How to Connect a Subwoofer to an Old Amplifier

Being a music lover suggests your appreciation of good music, as well as your familiarity with the technical aspects of music production. Assumedly, you’d also want to have a professional audio setup to achieve the best possible sound quality. To this end, true music lovers know just how necessary a subwoofer is for getting the best out of any audio system.

Most current subwoofers come with an amplifier. However, you might have an old amplifier and subwoofer that you want to connect to a speaker. Simply put, the best way to do this is by connecting your old amp to your speaker and subsystems via the speaker or RCA jack outputs.

The port you use will be determined by the subwoofer and amplifier you are connecting to. Although seemingly straightforward, there are some nuances when it comes to setting up. To help you with this, this article will outline how to connect a subwoofer to an old amplifier.

Types of Subwoofers

Before delving into the technical know-how, it’s good to familiarise yourself with the different types of subwoofers out there. There are two main types of subwoofers:

  • Powered/active subwoofers
  • Non-powered/passive subwoofers

Powered subwoofers operate on a low signal. This signal is amplified by the built-in speaker amplifier, crossover, and power supply. Most of the time an RCA style input jack is used for connecting it to your receiver.

Non-powered (passive) subwoofers are located within the bass box directly linked to the passive bass crossover inside the speaker or at the speaker terminals. These varieties are uncommon.

The significant difference between these two subwoofers is that powered subwoofers contain an internal amplifier as well as one or more signal input options, which include speaker RCA inputs, and in some circumstances digital audio inputs.

How Do Subwoofers Work?

The role of an amplifier is to enhance the low-level input signal to drive the subwoofer’s voice coil with enough power to transmit sound through the speaker cone. Deep bass is produced as the cone vibrates and strikes the air inside a specially built speaker box.

The purpose of subwoofers is solely to produce low-end bass. The good news is that a powered subwoofer already has an amplifier built into the subwoofer enclosure. The built-in crossover will suppress higher sound frequencies, producing smooth bass.

On the other hand, without a crossover, non-powered subwoofers work less well when connected to an amplifier.

How to Connect a Subwoofer to an Old Amplifier: General Methods

As we mentioned above, passive subwoofers require an external amplifier in order to communicate with other output/input system. To use a subwoofer with other systems, you’ll need RCA cables to connect the amplifier with speakers and your subwoofer. It’s important to note that the subwoofer will work without an external amplifier if the receiver has an RCA jack.

An RCA cable set consists of white, yellow, and red terminals. When setting up your subwoofer, be mindful of where you place it within a room–consider the connections and accessibility of input/outputs, as well as the direction of the sound. When connecting it to your other systems, ensure you turn off your amplifier and subwoofer and disconnect them from any power source.

Once this is done, you can then connect the RCA cords from your receiver to the subwoofer. While one set of RCA cables will provide sufficient output, two sets of RCA cables will provide for a richer and deeper sound. The RCA jack is typically labelled “subwoofer output” on most amplifiers.

Next, be sure to connect the receiver’s input channel to the subwoofer’s output channel. Once these are connected, link your receiver to the speakers. The amplifier’s speaker outputs are often situated on the back of the device. The speaker cables (sometimes these will be exposed wires) must be routed into each speaker output.

Connect the right output wire to the right speaker and the left output wire to the left speaker. If you have receivers with labelled negative and positive terminals, connect the speakers’ positive and negative terminals to the corresponding points on the receiver. Reconnect the amp and sub to their power sources and turn them on when you’re finished.

How to Connect a Subwoofer to an Old Amplifier


Understanding Old Amplifiers with Vintage and Modern Receivers

Modern receivers with advanced home stereo systems, particularly home theatre receivers, contain a subwoofer output jack dedicated to bass. This is usually not the case with old amplifiers.

Subwoofers typically generate “.1” channel sound in a multi-channel sound system, such as DTS or Dolby Digital. For example, you might see numbers like “2.1” or “5.1” on surround sound audio or speaker systems. The first number reflects the number of key speakers in this scenario, while the “.1” denotes a sound channel confined to the production of bass through a subwoofer.

