Speaker Watts, Sound Quality, and Loudness Explained

Updated on November 18, 2015
Will Apse profile image

Scientist, writer, audiophile and smartphone addict, Will Apse, loves explaining tech issues in a way that anyone can understand.

Everyone wants great, high-quality sound from their audio system. Usually people want a sound that fills the room and has a deep bass, a clear treble, and a rich middle range. The sound quality should not deteriorate when you crank up the volume, and you certainly don’t want insane vibrations, static hiss, or smoke to come out of the speakers!

In your quest for quality sound, speaker watts are one figure to understand and consider. Other important values are the speakers’ sensitivity and total harmonic distortion (THD). This article will help you interpret the manufacturer’s specifications to understand what a sound system will deliver.

Loudness and Power Explained

Decibels are a measure of loudness. This number is important when choosing speakers, especially if you like to listen at a high volume. Something to remember about decibels: For every 10 decibel increase, the noise is twice as loud, so small increases in decibel levels mean big impact on your ears.

Power in Watts (W): A watt is a measure of electrical power. As an amplifier processes sound, the output is measured in watts. All speakers have a maximum number of watts that they can cope with and the manufacturer will tell you what this is. Make sure that the amp you use does not put out more power than your speakers can handle, or the speakers could be damaged.

Usually, manufacturers provide two power figures for both amplifiers and loudspeakers:

For amplifiers:

  • RMS = the power an amplifier can put out over a long period
  • Peak = the power an amplifier can put out in short bursts.

For speakers:

  • Nominal power= what a speaker can handle long term without being damaged
  • Peak power= what a speaker can handle in short bursts without being damaged

Very good speakers are more sensitive than mid-quality speakers and can deliver a lot of sound with only a little power from the amplifier. Mid-priced speakers need more power to provide the same volume.

Speaker sensitivity is expressed in terms of the number of decibels (dB) of sound pressure level (SPL) per watt of amplifier power measured at one meter from the speaker. To simplify this, manufacturers usually drop the SPL/W/M and just say dB.

Most speaker sensitivities are in the 85 to 91 dB range, so anything less than 85dB is not so hot.

How Do Watts Translate Into Decibels?

Numbers are for reasonably sensitive speakers, about one meter away. Look for speakers that can handle between 85 dBs and 110 dBs. Anything more than this will destroy your hearing. For mid-price home speakers, 120 watts is about the most you should

For comparison . . .

If you like really loud music, look for speakers that can deliver between 85 and 110 dBs. A loud rock concert is about 120 dBs.
If you like really loud music, look for speakers that can deliver between 85 and 110 dBs. A loud rock concert is about 120 dBs.

Judging Speaker Sound Quality

Shopping for speakers, look for these figures as well.

  • Total Harmonic Distortion: TDH is a measure of how faithfully speakers translate what is on a disc or hard drive into sound. The lower the figure, the less distortion, so lower numbers are better. Usually values between 0.05% and 0.08% THD mean a quality "clean" system, but any figure below 0.1% THD is pretty good.
  • Speaker Impedance: This number tells you how much current a speaker will draw. Eight ohms is standard. Four ohms is very good but usually a lot more expensive. If you are buying four-ohms speakers you will need a very good amplifier to get the most out of them.
  • Headroom: This figure is a measure of what a system can deliver in short bursts. A large headroom figure is important if you have a home cinema system and want to get a jolt from the explosions in action movies.

Buying Speakers Online

Amazon and eBay are great places to buy audio equipment at a good price, but both sites often fail to provide all the numbers needed to make an informed choice. On the other hand, buyer reviews on Amazon, Target.com, and Buy.com are more valuable feedback on products than you will find almost anywhere else. If a person buys something that they don't like, they will complain like crazy! On the other hand, satisfied audiophiles are quick to share their opinions too when they discover a great product.

I picked out a selection of speakers from Amazon that are worth looking at:

Polk Audio RTi4

Polk Audio RTI A3 Bookshelf Speakers (Pair, Cherry)
Polk Audio RTI A3 Bookshelf Speakers (Pair, Cherry)

This is a bookshelf speaker with incredibly high performance for the modest price tag—modest online, at any rate. The people who buy these speakers have almost nothing bad to say about them.


