Parasound, a purveyor of fanatically high-end consumer audio equipment, has introduced a CD player that’s controlled by an internal Mini-ITX computer running embedded Linux. Using a CD-ROM drive for playing CDs, the “Halo CD 1” sucks in the CD’s contents at 4x normal speed, giving its CPU time to detect and eliminate disc errors before outputting near-perfect audio.



By reading data from the disc at four times the speed of a conventional CD player, the device’s embedded Linux computer can read each section of the disc multiple times, checking for discrepancies between the reads. When differences are detected, the sections are read again “as many times as needed to significantly reduce errors and, accordingly, [to eliminate] the negative effects of error concealment.”

The result, according to Parasound, is a “nearly bit-perfect data stream.”





Parasound Halo CD 1 front view

(click image to enlarge)



Some key features of the Halo CD 1 include…

User choice of an op-amp or discrete analog output stage

44.1 kHz CD data is up-sampled to 352.8 kHz by an 8x interpolator

Six layer DAC board for lower noise and point of use power delivery

High performance, jitter-resistant Analog Devices AD1853 DAC IC

Ultra-quiet National Semiconductor LME49990 audio op-amps

0 or 180 degrees absolute polarity selection by remote control

Choice of silent or audible fast forward or fast back

Unbalanced RCA and balanced XLR outputs

Optical, coax, and BNC digital outputs

Full-function remote control

You can see the CD 1’s rear panel connections in the photo below.





Halo CD 1 rear panel

(click image to enlarge)



Parasound says the device meets the following audio specs:

Frequency response: 20 Hz to 20 kHz, +0/-.05 dB

THD distortion: < 0.06% at 1 kHz

S/N Ratio: > 108 dB, IHF A-weighted

Crosstalk: > 77 dB at 20 kHz

Max. output level unbalanced: 2.0 Volts

Max. output level balanced: 4.0 Volts

Output impedance unbalanced: 100 Ohms

Output impedance balanced: 200 Ohms

The Halo CD 1 typically consumes 45W when active, and 0.5W in standby mode. Its horizontal dimensions are 17.3 x 13.9 inches and its height is either 4.1 or 3.5 inches, depending on whether its feet are present or removed.



Under the hood

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Here’s a look inside the Halo CD 1, showing its Mini-ITX motherboard and other components:



Halo CD 1 internals, showing its Mini-ITX computer, etc.

(click image to enlarge)

Note how aluminum partitions provide electromagnetic isolation between its internal subsystems.



Technology

Parasound developed the Halo CD 1 through a collaboration with Holm Acoustics. An interesting technical whitepaper describes how the CD 1 works its magic. Basically…

“The CD 1 reads a CD multiple times before committing data to an enormous memory buffer stored in RAM,” continues the explanation. “Every data sector is initially read twice and the two reads are compared. When the two reads match it is because no bit errors were detected and that is accumulated in the buffer memory. When the two reads do not match it is because an error has been detected. That sector is then read repeatedly until good data is obtained. If the maximum repeat read threshold is reached and the 30 seconds buffer is about to run out, the system switches to its pre-interpolation analysis mode. Data reading is then moved forward by only one sample at a time until the bad fragment is isolated. This process almost always results in error-free data. When interpolation techniques are needed, they are confined to the single small bad fragment, thereby minimizing their negative sonic side-effects.”

Regarding the device’s use of embedded Linux, the whitepaper explains that “the Linux operating system is bulletproof and there are no other programs, so there is little likelihood of it freezing or crashing, as with computers running Microsoft Windows or Apple OS.”



Further information

The Parasound Halo CD 1 CD-player comes in silver and black, and is priced at $4,500. For more information, visit Parasound’s website. The device’s technical whitepaper is available for download here (pdf file).

