Sorry, we couldn’t resist the headline. For the record: We’re not predicting the early demise of AMD’s new Live Home Cinema reference platform (which is code-named Maui). AMD sent us a sample build several months ago, but we wanted to live with it for a while before publishing our thoughts on the design.
We’re big fans of home-theater PCs, especially the build-it-yourself variety (be sure and check out the May issue of Maximum PC for Will Smith’s terrific how-to guide to building one of your own). If AMD can resolve one major issue, we think Maui will be the best home-theater PC platform on the market.
With a home-theater PC, you can stream all manner of Hollywood content for free (from websites such as Hulu) or for a small fee (from online stores such as iTunes, Netflix, and Amazon’s Unbox). While you can accomplish the same thing with a media center extender and any PC equipped with a version of Windows that includes Windows Media Center, a dedicated HTPC leaves that other machine available for other tasks. A home-theater PC with a Blu-ray drive can play HD movies, too, but comparing home-theater PCs to Blu-ray disc players—which are becoming increasingly PC-like—is more problematic. We’ll get to that soon enough; for now, let’s take a detailed look at AMD’s Live Home Cinema platform.
The hardware to build this particular AMD reference design would cost around $900 at retail. It’s based on an AMD Phenom X4 9350e quad-core processor plugged into an MSI MS-7411 micro-ATX motherboard (which MSI markets as the Media Live Diva). The MS-7411 uses AMD’s RS780M/SB700 chipset with an ATI Radeon HD 3200 integrated graphics core (the RS780M is a mobile, low-power version of AMD’s RS780G chipset, with added support for component video output). AMD stripped all legacy components (except VGA) from the motherboard’s design; you won’t find serial or parallel ports, PS/2 mouse or keyboard ports, or even a PCI bus.
The CPU is cooled by a closed-loop cooling system, the Noise Limit SilentFlux Media heatsink and fan. The SilentFlux boasts a very low profile that’s optimized for horizontal installations, such as a home-theater PC: Its radiator rises just 2.36 inches above the CPU. It’s also extremely quiet, with a stated noise level of just 21dB. We didn’t encounter any problems running the PC in our enclosed entertainment center, even those times when we forgot to turn on the ceiling-mounted cooling fan inside there.
AMD shipped this evaluation system with 2GB of Aneon DDR2-667 memory, a Pioneer BD202MR Blu-ray, and a 500GB Seagate Pipeline HD hard drive.
The Maui design’s biggest claim to fame is the presence of a D2Audio DAE-3 digital audio engine, which can output 2.1-channel analog audio from the motherboard. Alternatively, you can pair it with either a five-channel amplifier card or a seven-channel pre-amp card. D2Audio designed both these components, and AMD sent both for evaluation. If you buy MSI’s Media Live Diva 5.1, you’ll get the amplifier card; purchase the Media Live Diva 7.1 and you’ll get the pre-amp card.
The amplifier delivers up to 100 watts per channel to passive speakers (you connect your eight-ohm speakers directly to the card, there’s no need for an A/V receiver or even powered speakers—other than a powered subwoofer, of course). The amp delivers an impressive signal-to-noise ratio of 105dB and total harmonic distortion (THD) of less than 0.5 percent. It will drive four-ohm speakers, too, in which case it will deliver 200 watts per channel. You’d have to spend a great deal of cash to find a stand-alone amp with comparable specs.
The pre-amp card boasts an even higher signal-to-noise ratio of 110dB (with 0.5 percent THD) while adding support for a pair of rear surround channels. You connect this card to your A/V receiver (or powered speakers) using conventional RCA cables—there’s no need for funky adapters or anything else in the signal path. Alternatively, AMD’s RS780M chipset can deliver compressed 5.1-channel digital audio over HDMI. The reference design also includes a Realtek ALC888 audio chip on the motherboard that delivers digital audio over a coaxial S/PDIF connection (optical S/PDIF is not supported).
Most people considering a home-theater PC will be looking to play Blu-ray movies, and this is where AMD’s solution (indeed, all PC solutions) falls short. There’s no problem getting high-definition video to your display: You can use either HDMI (integrated into the motherboard, so here again, you don’t need an adapter) or component video cables (although you might have a problem transporting DRM-protected video over component cables). The problem lies in the audio realm, an area in which this solution is otherwise absolutely marvelous. It has nothing to do with technological limitations and everything to do with the D-word (DRM, or digital rights management).
The AACS (Advanced Access Content System) copy-protection system used to encrypt Blu-ray discs dictates that Blu-ray player software (e.g., Cyberlink’s Power DVD Ultra) must use a so-called “protected path” to send high-definition audio (e.g., losslessly compressed Dolby TrueHD or DTS-HD Master Audio) across a user-accessible bus such as PCI or PCI Express. The objective is to prevent anyone from intercepting the unencrypted audio and making a bit-perfect copy. The Blu-ray video bit stream is subject to the same restriction, but the Windows ecosystem is capable of handling this.
The D2Audio chip on the Maui platform uses a closed, proprietary bus, so it does seem to be in compliance with AACS. Unfortunately, AMD has so far been unable to convince any of the companies developing software Blu-ray players to send unencrypted HD audio over that bus.
