Ultimate Guide To Clean Voice Coil Gap In Subwoofer?

A voice coil in a subwoofer does the job of converting electrical energy into mechanical energy with the help of the magnet’s magnetic field.

To do the job efficiently the voice coil is typically placed at the center hole of the magnet over a pole (pole-piece).

The pole piece keeps the voice coil aligned in the gap and ensures its linear movement.

A moving voice coil in the gap further moves the suspension system of the subwoofer to create sound.

In this article, you will understand what voice coil gap is, the importance of keeping it clean, along with the step-by-step instructions.

What is a Voice coil gap in a Subwoofer?

The voice coil gap is the dedicated space at the center of the magnet where the coil moves in a back-and-forth motion.

It is a small hole that looks like as a ring hole in the center of the magnet and you can refer to the image below for a better understanding.

Voice Coil Gap Diagram

The pole piece covers the gap from one end while the other end is left uncovered dedicated to the voice coil which is called the voice coil gap.

This gap is also referred to as the speaker gap or subwoofer gap.

It is typically centered between the north and south poles of the subwoofer magnet’s magnetic field.

The size of the gap in subwoofers and speakers depends on the size of the voice coil such as its diameter.

As soon as the electrical current is sent through the voice coil a magnetic field is created within this gap.

The voice coil then reacts with this mechanical conversion and starts vibrating or moving in this particular gap.

Any obstacle in the gap can lead to a buzzy or rubbing noise from the sound system. It is quite a common factor responsible for sound distortion sometimes called subwoofer clipping.

Moreover, dust and dirt accumulation in the gap will prevent the voice coil from moving freely, and over time it can also lead to damaging the voice coil.

You will have to go through expensive repairs, however, in most cases, you will have to replace the voice coil.

How to clean the voice coil gap in subwoofers?

If the voice coil in your subwoofer isn’t moving as it is supposed to or if you notice a buzzy or rubbing noise from the unit, it’s time to inspect and clean the gap where the voice coil moves.

Over time accumulation of dust, dirt, debris, and sometimes rust can prevent the voice coil from moving.

However, we will discuss two methods of cleaning the voice coil gap, method one will require disassembling the entire driver, and the other method with partial dismantling.

Things you may need:

  • Pair of screwdrivers including a Philips screwdriver.
  • Sharp objects such as knives or cutters.
  • Strong Adhesives or glue (ideal for subwoofers and speakers).
  • Re-coning kit (if required).
  • Clean cloth, water, and bowl.
  • Soft brush.
  • Shim or a thin card and masking tape (for method 2)

Let us proceed with the methods below:

Method 1: Clean the Voice coil gap by disassembling the subwoofer driver

Step 1: Disconnect the subwoofer from power

Disconnect the subwoofer from the power source and remove other wire attachments to the sound system if applicable.

Step 2: Unmount the enclosure

Unscrew and remove the subwoofer bracket from the enclosure with the help of the Philips screwdriver.

The screws are typically secured to the edges of the subwoofer’s enclosure.

Place the enclosure aside while securing the screws in a bowl as you will need them later while reassembling.

Step 3: Locate the Voice coil

With the subwoofer bracket removed, you will have access to the suspension system such as the dust cap, surround, and cone.

In some cases, you can gain access to the voice coil by only detaching the cone.

This is a pesky task and you will need to be very careful in removing the suspension parts.

If you can do it carefully make sure to use a sharp object such as a knife or a fine cutter.

Try to locate a fine gap by glancing around the edges where you can insert the knife.

Push the knife carefully into the gap and slowly move it through the edges to separate the surround and cone from the bracket.

Note: In case you end up damaging any parts, you will need to buy a re-coning kit to get it repaired or replaced.

Step 4: Remove the voice coil

Before you remove the voice coil make sure the terminal leads are disconnected.

Usually, voice coils can be removed by unscrewing the screws that secure the coil in place.

Remove the screws and secure them in a bowl along with the ones removed before in Step 2.

Next, pull the old voice coil out of its assembly which is the magnetic gap.

Note: At this point, you can use Method 2 to clean the gap mentioned in the article below.

Step 5: Remove the pole piece to gain complete access to the voice coil gap

This is another difficult task i.e., separating the pole piece from the magnet because they are usually stuck together.

