I have been looking at the “High CRI” LED 7w dimmable bulb at this web page:
Many LED (and CFL) low energy bulbs have flickering and buzzing noises when dimmed; can I ask how much this bulb is affected by that, and also compared to other LED bulb brands?
Thanks in advance for any answers you can give
Thanks for the interest and the technical question.
Buzzing/whistling in particular is indicative of issues of incompatibility between dimmer and load (lamp) and under normal circumstances should not occur if units are compatible. Note that overloading a dimmer unit with a load that exceeds permissible ratings can also give rise to noise, most if not all in both cases coming from the dimmer unit.
Generally if there is noise, primarily from the dimmer pack and possibly occasionally from the lamp(s) it is advisable not to operate the units together without seeking assistance.
We, and others, have exhaustively tested our lamps with commonly used dimmers used by electrical installers and found them to operate satisfactorily with respect to noise and dimming ability, free from flicker, over the full operating range. Regretfully we cannot comment on the performance of lamps from other manufacturers for obvious reasons.
There is a tremendous choice of dimmer units available and it is impossible to test all, some have been installed and used well before the advent of CFL and LED lighting and intended only for incandescent lamps only. As a generally rule of thumb dimmers have a minimum (and maximum) load rating, compliance is essential for correct performance.
Older units may have a minimum loading of 25-40w and are generally intended for use with incandescent lamps. They will not work correctly with loads less than the specified minimum and will certainly not work with low energy devices such as LED lamps which use so little power. The filament of the lamp actually is part of and therefore essential to the operation of the dimmer.
Certain dimmer units not intended for LED lamps may actually work satisfactorily without noise but again because of the low power requirements may not dim the unit over the entire operational dimmable range. Typical operation under these conditions is indicated by the LED failing to extinguish at minimum settings on the dimmer unit and not responding until the dimmer is well advanced.
We are aware of and have tested dimmers, some described as digital dimmers, that are manufactured in the Far East that purport to effectively dim LED lamps which not only don’t but seem to have difficulty in dimming incandescent lamps, such is the variety of units available.