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Inside view of the VSX-1016 showing the power supply on the top left, the amplifier section in the middle and the tiered I/O distribution boards and main processing boards on the top right.
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All signals eventually lead to the heart of the system: the DSP block. According to Suzuki, the first estimates before starting the design indicated that some combinations of functions would push the processing requirements to more than180 Mips. That would exceed the limits of the Freescale DSPC56371AF180 24-bit DSP the company had been using. Nonetheless, "our DSP software engineers were determined to achieve [the design] with only one DSP LSI" to keep costs down, said Suzuki. An intense cooperative effort with Freescale's own DSP development team yielded success.
The single DSP now runs Pioneer's Digital Core Engine, providing all of the receiver's multichannel sound processing. That processing covers eight advanced concert and cinema surround modes, including the various Dolby modes, Pioneer's own Multi-Channel Acoustic Calibration system and other original sound enhancement processing, along with THX and WMA9 Pro.
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The main processor board comprises a Freescale 24-bit DSP (right) supported by AKM converters and an XM-HD tuner (bottom, middle).
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The DSP is supported on the same pc board by the popular AKM AK4628A 96-kHz/192-kHz, 24-bit, two-channel A/D converter and eight-channel D/A converter (with on-chip switched capacitor filter and 106-dB dynamic range), the AKM AK4114VQ digital audio interface and an XM satellite radio tuner. The team went with the AKM converters "to achieve the high-quality S/N [signal-to-noise], frequency response and THD [total harmonic distortion] required by THX," said Suzuki.
The video decoder and overlay board comprises the two HDMI inputs and single HDMI output. These are driven by an Analog Devices ADV7184 multiformat SDTV video decoder with fast switch overlay support as well as an Analog Devices ADV7172 digital PAL/NTSC video decoder.
The addition of HDMI interfaces proved problematic. The addition is new for the VSX line, and the radiated interference caught the design team off guard. "Some engineers in charge of HDMI, the digital audio block and the main motherboard were suffering from the radiation problem," said Suzuki. While he would not be specific in terms of how the team resolved the issue, he said that the team members are expert at resolving such radiation problems and that they applied their own "theoretical method and experience."
The amplifier section, meanwhile, relied on Pioneer's own Advanced Direct Energy (ADE) MOSFET design to produce highly efficient, high-end sound for each channel. According to Suzuki, the technique allows loudness with high quality, a sometimes difficult combination. The amplifier section comprises 14 SK SAP 17 MOSFETs spread across two finned heat sinks.
It's interesting to note that after I presented a teardown of the VSX-1016TXV at the Freescale Technology Forum in June, two designers from a high-end audio/ video company (which shall remain nameless) approached the podium and expressed disbelief that Pioneer had combined the parts and features of the amplifier at such low cost. One went so far as to say that his company used many of the same parts and components, but their price point was much higher.
The comment served as testament to the tenacity of Pioneer's VSX-1016TXV design team.
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