How to make your guitar cabinet sound better with bubble wrap

I recently bought a no-name 4x12 for pocket change.  As expected,  it didn't sound too hot, so I figured I'd take a look inside and see what I could do.

Obviously I can't do much about the cheap particle-board frame or the underwhelming 8 ohm speakers with tiny magnets, but the wiring is good and there's a few things I can fix right off the bat.  First I scrubbed down the inside with bleach and water to kill the horrifying rainbow of mold growing everywhere.  Then I tightened every internal screw I could find, especially the ones holding the speakers to the baffle.  Even top shelf cabinets need this from time to time.

Next, I added some bubble wrap to all four sides and the back baffle to suck up some of the low end resonance and allow me to turn up a bit louder without rattling the whole box.

I wasn't terribly precise with this, and if I'd had some eggcrate foam or carpet felt or something I might have laid that down first with glue.  As it is I got a noticeable boost in the mids and more focus without adding any real weight to the thing.

Then I cannibalized some feet off an old DJ mixer and scrounged up some drywall screws and rubber cement for good measure.  The box already had holes drilled so presumable there were feet or casters on it at some point.  Just getting the base off of the floor cut out a ton of ugly low-end resonance and added more energy to the high end.  This is a very simple step than can have a huge effect - too many people ignore this.

That's it for the moment.  I'm going to replace the long-gone handles if I can find some to match and eventually try to find some better speakers but this hour of work made a huge difference already, for no money and a light rubber cement buzz.


 Here's the spectral analysis - green is before, pink after.

No guarantees about the accuracy or reliability of any of this info.  In other words, don't expect this to work on every cabinet and don't blame me if you screw it up.