Wiring a Subwoofer to an Amp: A Bloke’s Guide to Better Bass
By Robert Jones · 2026-03-09
Right, you’ve got the speakers, maybe a decent amp, but there’s still that little niggle, isn’t there? Learn how to wire it up properly for proper bass.
 *Wiring a Subwoofer to an Amp: A Bloke’s Guide to Better Bass — tested in the SpeakersMag workshop.* ‘‘‘Right, you’ve got the main speakers humming away nicely, maybe even a decent amp pushing them. But there’s still that lingering feeling, isn’t there? That something’s just not quite hitting home, especially when the bass drops or a film explosion rumbles. That’s usually the subwoofer – either it’s not there, or it’s not hooked up properly. And let’s be honest, getting it sorted can feel a bit like trying to decipher ancient runes if you’ve never done it before. But trust me, it’s not as daunting as it looks, and I’ll walk you through it. I’ve been mucking about with audio gear for well over two decades now, ever since SpeakersMag first opened its doors. I’ve seen some right disasters and some absolutely brilliant setups. The difference often comes down to the sub, and more importantly, how it’s wired in. Honestly, get this bit right, and you’ll unlock a whole new dimension to your listening. **Quick Verdict: Wire your subwoofer correctly, and your whole system will gain a depth, richness, and impact you didn’t know it was missing.** ## Before You Touch a Single Cable: The Essential Prep Now, before we start yanking cables and fiddling with connections, let’s get our ducks in a row. You wouldn’t start baking a proper Sunday roast without checking you’ve got all the ingredients, would you? Same principle applies here. A bit of foresight and preparation can save you hours of faffing about and a good few grey hairs. Trust an old hand on this one – it’s worth the five minutes of planning. ### Know Your Subwoofer: Active vs. Passive First thing’s first, you need to know what beast you’re dealing with. Is your subwoofer active or passive? This isn’t just a fancy bit of jargon; it fundamentally changes how you’ll wire it up. * **Active Subwoofers:** These are the most common type you’ll find in home cinema and hi-fi setups these days. They’ve got their own amplifier built right in. That means they just need a low-level audio signal from your main amp or AV receiver, and a power socket. Easy peasy. You’ll usually see an RCA input (sometimes two for stereo, but often just one for LFE) and a power lead coming out the back. Most of the subwoofers I’ve reviewed for SpeakersMag over the last decade have been active; brands like BK Electronics, SVS, and REL pretty much exclusively produce active units for the home. * **Passive Subwoofers:** These are a bit rarer for home use now, more common in car audio or very specific custom installations. A passive sub is basically just a big speaker driver in a box, exactly like your main stereo speakers. It needs an external amplifier to power it. So, you’d connect it to a dedicated subwoofer amplifier, or sometimes, if your main amp has a spare channel designed for it, you might use that. Honestly, unless you’ve got a very specific reason or you’re matching an older system, I’d steer clear of passive home subs. The active ones are just so much simpler and usually offer better performance for the money. ### Check Your Amplifier or AV Receiver: The Hub of Your Sound Next, have a good rummage around the back of your main amplifier or AV receiver. This is the brain of your whole setup, and its connections will dictate your wiring options. * **Dedicated Subwoofer Output (LFE/SUB OUT):** If you’ve got an AV receiver (the sort with five, seven, or more channels for surround sound), you’ll almost certainly have a dedicated ‘SUB OUT’ or ‘LFE’ (Low-Frequency Effects) RCA socket. This is your best friend. It sends a filtered, low-frequency signal specifically for the subwoofer. It’s designed for active subs and simplifies everything. My old Denon AVR-X3700H, which is in my home setup, has two of these, letting me run dual subs – a proper treat for movie nights. * **Pre-Outs:** Some higher-end stereo amplifiers or AV receivers will have ‘Pre-Outs’. These provide a full-range, low-level signal that you can use to feed an active subwoofer. You might see ‘Pre-Out L/R’. You’d typically use just one of these (usually L, but check your sub’s manual) or a Y-splitter cable if your sub has stereo RCA inputs. * **Speaker-Level Outputs:** If your amplifier or receiver