AMD Maui: Ultimate HTPC Integration

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TESTING THE AUDIO

The challenge was how to assess the quality of the Maui amplifier. We didn't have easy access to a good multi-channel music or audio/video system, so that kind of comparison was out. SPCR happens to be home to an excellent if aging high end conventional 2-channel audio system, however, and since it's primarily the quality of the sound we wanted to assess, it was decided that a drop-in of the Maui system as a replacement for key components would make a useful comparison. Of course, it is an unfair comparison, but it will tell us something about the sound quality of the Maui amplifier.


The clutter during the audio testing.

Existing Audio System Details

The speakers are on the short wall facing into a fairly large, 12' x 30' living/dining area. The acoustics are fairly live. As a rough guide to the quality of the existing audo gear, when it was new, the total cost of the above components was nearly US$7000.

TEST PROCEDURE

We determined early on that the Maui PC as shipped to us was not quiet enough for our taste. In idle, it measured 30 dBA@1m, and the sound character was not particularly pleasant. The fans were obvious culprits. Replacing the Silent Flux heatsink/fan with an Arctic Cooling Alpine 7 made a big difference, especially with the fan slowed through the MSI board BIOS. So did undervolting the 60mm exhaust fans and removing the wire grills over them. By the time we finished tweaking the system, the measured SPL in our anechoic chamber was ~22 dBA@1m, which is quiet enough, especially with music playing when the system is on.

A variety of music was played for several listeners on the existing system. Then, the AMD Maui PC system was plonked in place of the Linn preamp/amp combination, priced originally at ~$4,000. The analog output from the MSB DAC went into the phono line inputs of the Maui, and the NHT 2.9 speakers were driven directly by the amplifier in the PC. The same music was then played again. The music selections were varied, and included, among others:

Our general reaction to the Maui PC amp was.... Wow! With the volume set at a fairly nominal living room level (peaks measured 80~85 dBA 1m from the center point between the two speakers), the change in the sound from the Linn preamp/amp was subtle. As with the Linn amps, the sound was lively, dynamic, detailed, clear, transparent. There were no obvious losses or degradations such as thinner bass or harsher sibilants. Mostly, the music came through much like before. It was quite impressive for a modest little $100 board inside a computer to come even close to matching $4,000 worth of discrete high quality audio amplifiers.

The power limitations became clear as the volume was increased. With peaks breaking 90 dBA, the sound became a bit harsher, and occasional clipping distortion could be noticed on bass transients. It also sounded more compressed and less "at ease" at this high volume. As long as the level was kept below 90 dBA, however, these limitations did not intrude. While pop music concerts are routinely loud enough to cause at least temporary hearing damage, probably well in excess of 120 dB at 1m from the speakers, 90 dBA@1m in a typical home environment is fairly loud.

The Maui system was kept in the audio system for about a week, during which time, it was used casually a couple of hours daily. The library of several hundreds of albums is usually on random song play, so this is a wide range of music types. No addtional hum or buzz was noted, nor were there any other audible artifacts. My wife noticed no change in the sound, but did wonder about the mess in the living room; that's telling.

Whether this high level of performance is evident when the Maui is driving five speakers is not clear from this test. Our take is that as long as the output power limitations are respected, there's no reason not to expect the same performance with all five channels going.



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