Buzzing from LV downlight transformers

[MarkP80]

Hi guys,

I was after some experiences in using dimmable traansformers for LV downlights. I've used these in a few applications and have noticed that when you dim the lights, some transformers buzz quite loudly. This can be quite a distraction if you are in a quiet room.

So, who has bought specific brands recently, and do you hear them at all when you dim them?

(I'm talking specifically 60vA units of the type you fit through the downlight hole, one per light)

Regards,
MarkP

[habrown]

Hi Mark.
The most silent on the market I have found to be Mode Lighting transformers, and reliability is good too! they are more expensive than others on the market, but you get what you pay for!

also be sure that it is not the bulb itself buzzing. the Philips Master line ES range are a bulb that stops vibration of the filament due to it's construction.

finally how are your transformers mounted? if they are just resting on a plasterboard ceiling, the ceiling will fell the vibration of the transformer and act as a drum skin, making the noise much more audible.

[MarkP80]

Hi habrown,

Thanks for the reply. I hadn't even considered that some of the buzzing may be coming from the bulbs, I'll have to check that. Also, I think the transformers are just on the ceiling - they were fitted by pushing them up through the hole. I have no other access so there's not a lot I can do there.

I'll have a look for the Mode Lighting unit you mention. Some rooms buzz more than others, so I think I need to do a good survey of what I have too. One thing I've noticed is the room where they buzz, they come on straight away, whereas in the quiet room there's a pause before they illuminate which I assume to be soft-start transformers.

I'll report back in due course, as this may be of interest to others.

Regards,
MarkP

[Bruce_]

what transformer are you currently using? does it specifically state that it's dimmable with inductive dimmers? it's not unusual for electronic transformers to be trailing-edge dimmable only.

if you get Mode transformers, be careful about which model. the ET-C is the good one, but not cheap. they have others, which work OK but might not be as quiet as the ET-C range.

there are some transformers that don't buzz, and are cheap. somewhat difficult to recommend though, as they often get updated each batch.

[MarkP80]

Hi Bruce,

Thanks for your comments. I'm not sure about the transformers in there at the moment, as I'm working away from home at the minute and I wouldn't ask MrsP to have a look! They weren't any fancy brand as I just bought them from my local electrical distributor. I don't know what type of dimmer I have, but it's a Crabtree unit, with a touch sensitive button.

Thankfully after a bit of head scratching I went for the ET-C units, which was a bit of a struggle when I was buying 10, bet hey-ho, in the scheme of things with what I've spent on av projects it's small change! I've resigned myself to being permanently skint.

Cheers,
MarkP

[habrown]

Good choice with the ET-C's. they will work with leading or tailing edge, so will be good however dimmed. by the sounds of the dimmer it is leading edge. trailing edge dimmers are not too common and are quite pricey, however are as silent as you can get!

[MarkP80]

Hi,

Just to report back, I've fitted these to the first couple of fittings and what a difference, absolutely silent when dimmed. Result!

Thanks all for the advice,
MarkP