doesn’t have a dedicated sub-out or pre-outs (this is more common with older stereo amps), don’t fret! You can still connect most active subwoofers using their speaker-level inputs. You’ll connect the subwoofer to the same speaker terminals as your main speakers. This can sometimes give a more cohesive sound with stereo setups, as the sub "sees" the same signal as your main speakers. Many REL subwoofers, for instance, actually encourage this method, even if you have an LFE out. Passive subwoofers *must* be connected to speaker-level outputs, usually from a dedicated subwoofer amplifier. ### The Right Cables for the Job You wouldn’t try to fix a leaky tap with a spoon, would you? Same goes for cables. Using the right ones, and critically, the right *quality* and *length*, makes a genuine difference. * **RCA Cables (Phono Leads):** For connecting an active subwoofer to an LFE or Pre-Out socket. Don’t just grab the cheapest thing from the supermarket. You don’t need to spend hundreds, but a decent, shielded cable will prevent interference and signal loss. Chord C-Line or QED Performance are good, sensible options that won’t break the bank. Get the right length too; measure the distance from your amp to where the sub will sit, and add a metre or so for slack. * **Speaker Wire:** If you’re using speaker-level inputs on an active sub, or powering a passive sub, good speaker wire is essential. We’re talking about carrying power here, not just a signal. Don’t skimp on the gauge – thicker wire (lower gauge number) is better, especially for longer runs. I generally recommend 14-gauge (AWG) as a minimum, and 12-gauge for anything over about 5 metres or for more demanding passive subs. OFC (Oxygen-Free Copper) is what you want. QED 79 Strand or Atlas Equator 2.0 are solid choices. * **Y-Splitter Cable:** If your amp has a single LFE out, but your active sub has two RCA inputs (L/R), a simple Y-splitter can be useful. It takes the single signal and splits it into two, feeding both inputs on the sub. * **Power Cable:** For active subwoofers, you’ll need a standard mains power cable. Make sure you’ve got a spare socket near where the sub will go. * **Tools:** A good pair of wire strippers (if you’re using bare speaker wire) is a must. Seriously, don’t use your teeth or kitchen scissors; you’ll end up with frayed ends and potential short circuits. A small screwdriver might be needed for some speaker terminals. ## Getting Down to Business: The Wiring Options Right, kit’s all sorted, you know what’s what. Let’s get stuck into connecting the actual cables. Always, and I mean *always*, make sure all your equipment is switched off and unplugged from the mains before you start connecting or disconnecting anything. You don’t want to blow anything up, do you? ### Option 1: Dedicated Subwoofer Output (LFE/SUB OUT) – The Easiest Route This is by far the most common and generally easiest way to connect an active subwoofer, especially with an AV receiver. * **Step 1: Connect the RCA Cable:** Take one end of your RCA cable and plug it into the ‘SUB OUT’ or ‘LFE’ socket on your AV receiver. * **Step 2: Connect to the Subwoofer:** Take the other end of the RCA cable and plug it into the ‘LFE Input’ or ‘Line In (Left/Mono)’ socket on your active subwoofer. If your sub has two RCA inputs (Left and Right) and your receiver only has one LFE out, you can use a Y-splitter cable. Plug the single end into the receiver’s LFE out, and then plug the two ends into the Left and Right inputs on the sub. This ensures the sub receives the full signal. * **Step 3: Power Up:** Plug your active subwoofer into a mains power socket. * **Step 4: Initial Setup:** Switch everything on. Now you’ll need to go into your AV receiver’s setup menu (usually found by hitting ‘Setup’ or ‘Menu’ on the remote). Tell the receiver that you have a subwoofer connected. You’ll then need to run its auto-calibration (like Audyssey or AccuEQ) which will measure your room and automatically set the subwoofer’s level, crossover frequency, and phase. If you don’t have auto-calibration, you’ll need to set these manually – more on that later. ### Option 2: Pre-Outs – For Stereo Amps or More Control If you’ve got a stereo amplifier with ‘Pre-Outs’ (or an AV receiver where you want to bypass its internal bass management), this is a good option for an active subwoofer. * **Step 1: Connect RCA Cables:** Use a pair of RCA cables. Connect one end of the Left RCA cable to the ‘Pre-Out L’ on your amplifier