When Things Go All A Tweeter

Sydney Morning Herald

Monday January 1, 1996

Greg Borrowman

YOU may have enjoyed your New Year's Eve party, but did your loudspeakers? Now may well be the best time to check whether the loud music you have been playing during the festive season has destroyed one or more of your speakers. The tweeters, those tiny speakers at the top of each speaker cabinet, are the easiest to damage and worse, are not covered by your five-year warranty.

If you have been unfortunate enough to lose a tweeter, you may be able to save money by repairing it yourself. Although there are hundreds of speaker brands on the market, most use tweeters that are readily available from electronics stores, such as Dick Smith and Jaycar, usually at prices considerably below those quoted for replacements provided by the original manufacturer.

To test if your tweeters are still working, play a piece of music with lots of high-pitched instruments and put your ear directly in front of one tweeter. If you can't hear any sound at all, it's likely the tweeter has been damaged. Check both left and right channels, because it's common for only one tweeter to fail.

Replacing a damaged tweeter can be quite simple. First, remove the screws holding the tweeter in place. Some manufacturers use adhesive to ensure an air-tight seal, so you may need to pry the tweeter away from the front baffle with a screwdriver. When the tweeter pulls out, you will see two wires attached to the rear, usually by spade connectors. One will be connected to the positive terminal and the other to the negative. Before you undo these wires, label them to ensure you can connect the replacement tweeter with the same polarity.

If you're in luck, the tweeter will have the original manufacturer's name on the rear. If you're particularly lucky, the tweeter will be made by one of the "big seven" - Audax, Dynaudio, Focal, Peerless, Philips, Seas or Vifa. Tweeters made by these companies are readily available in Australia via local agents or wholly owned subsidiaries. Your hi-fi dealer will be able to provide a contact phone number. Once you have sourced the replacement, it's simply a matter of reconnecting the wires and screwing the tweeter back into the baffle. Use silicon to ensure an air-tight seal.

If the tweeter is not labelled, or carries the same brand-name as the loudspeaker itself, ring the local distributor and ask whether it was made by one of the seven manufacturers mentioned. If it was, request an original part number then proceed as outlined above.

In the event the tweeter was not made by one of the big seven, find out the price of an "original" replacement, but don't order it straight away. Instead, contact your local hi-fi dealer and explain your problem. The dealer may be able to provide an identical tweeter at a substantially lower cost. Sometimes, you may get a better tweeter for the same price.

How is it possible to buy a better tweeter than the one originally fitted? Often, speaker designers cut production costs by ordering special runs of tweeters with smaller-than-usual magnets, or by accepting batches that don't quite reach specification. When you buy direct from the original tweeter supplier, you are guaranteed a bigger magnet and a unit that meets its specs.

Even where the designer used the best quality tweeter available at the time, better versions may now be available.

Watch out, because tweeters are not generally interchangeable. Unless you are swapping a tweeter with an identical model or a MKII version that has been verified by the manufacturer as being compatible, make sure you get expert advice before proceeding.

How much money can you expect to save by doing it yourself? If your tweeter turns out to be a Vifa D19, which is highly likely, figure on saving at least $60 each pair on the parts' costs alone. If it's a Vifa D26, you will save at least $170.

Protecting tweeters from burning out is not just a matter of commonsense. Most tweeters are destroyed not because the amplifier driving them is too big, but because it is too small. Paradoxically, you are more likely to damage a tweeter by using an amplifier rated at 30 watts per channel than one rated at 80 watts per channel.

This is because it's easier to distort a low-powered amplifier than it is a high-powered amp, and it's the distortion that causes the damage, not the power.

Some manufacturers protect their speakers by inserting a positive temperature co-efficient (PTC) resistor in series with each tweeter. Others use ordinary fuses. Neither system is common.