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.
Contents
Home stereo subwoofers explained
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
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.
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
1. Connecting a receiver to a subwoofer with RCA input jacks
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, also called speaker level converters or “hi-lo converters”, are small adapters that accept speaker wire connections and scale down the speaker level signal to a low level signal (RCA jack) type output used by amplifiers. 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 are still really useful there, too.
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?
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.
- PRO Series 2-Channel High Power Line Output...
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- Speaker level input to RCA level output
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2. Subwoofers with 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. Generally speaking, 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.
Most speaker to line level adapters have a relatively high input impedance (resistance), which will only have a marginal effect on the total speaker Ohms load seen by an amp or receiver. However, a few do have lower input resistance that can potentially cause an issue so they’re best avoided.
Note #2: For best results, I recommend (when possible) using a speaker level adapted with an input impedance specification of 60 to 80 Ω or similar. Lower ones (ex: 16 ohms) can drop the total speaker load by several Ohms when used in parallel.
3. Using a mini amplifier for passive subwoofers
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.
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.
4. Connecting receiver speaker outputs to a passive sub
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
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.
Hi Marty,
I’m struggling to find a definitive solution to my problem.
I have a Yamaha AX V401 amplifier and was going to use a powered sub connected to my B-speaker outputs.
Unfortunately, the active woofers in my price range don’t have speaker terminals on them. Instead they have XLR inputs / TRS jacks. (Or RCA unbalanced).
I’m wondering can I connect Speaker-B terminals (with bare-wire) to either XLR or RCA ends?
Any help would be much appreciated.
Thanks so much. Dave
Hi Dave I actually covered this in the diagram (example #1). You’ll need a converter as speaker level signals aren’t compatible with RCA inputs or balanced inputs. Best regards.
Ah so sorry! Thank you for your (patient) reply.
No problem, Dave. My pleasure & I appreciate you dropping by. All the best! :)
Hello again Marty.
Obviously I’m trying to get this right the first time…
Is this the kind of small/inexpensive piece of kit that will allow for a healthy signal to a Sub?
(Does it matter that it’s listed use is for Auto? -I need it for home studio set-up).
https://www.amazon.co.uk/Stereo-Converter-Subwoofer-Amplifier-Adapter/dp/B07S8TGT37/
Thank you!!
Dave
Hi Marty. Hope all is well with you.
I’m wondering if you might have missed that final query I had?
Any clarification would be so appreciated.
Thanks
Dave
Hello Dave. Yes, it seems I must have missed your last comment/question; sorry.
That one looks like it’s probably fine. I can’t vouch for that particular one but my general impression is it’s likely good. Usually I recommend brand names like PAC, Metra, Scosche, etc. since I know those from use (they’re pretty affordable too usually). Best regards.
Hi Marty,
New to this audio thing and could definitely benefit from some direction. Current audio equipment:
Receiver
Sony STRDH790 7.2 Receiver
4 sets of speakers as follows:
2 Polk Atrium 8 SDI Speakers
2 Polk Atrium 5 Speakers
2 Klipsch AW-650 Speakers
2 PSB CS-500 Speakers
Subwoofer
Polk Atrium 100 Sub
I realize now that I don’t have enough channels to support the 8 speakers, and the Sony STRDH790 doesn’t support passive subwoofers. Can you please advise on an amplifier that will allow me to play all 8 speakers (willing to add a 9th for the center channel) and the subwoofer? I can concede to 7 speakers as long as I find a solution for my passive sub.
I should add that I don’t want to replace my Sony Receiver, I just want to add an inexpensive amp that can support 2 speakers and a sub that will extend the audio from the receiver. I should also mention that the Polk sub requires two separate channels for optimum sound because it’s dual coil.
Hi, you’re probably better off using two 4 channel amps or etc. rather than a single one in order to find something easier to buy as well as for a good price.
You can then connect them to the RCA outputs on the receiver and use as many speakers as you’d like, although additional speakers are a bit redundant when surround sound is used. Best regards.
