Setting up a home theater system can be a confusing process if you’re new to it. And things can become even more complicated if you have a passive subwoofer, which is different from what most people own. Can you even use it with an AV receiver, or do you need to make other arrangements for it to work correctly?
You can use a passive subwoofer with an AV receiver by connecting it to an external amplifier, which makes it work as a powered subwoofer. You can then connect the input of the external amplifier to a receiver using the pre-out socket. Never connect a passive subwoofer directly to an AV receiver.
You’re probably wondering why you can’t use a passive subwoofer by connecting it directly. Read on to learn how passive and powered subwoofers work and why an external amplifier is the best way to connect a passive sub.
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The Difference Between a Passive and Powered Subwoofer
A subwoofer is a speaker that produces low-frequency sounds, specifically 20-200 Hz. They require more power to reproduce these sounds, and so an amplifier is needed to meet the subwoofers’ demand. This means every subwoofer needs to be connected to an amplifier. But how do passive and powered subwoofers differ?
A passive subwoofer is called passive because it requires an external amplifier to function, just like traditional loudspeakers. A passive sub doesn’t even have a subwoofer line; all it has are speaker connectors. Directly connecting it to an AV receiver doesn’t work.
When you buy this type of subwoofer, you’ll need to purchase an external amplifier that can output enough power to sustain bass effects. The exact amount of power required depends on the needs of the subwoofer, the size of your room, and how much bass you want.
On the other hand, a powered subwoofer does not need an external receiver or amplifier. The manufacturer optimally configures the qualities of the subwoofer and amplifier, and the combination is packed in a single box. For a powered subwoofer, all you need is a single cable connection from the subwoofer to the receiver.
Powered subwoofers are much more common because they have their own built-in amplifiers. This makes it easy to install with our home theater receivers, and it also makes them more cost-effective. On the other hand, you may have to pay more than your passive subwoofer’s cost to buy the amplifier required to make it work.
How to Connect a Passive Subwoofer to an AV Receiver
AV receivers have lots of toggles, switches, and ports, which means there are a lot of wires as well. This can make it challenging for a newbie to set up their home theater system. However, the good news is that you don’t have to worry about all these connectors and sockets. There are only two ways to connect a subwoofer to an AV receiver: pre-out sockets and speaker connectors.
As mentioned earlier, powered subwoofers can be directly connected with an AV receiver. But passive subs cannot be used in the same way. The lack of a built-in amplifier means the sub will not be able to produce low-pitched sounds if connected directly. And what’s the point of a subwoofer if you can’t feel the bass?
Denon, a Japanese electronics manufacturer, recommends not to use a passive sub directly with an AV receiver. Instead, the company suggests you should first connect it to a suitable external amplifier. This will turn your passive sub into a powered one, making sure it receives enough power to function optimally.
Then, you can connect the amp with a receiver using the pre-out socket. A pre-out socket is meant to work only with powered subwoofers. That’s why directly connecting a passive sub to an AV receiver doesn’t work. A direct connection will not be able to supply enough power.
Using an external amplifier is not the only way of doing things, though. Another method is to treat the passive subs as speakers and connect them directly to a receiver through the speaker connectors. For this to work, you will have to change the settings of your AV receiver.
Which Method Is Better?
Subwoofers require a lot of power to reproduce bass lines, and you need to make sure enough power is delivered. Your AV receiver might not provide the amount of power required if you use a direct connection through speaker connectors.
Therefore, out of the two methods, using an external amplifier is preferred because it converts your passive sub into a powered one. It takes care of the power supply and ensures that your subs work optimally.
How to Pick the Best External Amplifier for Your Passive Subwoofer
Now you know that an external amp is required to make a passive sub-function. But you can’t just go to Amazon and buy an amp with the most positive reviews. It is crucial to consider the needs of your subwoofer to pick a suitable amplifier for it. Here’s how you can decide which amp is the best for your sub:
How Much Power Do You Need?
Root Mean Square (RMS) rating tells you how much power the subwoofer can handle regularly. And the peak wattage indicates the maximum amount of power the sub can take without incurring damage. Supplying too much power will result in a damaged subwoofer.
Therefore, you should always match the RMS watts of the subwoofer to that of the amplifier. If you have multiple subs, multiply the number of woofers by the RMS rating of each of them. Now, look for an amplifier that can supply 75% to 150% power of the total requirement of your system.
How Much Impedance Do You Need?
After the RMS rating, another essential factor to consider when looking for an amplifier is impedance. The good news is that choosing impedance is relatively easy when you’re installing only one subwoofer. Most passive subs in the market offer you the option of selecting a two- or four-ohm rating.
However, things become complicated when you have multiple subs or dual-voice coil (DVC) subwoofers with two input connections. For example, say you have two subwoofers with four ohms each. In that case, you’ll need an amplifier with an eight-ohm impedance rating.
When wiring multiple subwoofers together, you also need to make sure they have the same coil and impedance.
I recommend referring to these subwoofer wiring diagrams to determine the best wiring option for your subs and amps.
Pick an Amplifier That Meets Both Qualifications
You need to look for an amp that can output the right amount of power (calculated in step 1) at an impedance load your subwoofers can handle (determined in step 2).
Note that amps are mainly available in two styles: mono (single-channel) and dual (two-channel) amp. Mono amplifiers are the most suitable for producing incredible bass sound. It is possible to wire multiple subs to a single-channel amp, and every sub will receive the same frequency.
Final Thoughts
Subwoofers are loudspeakers designed to reproduce low-frequency sounds known as bass. We can listen to songs using any speaker, but subwoofers help us feel the music. There are two types of subwoofers: passive and powered.
Powered subwoofers can be directly connected to an AV receiver because they have a built-in amplifier. This isn’t the case with passive subwoofers; you first need to connect them to an external amplifier.
Using an external amplifier converts your passive sub into a powered one. When buying an amp, you need to make sure it meets the power and impedance requirements of your subwoofer.
