Analysis of Onkyo TX-DS939 AV Amplifier

TX-DS939 AV amplifier was launched at the beginning of the release of Do1ly AC-3 technology. Its golden appearance and simple and elegant design give people a noble feeling. Its AC-3 decoder adopts 56009 and 56004 24-bit digital processing chips produced by Motorola, which are used to process Dolby AC-3 and THX control programs respectively. 56009 is the world's first AC-3 decoding chip with 24-bit design. Its operating frequency is 80MHz and its maximum transmission rate is 40MIPS, while the traditional 20-bit chip has an operating frequency of 66MHz and a maximum transmission rate of only 33MIPS. In addition, 56009 consumes less power than traditional chips, and the heat generation is greatly reduced. This is very meaningful for AV amplifiers with high heat generation, and can greatly reduce the heat dissipation design work of the chip. When it is used with the THX processing chip 56004, which is also 24-bit, it can be seamless.
The most special feature of Onkyo's TX-DS939 amplifier is that it comes with a measurement microphone, which can automatically set the speaker level and placement distance. The speakers are placed at different distances in the listening range. General technology can only adjust the appropriate sound pressure level for the first channel. Onkyo's unique ARA sound field analysis system can not only automatically adjust the sound pressure level of each channel, but also set the delay time of each channel, so that users can easily obtain the best effect and accurate frequency response.
In addition to using high-quality fever components in the power amplifier part, the TX-DS939 uses a large transformer weighing 5.5kg, plus a thick sealing layer, which not only has a heat dissipation effect, but also prevents resonance. The 5 power amplifiers of the TX-DS939 are low-impedance drive methods with all discrete components, and their power is as high as 200W×2 (front left/right channel 6Ω) and 185W×3 (center/surround channel 6Ω). From the perspective of pure music, when its total harmonic distortion is 0.003%, the power of its front channel is as high as 120W×2. It is enough to easily drive any AV speaker. All five channels of TX-DS939 use large anti-magnetic binding posts to ensure smooth audio current flow. The ultra-quiet cooling fan on the back panel of the chassis greatly improves the heat dissipation performance of the whole machine. The fan adopts an intelligent control design and is only turned on when the whole machine is working at full load, which reduces the interference of the fan current to other parts and also reduces the burden on the power supply. TX-DS939 provides extremely complete input terminals, including 4 sets of analog inputs, one set of AC-3 RF inputs, one set of coaxial inputs, two sets of optical fibers and three sets of video and S-Video inputs. In this way, TX-DS939 can ensure that you can easily connect various types of AV equipment.
When TX-DS939 plays CD stereo, the sound quality is slightly stiff, but crisp and full of vitality. It cleverly mixes moderate viscosity and clarity, especially in the mid-low frequency band, and the performance is extremely charming. Although the bass frequency is not rich, the layering is quite clear, proving that this machine has very good resolution. When replaying surround sound, the most charming thing is the thick and sticky sound field of THX5.1 channel. The texture of the lines is a little too soft, but the surround sound effect is very rich and wide. Whether it is 2-channel stereo or surround sound playback, the stability of the sound is outstanding, which is of course closely related to its rich power supply. With such excellent spatial reproduction, it can be said that it has opened up a new realm for home theater systems.