Speaker Watts, Sound Quality, and Loudness Explained
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
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.