Subs intermittently sound bad

[Nerdles1]

Running pac audio AP4-FD31 to JL rd 1500 to 2 jl13.5 subs all was good for years. Took to dealer for oil change and told them I had some noise sometimes at low speed in left front tire could be bearing. Any how came back from dealer seemed like my subs were cutting out and sounding like garbage occasionally. The amp stayed on while this was happening. Figured maybe amp was blowing I replaced the amp seemed ok for a hour or so and then acted up again. I thought maybe pac ap4 could be bad swapped it out for another still same result. Could my speakers be blowing or slightly blown? Any way to test them? All is good at times and then acts up. Anyway back to something the dealer said that doesn’t make sense they said I have 2 positives running to my sub output and that could be what is making the noise I’m hearing in the wheel. Why would they say that?1. Subs are not connected to stock speaker wires. 2. They would not touch anything aftermarket. 3. How would they even test that and why?
I think they had some fun turning up the volume blew my crap up and then said that to cover their ass. Thinking about putting my subs in my wife’s truck to test them and see if it does the same.

 

[HighwaySentinel]

Definitely suspect that they are giving you information on your sub outputs when you asked them to fix a noise in your front wheel area.

To test your subs, grab your multimeter and watch this video. Useful info begins around the 1:30 mark.

 

[Nerdles1]

Thanks didn’t realize was so simple. Gonna test tomorrow. Thinking they heard the wind up feedback when you just start the truck cause my gains are set a little to high. Anyhow I’m in an amp I didn’t need may be able to return. I’m hoping I don’t have an input problem from the head unit. If it’s bad there’s no way they would warranty with aftermarket setup.

 

[SoundsGoodStereo]

Make sure you check your ground/power connections at the battery. If you used the rear wall for ground, the glue joints could have released enough to cause these issues. If you haven't already, run the ground to the battery. Also, make sure the power/ground of your PAC uses those connections and not the factory power/ground. If ground is good, then the dealership might have got carried away with your system and blew the subwoofers.

 

[Shane361]

How do you know your gains are set too high? FYI a gain is not a volume knob. Litterally the biggest misconception in mobile audio. There is one spot that gain is suppose to be...just one. I have a DD1 and an Oscope to set mine and I like the 50.00 Oscope better. First you need to understand where your head unit clips or distorts at. My 2020 Raptor is at 37..so with the volume at 36 and my bass knob at 100% I tune my gain knob just before clipping.

 

[Nerdles1]

Yep I agree just hadn’t spent the time setting it correctly. The highest volume I could physically take was at 25 but still didn’t clip out or distort. Had it set lower before so volume went higher also no engine noise at start up(mainly on 4 channel amp). I also made the mistake with the sub amp of not setting it at max right before it clipped. I listen to all kinds of music and Van Halen lets you crank up the bass without clipping compared to Kanye songs. So someone other than me could turn the knob up and do some damage to system. Also thanks for the tip SGS and yes I have a straight run to the battery can’t remember how I supplied the ground to pac but I will check. Everything has been perfect till I got it back from dealer so just bummed I might be buying another set of 700 a piece speakers again