I was irritated by the fact that my Samsung SyncMaster 770 had an audible buzzing sound. I thought maybe the grounding was bad so I used different outlets to no avail. I was considering returning the monitor when I noticed that the sound is only made when the brightness is at 90 or below. So as long as I keep the brightness level at 90-100 I have complete silence.
when analog dimming is used the operating point of the lamps is changed and the the color spectrum emitted by the lamps varies a bit. This in turn affects the color on the front screen.
Dependent on how much the spectrum is allowed to change you get a specific operating range for dimming. The resulting range is smaller compared to PWM dimming, where the operating point is always the same.
PWM means: you just turn on and off the lamps at a fixed frequency(synchronized to vertical frequency to avoid flicker). Changing the ratio of the on/off time ratio the intensity varies. When the lamp is on it has always the same operating point (=voltage & current) ).
Another drawback is the reduced dimming range (compared to PWM). This is a consequence of the allowed operating range for a CCFL (cold cathode fluorescent lamp).
There is no perfect back light system avaliable right now. LED backlight is in preparation (=> www.lumileds.com)...but I wouldnt wait for that.
Are you saying that all new LCD monitors make noise?
I just read of another person who had a buzzing sound and fixed it by turning the brightness past 45. I also read of someone else who said their LCD is completely silent. So I'm not sure what the conclusion of this thread is.