Estimated Reading Time: 8 Minutes
As their name suggests, power amplifiers are used to increase the power availability of an electronic source with low-powered audio signals. One particularly common need for power amplifiers is when incorporating passive loudspeakers into a sound setup. While amps and passive speakers allow for increased personalization, finding the perfect combination of the two takes some extra consideration and research to ensure the best results.
All speakers require amplification to function; however, powered speakers come with amplifiers built-in, whereas passive speakers operate using external power amplifiers. Amped speakers deliver a rich, clean sound that accurately reproduces every nuance of your audio without distortion. The mix-and-match nature of passive speakers and power amps allows you to coordinate, scale, and personalize your audio setup to meet changing needs over time.
This makes the amp/passive speaker pairing a popular choice among contractors and installers of professional audio setups. However, choosing the wrong amp may result not only in poor sound quality but in damage to your equipment, so finding a power amplifier that compliments your speaker system is crucial. The key is understanding what your speakers need, and what a specific amplifier can handle.
CHOOSING A POWER AMPLIFIER TO MATCH YOUR PASSIVE SPEAKER
First, you need to take stock of your specific application. Providing background music to a restaurant or retail environment will require different amounts of power than a rock concert, for instance. The louder the sound system, and the bigger the space, the more power you’ll need.
How much power you need is also determined by the type of speaker you’re amping—in particular, what sound pressure levels (SPLs) a particular model can handle. A highly sensitive speaker will require less power than one with lower sensitivity. Essentially, finding the right amp for your application starts with finding the right speaker for your application; by choosing a speaker that has the SPL capacity for your application, you can avoid the temptation to use an amp to push a speaker beyond its limits and suffering either inferior sound or damaged equipment in the long run.
Matching an amp to a single passive speaker boils down to two factors:
Impedance (measured in ohms or Ω)
Impedance refers to the level at which electricity is opposed (or “impeded”) in an appliance’s circuit. Nominal Impedance is commonly listed in 4, 8, or 16 ohms, and is the number you’ll want to look for when matching an amp and speaker’s impedance levels. The exact impedance level varies according to the frequency that a speaker receives at any given time, but the manufacturer’s impedance rating is a good approximation of the speaker’s average impedance level during regular operation.
Look for an amp with a nominal impedance rating that is either equal to or a bit less than the speaker’s nominal impedance. If you try to power a high-impedance speaker with a low-impedance amp, the result will be the amp will not be able to boost the speaker’s sound enough—defeating the purpose of using an amp in the first place. On the other hand, if your amp’s impedance is too high for your speaker, it could damage the amp’s internal components.
Power (measured in watts or W)
In audio gear such as speakers, “power” doesn’t represent volume (or “loudness”), but rather how quickly energy is transferred through electronic circuitry. Continuous Power Handling rating (sometimes listed as IEC Rating, RMS, or Power Capacity) outlines the power capacity (or wattage) of the speaker. Continuous power is not to be confused with peak power—peak power refers to the highest level of electric power a speaker can handle for a brief time, but the continuous power rating tells you what a speaker can handle for extended amounts of time.
As with impedance, choosing an amp that supplies the right amount of power is a delicate balancing act. Too much power can push your speaker beyond its capabilities. If your amp is not powerful enough, however, it will struggle to supply the wattage your speaker needs to function…the temptation here would be for you to continue turning up the signal. Both too much and too little power in an amp can result in distortion of your sound or permanent damage to the speaker.
Look for an amp that has a power rating that is higher than the speaker’s power rating. This allows the speaker to comfortably reach its peak power without pushing it too hard. The exact amount of power you need will vary according to your application. For quieter audio, such as background music, you may only need an amp with 50% more power than the speakers. However, an amp with twice as much power as the speaker is better for louder applications, such as rock concerts.
Don’t Forget to Check the Specs!
Much of the information you need to make this decision is listed on the back panel of both the speaker and the amp. You can also look at the owner’s manual, specification sheets, or manufacturer’s website. Additionally, Sound Productions tries to include specifications and documents on product pages to provide a convenient way to check the specs of the speakers and amps we carry.