and the other end to the ‘Line In L’ on your active subwoofer. Do the same for the Right channel: ‘Pre-Out R’ to ‘Line In R’ on the sub. If your sub only has a single ‘LFE’ or ‘Mono’ input, you can usually just use one RCA cable from the ‘Pre-Out L’ (or use a Y-splitter from both Pre-Outs into the single sub input, though this is less common). * **Step 2: Power Up:** Plug your active subwoofer into the mains. * **Step 3: Initial Setup:** Switch everything on. With this method, your main amplifier typically won’t have any subwoofer settings. You’ll need to control the crossover frequency, phase, and level directly on the subwoofer itself. This requires a bit more ear-tuning, but it can give fantastic results when done right. ### Option 3: Speaker-Level Inputs – The "No LFE Out" Lifeline This is your go-to if your amplifier or receiver doesn’t have a dedicated LFE or Pre-Out socket, or if you prefer the sound of speaker-level connections (many REL users swear by it). This applies only to active subwoofers that have speaker-level inputs. * **Step 1: Prepare Speaker Wire:** Cut three lengths of speaker wire for each channel (Front Left, Front Right). If your subwoofer has a specific high-level input cable (often a Neutrik connector like on REL subs), use that. Otherwise, you’ll be connecting bare speaker wire. Strip about 1.5cm of insulation from each end of the wires. * **Step 2: Connect to Amplifier:** Connect one end of the Front Left speaker wire to the ‘+’ (red) terminal for the Front Left speaker on your amplifier. Connect the other end of that same wire to the ‘+’ terminal on the speaker-level input of your subwoofer. Repeat this for the ‘-‘ (black) terminal of the Front Left. Do the same for the Front Right speaker channels to the subwoofer’s Right speaker-level input. Some subs have a single speaker-level input that takes all three pairs (Left +, Left -, Right +), and then you usually run a common ground from the Right - to the sub’s - terminal. Always check your subwoofer’s manual for the specific wiring diagram. * **Step 3: Connect Main Speakers:** Your main speakers will also connect to the same speaker terminals on your amplifier, sharing the connection with the wires going to the subwoofer. Don’t worry; this is perfectly safe and designed to work this way. * **Step 4: Power Up:** Plug your active subwoofer into the mains. * **Step 5: Initial Setup:** Power everything on. Again, your main amplifier won’t have subwoofer settings here. All adjustments (crossover, phase, level) will be made directly on the subwoofer. This method requires careful tuning by ear to blend the subwoofer seamlessly with your main speakers. ### Option 4: Passive Subwoofer Wiring (External Amp Required) This is less common for typical home setups, but if you have a passive sub, here’s the gist. * **Step 1: Connect to Subwoofer Amplifier:** You’ll need a dedicated amplifier for your passive subwoofer. Connect speaker wire from the ‘+’ and ‘-‘ speaker output terminals of this *subwoofer amplifier* to the ‘+’ and ‘-‘ terminals on your passive subwoofer. Pay attention to polarity! * **Step 2: Connect Subwoofer Amplifier to Main System:** The subwoofer amplifier itself will need an audio signal. This usually comes from the ‘SUB OUT’ or ‘Pre-Outs’ of your main AV receiver or stereo amplifier (see Options 1 or 2). Use RCA cables to connect these to the ‘Line In’ on your subwoofer amplifier. * **Step 3: Power Up:** Plug in both your main amplifier and your subwoofer amplifier to the mains. * **Step 4: Initial Setup:** Again, you’ll be setting levels, crossover, and phase on the subwoofer amplifier, or in your main AV receiver’s setup menu if it’s providing the LFE signal. ## The Fine Tuning: Making it Sing Once you’ve got everything wired up, the real fun (and sometimes frustration) begins: tuning the subwoofer to blend with your main speakers. This isn’t just about making bass; it’s about making *good* bass – tight, controlled, and integrated, not just boomy. ### Crossover Frequency This is probably the most critical setting. It determines the point at which your main speakers stop producing bass and your subwoofer takes over. * **Rule of thumb:** If your main speakers are small (bookshelf speakers), you’ll likely set the crossover higher, say 80Hz-100Hz, or even 120Hz. If you have large floorstanders, you might set it lower, perhaps 60Hz-80Hz. * **If using an AV receiver with LFE out:** The receiver will manage this, often setting it