How to Test a Subwoofer

No matter how old or expensive your subwoofer is, it might deliver worse sound over time. So, both the 10-year old premium sub and the brand-new best home theater subwoofer under $300 require proper testing in case they sound worse than you expected. Testing your sub, you can determine the following important factors:

  • How bad is the breakage—the sub can be broken or simply be in the wrong place, producing a non-quality sound.
  • What’s the reason—there are some parts that might wear out or get blown.
  • What to do—once you have a complete picture, you can decide whether to repair or replace the sub.

Since a subwoofer is an electronic device with an audio output, it can be tested by different methods:

  • cones testing;
  • coils testing;
  • sound testing;
  • no-amp sub testing.

Want to learn how to test a subwoofer in detail? Follow the guide below!

Cones Testing

In order to deliver a strong bass, subwoofers feature rigid cones that are fixed with the suspension system. Such a construction allows the cone to move forward and reverse, catching and whirling a lot of air and creating the sub-low frequencies.

The movement of the cone should not be random, however. Instead, the proper cone’s mechanics can be described as parabolic, with additional upper loops after the principal loop. The motion should be regular but not stiff or lax.

Follow the next steps to check for the proper functioning of the cone in your sub:

  1. Take off the subwoofer grill.
  2. Inspect the cone. If you see some mild scratches, bends, or even signs of tearing, it’s time to replace the cone.
  3. Test the cone’s movement. Put both your hands on the sides of the subwoofer’s box, touching the cone with your palms. Press the cone gently to check whether it moves. Probably the suspensions have stretched or broken if you feel some looseness or rigidity.
  4. Listen to the cone’s movement. Place your ear close to the cone, and repeat pressing mildly on it with your two hands. If the cone moves as it should but there are rustling or even scratching sounds, the suspension might be wearing out.

Coil Testing

The voice coil is the part of the subwoofer responsible for transmitting the electric signal into the cone’s motion. It does so by moving the magnet and creating the magnetic field, which in turn pushes the cone.

The voice coil can get worn out over time or blown up by the power surge. Get your multimeter ready and inspect the coil in your sub as follows:

  1. Disconnect the subwoofer from the power source.
  2. Take off the grill and unscrew the fixations of the subwoofer box. Remove the back and, if possible, side panels. Be careful not to cut any wires while doing this.
  3. Inspect the rear part of the cone and find the voice coil (it’s fixed on the positive and negative terminals).
  4. Using a screwdriver, unscrew the terminals. Don’t take the voice coil or the cone off.
  5. Connect the multimeter’s connectors to the voice coil terminals (negative to negative, positive to positive). Check if the readings are above 1.0 Ohm. If so, the voice coil generates enough power. If the resistance is less, the voice coil is probably damaged or worn out. If the multimeter shows no resistance at all, the voice coil is most likely blown.

Sound Testing

If you don’t feel like taking your sub apart and testing its cone and voice coil, you can still conduct the sound testing. Follow the next steps for it:

  1. Connect the subwoofer to the audio source, and to the power, and turn it on. Set the volume in the middle position.
  2. Turn on music on your audio source.
  3. Stay close to the subwoofer and listen to the sound it produces. Increase and decrease the volume. If you hear the sound weakly or don’t hear the music at all, the inner mechanism of the sub is probably damaged. A static noise may be present in the background indicating the wire and connections should be inspected.
  4. Turn on the composition with a precise rhythm. Listen to the subwoofer response. If the response is uneven, with gaps, the cone is likely to be displaced or not fixed precisely with the suspension.

How to Test a Subwoofer without an Amp

Many subwoofers have their own amplification mechanism letting them be compatible with any speaker system. However, there are also passive subs requiring the external amp connection to produce the audible bass. Here’s how to test a subwoofer without an amp. Prepare the two 16-gauge wires about 8 inches long and a portable 9V battery.

  1. Disconnect the subwoofer from the power source.
  2. Take off the grill and unscrew the fixations of the subwoofer box. Remove the back and, if possible, side panels. Be careful not to cut any wires while doing this.
  3. Each wire should be connected to a single subwoofer terminal. It can be done in any order.
  4. Touch and hold one of the wires on the positive post of the 9V battery.
  5. Keep an eye on the cone and put the end of another wire to the battery’s negative post. The cone should start moving back and forth (or up and down, depending on the position). Some noise can also be heard. The voice coil or other inner mechanism parts are most likely broken if the cone does not move.