I have some 10 W, 8 Ω speakers. I'm building a Bluetooth speaker set. I've hooked up a 3.7 V, 8000 mAh portable charger battery to an XL6009 buck converter to pump it to 9 V.

I have a Bluetooth audio amplifier (not sure what class) connected. The aAmazon page for the Bluetooth amplifier states 12 V for two 10 W, 8 Ω speakers, however, the distortion I'm hearing goes on at 12 V, 14 V, and 9 V. I think it was from a question on this site that I got the idea to switch to 9 V.

I'm having difficulty measuring the current when I use the multimeter from the positive connector on the Bluetooth amplifier to the positive of a speaker, but it does play audio when I do it. I've measured the current at 0.5 A (I believe the multimeter measures in amps) when hooked up straight from the battery to a little DC motor. When I play the speakers at full volume or a bit above half way volume it's distorted and just awful sounding, and I'd like to get this fixed.

The plan is to also hook up three orange LEDs (20 mA and 2 - 2.2 V). I'm using 22AWG solid-core tinned copper wiring for all of it.

I want to know how to find the current from the Bluetooth board to the speakers and hook up a resistor to ensure it can play non-distorted at full volume (if this is the issue). I'm learning as I go so please explain fully.


1 Answer 1


The minimum input to your boost converter is 5V. Maybe you should measure the converter output voltage to se if it is stable. It may not work properly and output ripply voltage.

Otherwise it does say 12V should be used for 8 ohm speakers.

But 12V is only needed for constant 1kHz 2x10W output. Please understand that it's a lot of power. An average shelf speaker that's not particularly sensitive can output 80dB SPL, measured at 1 meter distance, when fed with 1 watt.

Speakers can also distort if the element is not properly loaded by the enclosure. You can't expect to get good sound from a speaker element that's without an enclosure, or the enclosure is not suitable.

  • \$\begingroup\$ It does output ripply voltage, can't I just put a capacitor on the end of the step-up to fix this? \$\endgroup\$
    – Hayden
    Commented May 25, 2023 at 22:07
  • \$\begingroup\$ The module already has a capacitor. No amount of capacitor will help if the problem is that the battery voltage is less than what the module requires for proper operation. \$\endgroup\$
    – Justme
    Commented May 25, 2023 at 23:21
  • \$\begingroup\$ Alright so I did that, and at first only Speaker 1 still sounded bad while speaker 2 was perfectly fine. Figured connections were loose, if it moved around too much the amplifier would turn off. So I soldered most of it together, and now both speakers are sounding bad again. Where can I go from here? \$\endgroup\$
    – Hayden
    Commented May 29, 2023 at 22:49

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