In most cases, the magnets are glued to the pole piece using strong adhesives.

These adhesives are not always waterproof and you can loosen the glue by dipping it into the water.

Warning: Do not attempt to use hammer or hit them with a hard object to separate the magnet and pole piece or else you will end up damaging the parts.

Simply, dip the stuck parts in a bowl filled with warm water for some time and keep inspecting for signs of loosening.

Pull the pole from the central gap of the magnet to separate the pole piece and plate from the magnet.

It will give you complete access to the voice coil gap.

Step 6: Clean the voice coil including the gap

You can use a soft cloth and either roll it or wrap it around a pencil to insert it into the gap.

Thoroughly clean the internal surface of the gap.

Next, wipe the pole piece and then inspect the voice coil for any misaligned windings. If found try to realign and glue the surface.

You can also use a mild cleansing solution to clean the magnetic gap.

Note: Do not use harsh chemicals to clean subwoofer parts, especially the magnet which can lead to degrade the magnetic properties.

If you notice rusting in the magnet’s gap, you will need to get it fixed by experts because it may require demagnetization.

Step 7: Reassemble the pole piece

To reassemble the pole piece you will need to apply a strong adhesive such as Epoxy glue or even Gorilla glue should do the trick.

Make sure to align the pole into the gap properly after applying the glue between the pole plate and magnet.

Let it dry for some time and then mount them to the bracket.

Step 8: Reassemble the voice coil

Carefully align the voice coil into the gap or its assembly.

Next, connect the terminal wires followed by fixing other components back to their places.

Step 9: Fix the surround and cone

To fix the surround and the cone you will need to apply glue to their adjoining edges and the bracket.

Let it dry before you mount the bracket to the enclosure.

Step 10: Test the sound quality

After mounting the bracket into the enclosure you can test the subwoofer by playing some music.

Wire the unit with your sound system and power on the subwoofer to play music.

Check if you hear any strange noise from the voice coil on a lower volume followed by increasing the volume to your desired level.

Method 2: Clean the Voice coil gap using a Shim

Most people prefer cleaning the voice coil gap using a piece of shim or thin card in a compression driver with the diaphragm unmounted.

This can be done without disassembling the pole piece from the magnetic gap.

  • You can use a shim or thin card stock and fold a piece of masking tape over it by keeping the sticky part on the outer side.
  • Start by inserting the shim in the fine gap and make sure to move it all around the circle to cover the entire diameter of the gap.
  • The accumulated dirt and dust in the gap will attract the surface of the shim.
  • Make sure to repeat the step until it appears clean.
  • Finally, you can use a vacuum cleaner to remove fine dust particles.
  • This particular process will help get rid of dirt, dust, and metal filings or pieces of old voice coil windings accumulated in the gap.

Why should you clean the voice coil gap?

Over time, voice coil gaps can attract dust and particles, especially through the moving coils.

This is quite common in subwoofers when exposed to airborne impurities which are typically applicable in environments with poor air quality.

In some cases, if the subwoofers aren’t used for a very long time there are chances of rusting, although it is rare there’s always a possibility.

The accumulation of dust particles can have a negative impact on the linear movement of the voice coil. It will result in non-linear distortion in sound.

Additionally, you will notice reduced sound quality and distortion.

Cleaning the coils and gaps can eliminate issues caused by mechanical faults, including other problems, and help maintain the subwoofer’s efficiency in the long run.

Also, you can avoid the occurrence of unwanted expenses in repairs and replacement of the subwoofer parts.

Final Thoughts

Cleaning the voice coil gap is a time-consuming process, however, it is not a daily task to perform and should be done timely or as needed.

The process requires the disassembling of various delicate components that can get damaged even with a subtle error, hence you will need to be confident enough to execute this process.

Regular cleaning of the voice coil and magnetic gap will eliminate most issues that can hurt your pockets.

Most importantly you should always avoid placing subwoofers in poor environmental conditions that can impact the efficiency of the unit.

Armed with a Diploma in electrical engineering and a remarkable 12 years of expertise, he excels in rejuvenating music systems, washing machines, dryers, and laundry-related appliances. Manish's profound insights and practical know-how establish him as a credible authority in appliance and music system repairs. Contact: manish.singh (at) subwooferblog.com. He's always ready to lend a helping hand!