Audio Systems: car audio fault finding, rockford fosgate subs, volt ohm meter

Question
hi,
   i have just installed a pioneer p7750 head unit with fokal front splits 6inch with tweeter, rockford power series 6.5 inch speakers in the rear doors, orion 4 channel amp, orion mono block amp and two 10 inch rockford fosgate subs. all speakers are running of the 4 channel subs off the mono block. problem. the rear left hand side speaker cuts in and out. i have checked the connection at the 4 channel and it is all fine. the earthing system i did in the boot is a little dodgy i think it might have something to do with it im not sure. i havent checked connections at the actual speaker yet which is what i plan to do next. is there any other suggestions u can give me as to why it is cutting in and out.

Answer
Yes, the thing you have to do is find out where the problem is; the amplifier itself, the power lines feeding the amp, the speaker wires or the speaker.

You can find out easiest by taking a loose speaker and short piece of wire, connect it directly to the amp output that is feeding the speaker that is intermittent.  If you get the same intermittent result on the hardwired speaker you know it is an amp or powerline problem.  If the hardwired speaker is okey you know the problem is in the speaker wires or the speaker itself.

The best tool I know of in cases such as this is a simple little vom (volt-ohm-meter; the best one for car use that I have found is at Walmart electrical department for $9.83) that allows you to check voltage on the lines and measure resistance on speaker lines, etc.

Good Luck. Sound like a fine system!  Hope you get it working to your satisfaction.

Cleggsan