How To Connect Subwoofer To a Receiver Without Subwoofer Output
By Robert Jones · 2020-09-12
No subwoofer output on your receiver? No worries, I've got you covered. As an old hand in audio, I'll show you the best ways to get that low-end rumble into your system, using methods I've tried and tested myself.
Right, listen up, because this is a question that pops up in my workshop almost every other week. You've got yourself a decent receiver, maybe an older model, or perhaps a budget one, and it's missing that handy "Subwoofer Out" or "LFE" RCA port. But you still want to get some proper bass into your system. Don't fret, mate, it's absolutely doable. You just need to know a few tricks of the trade, and I'm here to walk you through 'em. I've been faffing about with speakers, amps, and subwoofers for over twenty years now, and trust me, I've seen every conceivable setup – and every head-scratching connection challenge. Connecting a sub without a dedicated output isn't as straightforward as just plugging an RCA cable in, but it's not rocket science either. It generally boils down to using either speaker-level inputs or line-level inputs, often with a few bits of kit to help you along. Let's get into the nitty-gritty, shall we? **Quick Verdict:** Connecting a subwoofer to a receiver without a dedicated output is definitely possible, usually by tapping into speaker-level signals or using a line-level converter, but quality and complexity vary. ### Who it's for: * Anyone with an older stereo receiver or amplifier lacking an LFE/Sub Out. * Those with budget home cinema receivers that skimped on dedicated subwoofer outputs. * DIY audio enthusiasts looking to integrate a subwoofer into a legacy two-channel system. * People wanting to upgrade their system's bass without buying a brand new receiver. ### Who should skip it: * Folks with modern AV receivers that already have multiple dedicated subwoofer outputs – you're sorted! * Anyone expecting ultra-simple, plug-and-play installation without reading the manual (yours or mine!). * Those looking for the absolute purest, uncompromised signal path for their subwoofer (though we'll get close!).  *How To Connect Subwoofer To a Receiver Without Subwoofer Output — tested in the SpeakersMag workshop.* ## The Core Challenge: No LFE, No Problem? So, your receiver's got no dedicated subwoofer output. What does that mean? Well, typically, a "Sub Out" or "LFE Out" (Low-Frequency Effects) is a dedicated, filtered, line-level signal specifically for your subwoofer. It's usually mono, and your receiver's bass management handles what frequencies get sent to it. Without it, your receiver is designed to send the full frequency range – including all the bass – to your main stereo speakers. The trick, then, is to 'intercept' that full-range signal and let your subwoofer extract the bass it needs. There are two main ways to do this: using speaker-level connections or, if your receiver has suitable outputs, other line-level connections. The best method depends entirely on what inputs your subwoofer has and what outputs your receiver offers. ### Understanding Your Subwoofer's Inputs Before we even think about the receiver, have a peek at the back of your subwoofer. What connections do you see? Most active subwoofers (the ones with their own built-in amplifier, which is most of them these days) will have a combination of these: * **RCA Line-Level Inputs (LFE/Mono or Stereo L/R):** These are the most common. A single RCA for LFE, or a pair for stereo. This is what you'd normally connect to a dedicated "Sub Out." * **Speaker Level Inputs (High-Level Inputs):** These look like regular speaker terminals – binding posts or spring clips. This is your primary route if you don't have a dedicated sub out. * **XLR Inputs:** Less common on consumer subs, usually found on studio or very high-end gear. We'll ignore these for this chat. Knowing what your sub has is half the battle. If it's got speaker-level inputs, you're in a much easier spot. If it only has RCA inputs, we'll need to get a bit more creative. ## Method 1: Speaker-Level Connections (The Easiest Route for Many) This is often the go-to solution, especially for older stereo amps or receivers without any line-level outputs. If your active subwoofer has 'speaker-level inputs' (also sometimes called 'high-level inputs'), you're in luck. This method takes the full-range speaker signal from your receiver's speaker terminals and feeds it directly into your subwoofer. Now, don't panic. Your subwoofer won't be competing with your main speakers for power. Its built-in amplifier will simply 'read' the signal voltage, extract the low frequencies, and then amplify those itself. It's a very elegant solution, actually. ### What You'll Need: * **Speaker Wire:** Just some decent quality speaker wire. No need for anything fancy, but make sure it's thick enough to carry the signal a few metres without issues. I usually grab a roll of 16-gauge OFC (Oxygen-Free Copper) for this sort of thing. It's perfectly adequate. * **Subwoofer with Speaker-Level Inputs:** Obvious, I know, but worth reiterating. ### How to Connect (Step-by-Step): 1. **Switch Everything Off:** Power down your receiver and your subwoofer. Unplug them from the mains if you're feeling extra cautious (always a good idea when messing with connections). 