AV Receiver Reviews

When Apple introduced the iPod, many industry observers scratched their heads, wondering why Sony hadn't been the first to deliver such a product. After all, Sony had invented the Walkman—the first speakerless, portable personal audio cassette player, and Sony has a strong presence in the computer market. Perhaps heads get buried in the sand when you're promoting a new high-resolution audio format and the world is heading in the other direction. It's human and corporate nature.

When Sharp Electronics unveiled its audacious line of 1-Bit digital AV receivers based on delta-sigma modulation amplifiers, each with a built-in, progressive-scan, universal DVD player, Sony again came to mind—and for good reason. These innovative products are unique, stylish, technologically advanced, and can play SACDs. What's more, their ultramodern appearance is compatible with the form factor of flat-screen TVs: You can mount them on the wall with the supplied, easy-to-use hardware, or you can use the supplied stand mounts, which allow the two chassis to sit comfortably on a shelf.

Whoever at Sharp signed off on the budget to develop this line deserves high marks. As with music that doesn't fit into an easily categorized niche, finding retail shelf space and marketing the concept won't be easy. Writing about Sharp's SD-HX500 ($1199) sure is.

The Two-Box Solution
Sharp makes a lower-powered, one-box version of the SD-HX500, the SD-PX2 ($599), which puts out 30Wx5. Most readers of Ultimate AV considering the SD-PX2—even for use in a bedroom or second home—will want the extra 40Wpc offered by the SD-HX500. That requires a second box.

The SD-HX500's first box includes the universal player, AM/FM tuner, digital decoding (DTS, Dolby Digital, Pro Logic II), and all other control functions. Box two contains Sharp's 1-Bit digital amplification, which operates at a sampling rate of 5.6MHz: twice that of SACD, and 128 times CD's 44.1kHz. Each box is about 14 inches wide, 8 inches tall, and less than 3 inches deep (6 inches if you include the stands), and finished in a high-impact plastic that looks like sleek, brushed aluminum. The clear acrylic borders glow blue when the SD-HX500 is powered up.

The boxes are connected via two long, flexible, relatively thick cables fitted with proprietary multipin connectors. These carry AC to power the control unit in one direction, and low-level signals to feed the amplifiers in the other.

The SD-HX500 does not offer video switching facilities. If you need those, the more expensive SD-HX600 features an outboard component-video switchbox. But in many installations, video switching is redundant: the SD-HX500 has component and S-video outputs for DVD, and most modern displays offer more than two component-video inputs; switching to an HD cable or satellite receiver can easily be accommodated.

Audio inputs and switching are more generous. There are coaxial and optical digital audio inputs for the TV input, an additional optical input for the Aux input, and three sets of analog audio inputs. There's also a single optical digital audio output.

The control box's front panel features a large, round display that's easy to read, a smaller round volume control, and that's it. Small, side-mounted buttons provide DVD functionality, On/Off, and source and AM/FM switching. There's even a mini-jack for stereo headphones. However, most users will prefer controlling the SD-HX500 via its remote control, which is less than ideal. It's neither backlit nor particularly well laid out; and there are too many small buttons—including volume up and down, which I still had trouble finding after weeks of use. The remote is not so bad that it's a deal-buster, however, and it does control both the DVD player and the receiver, as well as current Sharp TVs. Codes are provided for other television brands.

Despite its apparent simplicity and its paucity of buttons, knobs, and switches, the SD-HX500 offers most of the standard receiver options for system configuration: speaker size, bass management with four crossover frequencies (80, 100, 120, and 150Hz), and speaker-delay and individual channel-level controls, settable using the built-in test tone. While there are no tone controls, there are seven presets in addition to Flat. Stadium and Hall are surround effects; Movie 1 increases the bass, Movie 2 the bass and dynamic range. With Music 1, "You can enjoy lively sound by producing the articulate sound"; with Music 2, "You can enjoy crisp, clearer sound." You can take the product out of Japan, but sometimes you can't take Japan out of the product. A Night setting adds some compression, which the instructions describe thusly: "Soft but powerful sound is achieved even at low volumes."

The DVD player is also full-function, including adjustability of aspect ratio, progressive scan, 2x, 8x, and 32x normal speed, slow motion, zoom, parental control, gamma, and sharpness.

The SD-HX500 also includes an AM/FM tuner that can be configured with station names, four different sound presets, 40 station presets, and a clock with sleep timer and clock-radio alarm.

Setup and Use
Thanks to the SD-HX500's reasonably detailed and well-organized instruction manual, setup was relatively straightforward. So is speaker hookup, thanks to the substantial speaker connectors on the amplifier's rear panel, which take banana plugs. The amplifier box also includes the subwoofer output jack (RCA). If you've ever set up a traditional AV receiver and separate DVD player, the Sharp should give you no trouble.

To watch a DVD (or to play SACDs, DVD-Audio discs, CDs, or MP3-encoded CDs), you push a button on the remote and the control unit opens like a clam: the hinged front panel descends so you can pop in a disc, label side toward you, like a piece of toast. You don't have to be careful how you do this—somehow, the transport straightens the disc out before it tries to play it. Hit the button again, the clam closes, and you're ready to roll. Switching between DVD layers, or between the 2- and 5.1-channel tracks of hybrid SACDs, is easily accomplished by pushing the remote's Audio button. Dropping discs into the SD-HX500's open jaws took some getting used to, but even when I wasn't careful—and as long as I didn't miss the opening altogether—the disc somehow managed to find its place when I closed the door.

Technology
Sharp has a long history with both SACD and 1-bit amplification. Back in 2000, the company introduced the 1-Bit SM-SX100 ($15,000), a drop-dead-gorgeous, integrated amplifier that I reviewed in the July 2000 Stereophile, I wrote, "It's unlikely that Sharp embarked on the high-tech, high-cost SM-SX100 project because it coveted a power seat at the high-end audio table. After all, to make a profit, a company the size of Sharp must feed at the mass-market trough. So what's behind this sexy-looking, beautifully built, upscale product?

"Clearly, the 100Wpc SM-SX100 is a promotional tool. It makes an 'image statement' about what Sharp is capable of producing, and showcases an exciting new amplifier technology. You can bet that Sharp plans to use this technology in less expensive future products—and, more important, license it to others."

At around the same time, Sharp introduced the less expensive SM-SX1 integrated amplifier and DX-SX1 SACD player combination, which included a unique Direct Bitstream Coupling system that allowed the 2.83MHz SACD bitstream to reach the 2.83MHz sampling amplifier directly, for the purest possible digital signal path. That concept is continued in the SD-HX500 and the other receivers in the SD series: the SACD bitstream is upconverted to 5.6MHz and amplified directly. Clearly, when Sharp developed and marketed those earlier digital designs, they had products such as the SD-HX500 in mind.

Explaining how Sharp's digital amplifier works is complex and confusing, even when stated in basic terms. The math was theorized by C.E. Shannon of Bell Labs back in 1948, but it wasn't until a few years ago that Shannon's concepts could be successfully implemented in a consumer-electronics product. Kiyoshi Masuda, chief of the SM-SX100 design project, explained it to me back in 2000, and it would take a great deal of space to cover adequately. Simply put, Sharp's digital amplifier design is a double-speed DSD converter (DSD, or Direct Stream Digital, is the 1-bit encoding scheme used for SACD) that creates an ultra-high-frequency digital "pulse train" corresponding to the amplitude of the source signal with a great deal of quantizing noise attached to it. Complex shaping and filtering of the noise is required to get it out of the audioband . The advantages of the circuit are compact size, light weight, low heat output, and, once the chips are designed and built, relative simplicity.