help...

[spwuinmk67]

Alright, I know I saw this somewhere, and I couldn't find it again. Being that my college doesn't allow freshman to have cars, I am taking my old system out and going to attempt to sell it here. But in the mean time, I would like to at least use the sub and sub amp in my room. What would be needed to run my car amp/sub indoors?

[LittleCar_w/12s]

I'll spell it out, so if you want to have more fun don't read this....

ok, what you will need is a power supply to run it. because it's audio equipment and not a lightbulb, it will need to be relatively clean power. you can do this in two ways: a computer power supply or a battery and carger.

Computer supply: you will get 12v, regulated, and clean. Supplies will produce 4-8 amps, depending on how old they are. really old ones produce more 12v amps because they used to drive disks that weighed 10lbs.. no joke.

Battery and supply: Your best option, especially if you want to surpass low listening levels, is this option. You will have a battery, the most convenient will be a lawn-tractor, but you can get a car battery to work, given you buy a set of terminals or a lug for side-post batt's. You will need a hosehold power supply for 12v DC. These can be any amperage, but I reccomend from 500ma (1/2 amp) to 2 amps. Anything larger is better, but will be larger as well... we want this compact. You will cut the tip of the wire off of the supply, and wire it directly to the battery, keeping + to + and - to -. The rest of the equipment connects to the battery as would a car. because your lengths are shorter you will not need such a larger guage wire. You will also be pulling a lot of power off of the battery when in use, and the charger will refill the battery later. You never want to run the battery too low, deep-cycling it is not good.

/\ Noise issues and other problems: First issue is ground-loop. you may want a ground wire from your battery or negative lead connecting to the ground of your source. A chassis to chassis wire is convenient if you have only one amp (say, computer screw to amp ch. gnd. screw.), and can be made from really thin wire and little lugs. NEXT issue is supply noise. You will have none with a PC supply and little with a battery supply. You will have a good bit if you run from, say a 2amp converter to the amp directly, but only if you run at the max a lot.

You will need the following with a battery/charger setup if you have a large current setup. During use, your 'system' of sorts will pull much more than your charger will charge... and a wall to 12vdc converter outputs a 12v DC, but has a 30hz (half of 60) form wall) overtone that will range about 15v. This keeps your battery topped off, and is absorbed by your equipment's capacitors and the battery. HOWEVER, when you draw the battery down a bit, the charger will ge tvery hot, may blow a fuse, and that overtone goes from 12-15v (3v diff) to much more at, say 9v, where you can easilly draw thast battery down to. You WILL hear hum from this, as your charger cannot keep up with yru equipment. A quick solution is to unplug the charger, but a switch is certainly more convenient.

Remember to turn on your amp somehow. A wire from 12v in to the turn-on lead is ok, as most good amps are buffered here with a cappacitor and little op-amps. This will however keep it on all the time, and can overheat your supply. Another solution is a little switch with two wires, which can be run up to yor convenient location. If you used a switch for your supply, a DPDT can be used here to operate both simultaneously. IF, and IF you use a computer for this, AND you have the chassis ground cable established, you can run a wire from a 12v line in the PC to the amp here, also a 5v may work as well, but you have both, so why bother.

Now, enjoy that HUGE amp with yor PC or walkman!
-Jerry