New guy, strange issue

[sn98gt]

Hey guys. I just did some upgrades to the sound system in my 2001 dodge ram diesel to modernize it a bit but I'm having some weird issues with the amps and or subs. Head unit is a kenwood ddx774, I have 2 alpine mrv-m550's feeding two 10" alpine type s subs wired to 2ohms (verified with an ohm meter). I've ran 0 gauge power wire from the battery to a distribution block back by the amps which then splits off to 4 gauge to feed each amp. Ground is setup the same way with two 4 gauge wires into a dist block and 0 gauge running from there direct to the frame on my truck. The issue I'm having is the system runs great most of the time but every so often the sub output goes down (only the subs, the other 4 speakers stay at the same output), the subs are still running and they aren't distorted or doing anything weird they just sound like someone turned the gain down, amps aren't going into protection mode or getting hot. Now the weird thing... If I hit the power window switch for either of my windows, the sound level comes right back. I figured it had to be a ground issue (even though the spot I used tested as a good ground) so I moved my ground from the truck cab body, and ran it direct to the frame. I thought that took care of it because it didn't happen for a few days but today on my way into work it did it again. I've gone over all of the wiring multiple times and tested what I can but I'm lost and need some pointers as to what to look at next.

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[LosIsATool 5,000+ posts]

Rewire the sub amps. Something is grounding out somewhere

 

[sn98gt]

Rewire the sub amps. Something is grounding out somewhere

Amps and all of the wiring are laid out and secured on mdf, only wiring not on the wood is the main power wire and ground and neither of them are grounding out.

 

[sn98gt]

Could I possibly have a bad amp that's grounding out internally? I'd think that'd throw the amp into protect mode but maybe not? Again its very random that it does this and not very often. I have a 45-60 min commute to and from work and it may do it once on the round trip. But by the time I pull over or get home its no longer doing it.

 

[evilmonstertruk Premium Member]

Amps and all of the wiring are laid out and secured on mdf, only wiring not on the wood is the main power wire and ground and neither of them are grounding out.

Can you ditch the ground distro for testing and do two grounds to the same bolt.
It also could be behind the radio, something touching or loose

Sent from my LG-H910 using Tapatalk

 

[sn98gt]

I can. I was thinking of disconnecting one sub and amp also to try and isolate the issue. I have my inputs ran through one amp to the other right now so I'd assume if the one amp is a problem it could be passing it on to the 2nd.

 

[evilmonstertruk Premium Member]

Do you monitor voltage? If so is that ok?

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[evilmonstertruk Premium Member]

Oh yea... I had a issue like yours, window changing the way it sounds. But mine was the door lock. Turned out to be a bad rca on the amp

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[sn98gt]

Voltage is staying pretty constant, around 12.5 volts. How did you diagnose the rca issue?

 

[LosIsATool 5,000+ posts]

Voltage is staying pretty constant, around 12.5 volts. How did you diagnose the rca issue?

12.5 isn't good.

 

[sn98gt]

12.5 isn't good.

What should I be seeing at the amp then? My reading varies from 12.5 to 13v with the truck at idle.

 

[wew lad 5,000+ posts]

12.5 isn't good.

12.5v isnt even close to protect, nor is it a discernible difference in output unless alpines threshold (doubt its a feature for the entry level amps, you'll see it on pdx models) is at a measly 12v but it might be. look at the manual and see if they have the system in place that cuts output when voltage drops.

you're sure 12.5 is your lowest voltage at the amplifier input terminals when the output drops?

What should I be seeing at the amp then? My reading varies from 12.5 to 13v with the truck at idle.

woah woah i thought that was loaded down. you should be seeing alternator output voltages at idle (14-15v). i doubt dodge has a computer voltage regulated alternator in 01. most vehicles added it 06-07+

 

[sn98gt]

I'm not sure about when the output drops. It's so random that I haven't been able to replicate it when trying to diagnose it.

 

[sn98gt]

woah woah i thought that was loaded down. you should be seeing alternator output voltages at idle (14-15v). i doubt dodge has a computer voltage regulated alternator in 01. most vehicles added it 06-07+

my trucks system puts out around 13.5v at idle, 14-14.5 at rpm at the alternator which is where the specs say it should be.

 

[wew lad 5,000+ posts]

my trucks system puts out around 13.5v at idle, 14-14.5 at rpm at the alternator which is where the specs say it should be.

what alternator does your truck come with stock?