Jaime-TA-84

iTrader: (1)

Ive had this problem now for a long time but I just got fed up with it.

When my 4 channel amplifier (Infinity 7541a) is on, it always emits random, constant static noise that seems to change in volume slightly in my rear left speaker. Once I turn up the volume it is not as noticeable, but when the volume is turned down, you can hear it crackling and hissing. Also, the rear left speaker pops loudly. At first I thought it was random, but yesterday I increased the motor RPMs while it was popping and the pops also seemed to speed up.

Why would it be doing this? At first I thought the rear left speaker channel of my amplifier was failing, but when I noticed the pops speed up when I increased the RPM, it made me think again.

Jeff91RS

iTrader: (1)

first test u should do is switch the rca from a known good channel to the one that is causing problems. if the problem stays with that speaker u know the problem is with the amplifier, speaker, or the wiring inbetween. if the problem moves to the speaker u swapped the rca with it narrows it down to the rca's or the radio.

if the problem stays with the rear left you can switch the speaker wire outputs on the amp. if the problem stays with the same speaker its either the wiring or the speaker. if it moves to the speaker u swapped then its the amp. in which case it may still be repairable so take it to a shop.

so the rear left is making noise still and its down to the wire or the speaker. so at this point u have to pull the speaker and hook another speaker up and if new speaker sounds good then u need new speakers. if the new one sounds bad then run new wire.

ok back to if problem switched to a different speaker with the initial rca swap.
pull the radio and swap rca's on the back of the radio. if the sound stays in the same speaker its the rca's, in which case either repair, or replace, if the problem moves to a new speaker then you have a blown output on your radio. depending on how nice of a radio it is it may not be worth replacing.
another check on the rca's is to check if they are ran to close to some 12volt power source like the power wire for the amp or anyother wiring. if it is move it atleast 10 inches away.

and of course through all of this check for good connections. i apologize if this seemed like a extremely over explained but i wanted to make sure i covered everything

Jaime-TA-84

iTrader: (1)

Thanks for the thorough reply I'm going to do all the tests you mentioned tomorrow and i'll post the results. It's a Pioneer DEH-P4800MP head unit so I'll get a new one if its bad.

Jeff91RS

iTrader: (1)

thats the radio i put in my gfs sunfire. decent radio i just dont like having to flip down the faceplate to insert a cd. i hope its a wire or a speaker. good luck

Jaime-TA-84

iTrader: (1)

I think the problem got worse. I had not noticed what I heard today before. When I turned on the amp and head unit, at very low volume, everything seemed OK, but as soon as I raised up the volume, the sound would start to garble/jumble/mix/distort. Eventually I turned up the volume even higher and then it stopped having the problem. I went for a drive and even shut off the car for about 20 minutes and the problem didnt occur again. I didnt notice the popping noises today, but the hissing/crackling was still there.

I disconnected both front and rear RCA cables from the amp and the hissing/crackling was still there on the left rear speaker. This leads me to believe the problem is in the actual amplifier or theres a problem with the speaker (and/or wiring), but I doubt the symptoms I've had are from a bad speaker.

Here is a video I recorded with my cell phone. Hopefully the audio is good enough so that you can hear what I described above:

http://www.youtube.com/watch?v=EGkObHI7-bc (I turned up the volume higher at around the 52 sec. mark and then everything was OK)

Jeff91RS

iTrader: (1)

u are probably right that the amp is bad, but wouldnt u feel like a fool if u dropped a couple hundred on a new amp and the problem still exhisted? just swap the speaker wire on the output of the amp just to clear out all other variables.

btw that sound is hellatious hopefully if its the amp it didnt dmg the spkr too

Jaime-TA-84

iTrader: (1)

I swapped the speaker cables and now the rear right speaker is popping so it is definitely the amp
I have the schematics so I'll probably open it up and try to troubleshoot it.

champnesupernva

it sounds to me like the rear left channel is getting a bad ground, or that channel's circuitry is messy. possibly it shook loose (if your amp is mounted to your sub box) or it just had a bad solder point.

you could also try regrounding the amp. maybe in a dif local in the car.

just what i could guess....im not an expert