Thanks Marty but I only have 2 subwoofer outputs from the receiver. I’m assuming that they will only send the low frequency signala and therefore I would not get the benefit of additional speakers connected to the amplifier.
I should also mention that all.of the speakers are for an outdoor setup. I read in another one of your threads that it may be possible to use my hdmi arc output and with a converter I could convert the audio signal to rca and connect additional speakers to an amplifier that way. Is that possible in my setup?
Hi Jay. Ah ok, pardon, I didn’t realize that about the limited RCA outputs. Somehow I overlooked that.
Yes, could use an HDMI audio extractor, but there’s a more cost-effective (and simpler) option: using a speaker level to line level converter connected in parallel with the main speaker outputs.
You can then run the RCA cable(s) as needed. You could even then use a wireless audio transmitter + receiver pair if you’d like to get a signal wirelessly outdoors.
With a good quality line level converter the signal quality will be pretty good. It’s a similar setup to example #3 in the diagram on this page and easy to do. Hope that helps!
Thanks Marty, really appreciate the information.
Always a pleasure. :)
Hi Marty,
I have a onkyo htr393 with pos/neg terminals sub out. And a jbl psw1200 with RCA low level input. How do I match that? Or do I just use the high level in/out connections for the speakers?
Thanks
Fred
Hi, yes you’d use the speaker level inputs in this case and you should be good to go that way. Best regards.
One last question Marty
I saw in one of your diagrams that both the Level-to-Line Output converter and the speakers are connected to the speaker output terminals simultaneously. Is there any audio degradation concerns with this setup or should I only connect the Line Level Converter, which means I would lose the ability to connect 2 speakers through the receiver and have to connect them through my amp.
Hi Jay. The good news is that 99% of the time there’s absolutely no issue at all. That’s because a good quality line level converter has a very high impedance (resistive load), meaning that it doesn’t have any real effect on the load placed on speaker outputs. They’re typically at least 10K Ohms or so, if not more.
• In parallel with your existing speakers, it’s as if it doesn’t exist as far as the amplifier/stereo/etc. is concerned. The total Ohms load is virtually unchanged also.
• You don’t want the cheapest quality converter – those can be bad with regards to frequency response and sound quality sometimes. However, even very good ones are under $15-$20. A decent quality one will sound pretty good actually. I’ve used them many, many times with great results.
• To be 100% honest, it’s not “audiophile” level quality, but most people would be hard-pressed to be able to tell the difference. In a good system you probably can’t hear the difference.
Any time you convert a signal from line level to speaker level (like from an amp to its speaker outputs) and then back again from speaker level to line level, there’s a small amount of loss of quality. But it’s often so tiny it’s not worth mentioning, at least not in a good system.
That’s actually a really good question you brought up and a good topic for an in-depth article with some examples and all the good details. Thanks for the idea and the topic about audio degradation as you’ve given me something to work on. :)
Have a great week!
Hi Marty
I hope you’ve been having a great week. I decided to read this article once more with extra scrutiny before purchasing a line level converter and additional amplifier for my setup, and I stumbled upon something significant that I overlooked previously. I actually think that I have everything I need to start enjoying my music right away.
So my Polk Atrium 100 subwoofer is dual coil and passive, and uses speaker wire connections to amplifiers and AVRs for power. It also has built-in crossover technology, and is intended to be connected to the left and right terminals on AVRs and amplifiers just like regular speakers as per the Polk documentation. My initial concern was the extra load that would be created on the Sony AVR if I connectied both my amp and Polk speakers to the same speaker terminals, which is why I was initially exploring the line level output converter and separate amplifier approach.
However after giving this article a 2nd read, you suggested that I may be ‘in luck’ with my subwoofer, and can safely connect both my speakers and amp to the same left and right terminals with no issues. Interestingly enough, the Polk Sub documentation suggests this as well, although their diagrams use amplifiers as opposed to AVRs.
What i am not entirely clear on is if this setup will work with a passive sub or if you were referring to an active sub with speaker wires, or both. Can you please confirm that my assumptions are correct, and that my AVR (145w per channel @ 6 ohms) should be enough to drive nice sound from my speakers and sub? I truly appreciate all of your help and insight.
