alright here's the deal
i have a installed JL components and added a sub all running of stock h/u. it performs pretty well, except for when there's a heavy bass note my amp cuts out but when i
restart it works fine again, what could be causing this??
also there's this annoying alternator whine when engine is running, how can i get rid of it??
How do you have the sub amp hooked up?
Second is ground loop, lemme find my sticky...
Weebel wrote:Im to smart to go to strip clubs.
Are all the problems revolving around the sub amp?
Sounds to me like a poor ground. Ground your amp with <4ft of wire, same or bigger than your power wire and grounded to bare metal. Not seat bolts, not strut bolts.
I've been seeing a lot of posts lately about engine noise, so I figured I'd write something up to put everything together that I've learned throughout the years on how to eliminate it.
A ground loop is the most common type of noise. It is a difference of resistance between your source and your amplifier. Easiest way to tell is if you get a hum while the car is running, and it increases in pitch when you rev it.
First things's first. The ground wires to everything. Check and make sure you have a clean solid ground from your battery to the body of the car, as well as a good solid clean ground from your battery to your engine. Almost all cars have rubber motor mounts, hence the two grounding locations. Test the grounds with a multimeter set to ohms. Put the one end of the meter at the one end, then the opposite lead of the meter at the other end of the wire. Which side you put the leads on doesn't matter. Anything less than 4 ohms is generally acceptable, but the lower the better. My grounds all have a .3 ohms or less resistance.
After you check that, we start troubleshooting the inside components. If you have a pioneer deck, they're notorious for blowing the pico fuse. ground the outer RCAs to the body of the radio. This will usually remove all the noise.
Start with each component to troubleshoot if you do indeed have a noisy component. Take a cheap pair of rcas and cut one of the ends off. strip and twist the two wires together. This will make you a muting plug. Fire up your car, turn the radio on, and plug in the muting plug directly into the amp. Check all of the channels of the amp. If there's noise from the speakers, then the problem is with your amplifier. Check the grounds for the amp, and if that doesn't cure it, replace the amplifier.
Next check any signal processors/line drivers/equalizers. Use your muting plug on the input of the device, never the output, unless you want a paperweight. If you do have noise coming from one of these components, take the ground of it and run it to the exact location of the ground for your amplifier. If you have no noise from these, we go on to the next step.
Pull your radio out. If you're using the factory ground, take a run of 12 gauge wire right back to the ground where the amplifer is grounded to. Better yet, if you can, run the wire right into the terminal of the amplifier. Upgrade your power wire as well, and be sure to fuse it.
To test if it's a bad radio or not - try another radio (duh) or use an mp3 player and plug it into either your eq/processor/driver or if those don't exist right into the amp. You can also hook up your head unit to a battery or a jump pack that isn't connected to your existing electrical system. If there's noise, then it's a bad unit. If not, keep reading.
Check and make sure your rcas aren't close to power wires. Check and make sure your speaker wires aren't sitting on long runs of power wire either.
The last thing that it could be is your alternator. Alternators make, by their nature, AC voltage. There's diodes or a rectifier inside of an alternator to change the AC into DC current. If your diodes are going bad, then this will then introduce noise. Get your alternator tested.
After all of this, and you still have noise, the next recourse is a ground loop isolator. It removes the DC noise from the outer shell. Be sure to get an isolator that uses transformers. The cheaper isolators will remove your midbass.
This should cover absolutely everything that you can check for your ground loop. I saw there's one floating around on the internet, but it was missing a few things.
Weebel wrote:Im to smart to go to strip clubs.
i have turned down the sensitivity on the sub channel and it looks like that resolved the issue with amp cutting out (temporarily at least).
but the freakin ground loop noise i still there.
it's f'ing terrorizing me, especially at higher rpms.. now, i have my amp grounded to a seat holding bolt, underneath that plate.. yeah not the best place for it i know, but i really don't want to drill holes right where my gas tank is (my amp is mounted on the back of rear passenger seat).. so where can i possibly ground it? i mean if i drill a hole in trunk and bolt it down, how will the bolt hold? would i need some kind of screwing bracket inserted to where the bolt goes?? i am really pissed with this noise, lanman, brad help me out!!
how big is your power wire to the amp? When you are hammering on the system, check voltage, AT the amp, not at the battery. And make sure you don't have the amp wired below manufactures recommendation on impedance.
lanman, nice write up mang!
like Brandon said check your voltage to the amp. Also What amp and sub are you running. If you are overloading your amp and have just cranked the gain up to compensate for the low output you are likely straining your amp, and pushing it into protection mode. Below I have inserted a guide to tuning an amp that was stickied in this forum. Use the guide to tune your amp so you arent overloading it. Pushing an amp past it's capabilities will send unstable signal to your woofer causing it to clip. You don't want that. If it's not loud enough for your after you tune it then upgrade your system.
FAQ Sticky wrote:Tuning your amps
The simplest and easiest way to get your amps tuned is to follow these simple instructions. Grab your digital multimeter and a calculator.
output = square root (watts * ohms)
First, take your amp's wattage at load. For example, let's say your amp does 300 watts rms at 4 ohm. That would be 1200. Take the square root of that and you'll get 34.64101615137755, so let's say 34.64. Take your multimeter and set it to AC volts. Disconnect your speakers from the amplifier. Grab this file here - http://www.realmofexcursion.com/audio/testtones/20Hz_to_120Hz.mp3 - and burn it to a cd. Turn your eq's off, turn your volume to 3/4 of the way up, hook up your multimeter to the + and - of the speaker outputs and play the sine wave. Your peak voltage should hit at the beginning of the cd - adjust your gain till it reads the voltage you figured out earlier, then leave it. Hook your speakers back up, and your gain is set. Don't turn your volume up above this volume or else you'll clip.
the funny thing is that the noise was already there prior to the install, on stock setup, it's just was much weaker.
well i checked the amp's ground and it's at 0.3 ohms so it's not that. also i turned the gains down and it helped quite the noise down a little, but it's still there.
i checked all my wiring and isolation and there's no violations there.
i guess there's only 1 thing left for me to do and that is ground the h/u to the chassis or better yet to where the amp is, or maybe even replace my stock deck.
i don't know what else to do......
