How To Hook Up A Car Subwoofer To A Home Stereo (With Diagrams!)

How to hook up a car subwoofer to a home stereo featured image

Thinking about putting that extra car sub to good use? Maybe you’re wondering if it’s possible to hook up a car subwoofer to a home stereo or amplifier at all.

The good news is that yes, in many cases you can use a car sub with a home stereo. However, it’s not as easy as just wiring them up any old way.

I’ll tell you what you need to know and provide some helpful diagrams. Let’s get started.

Contents

Can I hook up a car subwoofer to my home stereo?

Can I hook a car subwoofer to a home stereo? Man thinking image

The quick answer is that it depends. There are several basic things you need to understand first before you try. These are important, too…so don’t be careless or you could damage your home receiver or amplifier.

You can hook up a car subwoofer to a home stereo directly if:

  • You have a subwoofer or more than one subwoofer that can be wired for at least 8 ohms total. This can be two 4 ohm subwoofers or a 4 ohm dual voice coil (DVC) subwoofer.  [See diagrams below for how] 
  • Your home stereo or amp can handle 4 ohm speakers (most can’t so let’s ignore this).
  • Using workarounds: this includes using a small 4-ohm capable amp between the receiver and sub or an inline resistor to bring up the speaker load. (Don’t worry – I’ll share these in detail below)

Even if you have the right car subwoofer(s) your amp needs to have enough power available to drive the subwoofer box. The good news is that for casual listening you don’t need a ton of power like you do for cars and truck use.

The single biggest obstacle is that most home stereos, home theater receivers, and home amplifiers can’t handle the 4 ohm speaker load of many car subwoofers. It’s 2x lower than the 8 Ohm minimum most require. (Some car subwoofers are even 2 ohms, in fact).

Why can’t I use a 4 or 2 ohm car subwoofer with a home stereo?

Diagram showing how to match speaker ohms to a home stereo

You’ll need to be sure to avoid connecting a speaker impedance (Ohms, speaker load) that’s too low to a home stereo amp or receiver. Doing so causes it to try to produce more electrical current than it’s designed for. This causes overheating and potentially permanent damage to your electronics.

Just like car amplifiers & car stereos, home stereos have a minimum speaker load, stated in Ohms, that they’re designed to handle. 

Never try connecting 2 or 4 ohm car subwoofers or speakers to a home stereo – they’re likely to overheat very quickly and suffer possible damage.

Why is matching speaker impedance important?

Matching the speaker load to your home stereo just means matching it up with the best Ohm load that will deliver the power & volume it’s designed to produce. As you can see in my diagram above, if the speaker is over the rated Ohm spec, it will work safely but at the expense of delivering a lot less power and volume than you’d like.

Using the correct Ohm load means you’ll get the rated power – and as you might guess – the maximum volume possible. 

However, using less than the rated Ohm speaker load (whether 1 or more speakers, the total Ohm load the stereo sees) is dangerous and won’t work. Don’t do it!

Tip: In cases where the subwoofer is less than 8 ohms total and/or the receiver or amp doesn’t have enough power don’t give up! There are some work-arounds that can you can use as we’ll see.

Do I need a speaker crossover for a car subwoofer?

Example of a passive subwoofer low pass crossover

Example of an 8-Ohm compatible low-pass speaker crossover for blocking all sounds above a low bass frequency (cutoff frequency). These are used to get “clean” sounding bass from a subwoofer when there’s no crossover already provided.

By the way, there’s another important part you’re likely to need and may not have thought about: using a speaker crossover for clear bass with a car subwoofer. Car subwoofers are normally used with a car amp with a low-pass crossover built in already.

That’s often not the case for home stereos, although some do have a subwoofer RCA output jack for use with an amplifier or powered subwoofer.

Diagram showing a passive subwoofer speaker crossover

The point is that unless you want to hear vocals and other sounds from the car subwoofer, you’ll need to hook up a subwoofer speaker crossover between the stereo & the sub. For clear bass, you’ll need a crossover to block higher-frequency sounds subs can’t play well.

If you’re lucky enough to own a receiver or home amp with a low-pass crossover built in you can use that instead.

How to wire a car subwoofer to a home stereo

How to connect a car subwoofer to home stereo diagram

As you can see from my diagram above, I’ve come up with 4 ways to connect a car stereo to your home stereo receiver or amp – but it greatly depends on the specifics. For example, using a 4 ohm car sub is relatively simple, while using a 2 ohm or another type can be more complicated.