Hello Jay. If you have unused full-range speaker output channels then you can connect the passive woofer to the receiver. Otherwise, you’ll need an amp to power it because the receiver can’t handle less than 6Ω.
Connecting two 8Ω speakers per channel, for example, would drop it below the 6 Ohm limit. You can however connect a speaker to line level converter alongside existing speakers in use without an issue. Then go to the amp to power the subwoofer.
Got it, I’ll go with the original plan. Thanks again Marty, your help has been invaluable.
I have a Klipsch Synergy Black Label Sub-100 which is a powered sub connected to the exact same mini amp pictured above (Mini HiFi Stereo 2.1 Channel Audio Amplifier). The amp has a sub output but it’s for speaker wire so I purchased speaker wire to RCA adapters. When the bass drops I hear a thumb from time to time unless I have the gain barely on. Is there a better option to run this set up?
Hi Tristan. You shouldn’t be using speaker wire to RCA plugs – that’s not compatible with an amp or powered subwoofer with line-level inputs (RCA inputs). I recommend you use one channel of a line out converter.
A line level converter can remove “thump” in many cases because it isolates the input from the output in addition to reducing the speaker level voltage to one an amp can use (line level). Pick one with adjustable outputs for the best results.
Marty,
I’m currently working with your example 1 setup. Emotiva A2m with the Pac LP3 line converter with RCA cables going into a passive klipsch sub 120. I have ensured the connections to the receiver are all correct. Audio comes out the speakers like normal just fine, but nothing is coming out of the sub and it produces a low hum as well. Any advice? Thanks
Please disregard, I figured out the issue!
Hi Tyler – that’s great that you found it. Would you mind mentioning what the issue was in case it could help someone else in the future? Thanks!
HI Marty,
I have an AV-Receiver with a disabled sub-woofer output because I have a passive sub-woofer speaker with one channel.
I am working on a 3 channel(left-Center-Right), 3-way passive crossover. Which means I will have 2-channel of low freq output from left and right channels.
My question : How do I efficiently connect one sub-woofer to both left and right outputs.
I was hoping for a sumation circuit in the crossover to produce one output…
Hello Brian. Just to be clear, you’re working on making your own crossover, is that correct? I’m a little confused however when you say “left-center-right” as normally bass is derived from the left and right stereo channels, not the center channel.
Center channel audio is normally bandwidth-limited (for example, in 5.1 surround sound formats and others) while stereo is full-range including bass.
It sounds like what you’re wanting to do is something similar to Bose Acoustimass speakers which use a passive crossover in the same way. You would need a two input, 1 output (stereo to mono) transformer + the low-pass crossover section to do this. Unfortunately those types of transformers are very rare now (not that they were ever easy to find).
It would be far easier to go about this one of the following ways:
1. Use a 3rd amp channel or a 3-channel amp to power the speakers separately, using internal crossovers if provided.
2. Use two subwoofers instead of one: One 2-way crossover or etc for each speaker/subwoofer channel pair.
3. Use the left/right stereo speaker level signals to go to a small amplifier for the passive subwoofer.
It’s much, much simpler letting an amp do the summation work before it’s amplified. Also, it takes fairly large inductors for low-pass crossovers in many cases. Also, if your subwoofer is passive powered like you mentioned, it may not perform like you hope.
As subwoofers are less efficient than full-range speakers it may require more power to match the main speakers & sound good.
I hope that helps! Here’s one thread about this at the diyAudio site in case it’s of use.
Hi, your writing is really clear and helpful. I am glad to find that a ‘speaker-to-line converter’ exisits Because despite that I’m now using 5.1ch surround system and my amplifier has sub-out jack, I plan to buy a new amplifier which does not have sub-out. Though your post depicits a scenario of 2ch (to 2.1ch) system, it’s also helpful for people like me (5.1ch system), so I suggest you to mention 5.1ch scenarios too. Thx again.
Hi there. Thanks and I’m glad you found it helpful. That’s a good suggestion.
I think I’ve shown an example elsewhere but I can adding something to this article to. Best regards!