How many Watts? – The Truth About Speakers and Power Output
Published on Friday 24 April 2020
Your local drive-in DJ, the next-door neighbour or even your best friend bragging about their new sound system might sound familiar to you. There are plenty of times when I’ve heard them say: “My new speakers are off the charts man, they’ve got 1,500 Watts of power!” This goes to show that a lot of people assume that more power means more volume, but really, it’s not that simple. Sure, a 1,500 Watt speaker is louder than a 10-Watt model but definitely not 150 times as loud. As a matter of fact, sometimes a 1,000 Watt speaker can produce more volume than a 1,200 Watt one. This blog is written to separate the facts from fiction and show you how it really works when it comes to the power capacity of speakers and amplifiers.
- Power capacity: giving and taking
- What does “100 Watts” mean exactly?
- Differences between manufacturers
- But 5,000 Watts means more volume than 100 Watts, right?
- So what do I look for?
- Sensitivity in dBs
- Maximum sound pressure level (SPL)
- PMPO
- Matching speakers and amplifiers
- Example
- What have we learned
- See also
Power Capacity: Giving and Taking
First of all, it’s important to know the difference between the giving and taking of power. An amplifier outputs power and passes it on to a speaker. In turn, the speaker takes the power and processes it. It uses the power to form a signal that’s ultimately reproduced as sound. Even though there are two different types of speakers – active ones with built-in amplifiers and passive speakers – the principle is the same: sound gets amplified. Many people don’t realise this but this is the crux of the matter.
What does “100 Watts” mean exactly?
Because speakers receive power, wattage isn’t something that they ‘have’. Let’s take a 100-Watt speaker for example. Basically, this means that it can handle, or rather, process 100 Watts of power. More specifically, the number of Watts indicate how much power a speaker can be burdened with under certain circumstances before it breaks. In practice, this means that a 100W speaker is often actually able to handle more than 100 Watts.
Differences between manufacturers
This last bit is exactly where things can bottleneck. Each manufacturer uses a different method to measure the amount of power their speakers are able to withstand and it’s often unclear how, but perhaps more importantly, which signal they’ve used for the calculations. Even when boasting the same power capacity, different speakers can come with different results when tested under the same conditions. That means that in real life, the specified number of Watts can sometimes cause more harm than good.
But 5,000 Watts means more volume than 100 Watts, right?
True, but people often make a mistake when they compare speakers to lamps and say that a 100W bulb burns brighter than a 10W bulb. While they’re absolutely right, the comparison is a little more complex and requires some nuance. The specified power output of a speaker isn’t the sole determining factor when it comes to how loud it’ll go. You can’t really compare a 5,000W speaker to a 100W one, simply because the difference is too extreme and doesn’t take other aspects into consideration. Granted, 5,000 Watts will lead to more volume than 100 Watts but if the numbers aren’t as far apart, say, 1,200W versus 1,000W, it might well be that the latter is louder because it comes with superior specifications in other regards. This can’t be overlooked when you’re weighing up the pros and cons of the speakers on your shortlist.
So what do I look for?
To get a better understanding of how loud a speaker can go, you’ll need to look at a few other aspects.
Sensitivity in dBs
First, the sensitivity. The sensitivity of a speaker is expressed in dBs, or decibels. Usually, manufacturers specify the amount of dBs that a speaker can produce with a single Watt of power at a 1-metre distance. In most cases, the number will lie somewhere between 84 and 92 dB with the rule of thumb being: the more sensitive a speaker is, the less power it needs to put out louder volume. Does that mean that smaller speakers are easier to power? No, because these are often less sensitive than larger units because they are forced to sacrifice a large portion of the sensitivity to reproduce a decent amount of low-end. To shape bass frequencies, a speaker will need to be larger so it doesn’t have to sacrifice as much to remain sensitive. So sensitive speakers certainly aren’t less good than more insensitive ones, as a matter of fact, they’re better! Keep in mind that instead of sensitivity, manufacturers sometimes use the term ‘efficiency’. Different word, same principle.
Maximum sound pressure level (SPL)
The maximum sound pressure level also plays an important role in determining how loud a speaker can go. It’s a way for the manufacturer to tell you how far the sound pressure can be pushed before the speaker permanently breaks down. Unfortunately, however, not every manufacturer includes the maximum dB SPL in the specifications of their gear.