Multimedia Speakers

Audioengine A2 Premium Powered Desktop Speakers - Pair (Black)
Audioengine A2 Premium Powered Desktop Speakers - Pair (Black)

Multimedia speakers for use with a PC are not usually associated with top quality sound or high volumes. A few makers have products that fit audiophile needs, although it is worth considering a DAC (digital to audio converter) to get the best from digitally stored music. The Audioengine A2B Powered Multimedia Speaker System delivers a rich multimedia experience.


Scary Loud 1,000W Speakers


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    • profile image

      SAJEEV 3 days ago

      Clear idea. Thank you

      One question

      What is the importance of inches diameter of speakers?

    • profile image

      nick 3 months ago

      eat kids everday yah

    • profile image

      bon 4 months ago

      am thankful.. helped me a lot with yoh explanation

    • profile image

      terry 6 months ago

      thanks good info easy to understand!!!

    • profile image

      bett 6 months ago

      I have a 1000 watt hometheatre with 1% thd and 3ohms.Is this quality clean sound?

    • profile image

      Seb 6 months ago

      Thanks this helped me!

    • profile image

      Daniel Hodgson 10 months ago

      Good article, helped me bone up on some stuff I haven't used in a while. Did anyone answer Mikosavi, Wattage in as a supply is simply an estimate of power consumption of the unit. If I'm wrong someone correct me.

    • profile image

      Tj 10 months ago

      Nice Article

    • profile image

      Mikosavi 15 months ago

      Can anyone tell me how these new digital amps state a wattage going in as supply but gives much more wattage to the speakers.

    • profile image

      DANIEL KAHINDI 17 months ago

      would like to understand difference between a sub-woofer and a home theatre in these case taking an example a sub-woofer 1350watts cost 8000ksh while a home theater 330 watts costs 17000ksh

    • profile image

      Clare 19 months ago

      Hi, I wanna know what would be the appropriate specs for a speaker set that I want to connect to my phone? I don't want to end up frying my phone in the long run, if that's possible..

    • profile image

      JoeKnows 22 months ago

      Generally you only get 4-ohm speakers for car audio or rarer home amps specifically designed to handle the current from that lower 4-ohm impedance. 8-ohm is standard for home and not really a measure of "lower quality" vs. 4-ohms.

      The details of why car stereo speakers became 4-ohms (vs. 8) takes some research, but apparently it's the higher current to voltage ratio in a 12V car system vs. a 120V home system.

    • profile image

      lapunmabs 2 years ago

      Thank you. That was very helpful.

    • Will Apse profile image

      Will Apse 2 years ago

      Speaker sensitivity varies enormously. Generally speaking, the better the speakers the less power they need to operate.

      The online Crown Power Calculator is a great resource for working out how much power you need at what distance for a particular volume.

    • TTGReviews profile image

      TTGReviews 2 years ago

      How else can you increase the dBs without increasing the power? For instance, what if you have a limited amount of power at an event.

    • profile image

      Curious 4 years ago

      Hi I was just wondering if theres a similar article to this relating to outdoors sound power etc. Im looking for a cheap portable thing for camping and bbq parties but the last one i got for £45 was a load of b*lls as far as volume was concerned. Admittedly it was louder through the radio than the aux input but not by much. Even when we were sat in a closed tent it wasn't great

      I understand its gonna get lost without any walls to bounce off but still. I dont want to spend too much but its gonna need to be battery powered and be louder than the chatter of people at a bbq

    • Will Apse profile image

      Will Apse 5 years ago

      I have have heard that said before but there is no evidence that it is true. Try Googling '10 db double volume'. There is some discussion.

    • TV Mount Guy profile image

      TV Mount Guy 8 years ago from On the Wall

      Great hub with very good information! I had to figure out all of this stuff when installing car stereos. Now, talk about some major watts! Now I have a stock car stereo and a pretty low-end home theater setup, but will be looking for some good speakers for it when I finally upgrade my head unit. Thanks!

    • Will Apse profile image

      Will Apse 8 years ago

      You are right Mike, the best way to buy is to hear the speakers in action. Since this is often impossible the technical data is important and, as you say, reputable reviews from reliable publications.

    • MikeNV profile image

      MikeNV 8 years ago from Henderson, NV

      Watts to average stereo consumers are like GHz to average computer consumers. Unfortunately that's how marketing is done. Pure clean power and a nice smooth crossover. It's pretty tough to find good speakers because there are so few professional listening rooms. It's not like you can evaluate speakers at best buy. So you end up trusting reviews of reputable publications.

      This is a nice hub... voting up.

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