Whether you’re setting up a sound system on-stage, installing a permanent setup, or simply want to round out your home’s audio system, amplifiers equip you to punch up the power. While certain amplifiers are designed for the stage, others are intended for permanent installation—such as commercial applications where ceiling speakers are being incorporated into a space. This is why SoundPro has sorted our selection of amps into two categories: Power Amplifiers for live sound applications, and Commercial Power Amplifiers for permanent professional spaces. Determining which category to explore can be a bit tricky if you’re just learning about power amps, so here are a few recommendations to help narrow things down:
Amplifiers for Live Sound
Amplifiers for Surface and Ceiling Mounted Speakers
CONNECTING MULTIPLE SPEAKERS TO ONE AMPLIFIER
Before you turn on any amplifier, you must ensure it’s connected to a speaker. But what if your sound setup is comprised of multiple speakers? Fortunately for space-saving and signal streamlining reasons, generally you can connect more than one speaker to a single amp—while this offers even more flexibility when done correctly, it increases the risk of damaging your equipment if it’s done incorrectly.
There are two methods of connecting multiple speakers. The method you choose is determined by how much impedance your amplifier offers. Depending on the impedance rating of your amp, you’ll either want to increase or decrease the total impedance of all the speakers you’re using.
To Increase Speaker Impedance – Use the Series Connection
If your amp’s impedance is much higher than the speakers you’re connecting to it, you’ll want to use the Series Connection method. This method links all the speakers to each other (often called “daisy-chaining”), connecting only the last speaker in the chain to one of the amp’s output channels. This increases the total impedance to the sum of all the individual speakers’ impedances. It’s recommended to use speakers of similar impedance ratings with this method, as linking a low-impedance speaker to a high-impedance speaker can damage the high-impedance speaker.
With Series Speaker connections, the total power rating is the sum of all the power ratings of the individual speakers. The amplifier needs to have a power rating higher than your speakers’ total to effectively boost the power of the entire sound setup.
To Reduce Speaker Impedance – Use the Parallel Connection:
If your speakers have a total impedance that is higher than the amp you’re using, you’ll need to reduce this impedance down to a level that’s compatible with the amp. This is when you’ll want to employ the Parallel Speaker Connection method. While more complex, this method is more commonly used than the Series Connection method.
Parallel Connection requires each speaker to be connected to the amp itself. The positive terminal of the amp’s output must be linked directly to the positive terminal of each speaker, while simultaneously the negative terminal is connected to the negative terminal of the speakers.
When connecting speakers in parallel, you need to divide the sum impedance of all your speakers by the number of speakers you’re connecting—so, if you are connecting three speakers to a single amplifier, you need to add together each speaker’s impedance, then divide by 3. The result is the impedance rating that your amp will need to handle.
Power rating requirements are the same for Parallel Connection as they are for Series Connection: your amp’s power rating needs to be able to handle the total power rating of all the speakers.
Connect with Care!
Because it requires accurate calculations to ensure proper amp-to-speakers compatibility, connecting multiple speakers is usually best tackled by an audio professional. If you have any questions about this process, contact an Account Manager at SoundPro to get more in-depth information.
AMP UP YOUR AUDIO
Power amplifiers benefit applications where a low-level audio signal needs a boost, such as sound reinforcement, live concerts, entertainment and special events, portable PA, home audio, or instrumental performances. Finding the right amp for your specific speaker setup involves finding the right balance of increasing power without overtasking or damaging your equipment or distorting your sound. While this may seem like a “goldilocks” undertaking, the reward is well worth the effort, enabling your audio to sound its absolute best.
Eager to learn more about what amp would be the best upgrade to your sound system? Contact Sound Productions’ expert Account Managers at email@example.com or call us at 800.203.5611 to get personalized advice.
Laura has been with SoundPro since July 2021. A native of Wisconsin, she spends her summers walking her dog, picking raspberries, and soaking up as much sunlight as possible before sweater season kicks in.