How Many Watts Do I Need for my Speakers? (What You Need To Know)

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The wattage of your speakers is a measurement of the amount of power that is needed to produce sound at a particular volume. The wattage rating of your speakers is the theoretical limit of the amount of power that they can handle. For most home speakers, 20-50 watts will be more than enough, but you might need more for a larger speaker.

When looking for an amplifier to suit your speaker’s needs it can seem tricky to determine what wattage is best, and higher wattage does not directly translate to higher volumes. You need to consider the other specifications, such as sensitivity, as well.

You want the wattage of your amplifier to be at or below the continuous wattage of your speakers so that you are not pushing them beyond their limit at high volume.

This article will go into more detail about how many watts your speaker will need, and what difference it makes overall.

how many watts do i need for my speakers

How to Test a Speaker with a Multimeter

If you want to check that your speaker has not suffered any damage due to incompatible wattage, you can use a multimeter to check the resistance.

  • Firstly, put the multimeter on the resistance setting.
  • Next, touch the red and black leads, either way around to the terminals of your speaker.
  • Look at the reading on the display.
  • The ohms shown should be within the range of the ohms that is advertised for your speaker.
  • A very low reading, or none at all, indicates a short inside the speaker.
  • A very high reading means there is a broken connection.

How do I Find the Wattage of my Speakers and my Amp?

Usually, the wattage of your speakers can be found on the back of the box your speakers came in, in the instruction manual, or online. You want to look for the RMS value (ending in W), which refers to the continuous wattage that your speakers can handle to output good audio quality. The maximum value will tell you how much your speakers can be pushed to without causing damage.

If you can’t find the wattage value, you can use the voltage and amperage numbers to figure out the maximum wattage. The voltage number (ending in V) multiplied by the amperage number (ending in A) will give you the maximum wattage value.

To find the wattage of your amplifier, you will want to first look in the instruction manual. It should give you the Watts that the amp can produce as a single value (ending in W). If you can’t find it there, the number is also usually printed somewhere on the back of the amp itself.

If you can see that the maximum wattage of your amp is not greater than the maximum wattage of your speaker then they should be compatible.

How Does Wattage Affect Volume and Sound Quality?

Most of the time, any amplifier, regardless of its wattage, is putting out the same amount of power as any other. This is because listening to most speakers at normal volumes requires less than 10 watts.

However, the higher the wattage output, combined with the sensitivity rating of your speakers, the great the volume in decibels you will be producing. Finding the sensitivity (dB), you can calculate the wattage your speakers require to produce different volumes. This is usually shown for the volume in-room, but if you want to know the volume for an outdoor space, add +3 dB to the rating.

This number tells you the decibels of volume produced at 1 Watt of power, but for every additional +3 dB that you want to increase by, the wattage power needed will be doubled. If you have an in-room sensitivity of 87 dB (the average for most speakers), then the output will be as follows:

  • 1 Watt will produce 87 dB
  • 2 Watts will produce 90 dB
  • 4 Watts will produce 93 dB
  • 8 Watts will produce 96 dB

You can continue this calculation to see how much wattage you will need to produce the volume that you want for your speakers. For speakers with this sensitivity to play at 102 dB, loud enough to fill a movie theatre, you would need an amplifier that produces 32 Watts. A 40- or 50-Watt amp would give these speakers more than enough range of volume with good sound quality.

How Many Watts is Safe for my Speakers?

It is possible to use a high wattage amplifier for a speaker that can only handle low watts, or a lower wattage amp than your speaker needs, providing you keep the volume low enough that it is not exceeding the speaker’s maximum range. If the volume is increased too high, however, you can cause serious damage.

Plugging a 1000W amp into a speaker designed to handle 500W isn’t a problem while the power is low, which is generally the case during regular listening. If you increase the volume too much, however, and the wattage exceeds your speaker’s range, the sound quality will be poor, and you can blow the speakers.

Underpowering your speakers is generally considered to be more of a risk than overpowering. Plugging a 10W amp into a normal household speaker and turning up the volume very high can result in distortion, and ultimately cause your speakers to fail. This is because the amp will start to clip and output a high level of voltage, which can burn out your speaker’s voice coils.

Conclusion Of How Many Watts Do I Need for my Speakers?

In conclusion, the watts that you need will depend on the continuous wattage value of your speakers. Any amplifier that you use should be producing that amount of watts or less. You can utilize a number of watts up to the maximum wattage value for your speakers, but the higher the output above the continuous value, the worse the sound quality will be.

For most speakers that are made for home use, an amplifier outputting 40 or 50 watts will result in good sound quality and a decent volume. If your speakers are designed to handle larger wattage and produce good sound quality at higher volumes, then you might be aiming for 100 watts within the home.

Outside of everyday listening, for big crowds or high volume outdoors, you might have speakers that can handle a much higher wattage, and you might be looking at amplifiers that produce upwards of 1000W.  This is highly dependant on what your speakers are designed for, and what volume they are able to produce high-quality sound at.

References

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