Dell Studio Hybrid: Small, Stylish... but Quiet?

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ACOUSTIC ANALYSIS

Much of the testing was done in a quiet 20' x 10' room with 8' ceiling where ambient conditions were 20 dBA and 22°C. Acoustic testing was done in this room as well as in the anechoic chamber, where the ambient level was 11 dBA. Idle measurements were taken 5~15 minutes after boot or reboot, whenever none of the temperatures had changed for several minutes. Load measurements were taken after >15 minutes of full load.

Let's go back to Dell's environmental data sheet on the acoustics. Note that ISO 7779 calls for a distance of about 0.6 meters between microphone and noise source, compared the the 1m distance we generally use at SPCR. For a PC that's truly meant to be placed atop a desk, like the Dell SH, the ISO 7779 measurement distance is more realistic than our standard one meter.

Here are the measurements from the anechoic chamber on our sample.

Acoustics: Dell Studio Hybrid
Test State
SPL (dBA)
System Power
1m
0.6m
Idle
21
26
23W
Maximum
31
35
62W

Subjectively, the noise is not exactly loud, but it becomes a bit grating over time. As the load on the system is increased, the fan ramps up in speed. According to SpeedFan, the system idles at 43°C CPU core temperature. The fan started to ramp up at 77°C. This seems a very high temperature, and it may not be correct, as Speedfan may not have correctly identified the sensors.

Unusually, it is not the higher pitched elements in the noise that are most annoying, but rather, the hum emitted by its hard drive. The overall noise is markedly improved by distance, and if it was placed a meter or more away, most people would have no trouble describing it as quiet. Alas, being small has its price: We expect to put it on the desk next to the monitor just as Dell pictures it. Then the seated user is very close to the SH, within two feet. At that distance, it doesn't sound quiet, not to us.

It's not clear why the measured SPL difference between 1m and 0.6m was so large. In theory, the difference should be just 3 dB. It may have something to do with the particular angle of the microphone with respect to the fan of the SH. Simple fact: The noise from the back of the unit is far worse than from the front. Point the fan towards you, and the sound quality and level get much worse, with the higher pitched tonal aspects of the sound far more apparent. Point the back end away, preferably to a sound absorbent surface (as in the anechoic chamber), and the noise improves, not only in level but quality.

The hard mounting of the relatively quiet notebook drive used in the SH was the main cause of the annoying hum. The 90Hz fundamental tone of the 5400rpm drive was exacerbated by every desk we placed it on. Placing a 1" thick piece of soft foam between the SH and the desktop helped reduce the hum. In the frequency spectrum graph above, the red line represents idle noise from a meter away. The mic was positioned at about 45 degree angle from the front. The black line represents idle at 0.6 meter. The lavender line is at 0.6m again, this time with the foam damping underneat the unit. The 90Hz peak is reduced 17 dB by the foam, compared to direct placement on the desk. The on-foam placement provides 5dB more attenuation than obtained by doubling the distance from the unit.

Look below at the idle frequency spectrum at the ISO 7779 operator position (captured in our anechoic chamber):

  • The very sharp peak at 90Hz is the tonal hum of the HDD, already discussed above.
  • The higher peak at ~430Hz is the main tonal sound of the fan, unfortunately placed smack in the middle of the musical range (440Hz is the A note above middle C), where human hearing is extremely sensitive.
  • Further peaks at 1kHz and 1.5kHz are both audible as minor tonal aspects.
  • Those with keen hearing will also hear the 3~4kHz peaks.

VS. OTHER SYSTEMS

How does the Dell Studio Hybrid compare to the Asus Eee Box mentioned earlier? The latter is a lower power PC that is not capable of HD video reproduction, but it is of similar size and it has the same basic intended usage: Right on the desktop next to the monitor, mostly as a nettop. Our assessment of the Eee Box acoustics was much more positive, as its sound did not exhibit the tonality of the SH, and it was considerably lower in level. At full load, there was no contest.

The newly released Anitec SPCR-certified SilenT3 was also added to the comparison mix. This is a system with capabilities quite similar to the Dell, including HD video playback. Its acoustics are better than either the Asus or Dell.

SPL at 1m: Dell Studio Hybrid vs Asus Eee Box vs Anitec SilenT3
Test State
Dell
Asus
Anitec
Idle
21 dBA
18 dBA
15 dBA
Maximum
31 dBA
20 dBA
15 dBA

MP3 SOUND RECORDING

These recordings were made with a high resolution, lab quality, digital recording system inside SPCR's own 11 dBA ambient anechoic chamber, then converted to LAME 128kbps encoded MP3s. We've listened long and hard to ensure there is no audible degradation from the original WAV files to these MP3s. They represent a quick snapshot of what we heard during the review. All the recordings listed below were made with the mic at 1m distance.

For the most realistic results, set the volume so that the starting ambient level is just barely audible, then don't change the volume setting again while comparing all the sound files.

Comparable System sound files:

  • Asus Eee Box B202 at idle, 18 dBA@1m and 14 dBA@1m (behind LCD monitor) -- The recording of the Eee Box was made with the unit at idle, and the microphone 1m away, first on a table in the hemi-anechoic chamber, and then mounted on the back of an LCD monitor, and the microphone 1m away from the front of the monitor. It starts with the room ambient, followed by the product's noise. The acoustics of the Eee Box barely changes with load, which is why only idle noise was recorded; there's virtually no audible difference at full load.


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