MYSTERY WHINE. So I have an Alpine 9000BT head unit that is wired in to the factory powers and grounds. I have good RCA's (I think) tsunami 4 channel twisted. I have an MTX 6001 that I'm using bridged for a 10" Solo Baric (old school round 2 OHM model).
And here is the issue I have a JL 300/4 with a alternator whine on the front Right Channel ONLY. It is grounded by 4GA wire to a bare metal contact on the Seat bolt.
In diagnosing this I am having trouble. I unplug the RCA's from the Amp and the noise goes away. I unplug the RCA from the Head Unit the noise goes away. Sounds like it's the head unit right? Well when I take an RCA from another (clean) channel say left front and plug it into the Amp's right front the same whine happens. So I tried hooking up my Sub through This channel with DIFFERENT RCA's and Same whine. It isn't in the speaker line because when I hooked up that Front Right speaker to the LF Channel of the amp it was fine.
I tried wiring the ground of the head unit to the Ground of the amps and still had a whine. I tried wiring the head unit Power directly to the Battery (both ACC and constant) and still whined.
Then when I gave up and wired everything back through the factory Harness and turned it back on it was SILENT. I turned it up and everything worked perfect. Until I turned it up more and started tuning….then the whine came back.
Any help you could give would be great. I’m at a loss.
And here is the issue I have a JL 300/4 with a alternator whine on the front Right Channel ONLY. It is grounded by 4GA wire to a bare metal contact on the Seat bolt.
In diagnosing this I am having trouble. I unplug the RCA's from the Amp and the noise goes away. I unplug the RCA from the Head Unit the noise goes away. Sounds like it's the head unit right? Well when I take an RCA from another (clean) channel say left front and plug it into the Amp's right front the same whine happens. So I tried hooking up my Sub through This channel with DIFFERENT RCA's and Same whine. It isn't in the speaker line because when I hooked up that Front Right speaker to the LF Channel of the amp it was fine.
I tried wiring the ground of the head unit to the Ground of the amps and still had a whine. I tried wiring the head unit Power directly to the Battery (both ACC and constant) and still whined.
Then when I gave up and wired everything back through the factory Harness and turned it back on it was SILENT. I turned it up and everything worked perfect. Until I turned it up more and started tuning….then the whine came back.
Any help you could give would be great. I’m at a loss.
Try connecting a speaker (not mounted to the vehicle) with a short length of wire to the noisy channel. Is it still noisy?
Using different channels doesn't always work because sometimes the signal line is the positive terminal and sometimes it's the negative speaker terminal. If the wire is pinched somewhere, moving it to a different channel may mask the problem.
Using different channels doesn't always work because sometimes the signal line is the positive terminal and sometimes it's the negative speaker terminal. If the wire is pinched somewhere, moving it to a different channel may mask the problem.
How close is the earth to the RCA input? Have seen that cause issues like these, also I would just try a different earth altogether-while you've sanded the seat bolt back the bulk of the contact area for the bolt will be painted and not a good earth.
Tried it
I tried moving the amplifier ground. I cut a hole in the carpet ground off the paint and tried that. It's still there.
Also my RCA's are about 2 feet away from the ground.
I am thinking of throwing in the towel. On this. Just to see what happens I hooked up that front right speaker to the head unit internal amp (14 watts RMS). It's only very slightly less clear than the others and I had to adjust the gain down on the amplifier a bit. It still sounds good.
I'm going to leave everything open for a couple days and I'll try anything anyone can think of.
Oh and I tried grounding the RCA's at the amp and behind the deck today. I did only test that with the offending channel. Do I have go ground them all? I also tried running a ground (18gauge ) out the door directly to the frame under the truck for both the head unit and Amp.
Thanks for the input and I'll try anything but im out of ideas.
I tried moving the amplifier ground. I cut a hole in the carpet ground off the paint and tried that. It's still there.
Also my RCA's are about 2 feet away from the ground.
I am thinking of throwing in the towel. On this. Just to see what happens I hooked up that front right speaker to the head unit internal amp (14 watts RMS). It's only very slightly less clear than the others and I had to adjust the gain down on the amplifier a bit. It still sounds good.
I'm going to leave everything open for a couple days and I'll try anything anyone can think of.
Oh and I tried grounding the RCA's at the amp and behind the deck today. I did only test that with the offending channel. Do I have go ground them all? I also tried running a ground (18gauge ) out the door directly to the frame under the truck for both the head unit and Amp.
Thanks for the input and I'll try anything but im out of ideas.
Hey Dander!! my theory in this is that you have to have a single point of ground for the whole system. If that require that you run an 8 AWG ground wire to your head unit from the amp's ground then so be it... Run RCA's out of the truck and see if noise enters this way. There's an oldschool method to see if your 300/4 (I have one myself) is the offending one: Make an RCA mute plug, that is, go to your local radioshack and get some cheapo RCA plugs (4) short ground and center pin on all 4, connect them to your amp and turn the gain all the way up with the truck running... If the amp is silent under this test, then the amp is fine and the noise is entering through the signalchain or the head unit.. test with a voltmeter if none of your speaker wires are grounded (hook em together and test with ground), unlikely but possible...
IMO, grounding RCA's to the head or the amp will only make things worse...
IMO, grounding RCA's to the head or the amp will only make things worse...
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