Here are the  4 ways you can do this:

  1. Two 4 ohm car subwoofers: This is one of the simplest setups possible. Just connect the subs in series for a total of 8 ohms and connect them to one of the stereo receiver speaker outputs. However, be aware that if there’s no speaker crossover in place or built-in, you’ll get vocals and sounds in the subs that won’t sound good, so a crossover may be needed. (see above)
  2. Single DVC 4 ohm subwoofer: Likewise, a single dual voice coil (DVC) subwoofer with 4 ohm windings can be wired in series to meet the 8 ohm requirement. Just like above, a low-pass (subwoofer) crossover may be needed.
  3. Single 4 ohm subwoofer or receivers without enough power – using a mini amp: You can use an affordable miniature amp to drive a 4 ohm car sub directly, avoiding the needed to lose power like you would in option #4. You can use a mini amp that can drive a 4 ohm or even 2 ohm car sub directly. Some also have a built-in crossover for great sound making them a great choice.
  4. Single 4 ohm subwoofer using a series power resistor: This is the simplest and most affordable option. Using a power resistor (a resistor that’s designed to handle higher power levels) just wire it in series with the sub to get the 8 ohms needed. Power resistors can be found for around $5 more or less. I recommend a 25 watt or higher rating, depending on your stereo’s power output.

Note that while option #4 is the easiest of all, I don’t recommend it because you’ll lose 1/2 or more of the stereo’s power output. That’s because the power is divided between it and the sub. 

Audio power resistor examples

Examples of power resistors you can use for speaker projects including hooking up a sub to a home stereo. These resistors can be found and electronic parts stores and speaker part retailers, or even Amazon or eBay. They’re often priced very affordably (around $5 or so for a pair or pack).

What to do if you can’t get the right Ohms together

Home stereo mini amp example

Example of a small & affordable amplifier that can be used to drive a lower impedance car subwoofer from your home stereo receiver. You can find these with a crossover built-in (as shown here) for under $30.

It’s a bit tricky in some cases – especially when using multiple car subwoofers and/or those like 2 ohm models, for example. A home stereo amp is a great answer to this problem and offers several benefits:

  • Can drive lower impedance subs directly
  • Low cost (often under $30) and very compact size
  • Some include a low pass crossover built in meaning you’ll save a lot of hassle

While I realize you might not want to have to spend money & wait for the stuff to arrive, it’s definitely worth thinking about. Here’s a good example of an inexpensive one I found.

How do you hook up a subwoofer to a receiver without sub output?

Image showing examples of line level RCA converters

Examples of line level converters use you can use to get an RCA low-level signal from a home stereo without subwoofer RCA outputs.

The good news that if you’re planning to use a small amp to power a sub at home but your receiver doesn’t have a subwoofer or other RCA outputs there’s a solution. You can use a line level converter, commonly used for factory-installed car stereos, to create some, then connect to a subwoofer amp.

You’ll want a good quality one with adjustable output level dials to be sure you don’t have problems with the signal level. They’re especially valuable to have as many vintage or older home stereos don’t have subwoofer outputs.

You can connect them just like you would a speaker, either to unused speaker outputs or also connect them alongside speakers already in use.

How many watts do you need for a subwoofer?

Man thinking about how much power for car subwoofer with home stereo

Car subwoofers are very inefficient speakers and are some of the most power-hungry you can find! The good news is that if you’re just looking forward to average listening levels you can get by with less power.

  • For easy listening, low-volume music levels, or sound from movies, you’d want at least 25 watts RMS of power per channel available to drive a subwoofer.
  • For a bit more “punch” that requires extra bass (especially the bass & thuds from DVD or BlueRay video sound) 50W+ would be much better.

If your home receiver is on the weaker side as some budget models are (for example, 15W-20W per channel) you’ll need a small external amp as I mentioned earlier. If you’re planning driving a car subwoofer with high volume and want some serious bass I’d recommend a minimum of 100W RMS and even more if you can afford it.

Bookshelf stereos usually can’t cut it – they’re just not designed to produce much power. However many decent quality home stereo receivers or home theater amps/decoders can do the job ok.

Home stereos vs car amplifiers

On the downside, home stereos don’t produce anywhere near the power of today’s car amps which typically have at least 75W to 100W or more per channel, if not several times that! On the plus side, when using a subwoofer inside your home you don’t have the terrible acoustical losses that you do in a car or truck.

