amp problem
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=27365
Printed Date: July 14, 2025 at 7:04 PM
Topic: amp problem
Posted By: makaveliwi
Subject: amp problem
Date Posted: February 27, 2004 at 9:03 PM
My sib keeps cutting in and out. the amp has power and the rest of the speakersa still work.
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milwaukee walt
Replies:
Posted By: forbidden
Date Posted: February 27, 2004 at 9:14 PM
Turn the gain on the amp down, next check the speaker wire from stem to stern to make sure it is not grounding out. ------------- Top Secret, I can tell you but then my wife will kill me.
Posted By: makaveliwi
Date Posted: February 27, 2004 at 10:06 PM
i checked all the conections, the speaker is not grounding out. i installed the amp and sub two days ago and it was working fine, today i turned the gain on the amp up a little and now it is acting funny. i turned the gain back down now. the sub stays on when the deck is at low volumes, but if you turn it up a little, then the sub starts cutting out. it is constantly cutting in and out.
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milwaukee walt
Posted By: forbidden
Date Posted: February 27, 2004 at 10:10 PM
Can you try a different sub on the amp? and double check the rca cable for groundouts as well. When the sub is cutting in and out, is the amp going on and off or in and out of protection?
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Top Secret, I can tell you but then my wife will kill me.
Posted By: makaveliwi
Date Posted: February 27, 2004 at 10:17 PM
i have a kenwood amp, it has a blue light on it, the light stays on constant while the stereo is on. the amp doesn't enter protection mode at all. my amp is rated at 800 watts and the sub is an MTX thunder 6000. the rcas are fosgate twisted pair, how do you check if the deck is giving an output through the rca jacks? i don't have another sub to test it with right now. the sub is pretty old, do you think that i possibly blew it?
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milwaukee walt
Posted By: forbidden
Date Posted: February 27, 2004 at 10:22 PM
It may have a flat spot on the voice coil, do you have a meter? Run a new temporary rca cable from the cdplayer to the amp overtop of the seats, it can be attached to the sub preout or the front / rear preout. By testing this way it will also check the output on the cd player.
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Top Secret, I can tell you but then my wife will kill me.
Posted By: makaveliwi
Date Posted: February 27, 2004 at 10:24 PM
i don't have meter until work tomorrow. thank you for your help. do you think that my problem is either the rca's or my sub?
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milwaukee walt
Posted By: makaveliwi
Date Posted: February 27, 2004 at 10:25 PM
what does flat spot mean?
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milwaukee walt
Posted By: forbidden
Date Posted: February 27, 2004 at 10:27 PM
A worn part on the voice coil that shorts out as the sub cone moves up and down, thus causing the sub to cut in and out. You might have a bad sub or a rca cable that is grounding out and maybe, just maybe a cold solder joint in the amp, this I doubt, it sure looks like the RCA or sub.
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Top Secret, I can tell you but then my wife will kill me.
Posted By: makaveliwi
Date Posted: February 27, 2004 at 10:33 PM
the amp is brand new two days ago. everything else is old. thank you again for your help. if the sub has a flat spot will the ohm check be any different? how can you tell by looking at it. will there be any spots or discolorations on the sub. Any recommendations for a new sub? ------------- milwaukee walt
Posted By: forbidden
Date Posted: February 27, 2004 at 10:43 PM
The ohm reading will vary on the sub as you physically push the cone in and out. Make sure the sub is disconnected from the amp to check it. If while you are pushing the sub in and out (gently) you get a reading of infinity or no reading, this is an indication of a flat spot on the voice coils and voice coil former. You will not be able to see it. There are lots of good subs on the market today, the magic is to match the new sub to the amp and the box that you have, so post up the box type and volume.
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Top Secret, I can tell you but then my wife will kill me.
Posted By: makaveliwi
Date Posted: February 27, 2004 at 10:49 PM
the box was custom built to fit in a truck, i am looking for a new box and sub(s) i have an 89 lesabre 4 door. i don't want to take up the whole trunk, but i want a lot of bass. ------------- milwaukee walt
Posted By: forbidden
Date Posted: February 27, 2004 at 10:50 PM
What is the model# of the amp?
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Top Secret, I can tell you but then my wife will kill me.
Posted By: makaveliwi
Date Posted: February 27, 2004 at 10:56 PM
KAC-7201<>wS('185','5') is the model number of the amp.
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milwaukee walt
Posted By: forbidden
Date Posted: February 27, 2004 at 11:03 PM
Well the bad news is that the amp does not make any where near the power that it claims, it is infact rated at 150 w rms x 2 at 4 ohm at 14.4 volts. The good news is that you still can get OK results out of this amp and then put in a monster down the road. Then this amp can be used to power a set of front speakers. To get loud, choose a pair of good 12" subs that work in a ported enclosure. An average size enclosure for two 12's ported is about 3 cubic feet, not that much loss of space in a trunk. Head out and find some subs that you like that are single 4 ohm voice coil rated up to 300 watts rms or find two dual 4 ohm voice coil subs rated about the same rms. Then we can work on box design. ------------- Top Secret, I can tell you but then my wife will kill me.
Posted By: makaveliwi
Date Posted: March 09, 2004 at 1:30 PM
i fixed the problem with my amp. the amp wasn't getting enough power, there was a voltage drop. i wasn't getting enough contact from the battery tap. i replaced the battery tap and it works fine now. thanks again, Walter ------------- milwaukee walt
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