Hey, I installed my deck, amp, and sub today. The amp is an oldschool Crossfire 4 channel amp. I have RCAs going to channels 1/2 for my front speakers. The second set of RCAs is going to channels 3/4 for my sub (bridged). No rear speakers are installed, however I will install them within the next few days and wire them directly to the deck (no amp for rear). Little other tidbits of info that may help -Battery in trunk -amp under seat -wires under carpet -rca / power ran separate -400w 10" Audiobahn When I have the key on ACC mode, everything works as it should. However, when I turn the ignition on, I get a high pitch whine out of the speakers. If I start the car, the whine is still there but louder. The only way I can get it to go away is to hit the power button on the deck. Turning the volume up or down does not effect it at all....however when I get the music loud enough, it will drown out the whine. The whine seems to get "higher pitched" at faster engine speeds too. I've played with the wiring. The problem will go away if I unplug either the speaker or sub RCAs, but as soon as both are plugged in....it whines. I've tried bridged / single channel for the sub. I tried using the "sub out" jack on the back of the deck (I want to use two RCAs so I can bridge it).....I've switched the two RCA cables around (sub rca to speakers / speaker RCA to sub)......blah blah blah blah. There is no problems with the deck, it worked fine when I pulled it out of my other car a few weeks ago. Sub and amp came from the same car (however I only had the sub ran on it before). It seems that the only way I can get the whine to go away is to either have the radio off, the key off, or have one of the RCAs unplugged. Does anyone have any ideas? The system sounds like shit without the sub hooked up, so I really want to run sub + speakers.
If I had to guess, the feedback you're hearing is the alternator whine due to a poor ground. Where are you grounding the amp? If you want to see if it is the ground, try grounding the amp directly to the battery and see if the problem stops.
I'll try grounding it straight to the battery if I can find a cable long enough for it. I currently have it grounded under the passenger seat bracket since the amp is under that seat. Its a bare metal contact freshly sanded
So, if you unplug the sub RCA, there is no whine in the front speakers? I'm also confused on the bold text above, is there whine with just the key in ignition location without the car running, and then the whine gets worse when the car is actually running?
The whine is not present on the first key location. When you roll the key one more click to "on" (when all the dummy lights light up) it starts to whine. When you actually start and run the car, the whine is even louder. If I unplug either RCA the sound will stop. It doesn't matter if I have the sub or the speakers unplugged.
Well it's not alternator whine if you hear it when the engine isn't running I'm too spent to think on this tonight... I put some thought to it tomorrow. I would think the sub can't produce the whine, so it may still be there if you are unplugging the front speaker RCAs. Right now it confuses me as to why unplugging the sub RCA eliminates the sound in the front stage.
I've been told that the megasquirt system can add a lot of interference, however I've been careful to run all my wires away from the Megasquirt. I've heard alternator whines before and this sounds VERY similar, but like you said its kind of strange that it happens with the car off as well. Tomorrow I'm going to run new and better grounds for the amp and deck to see if that does anything. I really don't think it will since I have really good grounds already...but you never know
Try running a ground loop to from the deck to the amplifier so they are grounded to the same place. Doesn't seem like it would matter but I know a few guys that used this method and it worked well.... but none were running Megasquirt.
What is a ground loop? I was just outside tinkering with it. I've run different grounds, grounded everything together, removed the crossovers, ran the wires in different locations, and used better wire. Nothing I did worked. I know the quick and easy answer would be to get a new / better amp....but I would rather not fork over money for a new amp if I can get this one working correctly.
As with anything electronic, you have to approach problems systematically to remove the root cause of the problem. I would have your amp be the last thing you need to remove. I've got a couple amps you can borrow to rule your amp out as the root cause. (1) New Ground(s) (2) New RCAs (3) etc, etc. It may also be advisable to perform the "big 3" grounding upgrade or at the very least consider cleaning the ground from the battery to the chassis. I agree with Ryan that it is not an alternator whine if it is not happening when the motor is not running; however, you could be experiencing a short from a faulty RCA still.
changed ground locations, ran new wires, new rcas, etc if you don't mind, bring an amp with you to install day so I can pop one in and see if thats the problem....if i figure it out by then I'll let you know
Wirelessly posted (Mozilla/5.0 (Linux; U; Android 2.2; en-us; Sprint APA9292KT Build/FRF91) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1) How old are the rca cables? Have you tried to get another set of rca cables and just run them over the carpet and plug them in? Could be a cable grounding out our something inside of amp grounding out
Yeah I've tried running all new wires. I had a rats nest of speaker, power, rca, and ground wires over my seats and on top of the carpet last night. I think it may be the amp ):
Does it sound like it comes from only one side of the car? As in, could you swap the L/R channels to determine if it is one specific channel in the amp. Better yet, just plug only one channel in at a time and see if the noise is present. And regarding an extra amp, be happy to bring one to the install day.
Alex, I don't hear it out of the sub (probably because the sub won't play such a high pitch), but regardless of what channels I have my speakers on it whines. As soon as I take the sub out of the system its problem free. I may wind up running a seperate amp for my sub.
Also, if the amp is mounted to metal, you might to try and put something between the amp and the metal. EX-Make a wood plate to mount the amp onto. Also, completely separate the ground from the RCA and Speaker wire. David Navone helped me trace down some engine noise I was having in a previous car. The problem ended up being the ground wire overlapping the RCA cable. I even swaped amps to an Alpine and the noise went away...so I thought it was the amp....it turned out Alpine amps have a very good noise filter and ground loop isolator built in. Engine noise can be tricky but not impossible to fix.
Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_2_6 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8E200 Safari/6533.18.5) Good point Eddie.
Got tired of messing with it. tried all kinds of different wiring, amp locations, sub locations, etc. Slapped a filter on it and call it a day
Since we are all into this, which wire would be best to use with 15 inch sub, that is rated at 2500. will be pushed by 1000 amp.
Ground the RCA's themselves. Where they plug in there is external metal shielding (not the plug itself but the external sheilding you can see without unplugging). Loop some thin wire around the metal and ground to something. See if that helps. Many radios and amps have some internal grounding that can blow. I had that issue on the Subaru hence the redneckified ghetto wiring that was in that area. I didn't want to rip it all out as I was driving on the interstate and this whining started.....that was a quick fix and it worked.