Why Won’t My Sub Turn On Unless It’s Really Loud? Part 1 – Causes

Picture this: You sit down to watch a movie or listen to music—everything sounds fine, but something’s missing. The bass. You crank the volume, and only then does your subwoofer suddenly roar to life… but now it’s too loud. Today we explore Why won’t my sub turn on unless it’s really loud? Part 1 – Causes.

This is a surprisingly common issue. Especially among home theater fans using budget-friendly or older subwoofers. Or AV receivers with lower-than-average LFE output. In this first part of our two-part series, we’ll break down the common causes behind this frustrating problem.

What’s Happening, and Why

Many powered subwoofers feature an auto-on or standby mode. It’s designed to help save energy when the sub isn’t actively in use. It’s a feature most of us appreciate—until it starts to misbehave. The idea is simple. The sub “sleeps” until it detects an incoming signal from your AVR or preamp, then it turns on automatically. You never notice it, until it doesn’t work correctly, and then it’s all you notice.

But here’s the problem: some subs have a signal detection threshold that’s too high. Unless the signal is strong and loud enough, the sub won’t wake up. When your movie is rocked by an explosion, the subwoofers kick in, and it scares the bejesus out of you!

However, this doesn’t mean your subwoofer is broken, you just might need to tweak some settings.

Common Reasons Your Sub Won’t Wake Up

There are several potential culprits here, some hardware-related, others due to system configuration.

The Sub Is Broken

I know this is a simple answer, but it has to be addressed. The answer could be as simple as something is broken internally. No matter how much tinkering you do, the auto-on feature, or subwoofer, will not work. If this is the case, your voyage has ended. You might be in the market for a new subwoofer or a repair. That, or you keep the subwoofer on at all times.

Auto-On Sensitivity is Too Conservative

The culprit could be something as simple as the auto-on sensitivity. Many older or budget subwoofers require more oomph to trigger and force the subwoofer awake. There is not a lot you can do about this. It’s built into the subwoofer and you need to find a workaround.

Poor Signal

If you have a really janky connection, or you are using unshielded RCA cables close to power cables, there is a good possibility that the signal from the AV receiver is not reaching the subwoofer with enough power to trigger the sub at lower volumes. It’s one of the more unlikely scenarios I have run across, but it is worth considering.

You Messed Up A Setting In The AV Receiver

This is a very common root problem. We are AV Enthusiasts, and we like to tinker. We don’t always remember what we did or why we did it, so troubleshooting becomes quite tricky.

A lot of times, I see people playing around with their LFE for LPF. By default, it’s set to 120Hz and you should never touch it. That said, one of the most common things I see in forums is: set all of your crossovers to 80Hz.

That is a THX standard, and it is typically for your five base-layer speakers, and not your LFE setting. By setting the LFE for LPF at 80Hz, you are reducing the amount of bass in the LFE signal that is reaching your subwoofer.

Our Take

To wrap up Part 1 of Why won’t my sub turn on unless it’s really loud? Part 1 – Causes. It’s clear that your subwoofer’s reluctance to engage at lower volumes usually points to a signal-level problem. This doesn’t necessarily mean a faulty unit. Whether it’s auto-on sensitivity, a receiver’s LFE settings, or signal routing quirks, most of these issues are fixable with a little know-how.

The good news? You don’t have to settle for boom-or-bust bass. In Part 2, we’ll walk you through practical fixes—from calibration tips to gear recommendations—so you can bring your subwoofer to life without needing to rattle the walls first.