Amp Overheating/Cutting out

[Swafflife]

I have a two amp setup in my boat. One mono block for a 10" sub and one 4 channel that runs 8 speakers (4 in cabin and 4 wake tower all 6"). I noticed my 4 channel amp was cutting out when I turned up the volume while under way so we can hear the music over the wind/motor/water noise. After checking the amps, I noticed the one cutting out was overheating (in protection mode). So a couple things: I'm curious what could cause the amp to overheat and...I noticed the same thing happens when the amp is cool to the touch. It bears mentioning a few things: I did not install this system, and the two amps share a power wire (amp 1 power connects to amp 2 power cable through a distribution block and then a fuse block and then to the battery). I'm in a 21' runabout stern drive. Thanks for any insight.

 

[Brandon5778]

Maybe I can help. 2 things that come to mind when an amp goes into protection mode are overheating and bad grounds. You say it overheated, but also say sometimes is cool to the touch? Can you clarify here, so it is hot sometimes when it cuts out but cool other times? That's odd.. You have 8 speakers on a 4ch amp, which makes me think might be too much. Wired in parallel its probably a 2 ohm load and after cranking it up is too much for your amp to handle. And check your ground for sure.

Another question, how big is your power wire? And about how long can you play music before it goes into protection mode?

It's definitely not good on the amp to keep running it into protection mode, it will only last so long doing this, trust me. You'll want to get it worked out.

 

[Swafflife]

Thanks Brandon. What I was trying to say was that, at a certain volume, the amp will cut out whether it's hot or I've just turned everything on and the amp is cool. There is a 4 AWG power wire from the 4 channel amp to the distribution block where the 8 AWG power wire from the sub amp comes in and then it's 4 AWG to the fuse block and to the battery. Currently, the ground for the 4 channel amp is grounded to the negative post on one of the house batteries.

 

[gm280]

An amp that cuts out, even when cool to the touch, isn't needing a better heat sink. It needs better current source. It sounds (pun not intended) like you are trying to drive the amp to the point of not being able to supply the speakers with the limited current provided. So clean up ALL connections and make absolutely certain you have the current needed to drive the circuits. And the bass frequencies will take the majority of the current to drive them to the sound level you want. JMHO

 

[dingbat]

A failing voice coil or a bad wire connection will also pull down an amp. Check the speaker cables for short circuits, cuts, breaks. If the cables are OK, check speaker impedance with a multi meter as the speaker itself might have a short or damaged coil.

 

[dizzy1]

Has it done this always or just started? How many batteries? Wiring sounds fine for what your running. I assume they inside boat speakers are wired in parallel as 2 ohm load on channels 1+2 while the tower is in parallel as 2 ohms on channels 3+4. Since occurs while just turning on and amp is cool, try to unplug the RCAs on the sub amp. Then turn it up and see if it still cuts out. Wondering if your battery voltage is dropping from both amps turned up and causing it to go into protection. Turning the sub off to see if it happens will eliminate or narrow down the problem. If still does it, sounds like your amp is going bad since only at high volumes which means the input is clipping hard or the output is sensing lower than 2 ohm ratings, all signs the amp is about to go. What brand is the amp and what type of speakers?

 

[Swafflife]

Thanks for the feedback....I've had the issue since I purchased the boat used. System was installed by previous owner. I've undertaken several projects since getting the boat. I installed 3 new batteries (1 start, 2 house) Optima blue tops and also a Blue Sea add-a-battery switch with an ACR. That led to the replacement of the alternator recently. My next step is to redo both amp power wires so they have their own power, fuses and grounds. The 4 channel amp is a Polk PA660 and the sub amp is a Polk PA880 with the in-boat speakers being 6" JL audio and the tower being 6" Polk. I will also chase down the speaker wires to check for any issues.

 

[Brandon5778]

It sounds (pun not intended) like you are trying to drive the amp to the point of not being able to supply the speakers with the limited current provided.

+1 to this, exactly what I'm thinking too.