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:
- RMS = the power an amplifier can put out over a long period
- Peak = the power an amplifier can put out in short bursts.
- 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?
For comparison . . .
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
Scary Loud 1,000W Speakers
Rohan Noronha on July 03, 2020:
Thank you for the explanation, very useful indeed
Tesla on June 25, 2020:
a found 2 speakers both have 120 watts and i like to have strong bass on speakers so is it good enough or should i look more?
Lisa on June 24, 2020:
im wantimg buy a speaker that has good sound loud and quilty sound to be to hear music like surrond sound music i want be abl to hearv all the channels in a song i want to be able to use ox cord and blue tooth sujestions please and i want it loud
Terye on April 22, 2020:
I purchased a Bosch LMH 0606/10 4ohm 6W speaker alon with a QTX digital sterio amplifier (55w per output). Sound is almost a whisper, should it be louder?
Any help appreciated. Thanks.
Lawrence D'Rozario on December 30, 2019:
Mic legacy on December 27, 2019:
Great i so much appreciate this thanks alot
Mark on December 12, 2019:
Absolute nonsense regarding THD! Please educate yourself before writing something like this ... The best speakers work with 1%+ THD at 1W@nominal loudness and most are above 2% THD...
Christine on December 02, 2019:
Great article. Very informative. So glad I read thus vegird making my purchase. Thank you.
apower on November 06, 2019:
hi i am just wondering about getting a microphone for use in a sports hall. would 10 watts be sufficient enough when teaching 30 pupils ?
Arun varma on April 24, 2019:
H P on April 15, 2019:
Very helpful. Thanks!
Winston ernest on April 07, 2019:
Really helped thanks!
Shamirha on September 09, 2018:
This is a good article. It explains in simple manner
Maksudur Rahman on September 04, 2018:
Thank you a lot.❤️
Sandra on May 11, 2018:
I have a 600 dual amplifier and I want to add a couple of speakers what size of speakers 12 would it be able to hold his 600 amplifier
christian on May 04, 2018:
Thx im doing a speaker project at my school and this will help me alot
Tanzanian on March 30, 2018:
Franny on February 27, 2018:
That was awesome it was easy to understand and a lot of useful information
SAJEEV on January 11, 2018:
Clear idea. Thank you
What is the importance of inches diameter of speakers?
nick on October 09, 2017:
eat kids everday yah
bon on September 14, 2017:
am thankful.. helped me a lot with yoh explanation
terry on July 09, 2017:
thanks good info easy to understand!!!
bett on June 27, 2017:
I have a 1000 watt hometheatre with 1% thd and 3ohms.Is this quality clean sound?
Seb on June 20, 2017:
Thanks this helped me!
Daniel Hodgson on March 03, 2017:
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.
Tj on February 27, 2017:
Mikosavi on October 08, 2016:
Can anyone tell me how these new digital amps state a wattage going in as supply but gives much more wattage to the speakers.
DANIEL KAHINDI on August 04, 2016:
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
Clare on May 27, 2016:
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..
JoeKnows on March 24, 2016:
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.
lapunmabs on July 25, 2015:
Thank you. That was very helpful.
Will Apse (author) on January 28, 2015:
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 on January 27, 2015:
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.
Curious on October 23, 2013:
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 (author) on August 12, 2012:
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 from On the Wall on December 05, 2009:
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 (author) on October 28, 2009:
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 from Henderson, NV on October 27, 2009:
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.