Subwoofer power question

[syn-]

I recently installed my 13w7 with 1000/1 in place of my old setup. I put a 5 farad cap (not the best brand, but it was free and has a voltmeter). If I play the sub with the truck off it sounds great, but after the truck is on it seems to lose its enuff. Does not sound the same by no means, don't get me wrong it hits just distinctly not the same. As for wires I have knu koncepts 0g to the cap and 4g to the amp. 8g from amp to sub, voltmeter on the cap says 14.7 and sometimes even 14.9. I have seen it in the 13, to 12 range with the car off and it seems to be tied to the sound being better. I have also done the big 3. Anyone have any ideas?

 

[PandorasCustoms]

Hmm... Never run across something like this before.

With the vehicle running, I can't think of anything except an issue that the it may have something to do with the signal coming from head unit. If with the vehicle off, the Remote is producing the required voltage of 12v, and maybe with the vehicle running it is higher? Same for the RCA signal, and so on so forth.

If the voltmeter on the capacitor doesn't flux with the vehicle running vs the vehicle being off, then that pretty much isolates that section of the issue. I would definitely recommend looking into the head unit signal angle first.

 

[barneyrubble318]

Could something be wrong with the charging system? When the Explorer is running so is the alternator.
When you do your test with it off, are you in the vehicle with the doors closed and windows up? Do you do the same thing with it running?
Is the head unit remote wire just turning on the amp and the cap, or do you have other equipment? Do you have a relay on your remote wire?
Are you running some kind of voltage regulator on your sound system, like a jacobs electronics?
Put a volt meter on the battery, test it in different situations. Cranked with the truck running, then off. Normal volume truck on, truck off, etc. Rev the engine, etc.
Turn off the lights, air any other accessories.