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Short Fuse - PA Speaker Repair

Suspension rings:

Most PA speakers have a cloth suspension ring which can become either brittle or ‘limp’ over time and can be replaced, providing the correct size is available.  Some drivers do have foam suspension rings and these too are available. Minor damage to paper suspension can be repaired in most cases and some age issues can postponed in antiques.

Coil Rewinds:        

A PA speaker can be “Open Circuit” for a number of reasons, overpowered, amplifier problem or corrosion. If the coil has failed, in most cases we are able to rewind the driver; the only time we are unable to do this is when the coil former is destroyed.  It is amazing what we are able to repair but sometimes they are “a little too far gone”.

Coil Rewinds

Coil Rewinds

A good example of Yes, we can do this. Before and after photos of a 15” Wharfedale rewind.

Our rewinds are so far proving to be stronger and with similar or greater sensitivity than the originals. 

Coil RewindsNo, not a rewind on this one This one caught fire!. We can remove and replace the coil and spider. Technically this would come under “Recoiling” These photos show classic signs of Amp failure with catastrophic burn at one end and mostly untouched at the other. In this case we can replace the coil assembly and spider with original, aftermarket and locally produced products.

 

 

Custom Made Coils:

We can do custom rewinds to change impedance but need to know why to be able to meet your needs. Changing from 8 to 4 ohms (for example) would generally mean, “put thicker wire on”! This would mean fewer turns of wire overall and therefore tend to be insensitive in comparison to the higher impedance driver. The same number of turns would give you the same sensitivity but add significant weight and may no longer fit in the magnet gap. We generally try not to go this path. For people trying to just ‘get more power‘ out of a driver, this is not the way.

Custom Made Coils

Custom Made Coils

We built a new coil former to repair this 15” JBL Driver

Reconing:

The ultimate repair, this replaces all the moving bits, everything bar the frame/magnet assembly. It is the next best thing to a new speaker. We can get many original re-cone kits and aftermarket supplies are becoming available for old standards and some hard or impossible to get speakers. If you have a volume of frames for re-coning on no longer available drivers we may be able to get them produced. Given transport and production times, you would need to balance this against outright replacement. In any instance, we would need a sample driver to measure

Horn Diaphragms:

Horn DiaphragmIn most cases we are able to rewind diaphragms, yes even those antique ones you have had forever. If the diaphragm or suspension is damaged, a replacement can be obtained with many kept in stock. If damage has been done, we can generally point you to the reason for the failure and suggest methods to stop or minimise future failures.

 

Custom Leads:

Leads can be custom made to any length and with any combination of standard ¼” (6.35mm) jack, Cannon/XLR and Speak-on plug or socket. We can direct you towards good local custom specialist lead makers for professional and studio use. 

Repairing Torn Cones:

Paper cones can quite often tear themselves apart, as per the photo below, often they can be repaired but sometimes the tear is unrepairable and a recone is required.

Torn speaker cone

 

Repaired & back in its box

Repaired & back in its box

Maintenance:

Major problems occur with PA drivers due to build
up of dirt and magnetic filings entering the magnet gap. 

We recommend regular cleaning of the following:

Suspension Ring:

By wiping gently around the edges either with a soft toothbrush or small paint brush.  Carpet dust—sand—fluff etc builds up in the these crevices and over time hardens and starts to eat into the material.  Check for holes or splits.  If damage is found, don’t attempts repairs yourself as each section of a cone requires specialised glues.  Use the wrong glue and you could have to replace the suspension ring.

Cones:

Gently brush both front and back with a soft paint brush.  Check carefully for fractures—these appear as little creases at first and if untreated can result in major cone damage.  This damage can cause vibration on a certain chord or volume.

Domes:

Check for any lifting or splitting.  Even a very small hole can cause distortion and will always allow dirt into the magnet gap, causing major damage.

Spiders:

These suck in the air around the box.  As they are porous, dirt and dust also get pulled into the magnet gap and build up.  Dust outwards from the cone with a soft toothbrush regularly.

Basket & Magnet:

Run around the magnet with masking tape to remove magnetic dirt.  Wipe basket with a cloth.

Leads:

Check that there is no corrosion or burning.  This can cause static or cutting in and out of your speaker.  Better to have them replaced than to be caught dead at a gig.

Boxes:

Should be vacuumed out at least every 3-6 months. There should be no sawdust or wood shavings inside (Caution MDF dust is Toxic), carpet dust and sand also find their way in.  This dirt gets sucked directly into the voice coil gap of your speaker and builds up.  Ideally the inside of the box should be painted.  Don’t rough handle boxes as the seals could weaken and cause box vibration.  Consider getting covers for them when not in use.

Speaker Rotation:

When taking the speaker out of the box you should mark the top so that you can rotate it on each maintenance.  This prevents gravitational dropping of the cone.  First rotation should be top to bottom then 90 degrees clockwise thereafter.

Horns:

Should have their magnet gaps cleaned out regularly.  The flares or front of horns or tweeters should be kept clean.

 

If in doubt about the performance of your speakers,
stop using them and have them checked out.

If you don't have the time to regularly maintain your equipment,
why not get us to do it for you?

Short Fuse Speaker Repairs - Tel: (08) 9417 4774- Email: sales@shortfuse.net.au