In this video, you'll learn what to consider when choosing an amplifier
For one, this will ensure the best sound quality possible,
but it will also help protect your equipment. Choosing the wrong amplifier can put you
at greater risk of causing damage to your speakers or the amplifier itself.
There are two factors that you'll want to consider when choosing an amplifier,
once you've already selected your speakers. Those two factors are impedance and power.
Impedance is measured in ohms and it refers to the opposition a circuit has on the flow of
electrical current. The first step will be to find the nominal impedance for your speakers.
You can find the nominal impedance of your speakers on the manufacturer's website within the
technical specifications. If your plan is to power multiple speakers with a single amplifier channel,
it's a bit more complicated to find the total impedance of all those speakers.
If that's your situation, you might find this video I made on calculating speaker impedance
helpful. The power rating for your speakers can also be found in the technical specs.
You'll probably find several power ratings. Peak power refers to the maximum short term power
a speaker can handle without damage. We're more concerned with how much power a speaker can handle
over an extended period of time. This is the continuous power rating of the speaker.
Let's say I'm trying to find an amplifier to power two QSC E115 speakers. I'll be looking for at
least a two-channel amplifier so that I can power the left speaker and right speaker separately.
We need to find an amplifier that can supply adequate power to the speakers at the speaker's
nominal impedance rating, which in this case is 8 ohms. Impedance and power are interrelated.
At 4 ohms the GXD4 is capable of supplying 600 watts of continuous power.
At 8 ohms, it's only capable of supplying 400 watts. Let's look at the GXD8, which supplies
800 watts per channel at 8 ohms. This is a better fit, as it gives us the headroom to comfortably
supply enough power to get the most out of our speakers. Choosing an amplifier that can supply
too much power makes it possible to exceed the limitations of the speaker.
Of course, as you start to hear that speaker distortion, you'd hopefully turn it down to keep
your equipment safe. On the other hand, choosing an amp that can't supply enough power is actually
more likely to cause damage. With an underpowered amp, you might have the tendency to keep turning
it up and up. At a certain point, that will only cause clipping. The speaker won't get any louder,
but the waveform will become distorted, which could cause the speaker to overheat.
The truth is, there really isn't a simple rule for matching amplifiers to speakers.
Any combination of equipment you get could lead to damage if improper gain structure is used.
My recommendation is to choose an amplifier that is capable of providing about twice the continuous
power rating of the speaker. Remember, a doubling of power is only a three decibel change.
This will allow the amplifier to provide adequate power to the speaker while maintaining
some extra headroom. To avoid the tendency to overdrive the input of the amplifier.
The best way to prevent damage and get the best sound quality possible is to choose speakers
that are designed to provide adequate sound pressure level for the application at hand.
That way, you won't have the tendency to turn up the speakers beyond their limitations.
For help with choosing the right speakers, download the free
Loudspeaker Technical Specifications Guide at audiouniversityonline.com/speaker-specs-guide.
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