How To Connect A Subwoofer To A Receiver Without A Subwoofer Output

Got a subwoofer with no sub output handy? Don’t worry – there are several simple ways to connect a subwoofer to a receiver without a subwoofer output.

Read on and I’ll show you several options along with easy and clear diagrams to help.

Update! Based on reader feedback I’ve added more info about passive subwoofer use. The diagram is also updated & improved.

Home stereo subwoofers explained

Passive vs active home subwoofers diagram

Comparison of non-powered (passive) vs powered (active) home stereo subwoofer enclosures.

Home stereo subwoofers are available in two different types: powered (“active”) and non-powered (“passive”).

  • Powered subwoofers use a low-signal signal that is boosted using a built-in amplifier, power supply, and output only bass using a 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 a bass enclosure.  It’s wired directly the speaker terminals or through passive bass crossover inside in some cases. These types are less common.

How a subwoofer produces bass

The subwoofer works by resting inside of a speaker enclosure where bass frequencies are captured as the woofer cone movies, producing deep bass sound. 

In order to produce clean-sounding bass without vocals or other sounds a subwoofer can’t properly produce, a low-pass crossover is used. The problem comes when you try to connect a subwoofer to a signal without a crossover – it sounds terrible!

The subwoofer output jack on a receiver is normally limited to passing bass only, either from stereo music production or from the “.1” subwoofer channel (dedicated subwoofer music content) of a surround sound system.

For example, when you hear references to “5.1” or “2.1” speaker systems or surround sound audio for movies, the first number represents the number of main speakers. The “.1” is used to represent a sound channel limited to optional subwoofer use.

Powered subwoofer inputs & controls you may (or may not) have

Powered subwoofer example with inputs and controls labeled

Example of a powered subwoofer with 2 types of signal inputs (speaker level and RCA jacks) along with sound controls. Note: Not all subwoofers have speaker level inputs, which makes it a problem connecting them to a receiver without a subwoofer output.

Powered subwoofers usually have several inputs and controls but it always depends on the brand and model. Here’s an example of what you’ll usually find:

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

The subwoofer input jack usually connects to a single mono output jack on the receiver, although some models provide stereo RCA inputs but can usually work with just a single mono connection. Mono (monaural) subwoofer output jacks combine both stereo channels into one so that no sounds are lost like can happen with only using the left or right side signal.

Receiver subwoofer output jack example

Example of the mono RCA subwoofer output jack found on many home receivers. These connect with a single male to male RCA cable to a powered subwoofer.

Some models also include speaker level inputs meaning they can be used with any modern or old home stereo receiver without a subwoofer output.

While that’s nice, if yours doesn’t have that feature, ordinarily you’d need to buy a different subwoofer and waste money.

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.

As I mentioned at the beginning of my article there are several ways to work around this problem.

DIAGRAM & EXAMPLES: Connecting a subwoofer to a receiver without a subwoofer output

Diagram showing how to connect a subwoofer to receiver with no subwoofer output

1. Connecting a 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.

For subwoofers with only 1 or more RCA input jacks (no speaker level inputs), a simple way to connect them to a receiver with no subwoofer output is by using a line level converter.

What is a line level converter, and how do they help?

Line level converters are small devices that accept speaker wire connections and scale down the speaker level signal to a low level signal (RCA jack) type output that the subwoofer can accept. They’re extremely handy in the car stereo world because they make it possible to connect a stereo without RCA outputs to any amplifier.

They’re not commonly used for home stereos but still really useful there, too.

Image showing examples of line level RCA converters

Shown here are two examples of line level/RCA speaker level converters that work well for home receiver/amp to subwoofer use. A line level converter takes the higher voltage speaker signal from an amplifier or home receiver and scales it down significantly so it’s safe to use with RCA inputs.

How much do line level converters cost?

A quality line level converters have a price range of about $15-$25 each. They’re connected to the speaker outputs of a radio, receiver, or amplifier. RCA cables are then connected to the jacks provided. The internal electronics not only scale down the speaker output voltage from a receiver but also help prevent noise from the audio path, too.

If you’re using a subwoofer with 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 one.

Subwoofers with 2 (stereo) RCA jack inputs, however, are fine using standard male-male RCA cable pair.

