silver.

Onkyo, which takes its name from the Japanese "On" meaning 'sound' and "Kyo" meaning 'harmony,' has been producing precision audio components for over a half-century. The company's philosophy is to deliver products that are superbly designed and built to a consistently outstanding standard of excellence. Today, Onkyo is at the forefront of the home theater and digital revolutions. For more information about this and other fine Onkyo products, visit www.onkyousa.com or call 800-229-1687.

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