AMPLIFIERS – 101

When it comes to matching the right speakers with your amplifier, it isn’t actually as easy as it seems. Amplifiers are as essential to the presentation and quality of sound like the speakers are. How difficult is it to match the amplifier to the speakers, you ask? 

An audio amplifier is a device that amplifies an audio signal. The audio signal is a low voltage and low wattage signal, ranging from about 10Hz to 20KHz, and the amplifier takes it and makes it louder by increasing the wattage before sending the signal out to the speakers. 

There are a few terms that you should learn in order to grasp a basic understanding of how the amplifier and speakers work cohesively:  

• The Power, which clearly is one of the most important attributes to focus on. So, when referencing the power in HiFi and home cinema products, it is all measured in watts. Don’t be mistaken and assume that more wattage means greater volume output because that’s not always the case. When discussing the wattage for an amplifier and speaker, it is all about the amount of power that the amplifier is putting out and the amount of power that a speaker is able to handle. Generally, most beginners would just put a low-watt amplifier with higher-watt speakers and consider it a finished project. Unfortunately, that isn’t always the best option, it may be easy but not ideal.  

 Amplifier spec sheets will often reference Continuous Power (output) and also Dynamic (peak) Power. Continuous Power delivers a fixed wattage to a constant resistance (commonly referred to as ohms). For example, 50 watts per channel into 4 and 8 ohms. 

On the other side, Dynamic Power has the ability to push 100 watts into 8 ohms and 150 watts into 4 ohms. Dynamic Power is made to ensure that the wide dynamics demanded by digital music and movie formats are properly powered the way that they should be. Dynamic Power is not frequently used (maybe only a millisecond at a time) and measuring the general amplifier power based on this would not be accurate. 

Different manufacturers display the wattage of a speaker in a few different ways. TruAudio displays its speaker power using Maximum Continuous Power. 

Be careful and focus on the Continuous Power and the wattage that your amplifier puts out, use that against the recommended amplification levels of your speaker. Using these two figures will assist you and your ability to gauge the match of the pairing.

• The Impedance is a common word found in product catalogs/ descriptions/spec sheets. But what is impedance? This is just a fancy word that is used to describe the measure of electrical resistance of your components, and it is measured in ohms. For resistance (also on spec sheets), it is usually represented with this “Ω” symbol. Luckily, knowing a lot about resistance isn’t too important as a beginner. Just learning the basics will help you out a lot. The impedance is what helps to determine the compatibility between your amplifier and your speakers, so it does have quite a bit of importance. Speakers are rated based on the number of ohms that they have, usually between 4 and 8 ohms. Then an amplifier is usually rated around 6 to 12 ohms. This is the easiest way to judge how well your speakers and amplifier will work together and if they really are compatible. Luckily when looking at products, these numbers can be found on any spec sheet and it makes it an easy comparison for you. The biggest thing to look out for when pairing your speakers to an amplifier is to be sure that the speaker is not a lower impedance than the amplifier, it is a great way to ruin your audio equipment! 
• Sensitivity is mostly related to speakers. However, if you are wanting to get an amplifier and don’t want to spend more money on a more powerful amplifier, then learning about the sensitivity of the speakers is actually extremely important. Sensitivity is the general measure of how loud a speaker is (in decibels per 1 watt per 1 meter in distance). You’re probably wondering why “sensitivity” is even important enough to be brought up. Well, it is important because it tells you directly how loud your speakers can get and because speakers and amplifiers are connected to each other, it’s all relevant. 

 When discussing the sensitivity of speakers, a speaker that has the same power applied to it as the distance from the speaker, a speaker with a lower sensitivity will sound quieter than a speaker with higher sensitivity.  Please be aware that a higher sensitivity speaker is not necessarily a better choice, it simply means that it will reach a higher volume than the lower sensitivity one.  

THINGS TO CONSIDER FOR THE RIGHT SYSTEM MATCH

 Matching systems or pairing them with a set of speakers and the correct amplifier is a crucial task that you need to get right in order to avoid blowing a speaker or ruining the amplifier. Things you need to consider before installing: 

• How will you be using these speakers? This has been brought up before, in previous articles, because it truly is important. If you do not plan on turning your system up too loud, then you could save money on the speakers and amplifier by purchasing fewer speakers with a lower-powered amp. 
• Where are they going to go? Which room and how big is that room? The bigger rooms usually require bigger speakers that have a higher sensitivity or even a more high-powered amplifier. Smaller rooms can actually have a lower-powered amplifier and lower sensitivity speakers.

WHAT TO AVOID  

A lot goes into the process of matching speakers and amplifiers together, learning about things to avoid (in this case) is simpler.  Obviously the last thing that you want to do during the setup process is to blow up your speakers and ruin your amplifier. 

That would be awfully expensive to replace! Two of the worst mistakes to avoid would be making the mistake of connecting your speakers to an amplifier that uses a Continuous Power rating that is way above the power capabilities of your speakers. In this case, the speaker gets destroyed because the speakers can not dissipate the heat energy that is coming from the amplifier’s output so it burns up the voice coil and the suspension in the speaker.  

Or do the opposite and try to connect the speakers to an amplifier that is too weak to power all of them. Users then will keep increasing the volume on their speakers to make up for the lack of power the amplifier is sending. The end result, the amplifier eventually overheats and can also send clipped signals to your speakers. The distortion and high-frequency energy will break your speakers and amp. 


Having an amplifier that is underpowered will result in less damage, but both examples, unfortunately, will leave you with broken products that you can no longer use. So pair with caution.