There are some situations where we have no option other than to compromise. One of such situations is using a bass amp as a subwoofer. Obviously, a bass amp is not designed to be used as a subwoofer. But is it a good idea to use a bass amp as a subwoofer?
It’s not ideal to use a bass amp as a subwoofer. That’s because bass amps are not designed to play as loud as subwoofers and they can’t play deep bass frequencies. So you risk damaging your bass amp if used as a subwoofer. However, you can use a bass amp as a subwoofer if you don’t play them too loud beyond the bass amp’s limit.
We’ll talk about why the bass amp is not an ideal replacement for the subwoofer. And right after, I’ll give you tips on how to use a bass amp as a subwoofer safely without any damage. But first, let’s talk about the difference between a subwoofer and a bass amp.
Difference between a Subwoofer and Bass Amp
Although both the subwoofer and bass amp are made to produce low audio frequencies, they play different roles when it comes to audio. For this reason, there is a significant difference between a subwoofer and a bass amp. Let’s start with the subwoofer.
Firstly, subwoofers are a part of a public addressing system (or PA system). And just as I explained in my article on PA speakers and HiFi speakers, PA systems are designed to play audio loud enough for a group of people to hear clearly. This is an important distinction between the subwoofer and the bass amp.
In essence, because subwoofers are part of a PA system, they are designed to play the bass in an audio loud enough for a large group of people to hear and feel the bass. With this in mind, subwoofer manufacturers use speakers with very long excursion drivers to pump bass audio waves as much as possible. Due to this, subwoofers require more power to play louder.
Also, subwoofers are not made to be used alone. Subwoofers are always paired with main speakers. The main speakers are usually designed to play the mids and high frequencies of audio. So the frequency range of the main speakers is usually between 250Hz and 15kHz.
And subwoofers are designed to play the low audio frequencies. So the frequency range of most subwoofers is between 20Hz and 250Hz. Subwoofers have a very small frequency range compared to other speakers.
Bass amplifiers are made to amplify and playback the sound of a bass or other low-pitched instrument. A Bass amp is a combination of an amplifier (or amp head) and a speaker (or bass cabinet), and can also be referred to as a bass combo.
The amplifier section of a bass amp boosts the weak signal from the instrument into a stronger signal, and it is played through the speakers. And although a bass amp can be very loud, they are only designed to be loud enough to be heard when playing in a band.
A bass amp is designed as a monitoring tool for a bass player and other band members. So they are usually loud enough for a stage, but not loud enough to fill an entire auditorium with bass unless the room is small.
Also, bass amps have a much wider frequency range compared to a subwoofer. That’s because they are usually used with bass guitars or synthesizers that produce not only lows but mids and high frequencies as well. So, to reproduce the sound as close as possible to the instrument’s sound, they have a wider frequency range.
On average, a bass amplifier’s frequency range is between 40Hz and 1000Hz. Of course, there are always exceptions. There are some bass amps with tweeters. These tweeters help bring out the overtones, and harmonics of a bass guitar.
Reasons Not to Use Bass Amp as a Subwoofer
Here are the reasons why you should not use your bass amp as a subwoofer.
1. Bass amps are not powerful enough to replace a subwoofer
As we’ve already talked about, subwoofers are made to play bass frequencies loud enough for a large group of people to hear and feel the bass. Subwoofers can play very loud without any issues. And it’s actually difficult to exceed its loudness limit without damaging your ears first unless they are cheap or faulty.
Bass amps are not designed to play that loud. The speakers (or cabinet) of a bass amp have short excursion drivers. This means if you crank the volume up to extreme levels, you’ll notice a distortion in the signal, and it’s only a matter of time before the bass amp blows. I explained this, in detail, in my article on how bass can damage speakers. I highly recommend you check it out.
2. Bass amps are not designed for line-level inputs
Bass amps are made to receive instrument-level inputs. These are weak audio inputs from a bass or a guitar that has to be preamplified for further processing. For this reason, every bass amp has a preamplifier built-in and has a gain knob for boosting the weak instrument-level signal to a line-level signal.
However, subwoofer inputs are made to receive line-level signals, which is already a strong signal. So if you decide to run a line-level signal meant for subwoofer into a bass amp, you risk damaging it. But how?
The line-level signal, when connected to a bass amp’s input, will go through another stage of preamplification, which will increase the signal strength even more. The signal will be too strong for the final amplification stage to the speakers. And this can cause the bass amplifier to overheat due to clipping.
If there is a thermal-overload protection circuit in your bass amp, it will instantly switch off the amp when it overheats. However, if there is no protection circuit, your amp may easily damage due to overheating. Read more on how overheating affects an amplifier.
3. Bass amps lack deep bass
What do I mean by this? Well, let me explain.
