Decided to ditch the factory sub setup completely and go as far as finding a trim panel that didn't have holes in it. I wanted to be able to remove the aftermarket sub without any tools or bare wires floating about. I also didn't want loads of cables (with or without suitable disconnects) visible at any time. So, thinking of where the DSP amp on later cars would live, I mounted my new amplifier in the space between the outer skin of the car, and the interior trim.
Best I could do is get a grey trim panel from an SE/other non-subwoofer model - nothing some black dye can't fix :)
So before I had this:
And now, without the subwoofer in place, I have this. For some reason one of the previous owners put carpet tape along the edges the loadspace cover sits in on both sides, maybe to try and stop vibrations? Don't know - still need to clean the residue up. I do now have a hole in the carpet... but I'm going to get/make a nicely sized box to sit in that space and bolt to the floor to stop it sliding around, one day...
The amplifier is mounted on a metal plate that I cut to suit, and welded some captive nuts onto, to make fitting easier. The amplifier is a Pioneer A3602 - nothing special, but the dimensions worked for the space available and the price was good. I'm not looking for stupid power - I just wanted more than the factory setup was giving me.
Amplifier mounted to plate, mounted in car. Ran a 6mm feed from the battery and left a bit looped up intentionally. The amp (on paper) will draw just under 15amps continuously at rated power, where my 6mm feed should be good for 40-50amps or so at a push. This lets me fit a small fuse box back here should I need to in the future. At some point, I will change the twin electric towbar wiring for a single 13pin socket with two decent relay-switched feeds taken from such a fusebox.
The only thing taken from the original subwoofer wiring is the 12v switched from the head unit - I removed the other pins from a socket taken from one of my old factory subs. The black cable at the bottom is the output to the subwoofer itself - 2.5mm round PA flex. Signal is delivered by a generic 5m RCA/phono/whatever you call it cable that I've had sat around for ages. Obviously, where the amplifier is mounted, I can't get to its gain/LPF controls at all, so I've preset the gain with it in bits and left the LPF off - using the head unit's filter/gain instead. Offers far more control that way anyway!
To make the subwoofer itself easily removable, I fitted it with a Speakon socket, and put a plug on the end of the 2.5mm flex. Rather than arse about filling in the hole the original wiring plate would have left, I left it in place, piggybacking my new socket wiring straight onto it. Has the advantage that if this box ever goes into another car with the amplifier mounted on the back, it can be wired up as it was originally and the Speakon socket ignored instead.
Bit of a long post, but I'm very happy with how it has turned out. The sound is hugely improved even with this cheap old sub and leaky box, and now I have greater loadspace when needed by simply unplugging and lifting out the box!
Southampton with a Nanocom for Thor/GEMS P38s
1996 4.6 HSE, then became a 4.0, now cubed.
1997-8 4.6 HSE Motronic/Wabco prototype vehicle. Now M57 powered. Still auto.