automatically during calibration. You might still tweak it slightly by ear. * **If using Pre-Outs or Speaker-Level:** You’ll set the crossover directly on the subwoofer. Start by checking the low-frequency extension of your main speakers (often found in their specs). Set the sub’s crossover a bit above that. You want a smooth transition, not a big gap or an overlap. ### Phase (0° or 180°) This one can be a bit tricky to get right by ear, but it’s crucial for good integration. Phase relates to whether the subwoofer’s cone is moving in or out at the same time as your main speakers’ cones for a given low-frequency signal. * **How to set:** Play some music with a prominent, repeating bassline. Sit in your listening position. Have someone switch the phase control on the subwoofer between 0° and 180°. Listen for which setting produces the strongest, clearest, and most impactful bass. You’re aiming for the point where the bass sounds most coherent and joined up with the main speakers, not just loudest. If your sub has a continuous phase control (0-180 degrees), it’s even better, but harder to set. You might need a test tone generator for that. * **Auto-calibration:** Again, AV receivers usually handle this, but it’s still worth checking by ear. ### Level (Volume) This is about matching the subwoofer’s output to the rest of your system. You don’t want it overpowering everything, but you also don’t want it to disappear. * **Start low:** Begin with the subwoofer’s volume control quite low. * **Increase gradually:** Play some familiar music or a film scene with good bass. Slowly turn up the sub’s volume until the bass feels present and supportive, but not drawing attention to itself. It should feel like a natural extension of your main speakers, not a separate sound source. * **Auto-calibration:** Your AV receiver’s auto-calibration will usually set this pretty well, but I often find I need to bump it up by 1-3dB afterwards, just to get that extra bit of impact I like. ### Subwoofer Placement Now, this isn’t strictly wiring, but it’s absolutely vital for good bass. Where you put the sub can make or break its performance. * **The "Subwoofer Crawl":** This is a classic trick. Place your subwoofer in your main listening position. Play some bass-heavy music or a test tone around 50-80Hz. Now, crawl around your room (yes, really, get on your hands and knees!) and listen for where the bass sounds smoothest, most powerful, and least boomy. That’s usually a good spot for your subwoofer. * **Corner Placement:** Often makes the bass sound louder and deeper, but can sometimes lead to boominess or a one-note bass. Good for movies, maybe less so for music. * **Near Wall:** Placing it near a wall (but not in a corner) can still give a good boost without as much boom. * **Experiment:** Every room is different. Don’t be afraid to move the sub a few feet here or there. Even small adjustments can have a big impact. I’ve spent hours nudging subs around my workshop, muttering to myself, until it just clicks into place. It’s worth the effort. ## Who It’s For & Who Should Skip It ### Who it’s for * Anyone feeling their music lacks proper weight or impact. * Film buffs who want to feel those explosions and rumbles. * Owners of smaller bookshelf speakers who need help with the low end. * Anyone who wants a more immersive and engaging listening experience. * Folks with AV receivers who want to make the most of their surround sound. ### Who should skip it * Those strictly listening to critical, minimalist classical music (unless you’re after subtle room reinforcement). * People with very large, full-range floorstanding speakers that already dig deep. * Anyone with neighbours who complain about loud noises at 3 AM (unless you use headphones, obviously). * If your current system is already overwhelming with bass; you might have other issues. ## Common Issues and Troubleshooting Even with the best intentions, things can sometimes go a bit pear-shaped. Here are a few common issues and what to check: * **No Bass at All:** Is the subwoofer plugged in and switched on? Is the volume turned up on the sub itself? Is the RCA or speaker wire connected correctly and securely at both ends? Have you selected ‘Subwoofer: On’ in your AV receiver’s settings? Check the crossover setting – if it’s too low, you might not be hearing anything. * **Boomy, One-Note Bass:** This is usually a placement issue or incorrect crossover/level settings. Try moving the sub. Reduce the