# Music cuts out at high volume



## vooshhz (Apr 10, 2016)

Hello,

I recently did an audio upgrade in my car. Everything is working fine and sounding great but if i keep my volume at a high volume for 20 or more minutes it eventually cuts off. I tried to lower my amp setting (gains for front and rear) to 30% and still the problem continues. The amp gets very hot in 20 minutes of loud music, if i touch it for 1 second it almost feels like its gonna burn.

Im running:

*Alpine SPS 610C*
Impedence: 4 Ohms 
Max RMS Power Capacity: 80W
Peak Power Capacity: 240W

Kenwood Excelon KFC-XW1200F
4-ohm subwoofer
RMS Power Range (Watts) : 50-350
Peak Power Handling (Watts) : 1400 

MTX THUNDER75.4 400W RMS 4-Channel Class A/B Amplifier 

Kenwood DPX791BH - Headunit

My research on this website has lead me to believe either:

-The amp needs more breathing room (Its under my seat)
-The ground wire needs a new / better location 

Any other suggestions/information? Thanks a lot!


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## Weigel21 (Sep 8, 2014)

Proper breathing room may help, but the ground could very well be one of the bigger issues. 

what wiring are you using and where is the ground attached in the car? Was said location free of any/all paint and residue? How secure is the connection?


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## vooshhz (Apr 10, 2016)

Weigel21 said:


> Proper breathing room may help, but the ground could very well be one of the bigger issues.
> 
> what wiring are you using and where is the ground attached in the car? Was said location free of any/all paint and residue? How secure is the connection?


Sadly I cannot post links/pics until I have 5 posts. 

The groundwire was put on one of the bolts that holds the driver seat on the back. 

We did not try to remove any paint from the area, even though it looks pretty much paint free.

That is my next step. I'm going to remove the ground wire and then try to sand the area around it including the bolt/screw.

From reading my specs, do you think maybe my amp just can't handle the system I'm running?

It runs fine for long at volume 20 but if i put it at 24+ it'll stop playing the music.


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## Weigel21 (Sep 8, 2014)

Seat bolts tend to be poor choices for mounting ground wires. I'd suspect the amplifier doen't have a strong enough electrical connection through the ground connection for the amount of amperage/current it's pulling to try and produce the amount of output asked of it. 

While the location may look free of paint, are you 100% sure there's no primer there, it should look nice and shiny. 

What gauge wire are you using as is it pure copper, tinned copper or copper clad aluminum? 

Another possible area of concern, how is you EQ? Are you boosting excessively on any particular frequency, specifically lower frequencies?


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## Weigel21 (Sep 8, 2014)

Oh, and was the ground merely placed on the top of the seat bracket or was it placed under any carpet and directly on the body of the vehicle (which hasn't been specified yet)


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## vooshhz (Apr 10, 2016)

Weigel21 said:


> Oh, and was the ground merely placed on the top of the seat bracket or was it placed under any carpet and directly on the body of the vehicle (which hasn't been specified yet)


We unhooked the bolt, placed the ground and then bolted back on. There is carpet in the surroundings of the area. Im just trying to figure out a better place to mount. 

Also it is not shiny, the area which is in contact with the ground. I will buy sand paper and try to clean that area including the bolt itself. Hopefully this helps, otherwise I'll need another area to ground on.


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## vooshhz (Apr 10, 2016)

Weigel21 said:


> Seat bolts tend to be poor choices for mounting ground wires. I'd suspect the amplifier doen't have a strong enough electrical connection through the ground connection for the amount of amperage/current it's pulling to try and produce the amount of output asked of it.
> 
> While the location may look free of paint, are you 100% sure there's no primer there, it should look nice and shiny.
> 
> ...


Also I believe its a 4 gauge wire, same type of wire used to connect the battery to the amp. The color of the wire looks like its pure copper but I'm not sure, could be copper clad aluminum.

Here are some pictures:


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## jb4674 (Jan 29, 2015)

And this is why I've never been a fan of amps being mounted under a seat.

OP, What kind of car is it?
Is the amp new?
What are you using the amp for? (Please don't say you're running your subs out of that amp...)

IMO, the ground on the amp is fine. If the amp is playing for 20 minutes and then it shuts down, that tells me that it's overheating and has nothing to do with a bad ground. If you were hearing noise, then I would say there would be a ground problem but, your post didn't really say and you were focusing more on the heating issue. Again, a bad ground wouldn't cause your amp to overheat. 

Move the amp to the trunk and ensure that it's properly ventilated, or get a better amp.


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## vooshhz (Apr 10, 2016)

jb4674 said:


> And this is why I've never been a fan of amps being mounted under a seat.
> 
> OP, What kind of car is it?
> Is the amp new?
> ...


Hey man, it's a 2016 nissan 370z

I am running a sub through that amp. 
The amp is brand new, I've only used it for 3 days now.

I do hear very little "ssssss" noise when a song ends and a new song comes on, but very little yet still hearable.

I am actually going to move the amp to the back so hopefully it can release more heat. 

Do you recommend I just purchase a 2nd amp for the sub?


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## Weigel21 (Sep 8, 2014)

You're grounding through the threads of the bolt, thus an inadequate ground. The seat bracket is painted and the body of the vehicle looks to be coated in some sort of under body coating. Scratch that, it's the carpet, which again, is just further hindering the electrical ground connection. 

