Speakers require amplifiers to properly drive them and increase the power of the sound they produce. But while picking an amplifier for your speakers may sound simple, it is actually quite tricky. You need to make sure these two devices are well-matched in terms of power and impedance in order to get the best performance from them and to enjoy the optimum sound.
An amplifier can be too powerful for speakers when it puts out a lot more wattage than your speaker can take. Speakers should not be driven way beyond their limits, or they can get damaged. Cranking up a far less powerful amp is also not good as it will result in clipping, which distorts the sound.
This article will talk about what power means for an amplifier and what it means for speakers. We will also discuss the importance of matching your amplifier and speakers in terms of power rating or wattage and other specifications, as well as how to do it and what happens if there is no synergy between them.
Does Your Speaker Need an Amplifier in the First Place?
Your speaker needs an amplifier because input audio signals need to be amplified so that they can drive it properly and output a more robust sound. Some speakers already have integrated amplifiers, while others require external amplifiers.
Speakers with their own amplifiers built into their cabinet are called active speakers. Meanwhile, those that draw power from separate amps are called passive speakers.
Looking for a matching amplifier and speaker system is essential if you want to achieve great synergy between them.
To do this, you don’t exactly need to try out all the speaker/amp combinations available. Instead, what you need to do is check their specifications.
The most important specs you need to focus on are the power rating, impedance, and sensitivity.
What Power Ratings Mean for Amps and Speakers
An amplifier’s power rating means the power output, while a speaker’s power rating means the power input. This rating is expressed in Watts for both devices.
The power rating of your amplifier represents the maximum amount of power that it is capable of generating when the gain is at its highest. It is the power output for the given impedance, which we will explain later.
On the other hand, the power rating of your speaker represents the amount of power it can take or handle without overheating or sound distortion.
If you take a look at your speaker’s specs, this number can be the maximum RMS power rating, which is the amount of power it is able to handle continuously over an extended period of time.
It can also be the Peak or Dynamic power, which is the amount of power it is able to take in bursts in less than a millisecond.
Some speaker manufacturers display both of these values, while some will indicate only one. There are also manufacturers that indicate the range of recommended amplifier power for the speaker.
When it comes to matching, you need to get an amplifier that is able to supply enough power to your speaker to the loudest volume you want without clipping.
As such, you should be able to feed your speaker the same amount of power it can handle or less, but never more.
Other Specs You Need To Check for Matching Amp and Speaker
You need to consider other specifications for your amp and speaker when pairing them other than power. These specs are impedance and sensitivity.
Impedance
Impedance represents the resistance of the electrical components of your devices. It is expressed in ohms.
Speakers usually have an impedance of 4 and 8 ohms. This number tells you how hard it is to drive the speaker or the kind of load the speaker represents to the amp.
A lower-impedance speaker is generally harder to drive compared to a higher-impedance one since it draws more current while maintaining the same voltage.
Meanwhile, amplifier impedance is typically given a certain range, like 6 to 12 ohms. This range tells you what kind of speakers it is capable of driving.
It is fine to connect an amplifier that can operate with a lower minimum impedance to a speaker with a higher impedance.
However, you should not connect an amplifier with a higher minimum impedance to a speaker with a lower impedance.
So if the amp’s impedance range is 6 to 12 ohms, that means it can drive speakers with an impedance of 6 ohms, 8 ohms, and 12 ohms.
Knowing the amp’s impedance is important as this value is related to its power rating. The power output of an amp changes with impedance. More specifically, power output becomes higher when the impedance is lower.
For instance, your amp will indicate that it can put in a power of 170 watts per channel at 6 ohms and 140 watts per channel at 8 ohms.
Sensitivity
The sensitivity of your speaker is expressed either as dB @1W/1m (decibels per 1 watt per 1 meter) or dB @2.83V/1m (decibels at 2.83 volts per 1 meter).
This value will give you an idea of how loud a sound your speaker can create given a particular power input. It also tells you how high the gain on your amp needs to be in order to get the best sound from your speaker.
As to how to take all these specs in properly matching a speaker and amp, here’s a video tutorial:
How Powerful Should Your Amp Be in Relation to Your Speaker?
Generally, your amplifier needs to deliver power that is at least equal to or at most twice the power rating of your speaker. While your amp can be equally powerful as your speaker, one that is twice as powerful will give you more headroom.
This headroom spells the difference between an amp’s normal operating level and the maximum level it can operate without distorting.
Enough headroom will allow you to accommodate variations when you are listening to sound or music with a dynamic range. As such, having a headroom ensures that only clean and undistorted signals get to your speaker.
As an example, a speaker with an impedance of 8 ohms and a power rating of 350 watts will work best with an amplifier that can generate a power of 700 watts into an 8-ohm load.
If we’re talking about a pair of stereo speakers, the amp needs to have a power of 700 watts per channel at 8 ohms.
What Happens if Your Amp Is Too Powerful for Your Speakers?
Small discrepancies between the amp wattage and speaker wattage would be fine, and it may even give you headroom.
If your amp has higher wattage than your speaker, you can just lower the gain to equalize their power. However, when this wattage gap between the two devices is too huge, there could be a problem.
Pairing an amp with an extremely high wattage and a speaker with an extremely low wattage means that your amp will feed much more power into your speaker than it can handle.
Even if you turn the volume up to its maximum level, there will be an over-excess in power. This excess power will get converted to heat, which, in turn, could fry the voice coil and damage your speaker.
Conclusion
When getting an amp and speaker for your audio system, make sure you know about proper pairing to get the best sound possible. Matching them involves knowing their power rating, impedance, and sensitivity.
These specs will tell you how powerful your amp and speaker should be.
Matching can get confusing, though. As a general rule, there should be equal power between the two. But a more powerful amp would also be a good thing as it gives you some headroom.
It is when the amp has excessively more power than your speaker that your speaker could overheat or blow up.