This means when using a car subwoofer inside your home you need less power to hear it well.

Subwoofer sensitivity (efficiency) & volume

Some subwoofers produce more volume for the same amount of power. This is actually a standard specification used to compare speakers and the official name is speaker sensitivity. In other words, the sensitivity of a speaker describes the volume output it produces for a given amount of power, in decibels (dB).

A standard dB reading of 1 watt measured 1 meter (1M) away is used for this measurement in the speaker industry.

When comparing two subwoofers, for example, one might have a sensitivity of 87dB/W while a 2nd one has one of 91dB/W. This means the second produces more sound with less power. Because speakers require a doubling of power to increase another 3dB in volume, that means a more efficient speaker can use 1/2 the power or less than another speaker for the same volume!

That’s something to think about when comparing subs.

Will a sub work without an amp?

can you use a sub without an amplifier question man thinking

This one’s easy to answer, although it’s important to be clear about power & amplifiers. In general terms, no, a sub won’t work ok without an amp.

Hang on a second, though! What does “amp” mean in that case? To be more clear, here’s the long and short of it:

  • A subwoofer, like any other speaker, must be powered by an amplified audio signal with a decent amount of wattage in order to produce sound.
  • To properly drive a subwoofer for it to work well, that’s different; in that case, yes, without question you need an amplifier of sufficient power to drive it well.

That is to say, you can’t hook up a subwoofer to a non-amplified signal output from any stereo or other audio source. You need an amplified speaker output with a fair amount of power in order for it to work ok and sound right.

As I mentioned earlier, for casual listening inside your home you can likely get away with 25 watts for subwoofers with decent efficiency. However, if you want to drive a subwoofer hard and get that real bass “thump”, you’ll need a lot more power: 80-100W or more for a home amplifier.

More great articles about speakers and audio

Don’t miss out – there’s a lot more great reading ahead! Check out some of my other detailed articles:

Got questions or comments? Feel free to leave a comment below!

How To Connect A Subwoofer To An Old Amplifier Or Vintage Receiver

How to connect a subwoofer to old amplifier or vintage receiver featured image

Got a vintage amplifier or receiver? When it comes time to add some great low-end bass you might be scratching your head wondering how – and if – you can add a subwoofer. 

The great news is that there are several ways to connect a subwoofer to an old amplifier or vintage receiver.

Even better, it won’t cost a lot, either! Read on and I’ll share with you 3 ways to connect a subwoofer along with clear subwoofer diagrams anyone can understand.

Contents

Home stereo subwoofers explained

Passive vs active home subwoofers diagram

Comparing passive (non-powered) vs active (powered) home stereo subwoofers. Powered subwoofers have an internal amplifier and one or more signal input options: speaker inputs, RCA input(s), and in some cases, digital audio inputs.

There are two kinds of home stereo subwoofers: powered (“active”) and non-powered (“passive”).

  • Powered subwoofers use a low-signal signal which is boosted greatly using the built-in speaker amplifier, power supply, and crossover. These types are one of the most common and in many cases use an RCA type input jack to connect to the receiver for sound.
  • Passive (non-powered) subwoofers are simply a subwoofer speaker inside the bass enclosure which is directly wired to the speaker terminals or a passive bass crossover inside. These types are less common.

How does a subwoofer work?

An amplifier boosts the low-level input signal in order to drive the subwoofer’s voice coil with sufficient power and move the speaker cone, producing sound. As the cone moves the air inside of a specially designed enclosure (speaker box) deep bass, contained in the musical input signal, is produced.

They’re designed for only low-end bass and not voice or other musical instrument frequencies.

A powered subwoofer includes an amplifier already inside the subwoofer enclosure. It also has a built-in low-pass crossover to block higher sound frequencies in order to produce clear and great-sounding bass only.

For non-powered subwoofers the problem comes when you connect one to an amplifier or receiver’s outputs without a crossover – it sounds terrible!

Old amplifiers and vintage receivers vs new receivers

Unlike older amplifiers, more modern home stereos and especially home theater receivers have a subwoofer output jack (or pair of jacks) dedicated to this bass signal a subwoofer uses to create sound. This is usually from stereo music signals or the subwoofer (“.1”) channel sound in multi-channel surround sound material such as Dolby Digital or DTS.

