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BIG 3 DONE, Lights dim, amp cuts off at 13v

Old 03-15-2010, 08:42 PM
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BIG 3 DONE, Lights dim, amp cuts off at 13v

ok so i done some trouble shooting to figure out why im still getting voltage drops, light dimming, and why my subs turn off when i play heavy bass songs, and this is what i came across

so today i measured for bad grounds, first i measured the battery with the car off, 12.6volts.

secound i measured from the neg side of batt post to chassis ground, got 0.01 as a reading on the DMM, so that means mininum resistance which is good right?

i turned my car on, turned on the wiper blades front and rear, turned high beams and headlights on, and put my heater on MAX

i put my HU to about 26/35 and measured the battery and it never went less than 13volts

so with everything still on, i measured the power cable and ground cable AT THE AMP, same reading 13-14 volts

this is the part where im confused, so with all that being done, my lights still dim, and when the heavy bass drops when im driving and listening to music, my amp seems like it cut offs, but the green light always stays on, so really its just my subs that cut off for like 1-3 seconds

so is it a bad ground at the amp? i have 17 feet of power cable and im running 1200 watts, do i need to upgrade my power wire to 2 gauge? Should i be worried that this will ruin my amp?

any other places i should meaure with my DMM?

heres a little background info

-harbor freight tool DMM, CEN-TECH model for $3
-1995 ford explorer
-130-140 amp alternator
-BIG 3, 4 gauge everywhere
-4 gauge amp kit from ebay
-Hifonics BXI1210D 1200 watts at 1 ohm, setted gains with DMM also and measured for 34.0 volts instead of 34.46 volts.
-2 12" pioneer subs 400 wrms per sub
-kenwood mpc 205 HU, 2 volt pre-outs

thanks guys for all feed back
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Old 03-15-2010, 10:40 PM
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i get the same with my new subs, though my amp doesn't cut off.


i'm thinking i should do another run or 2 of 4 gauge wire for the big 3 and run 2 new lines for the amp.

(though my alt only does 100amps)
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Old 03-15-2010, 10:44 PM
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you need to measure the voltage at the amp when you are playing just below the volume where it shuts off. just because your battery is at 13v doesnt mean that your amp is seeing 13v all the way in the back. You may be shocked at the number you see
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Old 03-15-2010, 10:45 PM
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The ground for the amp should be addressed as that is probably you issue.
Grind away the paint and use a bolt to secure it.
I had dimming issues, fix the ground for the amp, no its gone.
1500watts and virtually no dimming.
I do need to replace the battery, its probably as old as the car.
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Old 03-16-2010, 02:21 AM
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[QUOTE=audiocustoms85;557817]you need to measure the voltage at the amp when you are playing just below the volume where it shuts off. just because your battery is at 13v doesnt mean that your amp is seeing 13v all the way in the back. You may be shocked at the number you see[/QUOTE

i mentioned in my post that i did measure the voltage at the amp, with my DMM, i set my scale to DC volts and put the negative on the ground terminal and positive on the power wire terminal on my amp, and it gave the same readings, is this ok? will my amp fry at 13v and higher?
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Old 03-16-2010, 08:07 AM
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You need to take those readings with the system playing and see what your amps are getting for power. It could also be clipping and momentarily be shutting down the outputs.
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Old 03-16-2010, 02:12 PM
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so lower my gain? if its clipping thats bad, but i dont get why EVEN bother using a DMM to set gains, when i setted it to exactly what the chart said, and now im clipping, so whats the best way to prevent this?
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Old 03-16-2010, 02:57 PM
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Try lowering your gains, if that doesn't work...
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Old 03-16-2010, 03:50 PM
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you can fix the issue with upgrading your battery to a hightoutput battery or adding a cap or a secondary battery in the back that way ur amp gets the juice it needs to run adding a bigger alternator will also help the issue go away but a second battery or a cap will be the cheapest way of taking care of the problom
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Old 03-17-2010, 01:52 AM
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i will run 2 gauge from the battery to the amp, but i hear caps are more worse for your amp, then good, since they cause more stress on your amp,

i dont know what or who to believe, but thanks for the input
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