Does your lighting effects switch pack, make a click or thump through your loudspeakers everytime a lighting effect is switched on / off?

Does your smoke machine click along to a good tune everytime the remote control is pressed?

Does your laptop or PC freeze whenever you switch your lights on / off?

If so, then your electrical system is the victim of interference, which is being picked up and amplified by your PA system.

Most electrical interference is created when an electrical device is switched on or off. This is caused by a surge of power flowing back down the mains and being amplified by other sensitive equipment. In this case, your PA system!. The created surge is amplified many times along with the rest of your audio signal and then reproduced as the 'Thump' which you here from your speakers. Left, unsuppressed in the long term, this can cause damage to HF coils and other components in the system, and so is not only annoying, but can also cost you money in the long run.

This is especially common, in the case of cheaper lighting switch packs often available for £40 or less from Ebay and disco equipment retailers, which simply use banks of illuminated rocker switches to switch the mains directly. These are very often left unsuppressed, and so when you switch on your lighting effects, interference is produced and amplified over the PA.

Fortunately, a solution is at hand.

In the past, interference has often been suppressed by fitting a capacitor across the switch terminals. However, although this often removes some of the interferences, choosing the right value from several types, and ensuring that the capacitor is the correct mains rated type is a minefield, and often the result is only a dulling of the problem rather than removing it altogether.

To remove all switching interference, I recommend fitting a dedicated contact suppressor across the switch terminals, and in 99% of cases, if done correctly this removes ALL interference.

Buy a Contact Suppressor Here

If you are suppressing a lighting effect switch pack, then you will need to buy one contact suppressor for each channel (switch) that you are suppressing. So if you have a 4 way switch panel you'll need 4 contact suppressors, if you have 8 switches = 8 suppressors and so on.

The suppressor should be fitted across the switch contacts. If your switch pack is the type which has illuminated switches, then you will need to identify which wire is the neutral feed for the neon in the switch (The wire is usually blue or black in colour) and ignore it.

If your smoke machine or lighting panel uses relays to switch the load, then you'll need to solder the capacitor across the relay switching contacts.

Remember, if in doubt to contact a qualified electrician or service engineer for advice!.