I can promise that a poor ground can cause an amplifier to build up heat, I've had it happen to me back in my younger days. 

Now is that to say the ground is the sole cause of the heat build up? No, but I'm sure it's playing a large part. 

HU has 4V preamps, amp support up to a 5V input. You "may" have the gains set a little high, no idea without testing. How was it you went about setting the gains? 

"I" see no issue with the amp being use to power a sub, in this case, it's 200RMS to a sub rated to handle 350RMS. Sure, more power would be nice, but no harm will come from such a setup if properly setup and tuned.


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## vooshhz (Apr 10, 2016)

Weigel21 said:


> You're grounding through the threads of the bolt, thus an inadequate ground. The seat bracket is painted and the body of the vehicle looks to be coated in some sort of under body coating.
> 
> I can promise that a poor ground can cause an amplifier to build up heat, I've had it happen to me back in my younger days.
> 
> ...


The gains were set by the person who installed it, although I've turned the rear gain (sub) to about 20% now while front (speakers) is about 50%.

Do you recommend me just trying to sand the coating off and reconnecting there or do you recommend I either find a new spot or drill one myself?


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## Weigel21 (Sep 8, 2014)

Go with a different grounding spot. In order to have that location work, you'd want to pull the seat out of the car, pull the trim, lift the carpet, scrape the area around the hole on the body of the car down to bare metal, clean it of any residue, place the ground wire's ring terminal against the body of the car and replace the carpet and seat. 

Gains sound improperly set, I mean half way is just too high unless they set the gain with the HU at low volume, in which case, you never should exceed the volume level used when setting the gain (which should have been the HU's maximum clean volume level or slightly lower). 

Nope, I'd move the amp to the trunk and do a more professional job, as the amp wasn't even mounted and the wires were a mess.


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## vooshhz (Apr 10, 2016)

Weigel21 said:


> Go with a different grounding spot. In order to have that location work, you'd want to pull the seat out of the car, pull the trim, lift the carpet, scrape the area around the hole on the body of the car down to bare metal, clean it of any residue, place the ground wire's ring terminal against the body of the car and replace the carpet and seat.
> 
> Gains sound improperly set, I mean half way is just too high unless they set the gain with the HU at low volume, in which case, you never should exceed the volume level used when setting the gain (which should have been the HU's maximum clean volume level or slightly lower).
> 
> Nope, I'd move the amp to the trunk and do a more professional job, as the amp wasn't even mounted and the wires were a mess.


Thanks for your help. Really appreciate it.

Im gonna try to set the gains as low as possible, see if that helps me.

I'll have to wait a few week before I can pay a proper place to fix all the **** ups. I'll just have them rewire the whole thing down the center, right now its through the sides, bringing the amp to the trunk rather than under my seat. 

They charge $60 an hour... I'm hoping they can do everything in 5-6 hours.. that doesn't sound so bad. 

Atleast that way if theres any problems I can take it back and have them fix it.


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## Weigel21 (Sep 8, 2014)

It's not difficult to run wire and mount an amp, just time consuming. I recommend you learn a little and do it yourself, you'll save a lot of cash, learn some things, and be able to have pride in knowing you did it and did it right. 

As for setting gains, one can set them by ear with the aid of test tones quite effectively. 

Using test tones to set amplifier gain

https://www.youtube.com/watch?v=WhrDqke8BKo


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## vooshhz (Apr 10, 2016)

Okay I'll use that website and video to set my levels again.

For a few weeks if I keep my volume to medium and keep the gains where theyre supposed to be, I shouldn't be worried about damaging my amp correct?


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## Weigel21 (Sep 8, 2014)

I'd still be concerned about that ground myself, as I believe it's likely to be at the root of your issues.


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## vooshhz (Apr 10, 2016)

Weigel21 said:


> I'd still be concerned about that ground myself, as I believe it's likely to be at the root of your issues.


After relocating the amp and rewiring (making it much more neater) I will probably have a new ground spot... Hopefully somewhere in the trunk/hatch.


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## vooshhz (Apr 10, 2016)

Hi guys,

after some more research and asking around, someone told me this:

"I think I see your problem. Your tweeters are bypassing the crossover, they need to be ran to the crossover as well as the woofer. New wire should always be ran but in your case what might need to happen is, Run new wire from the amp directly to the crossover. You can use the stock wires that are going to your speakers but make sure they are going to the crossover. Sounds like your tweeters and woofers are running in parallel and putting a 2 ohm load on your channels instead of 4 ohms."

Could someone possibly explain what he means... I don't really understand the 2ohms / 4ohms stuff. Thank you!!


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## Weigel21 (Sep 8, 2014)

I have a set of those speakers waiting to be installed in my car (and have been waiting for a couple years already LOL). They DO NOT have external crossovers like many older component setups, instead, the tweeters have an inline capacitor acting as a high pass filter and the tweeters are to be wired to the woofers, so yes, they are wired in parallel, but since they are playing different frequencies, they don't drop the impedance to 2 ohms, it's a 4 ohm final, at least DC resistance. When wired up and playing, the impedance will continuously change and likely rarely drop to 4 ohms or lower.

Ever address the ground? Any changes if so?


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