The cabinet only had 1 small speaker mounted at the bottom left. This was replaced with a fan to suck in fresh air to keep the temperature down inside the cabinet.

The replacement speakers needed to be amplified (the cabinet muffles the sound somewhat), have a flat surface, and have a fairly simple layout inside. Low cost was more important than looks as they were going to be ripped apart anyway. :)

The speakers I ended up with met most of the requirements, and as an added bonus, could plug straight into the mains for power (yay, no external PSU!). The speakers had a slightly more curved surface than I thought, so they had to be recessed further into the cabinet.

I had no idea where the speakers would be placed, but space inside the cabinet was now limited to two 'shelf' type areas on the upper left and right sides of the cabinet. The first photo below shows how the speakers stayed until I finally decided to poke them through the top of the cabinet. The second photo shows the original screen that was in the cabinet. Take note of the empty space between the tube and where the speakers sit on either side.

When I first fitted the monitor inside the cabinet, I was getting interference from the speakers (which were supposed to be shielded). The speakers would also crackle and then make a low buzzing noise when the monitor was turned on. The problem would get worse once I removed the speakers from their casing and mounted them inside the cabinet, so the only solution was to make up my own shielding.

The shielding I made was some sheet-metal from some old 286 cases, which were cluttering up the garage, sandwiched between some plywood. The shielding also hides away some of the wiring mess at the bottom of the cabinet. The first photo below shows the inside of the cabinet with the shielding in place and the speakers mounted on the lid. The next two show the top of the cabinet with the speakers installed.