On sale now!
PAC LP3-2 L.O.C. PRO Series 2-Channel Line Output Converter
  • PRO Series 2-Channel High Power Line Output...
  • Designed to optimize audio levels between...
  • Ideal for use when adding an amplifier to an...
  • Speaker level input to RCA level output
  • Single dial, precision matched stereo, level...

2. Subwoofers with speaker level inputs

Example of subwoofer speaker level inputs

If you own a subwoofer with speaker level inputs you’re in luck! You can connect these directly to your receiver’s speaker outputs, either by themselves (on unused speaker terminals) or at the same time with speakers connected to the receiver.

Subwoofers with this feature contain internal electronics that scale down the speaker signal from the receiver before it reaches the internal amp that powers the sub. It’s just a line level RCA converter already provided, essentially.

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.

Connect these directly to the receiver just like you would another pair of speakers, either on unused speaker outputs. You can connect these to receiver speaker outputs already in use as they will not bring down the total Ohms load the receiver or amp sees.

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. Using a mini amplifier for passive subwoofers

Example of a 2.1 stereo mini amplifier with sub output

When wanting to add a single voice coil (SVC) passive subwoofer, several issues come up. Hands-down, the simplest solution is using a mini amplifier with a mono low pass subwoofer speaker output.

For this setup, you’ll do the following:

  • Use a line-level RCA converter to get an RCA signal to the amplifier.
  • Connect the passive sub to the subwoofer output.
  • Use the AC-DC power supply to power it.

That’s pretty much it! Having a built-in sub crossover means the sound will be nice, clear bass without vocals much like a self-powered subwoofer provides.

Today’s small amplifiers are typically very compact in size as many use an efficient class D amplifier design. They’re sometimes called a 2.1 amplifier as they usually have both stereo speaker outputs and a dedicated subwoofer channel.

Facmogu ST-838 2.1 Mini Amplifier With Subwoofer Output
20Wx2 stereo + 40Wx1 subwoofer output. RCA and 3.5mm input jacks. Easy to use speaker terminals. Bass, treble, and volume controls. Includes power supply.

Cost and other notes

They cost around $35 to $50 or so depending on the model. The downside is that if you want a ton of power, they’re not the best choice as many offer about 35W to 68W sub power. If that’s not enough you’re better off getting a more expensive amplifier.

Note: Mini amplifiers may or may not include the power supply so be sure to check when shopping.

4. Connecting receiver speaker outputs to a passive sub

Example of a passive subwoofer low pass crossover

Example of a passive subwoofer low-pass crossover. Passive crossovers, unlike electronic crossovers, work using capacitors and inductor coils instead of electronic components.

If you’re wanting to use a non-powered (passive) type of subwoofer, there’s still hope, although it can be a bit harder to find the right parts and set up vs using a powered subwoofer.

To use a non-powered subwoofer, as shown in my diagram above, you’ll use a low-pass subwoofer speaker crossover which is connected between the receiver and the subwoofer enclosure. These filter out higher frequency sounds before they reach the sub to help provide clear & nice-sounding bass only.

How to choose a subwoofer crossover and where to find them

Speaker crossovers like this are sold single channel (one speaker) or dual channel (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, subwoofer crossovers designed for 8 ohm speakers must be used only with those. Otherwise, the sound filtering is radically different and won’t sound as expected since the crossover filter is based on the expected speaker impedance.

For example, you can’t correctly use an 8 ohm sub with a 4 ohm crossover.

Normally you’d choose one with a low-pass frequency of close to 100Hz or in that range. Speaker crossovers are sold where speaker parts & related components are sold as well as marketplaces like Amazon or Parts Express.

Stereo vs surround sound receiver subwoofer output differences

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.

One thing to bear in mind is that when connecting a subwoofer to a receiver without a subwoofer output, you can’t get a convenient “.1” bass channel like can with surround sound receivers.

On the other hand, it may not even be an issue. In fact, the surround sound receiver “LFE” (low-frequency) output is considered optional – hence the “.1” name. There is a drawback, though: for some movies, especially action or other types, movies and music in surround sound can sound even better.

While using a regular receiver to connect to a subwoofer means you can’t get quite the same effect, the good news is that in stereo mode, both new and old receivers have very similar subwoofer behavior when connected as you’ve seen here.

Also, listening to a surround sound movie through a stereo connection to your standard receiver is still good. For stereo, surround sound tracks are downmixed, meaning all the sound information is mixed into the two channels.

