We've got Surround Sound
No pictures of this, it would be hard to take a picture anyway... Last night I went in and clipped the interior/cabin speaker wires off the back of the Sony radio and installed an amplifier.
The particular amplifier I am using is pretty neat, as it has a full DSP front-end, programmable by way of an RS232 cable. It has a power output of up to 46 watts x 4 at 2-ohms, (Maine, it is RMS power!) with an additional 100 watt subwoofer section. Trick is, you need to provide a 1-ohm load to get that much power out of it. The amp is hovering at around 90% efficiency, so very little heat is being given off during operation. It has a peak current draw of just under 30 amps and has a normal average draw of only 5 amps at normal(?) listening levels.
Back to the DSP. With the computer connected, I can go in and tweak a lot of paramemters for each of the five channels... gain, compression, crossovers, crossover slope, delay, channel mixiing, two different sets of EQ, what have I missed?
Anyway, I took advantage of some very basic surround sound theory, specifically that rear information is largely encoded in a "left-minus-right" and "right-minus-left" manner. For the rear speakers, I employed this basic technique to remove all center channel information, leaving only ambient information and steering cues intended by the surround-sound mixing engineer. The result is pretty convincing. While it is not Dolby Pr-Logic, or any of the other newer surround sound technologies, all of them are based upon this fundamental method of rear-decoding and it works pretty good. It also is MUCH better suited to music where you still want a stereo image, as opposed to "all center speaker, all the time" way many surround systems treat music.
I will be adding a subwoofer... I have the actual woofer in the shop now, I just need to build a sealed enclosure for it and get it wired in. It is an 8" unit, and will probably go in the forward dinette seat base. The enclosure needs to only be about a half-cubic foot, and it will mount inside the dinette seat up against one of the seat base walls, with the woofer firing into the listening area.
I took advantage of the radio's fader control in all of this. It is easy to fade back so that only the cockpit speakers are playing, or I can fade all forward, so that only the surround sound cabin system is playing. I can also set them both at a comfortable mix of front to back, so that there is sound everywhere.
After all of this, we will probably never watch TV or movies, instead just using the stereo for music, but it is fun, and helps me keep my job a hobby, so I do it...
Pics soon hopefully, once I get everyting tightened up.