How to Connect a Subwoofer to an Old Amp

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If you have an old amplifier that is dear to you and you want to use it again to groove, you’re in for good news.

I am a fan of amps myself, and I’ve seen many people lose faith in their devices when they get old and start performing poorly. 

But you can fix it instantly by connecting a subwoofer to your old amps.

You need to connect a subwoofer to an old amp, but how can you do this? Luckily, there are ways – and the best part is that these ways are easy to execute.

So, in this complete guide, let’s look at the different methods that can connect active and passive subwoofers to your home theater system.

How Does a Subwoofer Work?

How Does a Subwoofer Work

Simply put, a subwoofer works when its built-in amplifier pushes sound signals into it. This signal triggers the subwoofer’s voice coil, which then creates a sound and pushes it into the enclosure with woofers that basically deepen and clean the sound.

This operation of a subwoofer is facilitated by several components. Some of these components include woofers and wooden enclosures. These are an integral part of subs. However, the inclusion of other components depends on the type of subwoofer that you are using.

So, we already know how a subwoofer works. Now, let’s discuss each part individually and its contribution to the subwoofer’s ultimate goal. 

In short, woofers are the essential parts of a subwoofer. You get more than one in a sub, enclosed in a wooden enclosure. Subs use this enclosure to convert sound signals into deeper, low-frequency sounds.

Additionally, the amplifier is a major component of a subwoofer, and it often comes built-in within the gadget, which is called an active subwoofer.

Note that passive subwoofers are another type of subwoofer that doesn’t include built-in amplifiers. You need to connect them to an external amplifier or an audio/video receiver. Again, these subwoofers aren’t very popular because of the lack of practicality in their design.

Talking about the other components, the wooden enclosure of a subwoofer can only sense and produce low-level frequencies. So, the gadget is built only to receive low-frequency sound signals. In addition to this high frequency, these subwoofers can relay, and the users can even set a lower input frequency.

To do so, you must use the crossover frequency knob to set its range. This is because the subwoofers use this setting to block higher frequencies of sound signals from the speaker.

Similarly, you can also set the frequency to a low range. But to keep the sound transition seamless between speaker and subwoofer, you should set it at 10 Hz above your speaker’s lowest frequency.

Another setting you need to use to get a better experience from your subwoofer is to minimize the delay between its sound and the loudspeaker’s sound, and luckily the phase switch will help you do this. It is set between 0 and 180 degrees and electrically delays the sound signals to the subwoofer allowing it to better synchronize with the sound system.

Why Should You Connect A Subwoofer to an Old Amp or Receiver?

Connect A Subwoofer to an Old Amp or Receiver

Adding a subwoofer to your home theater system can enhance your overall audio experience in several ways. Here are some reasons why you should consider adding a subwoofer:

Better Bass Response

 Subwoofers are designed to reproduce low-frequency sounds, which can be difficult for smaller speakers to handle. Adding a subwoofer to your home theater system can improve the bass response, resulting in a fuller and more impactful sound.

Enhanced Movie Experience 

Many movies feature deep bass sounds, such as explosions or rumbling sound effects, that a subwoofer can reproduce more accurately. This can create a more immersive and realistic movie-watching experience.

Improved Music Playback 

Music with a lot of bass, such as hip-hop or electronic music, can sound more dynamic and powerful with a subwoofer. Even music genres that don’t typically have a lot of basses can benefit from the added depth and clarity that a subwoofer can provide.

Better Overall Sound Quality 

A subwoofer can help balance the sound of your home theater system by filling in the lower frequencies that other speakers may not be able to handle as well. This can result in a more even and natural-sounding audio experience.


Adding a subwoofer to your home theater system can give you more flexibility in terms of placement and speaker size. You can choose a subwoofer that fits your space and aesthetic preferences, and you can also experiment with different placement options to find the best sound for your room.

Overall, a subwoofer can be a valuable addition to any home theater system, providing an improved bass response, enhanced movie and music playback, better overall sound quality, and flexibility in placement and speaker size.

How to Connect Subwoofer to an Old Amp or Receiver

Connect Subwoofer to an Old Amp or Receiver

The only problem that prevents you from connecting your subwoofer to an old amp or receiver is that the latter doesn’t offer subwoofer-level frequency. This is because the only output available from most old receivers and amplifiers is speaker-level output. 

This output gives mixed signals of high as well as low frequencies. However, subwoofer inputs are designed only to receive line frequency. 

So, how can we connect the output of mixed frequency to an input of low frequency? Well, we can include a bridge that can convert one frequency into another. 

Here are a few bridges or converters you can use for the right frequency to reach your subwoofer, even when your receiver is not offering this frequency. 

Connect with the Speaker-Level Inputs

If you still have to get a subwoofer for your vintage receiver or old amplifier, you should go with active or powered subwoofers with speaker-level inputs.

You don’t need to use indirect methods if your subwoofer has arrived with speaker-level inputs. As the name suggests, these inputs can detect higher-level frequencies just as well as line-level signals.

After accepting these signals, the internal electronics of the said subwoofer will divide these signals and bring them to line level. These subwoofers also have built-in low-pass crossover, which allows only high-quality, low bass to reach your ears without any other unwanted music or sounds from the receiver.

Additional Information

Speaker-level inputs for subwoofers and speakers offer a high level of impedance. So, it’ll be okay if you connect your subwoofer to the same speaker wire terminal that gives audio signals to the speaker.

On the contrary, if you are connecting both output devices to the same terminal, make sure to connect them in parallel by connecting positive speaker inputs to positive outputs and negative inputs to negative outputs.

