Samsung SyncMaster XL20 LED-backlight monitor

Audio|Video|Misc
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THE LITTLE FAN

I mentioned at the beginning of this review that the XL20 has an audible fan. It wasn't immediately noticeable at first, but once I settled down in front of it with my head no more than two feet away, I became aware of a steady whoosh, like white noise. It wasn't immediately attributable to the monitor, but I realized that where it was coming from after a minute or two. An examination of the back of the unit revealed its location.


The little fan, seen from the back, at the lower center, behind the post of the stand.

The fan's diameter is about 40mm, and it seems to be thermally controlled, as it gets louder after the monitor has been on for a while, shifting slowly from a white noise type of shhhh to a more machine-like whirr. At 20-22°C ambient, this transition occurred slowly, taking at least half an hour. Sound Pressure Levels were measured with our trusty B&K 2203 sound level meter from two feet directly in front of the monitor. The noise is slightly louder from behind the monitor, by 1-2 dBA depending on how far you are.

Samsung XL20 Fan Noise (SPL)
@2ft
At turn on
after one hour
XL20
21 dBA
23 dBA
XL20 + PC
23 dBA
25 dBA

The SPL at two feet represents the approximate distance between the monitor and a typical seated user. The first line of SPL readings is with just the monitor alone. The second set is the more realistic combined level of the monitor and the PC. (The monitor would not be on without the PC also being on.) For SPL at the standard one meter, just subtract 1 dBA.

When the monitor first turned on, the level is low enough to be masked by the ambient noise or the noise from the computer, even one as quiet as mine under the desk. (It measures about 22-23 dBA@1m but it is nearly inaudible from the seated position.) But as the fan in the XL20 slowly speeds up, after an hour, the noise becomes loud enough to be a bit bothersome if you're used to a very quiet computer and no noise from your monitor.

NOISE RECORDINGS IN MP3 FORMAT

Most of our audio recordings have been made at 1m distance, in keeping with the distance we use to measure SPL. Some recordings are also done at 30cm distance, mostly for those sounds that are difficult to hear from a meter away. In this case, the rules have been broken, for a good reason: No one sits a meter away from a 20" monitor; you have to be within about two feet to work with it. No one sits just a foot away either, except when you're peering at a fine detail momentarily. So, the recordings were all made at 60cm or 2' from the front of the monitor. When comparing against other 1m distance component noise recordings, just treat them as if they were all recorded at the same distance. More details about how we make recordings can be found in our article: Audio Recording Methods Revised.

Each of the XL20 recordings begins with a five second interval of just ambient room noise, with no machines making noise in the room, followed by 10 seconds of the component noise. For best results, set your volume control so that the starting ambient noise is just barely audible. Be aware that very quiet subjects may not be audible — if we couldn't hear it from one meter, chances are we couldn't record it either!

Comparative: Reference 120mm fan: 5V-7V-9V-12V, 5s Ambient between levels: One Meter, One Foot

Why is a fan needed at all? This seems especially curious, because LED backlight monitors are commonly touted as being more energy efficient than the Cold Cathode Fluorescent Lamps (CCFL) used in most LCDs. I did notice some heat when I ran my hand across the top vents in the back, and the screen itself. It was time to measure the power consumption, which would tell us how much heat is being generated in the monitor.



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