A milestone in Onkyo’s 70-year journey towards the delivery of lifelike transient response, Discrete SpectraModule lies at the heart of the A-9150’s main amplifier stage and is key to its outstanding performance. Discrete SpectraModule delivers a class-beating 500 V/μs slew-rate for flat linearity approaching the megahertz bandwidth. Superior slew rate enables fast and natural transients, improves signal control, and helps speakers to express subtle nuances in music, from delicate piano notes to an orchestra in full flight. High voltage performance preserves signal bandwidth for a wide soundstage with accurate instrument localization and compelling stereophonic placement in studio mixes. Improved soundstaging was an important factor in Kawai’s decision to adapt Discrete SpectraModule in its NOVUS NV10 Hybrid Digital Piano. The technology was then customized to incorporate Kawai’s tuning know-how before adoption in the A-9150.
DIDRC Filter improves listening quality with digital audio sources. Conventional circuits produce noise known as “beat”. When high-frequency signals interfere, a new frequency is generated. This presents as noise, distorting tonal character and compromising fidelity of sound you hear. Onkyo identified the mechanism that generates beat and developed DIDRC (Dynamic Intermodulation Distortion Reduction Circuitry) to eliminate this noise. Deployed on the output stage of a premium 768 kHz/32-bit DAC from AKM, the circuitry reduces noise levels to less than -140 dB, lower than audible range of about -120 dB. The design is particularly good with Hi-Res Audio sources played via the amp’s digital audio inputs. Kawai selected DIDRC Filter for its NOVUS NV10 to assist in accurate reproduction of piano tone, and in turn, Onkyo benefited from Kawai’s tuning expertise when applying DIDRC Filter in the A-9150. This technology is key to the A-9150’s uncommonly natural handling of digital audio sources.
Onkyo invested great care in the A-9150 phono stage to get best performance from any turntable. A separate audio circuit board includes dedicated MM and MC equalizers. Signals from MC cartridges are handled in discrete configuration by a top-quality customized head-amp refined after exhaustive listening tests. In addition, a relay system―not a push system―was adopted for the MM/MC selector to shorten the signal path on the circuit board. By closing the ground-line loop with a separate closed-loop earth, delicate signals can be amplified as-is for rich and authentic analog sound.
High current is vital for maintaining linearity as speaker impedance fluctuates, placing huge loads on the amplifier. The A-9150 generates high current with a custom-fabricated high-output transformer featuring strengthened windings. Two custom 10,000 μF capacitors are connected to discrete output-stage transistors via copper bus bar. This high-current low-impedance drive improves dynamic response, ensuring the full reserve of power is instantly available. Speaker transducers can react to intermittent bursts of loud and soft sounds in complex musical passages with incredible accuracy. An inevitable consequence of high electrical current is heat. To keep the output stage cool, Onkyo includes a heavy-duty extruded aluminum heat sink. This oversized unit is highly effective at absorbing heat, minimizing thermal distortion and increasing overall stability at high volume. All of these technologies combine to drive almost any loudspeaker with confidence and musicality.
Audio circuitry is protected from mechanical noise by a full-flat 1.6 mm-thick metal chassis. This strong and rigid structure suppresses high-frequency vibration generated by the power supply. Together with a thick aluminum faceplate and volume control―reinforced to eliminate another area potentially prone to vibration―the robust chassis dampens resonance and facilitates high-fidelity audio reproduction with minimal tonal coloration.
To preserve signal integrity and facilitate lossless audio transmission, the A-9150 features gold plating on select terminals including the speaker posts and RCA line-level inputs. For those looking to upgrade further, the AC inlet conforms to IEC standards, enabling users to exchange the supplied power cord to their preferred aftermarket cable.
Power Amp mode allows enthusiasts to connect an existing pre-amplifier or A/V receiver to A-9150’s MAIN IN terminals*. This is great if the owner wishes to customize sound response, or use the A-9150 to power selected channels on a compatible AVR. It’s also possible to connect a power amplifier via the PRE OUT terminals and enjoy the A-9150’s outstanding pre-amp stage, phono stage, and high-quality DAC with any source device. Whatever way you set up the A-9150, expect sound of the highest quality.
* Warning: do not connect a source device directly to the MAIN IN terminals, as this will irreversibly damage the amplifier or speakers. Please refer to operating instructions for more information.
* Speaker A and Speaker B terminals support pairs of 4–16 ohm speakers used separately. Speaker A and Speaker B simultaneous operation is supported with speakers between 8–16 ohms. Please see owner’s manual for more information.