As we have already established, subwoofers have a small frequency range, between 20-250Hz on average. On the other hand, most bass amps frequency response is between 40-1000Hz on average.
This means bass amps can’t reproduce the deep bass in music. It can’t provide a heavy enough bass that will get the crowd moving.
If you are planning to use your bass amp as a subwoofer at a party, chances are that there will be a lot of dance and pop music being played. And a bass amp lacks the ability to playback the deep bass frequencies in many electronic dance music songs. They just don’t sound great.
Tips for Using Bass Amp as a Subwoofer
If you researched on whether you can use a bass amp as a subwoofer, I’m sure you already knew it was a bad idea, but you want to compromise anyway. And I totally understand. Sometimes you run out of options and compromising is the only way forward.
So I’ll give you some tips on how to use a bass amp as a subwoofer. You can apply all of these tips, or apply the ones that you can.
However, keep in mind that the bass amp will not sound like a subwoofer but it can add some extra low end that can make the music sound much fuller. Also, if your bass amp is too expensive and you can’t afford to damage it, I would recommend not to use it as a subwoofer. But some of these tips will eliminate the risk of damage. So let’s get into it.
1. Use Bass Amp as a Subwoofer only in small venues
I highly recommend that you use a bass amp as a subwoofer only in small events where you are playing for not more than a hundred people. If the venue is small, you won’t be forced to crank up the amp’s volume way too high, which could potentially blow the speakers.
The bass amp, with the volume, turned half-full can fill up the entire space with bass, provided the venue is small.
2. Use a crossover
For those who don’t know what a crossover is, this is a device that splits full-range audio into low frequency, mid-frequency, and high-frequency bands, and distributes them to the speakers that are designed for such frequencies.
Here is why it’s important to use a crossover, especially for a bass amp.
As I mentioned earlier, bass amps have a wider frequency range than subwoofers, and they can play the mid and sometimes high frequencies.
This means, when you play audio through them, they will not only play the bass frequencies of the audio but the mids as well. And since you have your main speakers playing the mids and high frequencies, this will increase the volume of the mids and the final output will sound muddy. In a few instances, they can cause phasing issues, where the mids from the bass amp cancel out the mids from the main speakers, making the mids quieter.
You certainly don’t want that. This is why you want to use a crossover to separate the lows from the mids and highs, and then send only the low-frequency audio to the bass amp.
Also, when you play full-range audio through a bass amp, you are essentially wasting the amp’s resources and energy on frequencies that cannot be played by the speakers.
Using a crossover will allow you to send only the low frequency to the bass amp. And all the energy and resources in the amp will be used to play only the bass, giving you a much better bass performance.
If you are looking to pick up a crossover for this setup, one that I’ll recommend is the Rockville RX230 Crossover (on Amazon). You can use it with either a 2-way speaker in stereo or a 3-way speaker in mono. And there is a dedicated subwoofer output that outputs a frequency range of 30-200Hz, perfect for many subwoofers and bass amps. However, the frequency range is adjustable, which is definitely helpful.
3. Monitor the bass amp closely
If you are using your bass amp as a subwoofer, you should keep an eye (or ear) on your amp. Pay close attention to how it sounds. If it starts clipping or distorting, you should turn it down.
That’s because it can lead to the speaker’s voice coils burning, or the amplifier overheating, which can potentially harm the bass amp.
You also want to monitor it when you are using it at parties. Drunk people at parties are notoriously known for cranking up the volume on speakers when no one is looking. So make sure you keep an eye on the bass amp to make sure no one increases the volume to a point where the speakers can blow.
4. Use a Limiter for Extra Safety
If you have a limiter at your disposal, you can use it to protect your bass amp from blowing. But how exactly will a limiter protect your amp?
What a limiter does is to prevent audio from going above a certain loudness that you set yourself. For instance, when a limiter’s threshold is 10dB, even when you play a 50dB audio through it, it will limit the audio signal’s loudness to 10dB. This is why a limiter can be excellent protection for your bass amp.
To use a limiter, simply plug the subwoofer output on a crossover into the input of the limiter. And then plug the limiter’s output into your bass amp.
A limiter isn’t necessary for this setup. And I wouldn’t advise you to buy a brand new limiter just for this purpose. But if you have one lying around, you should definitely use it.
In summary, using a bass amp as a subwoofer is a sure way to damage the amp. That’s mainly because bass amps are not as powerful as subwoofers so they can’t play very loud. Pushing your bass amp beyond its limits by playing them too loud will easily damage the voice coils of the amp.
However, by taking a few safety precautions such as using a crossover and a limiter if possible. And also you should only use a bass amp as a subwoofer in small venues. Just keep in mind that a bass amp will not sound as good as a subwoofer because that’s not what it was designed for.