I'm working on building Bluetooth speakers using old earbuds and I've hit a snag. I need to provide two different voltages: the earbuds work between 3.3V and 5V, while the amplifier requires 8V to 12V. I've tried a buck converter along with an Arduino power supply to step down the voltage, but this setup causes a lot of audio noise. Interestingly, when I use separate power supplies for each, there's no noise. What can I do to resolve this issue?
3 Answers
To start, make sure you know how many amps or milliamps each part needs. Switching supplies can introduce noise that's especially problematic for audio, since they create harmonics at their switching frequency. While you might add filters, they won't solve everything. If your current draw is low, consider using linear regulators instead, like the 7805 for 5V or the 7812 for 12V. They’re simpler and usually quieter.
From experience, this is a common audio problem. Noise typically stems from two areas: the noise from your switching power supply and potential ground loop issues, especially if the earbuds are designed for battery operation. I suggest starting with a linear regulator for the earbuds' power supply, ensuring you have good inductive and capacitive filtering to reduce those impulses. You could also isolate your grounds using a ground loop isolator or an isolated power supply for the earbuds. Combining these approaches can help clean up the noise significantly!
It sounds like the noise may be due to ground loops or interference from sharing a single power source. One solution is to use an isolated DC-DC converter instead of a buck converter, which can help eliminate ground loops. You can also add decoupling capacitors (100 µF and 0.1 µF) to filter out noise. If you can, stick with separate supplies; if not, ensure both your devices share a common ground point to help minimize interference. This could really improve your audio quality.