DIY portable audio boombox with focus on recycling

Not sure if this is the right place - moderators please feel free to move it if necessary.

Just a quick post to share a little project I built, mainly for my son, and with special focus on recycling electronic parts to avoid waste in benefit of our planet. Hopefully might inspire someone for similar projects. Final cost was almost zero!

The base was a (partially defunct) surround system I was given, I used half of the amplifier board (literally broke the PCB in half), modified and tweaked it until was sounding good (is based on nice sounding TDA chipamp (TDA7375)) as a 3.1 amp. I also used the box of the sub (heavily modifying it to become smaller) so I could fit the amp board, two heavy NiCd-Battery packs which came from an old Hi-8-Video camera (another part of recycling - they would be a significant and problematic waste as we all know), two small speakers from powered computer speakers I had which were also partially stopping to work, the original subwoofer speaker from the surround system inside and all the needed interface/circuitry to connect everything. I also installed a small ready-to-use 5V USB power socket (with internal converter), the only new thing I bought for this, so this can be used as a heavy duty power bank to charge phone or mp3 player when outdoors.

I wired it up in a way that allows connection of external power supply for using it stationary (like my son now does using it in his room with a small CD player I repaired for him - basically his first stereo system, with reasonable quality :p ), or with battery (via a switch and a relay, it's quite practical), also a connector for the charger (I modified it so I could use a cable instead of having to insert the battery packs in place), RCA in and volume and bass control. Also two blue LEDs. (Yes, I know, it's getting way too much these days, gotta return to good old fashioned yellow and green LEDs, but the USB socket already had a blue one :rolleyes:).

It really sounds nice, despite its severe limitations from the point of view of a speaker cabinet.
Batteries last about 2:30 h with quite high volume. That's enough for us.
Volume is room filling before starting to appear some woofer "noise", I'm not quite sure what it is, maybe lack of damping or waves internally cancelling each other (I did install some blockages, which can't be seen on picture and which improved but didn't solve the issue). But we can live with that, as it only starts at really high volume and only with music that has heavy bass.
 

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Thanks :)
Indeed it does sound better than most of the smaller bluetooth speakers I've heard. What I find most "annoying" of the majority of them is their "unnatural" sound, I mean, some of them have low distortion and good detail, but most of them have so much EQ and heavy bass on them that they simply don't sound right to my ears, it's almost like they were "on steroids" :p