Hissing or humming with ANC on
You put on your new headphones, turned on noise cancelling, and expected blissful silence. Instead, one channel has a steady hiss, static, or a low hum — a bit like an old TV at night after the programming has ended. Not exactly what you ordered.
Good news: this is almost always either normal ANC physics or something easy to fix. Bad news: you can't break the laws of physics. But let's go through what you can do.
Why does ANC hiss?
Active noise cancelling works by having microphones listen to ambient sounds and the circuit generate an opposing sound. This process isn't perfect — it creates a small noise floor, often called the "ANC noise floor." In all noise-cancelling headphones. Across all brands. It's physics, not a fault.
You can hear it most clearly when you're sitting in a very quiet room and not playing anything. In that case ANC doesn't really have anything to cancel, yet the circuit is still running at full tilt and you're essentially hearing its noise floor.
However — if the hiss is clearly louder in one channel, or it's more of a hum than a steady hiss, there may be a real issue.
How to fix it
- Switch ANC mode: Press the ANC button on the left earcup to cycle through all modes (ANC → transparency → ANC off → ANC back on). This resets the noise-cancelling circuit and surprisingly often helps.
- Restart the headphones: Power off, wait ten seconds, power on. A classic for a reason.
- Check the fit of the ear pads: ANC needs a proper seal around your ear. If the pad is worn, compressed, or hair gets in the way, the noise cancelling starts compensating for the leak and the noise increases. Try pressing the headphones lightly against your ear — if the noise decreases, the pads need replacing.
- Reset the headphones: VMK25: plug in a 3.5 mm AUX cable and unplug it. VMK25.2: charge to full, press Vol+ and Vol- at the same time for three seconds until you hear the "du du" sound.
- Test the environment: Try the headphones in a different location. Sometimes a device in the room — a fridge, ventilation, a fluorescent light — produces sound right at a frequency ANC can't fully cancel, and the result sounds like a strange hum.
If the hiss is clearly only in one channel
A steady, slight noise floor in both channels is normal. But if one side hisses or hums clearly more than the other, it may be a faulty microphone or circuit. In that case:
- Take a photo of the headphones and find your order number
- Send both to info@valco.fi
- Tell us which channel has the issue and when it started
Our service team in Kajaani will take care of it. We repair headphones — we don't throw them away.
If that doesn't help
If none of the above works and the hiss genuinely interferes with listening, contact us at info@valco.fi. Include your order number and a brief description of when the issue occurs. The more detail you provide, the faster we can get to it.
And remember: quiet room + ANC on + no music = you hear every possible noise floor. Put on a track and the hiss will vanish like child support payments from your account on payday.