2. **Locate Receiver's Speaker Outputs:** Find the main left and right speaker outputs on the back of your receiver. These are where your main stereo speakers are currently connected. 3. **Connect to Receiver:** Take one length of speaker wire. Connect the positive (+) terminal of the receiver's *left* speaker output to the positive (+) terminal of the subwoofer's *left* speaker-level input. Do the same for the negative (-) terminals. 4. **Repeat for Right Channel:** Take another length of speaker wire. Connect the positive (+) terminal of the receiver's *right* speaker output to the positive (+) terminal of the subwoofer's *right* speaker-level input. And again for the negative (-) terminals. 5. **Connect Main Speakers:** Now, this is important. Your main stereo speakers still need their signal! If your subwoofer has "Speaker Level Outputs" (sometimes called "Pass-Through" or "High-Level Outputs"), you'd connect your main speakers to *those*. The subwoofer acts as a sort of middleman, taking the signal, using what it needs, and passing the rest on. However, many subwoofers *don't* have these pass-through outputs. In that case, you'll connect your main speakers *directly to the same speaker terminals on your receiver* as the subwoofer wires. You'll be essentially running two sets of wires from each terminal. Just make sure the connections are solid and aren't shorting anything out. Double-check your polarity – positive to positive, negative to negative – for both the subwoofer and your main speakers. 6. **Power On & Calibrate:** Plug everything back in and power it up. Now comes the fun part: calibration. You'll use the subwoofer's built-in crossover and volume controls to blend it seamlessly with your main speakers. We'll cover basic calibration later. ### Robert's Take: I've used this method countless times. It's reliable and often sounds surprisingly good. My old Marantz stereo amp, the PM6006, doesn't have a sub-out, but I've run a decent little Monitor Audio Bronze W10 subwoofer off its speaker terminals with excellent results. It takes a bit of tweaking to get the crossover and phase just right, but once it's dialled in, you'd be hard-pressed to tell it wasn't a dedicated LFE connection. The biggest advantage is that it means your main speakers still get the full signal, which is great for stereo music. The subwoofer just adds what's missing at the bottom end. **Pros of Speaker-Level Connection:** * Often the only option for older stereo receivers. * Keeps the full-range signal going to your main speakers. * Relatively simple to wire up. * Uses the subwoofer's own crossover, which can be beneficial. **Cons of Speaker-Level Connection:** * Requires speaker-level inputs on your subwoofer. * Can be a bit trickier to hide multiple speaker wires. * No dedicated bass management from the receiver, relying entirely on the sub's controls. ## Method 2: Using Existing Line-Level Outputs (If Available) What if your subwoofer *only* has RCA inputs, and your receiver *doesn't* have a dedicated "Sub Out"? Don't throw in the towel just yet! Many receivers, even older ones, might have other line-level outputs you can hijack. We're talking about things like "Pre-Outs," "Tape Out," or "Zone 2 Out." ### Option A: Pre-Outs (If Your Receiver Has Them) Some integrated stereo amplifiers or AV receivers will have "Pre-Out" connections for the main left and right channels. These are line-level outputs that carry the full audio signal *before* it hits the receiver's internal power amplifiers. If you have these, you're in a good spot. ### What You'll Need: * **RCA Cable(s):** One or two, depending on whether your sub has a single LFE input or stereo L/R inputs. * **Subwoofer with RCA Line-Level Inputs.** ### How to Connect: 1. **Power Down:** As always, switch everything off. 2. **Connect Pre-Outs to Sub:** Run an RCA cable from your receiver's "Left Pre-Out" to the subwoofer's "Left (LFE)" input. If your subwoofer has a dedicated LFE input, just use the left pre-out to that. If it has stereo L/R inputs, you can use both left and right pre-outs for a slightly stronger signal, though one often suffices for LFE. 3. **Calibrate:** Power everything up and adjust your subwoofer's crossover and volume. Your receiver's main volume control will now affect the subwoofer's output, which is generally what you want. ### Robert's Take: Using Pre-Outs is usually my preferred line-level method if speaker-level isn't an option. It keeps the signal clean, and the volume tracking is spot on. I once had a lovely Rotel RA-02 amp with Pre-Outs, and that was perfect for adding a BK Electronics XLS200-DF subwoofer. The sound was tight, musical, and the integration was seamless. This method is really only for stereo systems though; it won't work for multi-channel home cinema if you