My Amp Is ON But No Sound From Speakers/Subwoofer Is Not Working
By Robert Jones · 2021-11-21
Amp on but no sound from speakers or subwoofer? It's a common headache. As an audio engineer for 20+ years, I'll walk you through the usual suspects to get your system singing again. Most fixes are simpler than you think.
Right, so you've flicked the switch, the lights are on, but all you're getting is deafening silence from your speakers or subwoofer. Don't fret, we've all been there. It's a bloody frustrating situation, especially when you're itching to crank up some tunes or get lost in a film. More often than not, it's something simple, something you've overlooked in your eagerness. I've seen countless setups, from tiny living room systems to full-blown custom home cinemas, and the problem usually boils down to a few common culprits. Let's get stuck in and figure out what's gone wrong. **Quick Verdict: Nine times out of ten, it's a loose cable, an incorrect source selection, or a protection mode issue.** ### Who it's for: * Anyone with an amp, AV receiver, or powered subwoofer experiencing no sound. * DIY enthusiasts looking to diagnose their audio system problems. * Newcomers to home audio wanting to understand basic troubleshooting. ### Who should skip it: * If your gear is visibly smoking or showing clear signs of severe damage – power it off and call a professional. * Those looking for advanced circuit board level diagnostics (this is about common user-fixable issues). ***  *My Amp Is ON But No Sound From Speakers/Subwoofer Is Not Working — tested in the SpeakersMag workshop.* ## The Grand Tour of Silent Setups: Where to Begin When your amp's powered up but your speakers are playing dead, it feels like a kick in the teeth. After twenty-odd years mucking about with audio gear, I've developed a bit of a system for this. You need to approach it methodically, like a detective. Don't just start yanking cables at random; you'll only make things worse or miss the obvious. ### 1. The Obvious First: Power and Input It sounds daft, I know, but trust me, even seasoned blokes forget these bits. Is the amp *really* on? I mean, fully on, not just in standby. Does the display look normal? Sometimes, a faint flicker or a blank screen is a clue in itself. Check the power light. If it's blinking oddly, consult your amp's manual – that's often an error code. Then, the input. Is it set to the right source? HDMI 1, Optical, Phono, CD? I can't tell you how many times I've gone to a mate's house, only to find their receiver is still on "Blu-ray" when they're trying to play Spotify through their "Streamer" input. It's the simplest mistake, and it catches everyone out eventually. Cycle through them, just to be sure. ### 2. The Mighty Cables: Your System's Lifelines This is where most problems live. Cables are like the veins of your audio system; if they're blocked or disconnected, nothing's getting through. We're talking speaker wires, RCA interconnects, HDMI, optical, coaxial – the lot. #### Speaker Wires Right, let's start with the basics: speaker wires. Give every single connection a good, firm wiggle. At the back of the amp, and at the back of the speaker. Are they properly seated? No frayed strands touching each other or the amp chassis? That's a classic short circuit waiting to happen, and your amp's protection circuit will definitely cut the sound if it detects one. I've had speaker wires that looked fine but had an internal break from being crushed behind a cabinet. You wouldn't know unless you traced them inch by inch or, better yet, swapped them out for a known good cable. If you're using banana plugs, pull them out and push them back in. Spring clips? Make sure they're clamped down tight on bare wire, not on insulation. #### RCA Interconnects If you're using RCA cables – those red and white plugs – to connect sources like a CD player, DAC, or turntable, check those too. They can work their way loose over time, especially if the cables are a bit stiff. Make sure the left (white) and right (red) are in the correct corresponding inputs and outputs. A common mix-up I've seen is plugging a source's output into another output, or an input into an input. Sounds daft, but it happens. #### Digital Connections (Optical, Coaxial, HDMI) For digital connections, it's much the same. Optical cables (TOSLINK) are particularly prone to coming loose or getting a kink in them, which can block the light signal. Make sure they're clicked in properly. HDMI can be finicky too. Try swapping HDMI ports on your TV or receiver, and even try a different HDMI cable if you have one spare. Sometimes, it's just a handshake issue between devices. ### 3. Subwoofer Specifics: The Low-Down If it's just your subwoofer that's gone quiet, that narrows things down a bit. Most subwoofers are active, meaning they have their own amplifier built-in. So, we've got a few extra points to check. #### Subwoofer Power First, is the subwoofer actually plugged into the mains and switched on? Does its own power light illuminate? Some subs have an auto-on/standby feature, which can be a bit unreliable. Try setting it to "on" rather than "auto" if it has that option. I've known plenty of subwoofers that just refuse to wake up from standby for no good reason. #### LFE/RCA Cable Most subwoofers connect to your AV receiver via a single RCA cable, usually labelled "LFE Out" or "Sub Out" on the receiver, and "LFE In" or "Line In" on the sub. Check this cable. Unplug and re-plug both ends. Is it damaged? Try a different