PMPO
Then there’s the PMPO, the peak maximum power output. While it sounds cool, it’s more of an irrelevant theoretical aspect than anything else. This indicates the amount of power a speaker is able to handle for a few milliseconds before it breaks beyond repair. It’s not the most useful of specifications because you don’t exactly want to try this.
Matching amplifiers and speakers
Now that you know that the wattage doesn’t necessarily indicate how much volume a speaker can produce, let’s eliminate the largest of misconceptions in the world of sound amplification. A lot of people believe that you can’t or shouldn’t match a 100W amplifier with a 200W speaker because you’d risk blowing the speaker up, but au contraire. It’s actually better to use an amplifier with a higher power capacity than that which the speaker can theoretically manage. How so, you ask?
Example
Let’s take a 100W speaker. Some would play it safe by hooking up an amplifier that’ll continuously supply it with 50 Watts of power. This would mean that the amplifier is only able to offer 50W before the sounds start to distort. When this line is crossed, clipping occurs. The threshold is actually a lot lower than most people believe, and trust me, your speakers won’t like it. If the amplifier isn’t powerful enough, it’ll push itself past its own limits and distort the sound to such an extent that the speaker will blow up, with the tweeter going down first because distortion mainly happens in the higher frequencies and causes the voice-coil to overheat. But, if you try really hard, you can probably give the other components inside the speaker a one-way ticket to the scrapyard as well.
More information about matching speakers and amplifiers can be found in our blog on the difference between passive and active speakers.
What have we learned?
The big takeaway here is that while the number of Watts of a speaker shouldn’t be overlooked, it doesn’t tell you how loud a speaker can go. The wattage also doesn’t indicate sound quality or possible lifespan but can be really useful when you’re looking to buy a suitable amplifier. Just keep in mind that it’s better to go with an amp that has ‘too much’ power. To get a better picture of how loud a speakers can sound, don’t just look at the amount of Watts but check out the SPL and sensitivity specifications.
Hopefully, you now feel confident and informed enough to make a choice based on the facts instead of the fiction. Still not entirely sure if that new amp or speaker will work well for you? Simply put your question in a comment below!
See also
» Blog – The Difference Between Active and Passive Speakers
» Blog – How To Connect Your Microphone to a Speaker
» Blog – How to Connect Your Speakers to your Audio Equipment
» Blog – Turning a Speaker Set Into a Fully-Fledged PA
» Blog – Buzz, Hum and How to Get Rid of it
» Buyer’s Guide – How do I Choose the Right Bluetooth Speaker?
» Buyer’s Guide – How do I choose the Right Studio Monitor?
» PA Starter Sets
» Speaker Sets
» Active Full-Range Speakers
» Passive Full-Range Speakers
» Subwoofers
» Amplifiers
» Speakers & Accessories
» Pro Audio Gear
QUESTION:
hI I am a 57 year old female and I’m quite confused. Simply put, can someone recommend a good wireless blue tooth speaker (or 2/syncing) with good sound I can purchase for my family reunion that will be held at a park. Volume is important as I would like for everyone to be able to hear the music.
Hi there,
Depending on your answers to a few follow up questions, we can recommend a few good speaker (combinations):
– How much are you willing to spend on the speakers?
– How many people are you expecting to be there at the reunion?
Love to hear back from you.
nice. although i was expecting to read more about the relations in ohm’s law for the voltage changes that runs to the speakers, and the problematic lack of standard to measure sensitivity (w/m or 2.83v/m) this – if understood correctly will absoultely help you understand what you are looking for and how loud you can expect this speaker play. when i understood what makes the wattage value is the combination of voltage and current – helped me understand better the concept and to match the gear much better even before going for a listen.
anyway – tnx, very nice
Very nice, simple write-up. What about wattage in practical terms, such as my electric bill? If I get a speaker that’s 1,000 watts RMS, will it always require that much power, even with low level use? Or does the wattage vary depending on the demands of the speaker? And how much could it vary?
Hi Jax,
Whether you’re running an active speaker or a speaker-plus-amplifier set-up, there are three factors at play:
Input
Amplification
Output/Capacity
The amplifier takes the input signal and amplification strength (so your gain/volume setting) to determine the output that goes to the speaker.
