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Subwoofer powered by Woopker D20

 I had an old unpowered subwoofer originally it plugged into the speaker output from my stereo. Inside the sub there was a filter circuit, it ran through an inductor and into the 2 internal subwoofer speakers. There were 2 outputs that went though an RC filter and to these two mini speakers that came with the subwoofer. The mini speakers went missing and I just plugged in the 2 mid-range speakers that came with the stereo. The problem with this is that the subwoofers filter was tuned for the tiny speakers. The sound coming out of was flat since most of the frequencies it was expecting had been filtered out. I wanted to run the mid ranges directly from the stereo, but I also wanted some bass. So, I decided to get a cheap amp and run the subwoofer from the subwoofer output in my stereo. I purchased the Wooper D20 from aliexpress.us since it was cheap and because it was panel mount, so I could wire it up to my sub and it would look like it was always a powered subwoofer. It had several features that I didn’t want, this post goes over my mods to the amp and my impressions of it.

Since I was just using it as an amp for my subwoofer, I just needed the line in I didn’t need the Bluetooth of the FM receiver, or the USB driver / SD card reader or the Mic mixer. All these features cam though the Amplifiers Bluetooth chip the HSC024B it’s an older mono version of the HSC025A.

 The bottom large circuit board has the switching power supply and the amplifier board. There are two smaller boards above that, the smallest just has the Mic inputs the other has the Bluetooth chip. I cut the power wire on the ribbon cable connecting the Bluetooth board to the amplifier board, it’s marked V on the amplifier board. I repurposed the led switch to switch power on and off to the Bluetooth board, in case I ever decided I wanted these features.

 

 Unfortunately, this disabled the line in input since all the inputs are going through the Bluetooth chip and it’s doing the input switching. To fix this I put a jumper wire from the input from the line in to the output from the amplifier, bypassing the Bluetooth chip.

There is only one wire since the circuit board bridges the left and the right signal. I made an adapter plate since the hole in my sub was slightly taller than the front panel of the amp. 

 
Then I connected the bass speaker output to the filter on my subwoofer.

The final result:

My thoughts about the Woofer D20 I like it, the sound is good enough and the power output is enough to power my sub. Some things to be aware of if you are thinking about purchasing one. It’s not stereo, it’s not 60 to 200 watts like advertised, it uses the CS3850 amplifier chip which can produce a maximum of 100 watts. I believe it was designed as a replacement board for a Bluetooth speaker with a single woofer and a small tweeter. But for my purposes it works if I turn the bass all the way up and the treble all the way down.

Comments

  1. BlueiceMay 20, 2026 at 5:00 PM

    Are the cats necessary for the build? I don't have cats but could borrow a neighbors if needed.

    ReplyDelete
    Replies
    1. Chris JudevineJune 4, 2026 at 9:51 AM

      The Cats are for quality assurance purposes, they are optional. If you do not have access to animals that enjoy low frequency sound, you can always request feedback from family and friends.

      Delete

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