RCA cable if you have one. Sometimes, these cables can go bad, especially cheaper ones. #### Subwoofer Settings Many AV receivers have a "Subwoofer On/Off" setting in their menu. Make sure it's enabled. Also, check the crossover frequency; if it's set too low, or if the main speakers are set to "Large" (full-range), the receiver might not be sending a signal to the sub at all. Ideally, your main speakers should be set to "Small" and the crossover around 80Hz for most systems. I've seen systems where the user has accidentally set the LFE output level to zero in the receiver's settings too. Worth a look. #### Phase and Gain While less likely to cause *no* sound, incorrect phase or gain settings can make the sub seem absent. Double-check your phase switch (0 or 180 degrees) and make sure the gain isn't turned all the way down. Turn it up slowly, mind, you don't want to blow yourself out of the room! ### 4. Protection Mode: The Amp's Self-Preservation Instinct Modern amplifiers and receivers are clever bits of kit. They have protection circuits designed to shut down the output if they detect something wrong. This saves the amplifier from damage, and sometimes, your speakers too. If your amp turns on but immediately clicks off, or if the power light flashes an error code, protection mode is a strong suspect. #### Common Causes of Protection Mode: * **Short circuit:** The most common culprit. Frayed speaker wire strands touching each other, or touching the amp's metal chassis. Check *all* speaker connections carefully. Disconnect all speakers, power cycle the amp, and see if it stays on. If it does, connect one speaker at a time to find the faulty one. * **Overheating:** If the amp is getting too hot, it'll shut down. Is it in a cramped cabinet with no ventilation? Are the vents blocked? Give it some space to breathe. Dust can also build up inside and act as insulation, so a gentle clean with compressed air (unplugged, naturally) can sometimes help. * **Impedance mismatch:** Connecting speakers with too low an impedance (e.g., 4-ohm speakers to an amp only rated for 8 ohms) can overload the amplifier and trip the protection. Always check your speaker's impedance against your amp's specifications. * **DC offset:** This is a more serious internal fault in the amplifier where a direct current (DC) voltage is present at the speaker outputs, which can damage speakers. If you suspect this, it's repair shop territory. You'd typically hear a pop or thump from the speakers when it happens, or they might try to extend or retract rapidly. ### 5. Source Device Woes: The Other End of the Chain Sometimes, the amp and speakers are fine, but the *source* device isn't playing ball. Let's say you're trying to play sound from your TV through your sound system. * **TV Audio Output Settings:** Check your TV's audio output settings. Is it set to "External Speakers" or "Audio System"? Is the digital output (Optical/HDMI ARC) configured correctly? Sometimes it defaults back to internal speakers after an update. * **Volume Control:** Is the volume turned up on the source device itself? Your TV, Blu-ray player, or streaming box often have their own volume controls, which can override or interact with your amp's volume. Make sure they're not muted or turned all the way down. * **Device Issues:** Try a different source. If your CD player works fine but your Blu-ray player gives no sound, then the problem isn't with the amp or speakers, but with the Blu-ray player or its connection. Simple elimination, that. ## Troubleshooting Flowchart (Sort Of) It can feel a bit overwhelming, so here's how I'd generally approach it: 1. **Check Power & Input:** Amp fully on? Correct source selected? (90% of issues are here, honestly). 2. **Inspect All Cables:** Wiggle and re-seat *every* cable – speaker, RCA, HDMI, optical. Look for damage. If only one channel is out, swap cables between left and right to see if the problem follows the cable or the amp/speaker channel. 3. **Subwoofer Specifics:** If it's just the sub, check its own power, LFE cable, and receiver settings. 4. **Isolate Components:** * Disconnect *all* speakers and inputs from the amp. Power on. Does it stay on? If so, the amp is likely okay, and the fault is external. * Connect one speaker at a time. Play some low-level audio. Does it work? If connecting a specific speaker trips the protection, that speaker or its cable is the problem. * Connect one input source at a time. If one source works and another doesn't, the issue is with the faulty source or its connection. 5. **Factory Reset:** As a last resort, many AV receivers have a factory reset option. This can clear out any corrupted settings. *Be warned*: you'll lose all your custom calibrations and settings, so only do this if you've exhausted other options. ## Common Brands and Their Quirks Over the years, I've seen specific tendencies with different manufacturers. * **Denon/Marantz:** Generally solid. Their protection circuits are quite sensitive, which is a good thing. Often, a quick factory reset can fix odd input switching issues. * **Yamaha:** Good workhorses. Their YPAO calibration system can sometimes mute channels if it detects an issue during setup, so re-running or disabling it temporarily can help. * **Onkyo/Pioneer:** Had a spate of HDMI board issues on older models a few years back, which would lead to no sound from digital sources. Less common now, but if you've got an older unit, it's something to consider. Often manifested as intermittent sound before total failure. * **Sony:** Their menu systems can be a bit convoluted, making it tricky to find the right audio output settings for external devices. Persistence is key there. * **Active Subwoofers (e.g., REL, SVS, Monitor Audio):** Their auto-on features can be a bit hit or miss. If your sub isn't coming on, always try the "on" setting first to rule out a sleepy auto-sense circuit. ## When to Call in the Big Guns (or just buy new kit) If you've gone through all these steps and still have no joy, it's time for a decision. * **Still in Warranty?