Worked fine, now it doesnt. HELP ME PLEASE

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Nicoter0

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Hello, i would like to just say right off of the bat.. i know a little but not nearly enough to diagnose this situation, so bear with me while i try to explain it the best that i can.

So here it is:

I have an mrv-f300 alpine amp (literally brand new, exchanged under MFG warrenty today, but problem apparently lies elsewhere.) which powers my four speakers (three speakers, the one is blown and i am sending it in to alpine as it was a defect not caused by me). They push 50 watts per channel running 2 ohm resistance.

Everything has been working fine from 6/18/13 (date of install) until a few days ago. Nothing new was put in, and nothing was changed before it started acting up.

The amp was shutting off (turning into protected mode with a red light), and i figured it was the ground, because it also lose audio quality before it turned itself off (usually 5-8 minutes at volume over half). I redid the ground to the point where it is bare metal to bare metal on a screw in the trunk (i scraped the coating). It can not move and will not unless unscrewed. The wires from the back of the stereo were spliced, as it is a stock head unit in a 2009 Chevy Cobalt LS XFE.

The autotechnician that i had install my system swapped the amp out today to try and see if it was perhaps a bad amp. Since then, the amp has went into protected mode only twice, but it cuts out at varius intervals for a few seconds (longest about 15) every few minutes (can be a couple times a minute to as little as once or twice every ten minutes). The fuses look okay, and i know it isnt my alternator/battery, or remote wire (the subwoofers and speaker amp share the same remote), as the subwoofers stay powered and slamming regardless. I have also not had any issues with power loss to the car.

The fuses seem to be okay, and i redid the remote wire (just the end connections, i havent been behind the radio to check those yet) so that it spliced two wires from the main wire (the one running with the speed cable from the front to the back). The subwoofers stay on, but after i did this i saw that (one time) when the amp cut off, the blue light flashed three times. Everyother time the amp has cut out, it has not lost the blue signal light, or it has gone into protected mode (red light) which in turn made me have to turn the car off and on again.

To recap, my subwoofers are fine, and use the same remote wire as the speaker amp.

My speaker amp is brand new, and is having the same issues as the one which it replaced.

The ground wire is as connected to bare metal as physically possible, and only runs three feet (kicker wiring kit from bestbuy is what all of my wires are)

The power wires have no corrosion, and none of the fuses look blown.

I am at a loss, and so is my coworker who installed it (professional install technician)

He is going to take a look at it tomorrow, and see what he can deduce, but in the meantime i would really love some possible thoughts from all of the experts out here! i figure somebody may have had the same issue at one point.

and keep in mind, i listed above as well as i could what all has been happening, but if you see that i am doing something majorly wrong, please inform me politely because i am a complete novice at this, but would love to become an expert one day!

thanks

Donny

 
Use a multimeter and test resistance on all your speakers. Make sure they are all reading within spec. Make sure you don't have a pinch in the wire somewhere between the amp and speakers, I've seen it happen way too many times.

 
8 gauge wire for all ground/power. one power to sub amp, one power to speaker amp, same with the grounds to the trunk.

The speaker has been blown since before the original install date, and the system in general worked fine other than that one speaker.

And i will have him check the multimeter tomorrow, i do not have one and he knows what he is doing more than i do.

and the amp for the speakers mrv-f300 running 50 watts per channel, three channels being used out of four

the amp for the subs is an mrp-450 if i remember correctly. i didnt purchase it, but intead received it from a friend.

 
I'd be running 4 gauge at the very least to the back if I was you for both of those amps, insufficient wiring will cause amps to run hot and can drop voltage too low, both of which are NEVER good for ANY amp(s)

 
on the amp, there is a switch to set it at 2 or 4 ohm. 4 ohm results in 75 watts a channel, but as my speakers are only rated 2 ohms thats what its turned to. As far as how they are wired.. im a little shaky on the terminology, but i mean the outputs from the radio are plugged into the terminals one by one (pairs being front left neg/pos, front right neg/pos, rr neg/pos, rl neg/pos) the speaker wire output is a connector that plugged into the amp that came with the amp, which is then (im pretty sure he spliced) spliced into the inputs for the actual speakers.

sorry if that was confusing. essentially it goes radio to amp in pairs (8 wires 8 terminals)

then amp to speakers all out one plug that goes directly into the opposite side of the amp, where the gain and switches for whatever other things are

and ill talk to him tomorrow about upgrading the wiring gauge if he thinks that might be the major issue, payday is friday so itd have to wait until then :p

EDIT: thanks to NIHL8ION for pointing out that it isnt a switch to switch the impedance load. Im just that kinda rookie lol :p yeah so disregard the aforementioned if you could

 
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on the amp, there is a switch to set it at 2 or 4 ohm. 4 ohm results in 75 watts a channel, but as my speakers are only rated 2 ohms thats what its turned to. As far as how they are wired.. im a little shaky on the terminology, but i mean the outputs from the radio are plugged into the terminals one by one (pairs being front left neg/pos, front right neg/pos, rr neg/pos, rl neg/pos) the speaker wire output is a connector that plugged into the amp that came with the amp, which is then (im pretty sure he spliced) spliced into the inputs for the actual speakers.
sorry if that was confusing. essentially it goes radio to amp in pairs (8 wires 8 terminals)

then amp to speakers all out one plug that goes directly into the opposite side of the amp, where the gain and switches for whatever other things are

and ill talk to him tomorrow about upgrading the wiring gauge if he thinks that might be the major issue, payday is friday so itd have to wait until then :p
- LOL that "switch" you are referring to is NOT to switch impedence! The amp sees whatever load you CONNECT to it, you can't change that by flipping a switch!
 
lol sorry >.

He set all of that up, and i didnt touch any of it, i just figured that was what it was..

with that in mind, i have absolutely no idea how the amp knows that the speakers are functioning at two ohm not four..

anyone have an explanation?

edit:

dang im dumb, you just said it just sees it. okay lol i guess thats how it knows, but yeah i havent messed with any of those switches or knobs, no idea what they do and i would break it more

 
That switch is more than likely to use "2" channels or the full "4" channels of inputs for the amp... In other words, it can have 1 set (left & right = 2 channels) of RCA's or high level speaker inputs to run all 4 channels, or 2 sets (left & right + left & right ~ Front & rear = 4 channels) of RCA or high level speaker inputs for all 4 channels giving you full fader / balance control from your source...

 
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Yeah, these are listed as 3ohms nominal and that is why you see the 2.7ohm rating (where they can drop to). There are a number of things wrong...
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Ouch, you are right! So I won't burn anything? This is great news!
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Nicoter0

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