Use a Line-Level Converter

A line converter is the most common bridge between the speaker-level output of a receiver and the subwoofer’s input. It reduces the voltage of high-frequency sound signals from the amplifier or receiver. 

These converters are designed to receive and turn speaker-level signals into line-level signals. In fact, they are most popular among automobile music lovers because of their practicality of in-car music systems. 

But it doesn’t mean they can’t be used in home theaters. So, if you are procuring a line converter for your home use, select those brands that have shown their worth for home theaters. 

This converter comes with speaker wires connected to your amplifier or receiver. Additionally, make sure to connect them according to the colors of these wires. For this, you will use an RCA male-to-male Y adapter to connect the converter to the subwoofer. 

Use a Mini Amplifier

A line converter may not solve your problem if you are using a passive subwoofer. 

A passive subwoofer doesn’t include an amplifier in its design. In other words, you have to rely on an external amplifier to feed its sound signals. 

Luckily, you can supplement old receivers without spending hundreds of bucks on an amplifier, as a mini amplifier will also work just fine. Note that the amplifier will only resolve the issue of signal feeding to the subwoofer. So, it will not help the latter in filtering out high-frequency signals. 

That’s why you will still have to ensure that the right frequency of sound signals reaches the subwoofer by using a line converter to complete the transmission. This line converter will now connect to the mini amplifier instead of the receiver. Again, don’t forget to connect the right colors. 

Finally, connect the other side of this converter to the subwoofer using an RCA male-to-male Y adapter, as we discussed in the previous section. 

Use a Low Pass Crossover

This is another method that you can use if you want to connect a passive subwoofer to your receiver or amplifier. This method allows you to connect the speaker output of your receiver or amplifier with the sub without using a line-level converter.

Instead, you will use a low pass crossover. An active subwoofer uses an electric crossover that detects and allows only low-frequency signals to transmit through it. On the other hand, a passive sub doesn’t have this component.

Eventually, you can eliminate this issue by adding a crossover that will prevent higher-frequency signals from passing. In turn, your sub will only receive higher-quality bass signals to produce sound. These low-pass filters are generally inexpensive, and most offer premium sound quality when attached to the subwoofer.

Again, look for a frequency range of 20 to 200 Hz for these filters to match the efficiency of an electric crossover. Simply connect the crossover with the speaker outputs of the amplifier or receiver on one end and the passive subwoofer on the other.

Additional Information

Unlike speaker-level inputs of the subwoofer, the low pass filter doesn’t offer high impedance, making it a bad choice to use in the same speaker output wire terminal that is connected to your speakers. So, only choose this option if you have run out of the other alternatives.


1. How do you hook up a subwoofer to an older receiver?

To hook up a subwoofer to an older receiver, you will need to follow these steps:
Check if your receiver has a subwoofer output: Older receivers may not have a dedicated subwoofer output. If your receiver doesn’t have a subwoofer output, you may need to use speaker-level connections instead.
Get the right cables: You will need an RCA cable or speaker wire, depending on the type of connection your subwoofer requires.
Connect the subwoofer to the receiver: If your receiver has a dedicated subwoofer output, connect one end of the RCA cable to the subwoofer output on the receiver and the other end to the input on the subwoofer. If your subwoofer doesn’t have an RCA input, you can use a speaker wire to connect it to the receiver’s speaker terminals. Simply connect the positive terminal on the subwoofer to the positive terminal on the receiver and the negative terminal on the subwoofer to the negative terminal on the receiver.
Set up the subwoofer: Once the subwoofer is connected to the receiver, you may need to adjust some settings on the subwoofer itself. Most subwoofers have volume and crossover controls that you can adjust to get the best sound.
Test the connection: Play some music or a movie with a lot of bass to make sure the subwoofer is working properly. If you’re not getting any sound from the subwoofer, check the connections and make sure the settings are correct.

Overall, hooking up a subwoofer to an older receiver is relatively straightforward, but it may require some trial and error to get the best sound.

2. How to connect a subwoofer to an amplifier without subwoofer output?

Firstly, it’s important to note that there are a few different methods for connecting a subwoofer to an amplifier without a dedicated subwoofer output. One option is to use a line-level converter, which will allow you to convert the speaker-level signal from your amplifier into a line-level signal that your subwoofer can understand. Alternatively, you could use a Y-splitter cable to split the signal from your amplifier between your main speakers and your subwoofer.

No matter your chosen method, it’s important to ensure that your subwoofer is properly positioned and calibrated for optimal performance. You may need to experiment with different placement options and subwoofer settings to achieve the best possible sound.

3. Can you connect a subwoofer to any receiver?

Technically, you can connect a subwoofer to any receiver, but you may need some adjustments to do so. For instance, if you are using a wireless subwoofer, you will need a Wi-Fi adapter to pair the receiver with the sub. Otherwise, if your receiver doesn’t provide subwoofer output, you can use one of the methods mentioned in this blog post.


We hope that by now, you must have understood the different ways of connecting a subwoofer to an old amp. 

Now, although all the options are quite fine, we recommend you try to do it with a line-level converter or by using a mini amplifier.

Both of these methods are quite easy and have a high chance of delivering the desired sound quality.

You can also check out the other queries related to your subwoofer in this article, as we’ve tried covering almost all the important aspects you need to know for its use case.

If you liked this article and found it helpful, share it with your friends and family members. Also, don’t hesitate to reach out to us if you have any queries or want us to cover something.