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There is no confusing Audio Research components with anything else. Their aesthetics worked out years ago right at the beginning of the company’s existence referring directly to lab or recording studio equipment has proven timeless. That’s a rarity. What we have here is a large aluminium enclosure with two handles mounted to the front. This was taken directly from pro audio racks where handles are used to slide components in and out of large stage racks. Here they merely serve decoration but serve it well. The large front features a green display, green LEDs and silver drive control buttons. The display is a classic type and sold bundled with the Philips CD Pro2R. It is small and assigned to the drive. It cannot be used to display other information like digital input sample rates or bit lengths. The latter data is not available but the sample rate is indicated by a vertical row of LEDs right next to the display. It is a pity that ARC did not use the display of its preamplifiers. The second row of LEDs shows the selected input (or CD drive) and the third row indicates the currently selected digital filter, power and upsampling. The upsampler is synchronous. While this choice is infrequent, it is well grounded as the necessary signal processing is significantly easier than with asynchronous upsampling. 44.1kHz and 88.2kHz signals are upsampled to 176.4kHz, 48kHz and 96kHz to 192kHz. The USB input is treated differently with only the base frequencies upsampled – 44.1kHz to 88.2kHz, 48kHz to 96kHz.
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The CD9 sports a balanced analog output stage, hence XLR and RCA outputs. The latter are particularly noteworthy. Although they bear the ARC logo they look to be CMC (Charming Music Conductor) and are of very good quality. The coaxial digital input comes from the same source and is found right next to three other inputs: AES/EBU, Toslink and USB. All accept 24/192. The USB input is of the asynchronous 2.0HS type. While nowadays it is an increasingly less used function, the CD9 can be used as a dedicated disc transport, hence the presence of BNC and AES/EBU digital outputs which are always active (at least I found no information whether they can be disabled).
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The disc is placed directly on the motor shaft or rather on a plastic receiver mounted to it and under a manual sliding door. We mount a lightweight aluminium puck atop the disc and its TOC is read after the lid closes. Opening it automatically stops playback. This is not a machine whose interior is mostly air dielectric. The entire space is tightly packed with circuits mainly due to the tube-based analog section with dedicated valve power supply. Both I/V conversion and gain/buffer stages are tube-based and employ the large 6N30P dual triodes from Russia's Sovtek. The two tubes in the power supply come from the same manufacturer and are the 6550WE beam tetrode and another 6N30P. I saw no coupling capacitors between the tubes in the signal path. We find Wima coupling capacitors in the output and RealCap and Multicap filter caps in the power supply which is very complex.
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I counted six secondary windings on a very large R-core transformer as well as many large filter capacitors and voltage regulating ICs. The power supply and analog circuits mount on a large circuit board bolted to the bottom of the enclosure. The side with the transformer is mechanically decoupled with dampening material beneath the board. Vibration isolation seems particularly important to Audio Research. All electrolytic caps feature damping material as does the underside of the top panel. The 6N30P tubes sport rubber rings to reduce microphonics.
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The digital section is mechanically and electrically isolated from the analog stage. It mounts on a small separate PCB bolted to the rear and side panels. At the input we have a Burr Brown SRC4391 sample-rate converter followed by two Burr-Brown PCM1792 stereo DAc chips, one per channel. It is these DAC chips that allow built-in digital filter selection. Their stereo channels have been paralleled for mono. The USB input is handled differently. Its PCB plugs upside down into the main board for easy future upgrade. The circuit is based on a Cypress Semiconductor CY7C68013A. Next to it is a Xilinx Spartan FPGA along with two master clocks, one for each sample-rate family. The company literature claims that signal from all sources is reclocked to minimize jitter. I would bet it happens here. All electrical digital inputs as well as outputs feature impedance-matching transformers. The CD drive mounts to a large T-shaped profile machined from solid aluminium and decouples with springs.
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The remote control looks old-fashioned like the component itself. It takes some skill to operate as the buttons are close to each other and quite small. In addition to the basic drive commands the remote can be used for input and digital filter selection, the upsampler and dimming or disabling the display.
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Specifications according to the manufacturer:
Frequency response (XLR output, 200kΩ load/192kHz input):3Hz - 96kHz (+0/-3dB), 20Hz - 20kHz (-0.15dB)
THD + N: <0.003% / 2V RMS/XLR
Signal/noise ratio: 110dB
Dynamic range (AES17): 110dB
IMD (SMPTE): 0.002%
Noise level (RMS): -95dBV (20-20kHz)
Gain:14dB/XLR, 7dB/RCA
Output impedance: 660Ω/XLR, 330Ω/RCA
Minimum load: 20kΩ (2000pF maximum capacitance)
Jitter: <10ps
Channel separation: 107dB/1 kHz
Power consumption: 120W maximum / sleep mode 1W
Dimensions (WxHxD): 480 x 134 x 390mm
Weight: 15kg |
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opinia @ highfidelity.pl
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