Parasound Halo C1 Controller PARASOUND C 1 DESIGN OVERVIEW, Component Selection, The Power Supply

PARASOUND C 1 DESIGN OVERVIEW 63

The Halo By Parasound components are designed to add extra distinction to Parasound’s 20-year reputation for rock-solid reliability, amazing sound quality, and unequaled value. Although built for the home, our components have seen extensive use in professional studios. Parasound equipment was used by Lucasfilm in the production of two Star Wars movies (we received screen credits for Episodes I and II) and by other production companies.

Our design brief for the Halo By Parasound C 1 was to produce a component that could serve as the cen- terpiece for even the most complex home theater, provide for future technical developments, and meet the needs of the most critical listener and viewer. Twenty-two highly talented design engineers on three continents collaborated to fulfill that mission.

Audio and Video Circuit Path Topologies

Some things are best done in the digital domain, oth- ers in the analog. Some situations call for extensive sig- nal processing, others for none at all. The circuit path topologies of the C 1 take these factors into account.

Signal processing, such as surround decoding, filter- ing, and tone control, works best in the digital domain, where even the most complex processing won’t add noise, distortion, or phase anomalies. Analog audio signals in the C 1 therefore pass through a 24-bit, 96-kHz analog-to-digital (A/D) con- verter at the input and a 24-bit, 96-kHz digital-to-ana- log (D/A) converter after processing. Because analog circuits can handle low-level signals with no loss of effective resolution, volume control takes place entire- ly in the analog domain. The analog volume and level- trim controls, designed in collaboration with the C 1 design team, have lower noise and wider dynamic range than any others in the world. And to ensure that the volume adjustments will track perfectly together for all channels, the volume-control stages for all channels are under precise digital control.

Signals that require no processing, such as those to the tape outputs, pass directly through the C 1, entirely in the analog domain. There is also a purist Bypass mode for the balanced analog input, which sends the signal straight from input to balanced left and right front output with no processing save the volume control; the same can be accomplished for unbalanced analog stereo signals by connecting them to the left and right channels of the 7.1-channel input. As insurance against any possible circuit interactions, the balanced circuits are on a separate board, which is disconnected from the rest of the C 1 in Bypass mode, and the 7.1-channel input has its own volume control.

For bass management, the C 1 uses a patented hybrid of analog and digital circuitry to optimize head-

room while reducing noise and distortion. It also preserves bass coherence by reducing time-smearing when channels with differing delay times are com- bined into a single subwoofer output.

The C 1 has a total of 7.5 output channels, including an extra subwoofer output, a low-passed output for use with floor-shakers, and two programmable chan- nels that can each be fed a user-selectable mix of signals from the other channels.

The video side of the C 1 handles composite video, S-video and component video signals. The component video circuits, which have more than enough band- width (300 MHz) for any of today’s high-definition TV or video signals, are also on a separate board that isolates them from the rest of the video circuitry. The two component video inputs can be assigned to any of the ten audio and A/V inputs.

Component Selection

Signals in the analog domain are handled by high-speed Burr-Brown op amps, running at high current in pure class-A mode, for linear performance and musicality.

The converters, chosen for their ultra-low jitter, flawless performance and superb sound quality, are 24-bit, 96-kHz codecs from AKM, long a leader in single-chip, multi- channel, analog-to-digital and digital-to-analog converters.

The signal processor is Motorola’s Symphony DSP56367, a 24-bit processor designed specifically for audio use. With the ability to handle 150 million instructions per second (150 mips), this DSP has enough processing power to perform surround decoding, tone control, the user interface, and more. The operation of this processor is managed by the finest DSP engine in the world, designed by Flextronics Design in Finland.

Other components include metal-film 1% resistors, polypropylene and mica capacitors, and high-quality, gold-plated input and output connectors. Muting is han- dled by high-quality relays. The chassis is of heavy-gauge steel. Circuit boards are of FR4 glass epoxy; some are of four-layer construction, to ensure near-perfect ground planes for minimum noise and distortion.

The Power Supply

The C 1 uses a high-energy switched-mode power supply (SMPS). Extremely efficient, such power sup- plies generate very little heat. This allows the entire C 1 to run very cool, even when left on continually, for extreme reliability. The C 1 employs additional LC (inductive-capacitive) filtering after the filters con- tained in the power supply for the utmost purity and refinement of audio details.