You’ll still get the same bass signal available that you can use to supply your subwoofer.

Your comments are welcome.
  1. Hi. Thanks for your through explanation on subwoofers.
    My setup would be like your example #2: ‘Receiver + Powered Subwoofer, with Speaker-Level Input.’

    Question: How far can the Subwoofer be located from the Receiver? I’d like to have my Subwoofer about 25 feet away from the Receiver. Using a Polk MXT12 powered subwoofer.

    Please advise.

    Reply
  2. Marty first of all thank you for the service/help that you are providing. It is greatly appreciated. My question for you concerns the diagram using the line level device connected as usual to run a powered sub. Would that work with two powered subs or not?

    Reply
    • Hi Ken, yes you can do it a few ways but using a “Y” adapter to split the signal to two subwoofers (if needed) will work fine.

      Thanks for your kind words by the way. :) Best regards.

      Reply
  3. Hi, I have a dual subwoofer setup I haven’t installed in years, that always ran perfect, and now I cannot get the subs on. The back of the powered one looks like, and is the Dayton SA100 — https://www.parts-express.com/Dayton-Audio-SA100-100W-Subwoofer-Amplifier-300-802 — and the other is passive, just receives a wire from the powered one. The 2 subs are part of a Tekton prototype that saw limited production as the OB4.5, with 2 subs sitting under 2 ‘bookshelf’ speakers that are basically 2 single cone Fostex drivers, one pointing forward, one up-firing from the rear. The upper speakers connect to the powered sub or to the amp — I guess I can’t remember. Plus I have 2 Decware Radials I am wiring into the amp or sub panel… I can’t remember. I have a Decware 2 watt SE84 tube amp with just 2 speaker posts, and 2 line-ins.

    I thought I was to wire the 2 sub lower speaker lines to each other, and the combination of speakers to the Decware posts. Yet the subs are not working this way. Appreciate any wiring diagram you can give me to rectify this. Thanks so much! Steve

    Reply
    • Hi, if your audio source doesn’t have RCA outs then you’ll wire the speaker outputs to the high-level inputs. From there (the “To speakers”) are pass-through connections which you can connect your speakers to. You could connect them directly to the amp as well – it’s all the same.

      If the subwoofer amp doesn’t appear to be switched on with the switch in the “On” position you can connect the RCA inputs to an MP3 player or cell phone, etc., to get a signal to check and make sure it’s working ok otherwise.

      Reply
      • Thanks, all is working and playing and light on, excerpt no bass on active or passive sub. Fuse good, plug good. I’ll start all wiring over…

        Reply
        • Hi Steve. If the powered subwoofer doesn’t appear to be working an you’ve already checked that it *should* be working by sending it a signal input, it could be something internal. But yeah, it definitely never hurts to start back over and check everything just to be sure.

          Good luck with it and best regards.

          Reply
    • Hello, Ben. You can use a “Y” RCA adapter, although some subwoofers can work ok with only one RCA plug connected (you can try it and see how it does). Best regards.

      Reply
  4. Hi! I have a pair of stereo speakers with no sub out (Singing Wood BT25 Active Bluetooth Bookshelf Speaker). One of the speakers has a built-in receiver with only one set of speaker-level outputs, which is connected to the other speaker. There are two pairs of RCA inputs on the receiver, one of which is connected to a vinyl player and the other to my computer. I can toggle between the two sources.
    Is it possible to connect a subwoofer to these speakers? Thanks!

    Reply
    • Hi, yes, you can use a pair of “Y” RCA adapters to split off the RCA inputs to the speakers and then out to your powered subwoofer or amp. Since you have two input sources, however, you may want to use a stereo RCA switch or an inexpensive electronic mixer to control which RCA pair is connected to the subwoofer side when listening.

      In fact, you could build a simple RCA pair switcher using a dual-pole, dual-throw switch yourself in a small project enclosure if you don’t mind manually switching it. Best regards.

      Reply
    • Hi Ethan unfortunately not without a way to get a signal output from the powered speakers. However, it may be possible (if you’re handy with tools) to bypass this problem by tapping off of the speaker wiring from the internal stereo amp and then go out to the speaker level inputs on a powered sub *or* use a speaker to line level converter.

      That way you’d solve both the Bluetooth and input problems at once.

      Reply
Leave a Reply to Marty Cancel reply