** Absolutely get onto the retailer or manufacturer. Don't try to open it up yourself; you'll void the warranty. * **Out of Warranty, but a quality piece of kit?** If it's a decent amp that cost you a few hundred quid or more, it might be worth taking it to a local electronics repair shop. Get a quote. Sometimes, a simple component replacement is all it needs. I've saved a few good amps from the tip this way. * **Old, budget kit?** Be honest with yourself. If a new budget receiver costs £200 and the repair quote is £150, it's probably time to upgrade. Modern amps offer better features, HDMI standards, and often improved sound for the money. Consider what you'd gain by investing in new gear. *** ## Comparison: Troubleshooting vs. New Purchase | Feature | Troubleshooting Old Kit | Buying New Kit | | :---------------- | :------------------------------------------------------------ | :--------------------------------------------------------- | | **Cost** | Potentially free (DIY) or repair fees (£50-£200+) | £200 - £1000+ (depending on desired features and quality) | | **Time** | Immediate (DIY) to weeks (repair shop) | Immediate (online order) to days (delivery) | | **Learning Curve**| Good for understanding your system, can be frustrating | Minimal; plug-and-play, usually user-friendly setup | | **Features** | Limited to existing; no modern connectivity | Latest HDMI, streaming, room correction, eARC, etc. | | **Reliability** | May be temporary fix; other components could fail | Brand new warranty, generally more reliable | | **Environmental** | More sustainable; extends product lifespan | New manufacturing has environmental impact | | **Satisfaction** | Huge sense of accomplishment if fixed; frustrating if not | Instant gratification, modern convenience | *** ## FAQ: Your Burning Questions Answered ### Q1: My amp clicks on then off straight away. What's that about? A: That's almost certainly the protection circuit kicking in. Disconnect all your speaker wires from the amp, then power it on. If it stays on, you've got a short in one of your speaker cables or within a speaker itself. Reconnect one speaker at a time to isolate the faulty component. Make sure no stray copper strands are touching between terminals or the amp chassis. ### Q2: I'm getting sound from my TV's speakers but not from my soundbar/receiver. Help! A: This is usually down to the TV's audio output settings. Go into your TV's sound menu and make sure it's set to output audio to "External Speakers" or "Audio System" rather than "TV Speakers". Also, check that the correct output format (e.g., PCM, Bitstream) is selected, and if using HDMI ARC/eARC, ensure that feature is enabled on both the TV and your receiver/soundbar. ### Q3: My subwoofer used to work, but now it's totally silent. The power light is on, though. A: If the power light is on, that's a good sign the internal amp is getting power. Focus on the signal path. Check the RCA/LFE cable going from your main receiver to the subwoofer – unplug and replug both ends. Try a different cable if you have one. Then, delve into your AV receiver's speaker setup menu. Make sure the subwoofer output is enabled and its level hasn't accidentally been turned down to zero. Also, check the crossover setting; if it's too low, or your main speakers are set to "Large", the sub might not be getting a signal. ### Q4: I replaced a fuse in my amp, and it blew again immediately. What now? A: If a fuse blows instantly after replacement, it means there's a direct short circuit or a significant internal fault. Don't keep replacing fuses; you'll just damage it further or potentially cause a fire risk. This is a clear sign that the amplifier needs professional inspection and repair. There's a serious underlying issue that a new fuse won't solve. ### Q5: What's the difference between "Line In" and "LFE In" on a subwoofer? A: Good question. "Line In" (often left and right RCA jacks) is for a full-range signal, expecting the subwoofer's internal crossover to filter out the highs. "LFE In" (Low-Frequency Effects) is a dedicated input for the ".1" channel from an AV receiver, which is already filtered to contain only the bass information. Most modern AV receiver setups use the LFE Out on the receiver to the LFE In on the sub. If your receiver only has a single "Sub Out", use that into your subwoofer's LFE In. ## Final Word Look, I know how maddening it is when your gear plays up. It's almost never a complete disaster, though. Most of the time, it's a silly cable, a wrong setting, or a protection circuit doing its job. Take a deep breath, go through these steps systematically, and you'll probably find the culprit without too much fuss. If you've exhausted all these options and it's still not playing ball, then it's time to weigh up a professional repair against the cost and benefits of a shiny new bit of kit. But don't give up after the first check; patience is a virtue in audio troubleshooting. Happy listening, or rather, happy fixing!