crossover frequency. Turn down the level. Check the phase setting. Sometimes, room modes are the culprit, and you might need room acoustic treatment, or a second sub. * **Disconnected Bass / Sub Sounds Separate:** This is a classic sign of an incorrect crossover or phase setting. Your sub shouldn’t sound like a separate speaker. Adjust the crossover – try lower first. Experiment with the phase switch. Ensure your main speakers are set to ‘Small’ in your AV receiver’s settings if they’re not full-range floorstanders. * **Humming or Buzzing:** This is usually a ground loop issue. Try plugging the subwoofer into a different mains socket, ideally on the same circuit as your main amplifier. You can also try a ground loop isolator (a small adapter that goes on the RCA cable), but these can sometimes degrade sound quality a touch. Good quality, shielded RCA cables help prevent this. * **Distorted Bass:** The subwoofer level is too high, or the sub itself is being overdriven. Turn down the volume on the sub. Check your amplifier’s output – are you pushing it too hard? ## Comparison: Active Subwoofers & Connection Types For a bit of clarity, here’s a quick rundown of typical active subwoofer connections: | Connection Type | Best For | Pros | Cons | Typical Equipment | |---|---|---|---|---| | **LFE/SUB OUT (RCA)** | AV Receivers, Home Cinema | Easiest to set up, dedicated bass signal, auto-calibrates well. | Only for active subs, requires an AV receiver or dedicated sub output. | Denon, Yamaha, Sony AV receivers with SVS, BK Electronics subs. | | **Pre-Outs (RCA)** | Stereo Amps, Advanced Control | Full-range signal, can offer fine-tuning control, good for music. | Requires manual setup of crossover/phase on sub, not always present on amps. | Rega, Arcam stereo amps with REL, Quad subs. | | **Speaker Level** | Stereo Amps (no LFE/Pre-Out), Specific Sub Brands | Excellent integration with main speakers (sub sees same signal), often preferred for music. | Requires more wiring, manual setup on sub, only for active subs with high-level input. | Older NAD stereo amps with REL, MJ Acoustics subs. | | **Passive Sub** | Car Audio, Custom Installs | Can handle high power, flexibility in choosing external amp. | Requires a separate subwoofer amplifier, more complex wiring, rare for home hi-fi. | Specific custom home theatre builds with dedicated power amps. | ## FAQ ### Q: Can I connect two subwoofers to my AV receiver? A: Yes, absolutely! Many modern AV receivers have two LFE outputs, labelled ‘Subwoofer 1’ and ‘Subwoofer 2’. If yours only has one, you can use an RCA Y-splitter cable to split the signal and feed it to both subs. Running dual subwoofers can really smooth out the bass response in a room and even out those pesky room modes. ### Q: Do I need special cables for my subwoofer? A: For the RCA connection to an active subwoofer, a decent quality, shielded RCA cable is advisable. You don’t need to spend a fortune, but avoid the super-cheap, unshielded ones. For speaker-level connections to a subwoofer, or for powering a passive sub, good quality speaker wire (14-gauge or 12-gauge OFC) is important. You’re moving power here. ### Q: Should I set my main speakers to "Large" or "Small" in my AV receiver? A: For most home cinema setups with a subwoofer, you should almost always set your main speakers (fronts, centre, surrounds) to "Small" in your AV receiver’s setup menu, even if they are large floorstanding speakers. This tells the receiver to send all the bass frequencies below your chosen crossover point (e.g., 80Hz) to the subwoofer, which is much better at reproducing those deep notes. If you set them to "Large," the receiver tries to send full-range audio to them, which can strain your main speakers and amp, and often results in less impactful or muddy bass overall. Let the sub do the heavy lifting! ### Q: My subwoofer has a standby mode, should I use it? A: Most active subwoofers have an auto-standby feature that puts the sub into a low-power mode when no signal is detected for a period. This is generally fine and saves a bit of electricity. However, some cheaper subs can be a bit sluggish to wake up, causing you to miss the very start of a bass note. If you find this happens, or if you simply want instant bass response every time, you can often switch it to ‘On’ or ‘Always On’ mode, but just remember it’ll draw a bit more power constantly. I usually leave mine on auto-standby for general listening, but switch to "On" if I know I