The work-around is for the Blu-ray software player to decode the losslessly compressed audio, down-sample the bit stream from its 96kHz sampling rate with 24-bit resolution to a 48kHz sampling rate with 16-bit resolution, and then pass the uncompressed eight-channel LPCM (linear pulse code modulation) bit stream to the D2Audio chip. The D2Audio chip converts the bit stream to analog and sends it to the pre-amp card, the motherboard’s line-level outputs, or the amplifier card. The D2Audio chip does not pass digital audio of any form over HDMI.
Needless to say, down-sampling is less than an ideal compromise. Then again, the mere availability of a movie on Blu-ray disc doesn’t automatically mean that it has a Dolby TrueHD or DTS-HD Master Audio soundtrack or that it’s encoded using the highest possible specs. You’ll encounter many films with audio encoded at a 48kHz sampling rate with 24-bit resolution, for instance, and many more that are encoded at a 48kHz sampling rate with 16-bit resolution, at which point down-sampling isn’t even necessary. The website CinemaSquid maintains a comprehensive searchable database of Blu-ray releases that includes such information.
Many people will contend that the average consumer can’t tell the difference between HD and lesser audio—but who’d be willing to spend $900 or more for a PC that can’t offer one of the features that a $300 Blu-ray player can. In our book, audio quality is the second biggest reason to buy any hardware that’s capable of playing a Blu-ray disc and Maui represents a compromise on that score—whether we can hear it or not is moot.
We played with the amplifier card for a bit, and while it does deliver excellent audio quality, we’re not ready to take our A/V receiver out of our entertainment center. For starters, the amp doesn’t accommodate rear surround speakers (it’s limited to left and right surrounds). And as terrific as it sounds, even a home-theater PC isn’t set up to handle all our audio sources (although the motherboard does have a pair of RCA jacks for analog line-level input. Plug in a stereo source—such as a VCR—and you can route the audio to the amplifier.)
But we also use a satellite receiver/DVR to watch and record television, and there’s no way to pipe surround sound from the satellite tuner to the PC. And while we could use the HTPC to stream music from our Windows Home Server machine, we still prefer the Sonos Multi-room Audio System for music listening. Besides, the pre-amp delivers a higher signal-to-noise ratio, and it sounds fabulous.
The reference design supports AMD’s OCUR TV tuner for use with the digital cable set-top boxes, but you can still only buy such a card as part of an OEM system build. Our reference design came with AMD’s ATI Theater Pro tuner card, but the value of over-the-air tuners such as this is severely by the fact that they can’t access premium cable and satellite channels (HBO, Showtime, et al).
AMD chose nMedia’s HTPC 1000B enclosure for its reference platform, the look of which fit right in with the other components in our entertainment system. The aluminum case has a single 5.25-inch drive bay for an optical drive and four internal 3.5-inch drive bays. The front panel has a cut-out for an LCD (the reference design had one, but the display is not included in the price of the case), and there’s a flip-down panel that hides one eSATA, one FireWire, and three USB ports; a media card reader; and 1/8-inch jacks for a mic and headphones.
We added Microsoft’s Wireless Entertainment Desktop 8000, but we swapped out the useless (in a living-room environment, at least) mouse for a Gyration Air Music Remote (which you can now find for a pretty reasonable street price of $85). We connected the PC to both an Epson Cinema 500 video projector and a ViewSonic N4285P 42-inch LCD television.
Everything went smoothly until we connected the Maui system to a Sherwood RD-7503 A/V receiver: The computer would not send the receiver a video signal over HDMI with resolution any higher than 640x480 (480p). Curious to see whether the problem was with the computer or the receiver, we then connected the HDMI from HP’s Pavilion HDX 9000 notebook PC, which is equipped with AMD’s Radeon HD 2600 XT videocard: We ran into the very same problem.
We then tried a second desktop PC, which was outfitted with an Nvidia GeForce 9800 GT (with a DVI-to-HDMI adapter). This time, the Sherwood receiver performed as expected. We also didn’t encounter any problems with the HDMI outputs from an upscaling DVD player and a Samsung Blu-ray disc player.
The last we’d heard from AMD, they thought the problem to be related to the computer not reading the receiver’s EDID profile correctly, although they told us they’d never encountered a problem with other A/V receivers they’ve tested.. Sherwood told us they’d seen a similar problem with a Motorola DCH3200 digital cable set-top box, but that they weren’t familiar with AMD’s Maui platform and had no further comment on the matter.
AMD’s engineers deserve a big round of applause for giving so much thought and consideration to audio while designing the AMD Live Home Cinema reference platform; sound is all too often overlooked in PC designs, and Maui’s D2Audio components are divine.
We know AMD is working hard to convince Hollywood and software developers that it provides the protected audio path that software Blu-ray players need to avoid down-sampling Dolby TrueHD and DTS-HD Master Audio soundtracks. Should they succeed, however, stand-alone Blu-ray players will still have one advantage over the PC: They can send both HD video and HD audio to an A/V receiver using a single HDMI cable: Maui will always need at least an HDMI cable for video and as many as eight RCA cables for audio.
Aside from those limitations, Maui is a splendid destination.