Because older receivers and amplifiers don’t have a subwoofer output, you will have to find another way to link your subwoofer.

Controls and Inputs of Powered Subwoofers

It’s worth noting that not all subwoofers include speaker inputs. If yours doesn’t, connecting the bass may be slightly more complex. Powered subwoofers frequently have a few distinct controls and inputs. It is always dependent on the specific model and type that you purchase.

Here’s what you’ll find most often on these devices:

  • On/off switch
  • Power input (AC outlet power)
  • Subwoofer crossover configuration
  • RCA input jack (one or more)
  • Subwoofer degree adjustment (the amplifier’s signal increase)

In most situations, a subwoofer input jack on a receiver uses a monaural signal that you connect with an RCA cable.

If you don’t have a receiver with an output port, someone may try to tell you that you just need to buy another subwoofer. This is simply not true. Subwoofers with speaker inputs are optimal, since they can be connected to the speaker outputs of an old amplifier or vintage receiver.

If you have a subwoofer with no speaker inputs, don’t worry. There are other ways to connect it.

Hooking Up A Powered Subwoofer To An Old Amplifier

Some useful knowledge when learning how to connect a subwoofer to an old amplifier:

  • Some old amplifiers will produce different outputs than current models
  • Some will have a straightforward mono output

For some models, simply locate the corresponding port connections on your subwoofer and amplifier and join the two. This will transmit a signal between devices. This is the simplest and best way to connect old amplifiers with subwoofers. However, some older amplifiers do not have such ports, so you may need to find a work-around.

To this end, your amplifier needs a few components to function correctly. For you to play through A and B at the same time, it will require two speaker outputs. Additionally, a powered subwoofer requires a high-level input option.

If your amplifier and subwoofer have both features, that’s great. Use A on your amplifier to connect to your standard speakers, while the B line should be linked to the high-level input of your subwoofer. When both are connected, you should notice an increase in bass.

How to Connect a Passive Subwoofer to an Old Amplifier

Passive subwoofers are significantly easier to connect to older amplifiers. Passive subwoofers have pass-through connectors that allow you to link the subwoofers through speakers. Connecting the passive subwoofer to the amp should be similar to connecting a loudspeaker, and is done by plugging it directly into the corresponding speaker connections.

Connecting a Subwoofer to an Old Amplifier Without an Output

Some old amplifiers may not have a subwoofer output. In this situation, it is still possible to connect your old amplifier and subwoofer. Depending on the brand, the amplifier should feature a pre-amp or pre-out. A Y adapter is required for subwoofers with only one RCA input. Y adapters have a male RCA on one end and two female RCAs on the other end.

If your amp doesn’t have a subwoofer output labelled “preamp” or “pre-out”, you can just treat your subwoofer as if it were another speaker. Simply connect the subwoofer to the speaker output using speaker cords. Pair the front-left and front-right to the subwoofer’s speaker terminal.


While many people don’t seem to mind the lesser sound quality that comes with not having a subwoofer, having a sound system that doesn’t transmit bass effectively can be incredibly irritating to music enthusiasts. However, there is a distinct difference in quality when it comes to playing music without a subwoofer that even inexperienced listeners can discern.

In terms of damping and tonal balance, when you connect your subwoofer to your old amplifier, the signals are received at relatively comparable frequencies. As a result, both emit the bass at the same time, making any latency between the two imperceptible to the human ear. This is especially significant if you’re making music in a studio, where synching is crucial.

Now that you’ve learned how to connect a subwoofer to an old amplifier or receiver, you should now be equipped to set up your sound system. The quality of sound produced by old amplifiers can inspire nostalgia in some people, and it makes sense why you would want to hook up an older system, especially if you’re looking to achieve a unique sound.

If you’re interested in learning how to make a homemade amplifier, check out some of our other great articles.

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