The power capacity of the amplifier in relation to the speaker plays a role as well but let’s assume they’re more or less properly matched.
Also, note that music is essentially a dynamic audio signal made up of signal peaks and troughs, but to measure the technical specifications, sine waves are used. A fixed sine wave (usually 1 kHz) is used to measure, among other things, the sensitivity of a speaker and its maximum sound pressure level (SPL).
A low input signal, combined with a certain amplification strength, yields a certain output.
Every amplifier continuously consumes a base amount of energy to power internal components, which can be something like just 50 Watts when it’s in stand-by. Thankfully, the mains power grid and average consumer unit are equipped to deal with signal peaks.
In any case, a 2,000W speaker system won’t draw 2,000 Watts of power the second it’s switched on.
With amplifiers that process dynamic audio signals (music), the rule of thumb is that the average maximum power consumption equals roughly 1/8th of the RMS power capacity.
Marnix | Bax Music
I read this post your post so nice and very informative post thanks for sharing this post. for more info sounds system for rent
Got into a lovely internet debate on the following: “How loud is a system that consists of 10, 1000 watt subs with matching Amplifier?”
My view is that its 1000 watts. Mainly because if I put 2 500 watt speakers together they don’t magically become 1000 watt speakers. The power requirement has increased but the output remains the same.
I have 90s 350 watt Technics amp, On the back of the 4 calble says 350 watts and then on each outlet for speaker devided by 2 sections with ohm says 8ohm per speaker and then 16 ohms par speaker. So I have two Technics 8ohm speakers 50 watt and then two Aiwa speakers on the 16 section but can’t remeber there what’s or ohms but they handle the bass great. The amp has a clipper monitor display and turns red if clipping. It also has a internal safty switch which disables the unit if it clips to high. I had to unscrew the thing and turn the switch back on. Anyway it’s very loud and I also have a 1000 watt Sony and have that hooked up to additional 8ohm Technic speakers. Basicly got a stack of speakers.
Hi!
I was wondering about guitar amps, specifically ones with a tube driven pre amp and a solid state power amp – given that tube watts and solid state watts are very different does the wattage refer to the power amp only or a combination of the 2?
Hi Rob,
The power will always come from the power amp section. When you just hook up a preamp, you don’t get any significant power out of it. So in this case, the power comes from the transistor power amplifier while the tube preamp adds it’s own kind of ‘special sauce’ to the sound.
Marnix | Bax Music
it is better to have more power then speaker is rated for,some speakers have protection
Informative!
“Just keep in mind that it’s better to go with an amp that has ‘too much’ power. ” Does this mean I can use a 200w RMS per channel amp on a 30w RMS speaker?
Hi Ganesh,
I can understand the confusion. Explaining about your earlier question: What the author meant by ‘threshold’ is how fast your speakers will distort if you try to run too much power through your amp. In the example, we use a 50 Watt amplifier to power a 100 Watt speaker. As soon as you hit the maximum power of your amp (50 Watt’s), then almost immediately your speakers will start distorting. That is what we mean by a low threshold: as soon as you go over the maximum power that an amplifier can give, your speakers will start distorting very quickly. There’s very little room for error here.
About the second question: I agree that the line with ‘too much’ isn’t clear. What we actually mean is that it’s better to go with an amp that can deliver more continuous power than the speaker requires. But there is a limit to this. A speaker usually has a maximum power capacity specified, which is the absolute maximum amount of power a speaker can handle in short bursts.
Say, we have a speaker with the following power handling specifications: 100 Watt RMS, 200 Watt Peak. This means the speaker needs 100 Watt to run continuously, and can handle at maximum 200 Watt’s in very short bursts.
We always recommend using an amplifier that can supply 150% of the required RMS load (“more continuous power than the speaker requires”). In this case, using an amplifier that can deliver 150 Watt continuously will result in a better performance for the speaker because you have an amplifier with a threshold that is higher than the speaker’s continuous power requirement. That’s what we mean when we say that it’s better to go with an amp that has ‘too much’ power.
Excellent article. Some queries…”When this line is crossed, clipping occurs.” Which side do you mean. “The threshold is actually a lot lower than most people believe, and trust me, your speakers won’t like it.” You mean the threshold down-wards or upwards. I take it us higher side as that is how the word is generally used. Did you mean for the amp wattage or speaker? I am a beginner and I got more confused.