For example, you may see terms like “5.1” or “2.1” speaker systems or surround sound audio listed for movies. In this case, the first number represents the number of main speakers. The “.1” is used to represent a sound channel limited to only bass for subwoofer use.

Older amplifiers and receivers don’t provide a subwoofer output so we’ll need to connect a subwoofer by other ways.

Powered subwoofer inputs & controls to know

Powered subwoofer example with inputs and controls labeled

Shown is an example of a powered subwoofer’s rear panel with 2 kinds of inputs: speaker inputs and RCA (low level) input jacks. Note that not all subwoofers offer speaker level inputs, meaning if yours doesn’t have them it’s a bit harder to connect the bass signal input.

Powered subwoofers usually have a few different inputs and controls. It always depends on the particular brand and model you buy.

Here’s what you’ll usually find on most:

  • Power input (AC outlet power)
  • On/off switch
  • RCA input jack or a pair of jacks
  • Subwoofer crossover adjustment
  • Subwoofer level adjustment know (the amplifier’s signal boost level)

In most cases, a subwoofer input jack, if you had one on a receiver, is a “mono” (monaural, 2 stereo channels combined into one) signal you connect with a single RCA cable.

Receiver subwoofer output jack example

Shown: What a receiver with a subwoofer output jack looks like as found on many newer receivers. These connect to the RCA input jack on the subwoofer, if present.

Of course, if you’re reading this it’s because you don’t have a receiver with a subwoofer output. In fact, some of the information you’ll find right now on the internet says that you have to buy another subwoofer if you don’t have a receiver with an output jack. That’s simply not true.

Subwoofers with speaker level inputs are great to have for exactly this reason as you can connect them directly to an older amplifier or vintage receiver’s speaker outputs.

Even if you buy (or already own) a subwoofer without speaker level inputs, it’s ok – there’s another way to basically connect it essentially the same way!

Below you’ll find a diagram showing how to connect an old amplifier or receiver without a subwoofer output easily.

Diagram & examples: Connecting a subwoofer to an old amplifier or vintage receiver

Diagram showing how to connect a subwoofer to an old amplifier or vintage receiver

1. Connecting an old amplifier or receiver to a subwoofer with RCA input jacks

Example of a powered subwoofer RCA jacks & RCA Y adapter cable

Left: Example of a powered subwoofer with 2, instead of the typical 1, RCA input jacks. Right: An RCA Y adapter that can be used with a line level converter to connect to a subwoofer with a single RCA input jack.

If you’ve got a subwoofer with 1 or 2 RCA input jacks and no speaker level inputs, here’s a simple and high-quality way to connect it: by using a line level converter.

What is a line level converter and how do they work?

Line level converters (also called RCA speaker level adapters) are small electronic devices that connect to speaker outputs from an amp or receiver and scale down the higher-voltage signal to a low level (“line level”). The outputs are RCA jacks which can then be connected to any amplifier or subwoofer with RCA jacks.

 While you almost never see them used for home stereo systems, they’re extremely handy in the car stereo world because they make it possible to connect a stereo without RCA outputs to any amplifier or powered subwoofer.

Likewise, they can be used for home stereo amps and receivers, too!

Image showing examples of line level RCA converters

Shown here are two examples of line level/RCA speaker level converters: a 2 channel RCA output model and a 4 channel RCA output model.

How much do line level converters cost?

Line level converters vary in price a bit depending on the quality and features, selling around $15-$25 or so in many retail stores and online stores.

How to use a line level converter

To convert speaker level outputs from your amplifier or receiver to RCA jack subwoofer outputs, you’ll connect the provided speaker wire connections (marked by colors and striped) just like you would regular speakers. You then connect RCA cables (or a single cable, depending on your particular one) to your powered subwoofer.

The internal electronics not only scale down the speaker output voltage from a receiver but also help prevent noise from the audio path, too. Most, but not all, speaker level adapters do not need a power source.

If your subwoofer has a single RCA subwoofer input jack, you may want to pick up a “Y” RCA adapter to combine both receiver channels on the output side into a single mono RCA plug.

Subwoofers with 2 (stereo) RCA jack inputs will need a standard stereo male-male RCA cable.

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3. Connecting a subwoofer with speaker level inputs

Example of subwoofer speaker level inputs

A subwoofer with speaker-level inputs is especially easy to connect to your older amplifier or receiver! To do so, just connect to the speaker outputs on the source unit using speaker wire and then to the matching inputs on the subwoofer. You can even power speakers from the amp or receiver at the same time.

If your subwoofer has speaker level inputs built-in you’re in great shape! Just connect them directly to your amplifier or receiver’s speaker outputs, either to unused speaker terminals or at the same time (in parallel) with speakers connected to the receiver.

Just like an off-the-shelf line level RCA converter I mentioned earlier, the subwoofer’s internal electronics will scale down the speaker signals to a much lower line level signal the internal amp can use.

You can still expect very nice sound quality as the signal used is just divided down and isn’t changed. Because speaker level inputs have a very high input impedance (total input resistance), in most cases it won’t hurt to connect them to your receiver or amp at the same speaker wire terminals where speakers are already connected.

To do so, you’ll just connect them in parallel: positive speaker inputs to positive speaker outputs and negative speaker inputs to negative speaker outputs.

Additionally, there’s a low-pass crossover built-in as well to produce great-sounding bass and no unpleasant parts of the music – just pure, low-end bass.

Note: Subwoofers with speaker level inputs and outputs provide a way to easily connect both at the same time. The outputs are internally connected to the input connectors, making it easier to add speakers and the subwoofer to a receiver simultaneously.

3. Connecting an amplifier’s speaker outputs to a passive (non-powered) subwoofer

Example of a passive subwoofer low pass crossover

A passive subwoofer low-pass crossover, unlike an electronic crossover, works using capacitors and inductor coils instead of electronic components to filter out the unwanted higher-frequency sound that would otherwise go to the subwoofer. This lets you power the subwoofer with only a lower bass sound similar to how a powered subwoofer works.

Using a passive (non-powered) subwoofer is definitely not as easy as a powered one. The good news is that it can be done, and relatively easily, too. In fact, it you don’t have to worry about going broke, either, although you will need to do a bit of shopping.

To connect your amplifier or receiver to a non-powered subwoofer as is shown in the diagram above, you’ll need to pick up a low pass crossover that you’ll connect between the amp or receiver and the subwoofer.

These will filter out sounds above the crossover frequency and provide only a nice bass sound to it.

How to choose a subwoofer crossover

Speaker crossovers like the one shown are sold both in a single (one speaker) or dual (2-speaker) models depending on the brand & supplier. They also have to be matched correctly to the impedance (Ohms rating) of the sub.

For example, for an 8 ohm subwoofer, you’ll need to use a crossover designed for 8 ohm speakers. Otherwise, the sound filtering is radically different and won’t sound right since the speaker load will change how the crossover filters the sound quite a lot.

Normally you’d choose one with a low-pass frequency of close to 100Hz or close to that. You may need to shop around to do so.

Where to shop for passive subwoofer crossovers

Speaker crossovers are sold where speaker parts & related components are sold as well as marketplaces like Amazon or Parts Express. Other speaker specialty stores where replacement speaker parts are sold may have them, too.

Stereo vs surround sound receiver subwoofer output comparison

Stereo vs surround sound receiver differences diagram

Unlike older or standard stereo receivers, surround sound receivers have a unique output that comes from the surround sound movie or music source. However, in regular stereo listening mode, they act the same as regular receivers.

Just as a side note, one thing to be aware of is that when you connect a subwoofer to an old amplifier or receiver you won’t be able to get the separate dedicated bass sound channel (.1 channel) like you can with a surround sound receiver. 

Those are able to extract the dedicated bass sound from a DVD or other media and route it to the subwoofer output jack. On the other hand, it might not even be a problem.

Did you know? The surround sound receiver “LFE” (low-frequency) output is considered optional – hence the “.1” name. 

Surround sound receivers and amplifiers are designed so that you can play nearly all the sound through the main speakers if needed.

In some cases, for example, some movies and music use the bass channel to really draw you into the experience. Using a receiver without that output means you can’t get the same effect, but that’s only for surround sound mode.

The good news is that in stereo mode, both new and old receivers & amps have very similar subwoofer behavior when connected as you’ve seen here. In other words, you probably won’t really miss it if you’re using an older receiver or amp.

That’s just something to be aware of in case you’ve considered upgrading at some point.

More articles with speakers, speaker wiring, and diagrams to help

I’ve got some other great info to help you learn more and get your system going:

Questions, comments, or etc?

Please feel free to leave a comment or question below – I’d love to help, and it’s appreciated. Note: please provide specific information like brand & model numbers, speaker ohms, and so forth so I can best help you.

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