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#1
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Possible amp repair? Please help...
Hello,
I have a rockford fosgate 800a4, 100x4 @ 4 ohms, 200x4 @ 2ohms. When using the RCA inputs to the amplifier, the amp sends a horrible high pitched squeel to my full range speakers, even with the car's engine off. When using the high level inputs on the amp, the noise goes away. Using another amp I had around and a test speaker, I have determined that the problem is not the head unit, noise coming into the RCA's, nor noise coming into the speaker wires. I have also tested the ground by moving it, and it does not appear to be the problem either. The sound is not noticable with subs hooked up, as they can't play that high of a noise. The amp has been in storage (cold garage) for the past two months. The last car I had it hooked up in, the amp made some noise with the engine on (alternator whine), but never with the engine off. After my testing, I believe the problem is in the amp itself. So, does any one with some electronics background know what the problem might be? Ball park estimate of what a repair might cost me? I read some posts by a guy called ampdoc, what do you think? I can continue using the high level inputs for now, it sounds pretty good, but this is not ideal. Any info is very appreciated. Thanks, Ben |
#2
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Possible amp repair? Please help...
ampdoc is very nice to deal with and very reasonable pricing give him a
call. He has his phone number in his signature. He has another amp of mine right now. "Ben Rakestraw" wrote in message news:wabPb.91187$5V2.212729@attbi_s53... Hello, I have a rockford fosgate 800a4, 100x4 @ 4 ohms, 200x4 @ 2ohms. When using the RCA inputs to the amplifier, the amp sends a horrible high pitched squeel to my full range speakers, even with the car's engine off. When using the high level inputs on the amp, the noise goes away. Using another amp I had around and a test speaker, I have determined that the problem is not the head unit, noise coming into the RCA's, nor noise coming into the speaker wires. I have also tested the ground by moving it, and it does not appear to be the problem either. The sound is not noticable with subs hooked up, as they can't play that high of a noise. The amp has been in storage (cold garage) for the past two months. The last car I had it hooked up in, the amp made some noise with the engine on (alternator whine), but never with the engine off. After my testing, I believe the problem is in the amp itself. So, does any one with some electronics background know what the problem might be? Ball park estimate of what a repair might cost me? I read some posts by a guy called ampdoc, what do you think? I can continue using the high level inputs for now, it sounds pretty good, but this is not ideal. Any info is very appreciated. Thanks, Ben |
#3
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Possible amp repair? Please help...
Spend the $40 to have it professionally installed.
"Ben Rakestraw" wrote in message news:wabPb.91187$5V2.212729@attbi_s53... Hello, I have a rockford fosgate 800a4, 100x4 @ 4 ohms, 200x4 @ 2ohms. When using the RCA inputs to the amplifier, the amp sends a horrible high pitched squeel to my full range speakers, even with the car's engine off. When using the high level inputs on the amp, the noise goes away. Using another amp I had around and a test speaker, I have determined that the problem is not the head unit, noise coming into the RCA's, nor noise coming into the speaker wires. I have also tested the ground by moving it, and it does not appear to be the problem either. The sound is not noticable with subs hooked up, as they can't play that high of a noise. The amp has been in storage (cold garage) for the past two months. The last car I had it hooked up in, the amp made some noise with the engine on (alternator whine), but never with the engine off. After my testing, I believe the problem is in the amp itself. So, does any one with some electronics background know what the problem might be? Ball park estimate of what a repair might cost me? I read some posts by a guy called ampdoc, what do you think? I can continue using the high level inputs for now, it sounds pretty good, but this is not ideal. Any info is very appreciated. Thanks, Ben |
#4
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Possible amp repair? Please help...
It sounds as if the ground pins of your RCA jacks have broken loose from the
PC board in the amp. It shouldn't be a problem to repair, you could do it yourself if you feel comfortable taking the amp apart & are good at soldering. Try GENTLY applying pressure to the RCA's with the amp on and see if the noise goes away. If you don't feel comfortable fixing it yourself, feel free to send it to us. We call with an estimate before we fix it. -- Jammy Harbin J & J Electronics, Inc 227 S. 4Th St. Selmer, TN 38375 731-645-3311 "Ben Rakestraw" wrote in message news:wabPb.91187$5V2.212729@attbi_s53... Hello, I have a rockford fosgate 800a4, 100x4 @ 4 ohms, 200x4 @ 2ohms. When using the RCA inputs to the amplifier, the amp sends a horrible high pitched squeel to my full range speakers, even with the car's engine off. When using the high level inputs on the amp, the noise goes away. Using another amp I had around and a test speaker, I have determined that the problem is not the head unit, noise coming into the RCA's, nor noise coming into the speaker wires. I have also tested the ground by moving it, and it does not appear to be the problem either. The sound is not noticable with subs hooked up, as they can't play that high of a noise. The amp has been in storage (cold garage) for the past two months. The last car I had it hooked up in, the amp made some noise with the engine on (alternator whine), but never with the engine off. After my testing, I believe the problem is in the amp itself. So, does any one with some electronics background know what the problem might be? Ball park estimate of what a repair might cost me? I read some posts by a guy called ampdoc, what do you think? I can continue using the high level inputs for now, it sounds pretty good, but this is not ideal. Any info is very appreciated. Thanks, Ben |
#5
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Possible amp repair? Please help...
Tell me o wise one, what might a 'professional' do that I have not? I
thought this group was supposed to be helpful. Anyone else have some constructive insight? Ben "Mark Zarella" wrote in message ... Spend the $40 to have it professionally installed. "Ben Rakestraw" wrote in message news:wabPb.91187$5V2.212729@attbi_s53... Hello, I have a rockford fosgate 800a4, 100x4 @ 4 ohms, 200x4 @ 2ohms. When using the RCA inputs to the amplifier, the amp sends a horrible high pitched squeel to my full range speakers, even with the car's engine off. When using the high level inputs on the amp, the noise goes away. Using another amp I had around and a test speaker, I have determined that the problem is not the head unit, noise coming into the RCA's, nor noise coming into the speaker wires. I have also tested the ground by moving it, and it does not appear to be the problem either. The sound is not noticable with subs hooked up, as they can't play that high of a noise. The amp has been in storage (cold garage) for the past two months. The last car I had it hooked up in, the amp made some noise with the engine on (alternator whine), but never with the engine off. After my testing, I believe the problem is in the amp itself. So, does any one with some electronics background know what the problem might be? Ball park estimate of what a repair might cost me? I read some posts by a guy called ampdoc, what do you think? I can continue using the high level inputs for now, it sounds pretty good, but this is not ideal. Any info is very appreciated. Thanks, Ben |
#6
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Possible amp repair? Please help...
Tell me o wise one, what might a 'professional' do that I have not? I
thought this group was supposed to be helpful. Anyone else have some constructive insight? Ok then don't. Just keep in mind which one of us is in here asking newbie questions. I hear your question all the damned time, and 95% of the time it turns out to be solvable by an experienced installer. Oh yeah, did you try messing with your HU ground? Probably not... |
#7
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Possible amp repair? Please help...
No, I did not try messing with the head unit ground, thank you for
suggesting it. What about the head unit ground would make the noise thru RCA's but not hi-level inputs, even when the engine is off? A ground loop? As I said in my first post, any info is appreciated. This group is full of DIY'ers. If you are that experienced, please use it to help us, not disrespect our newbie questions (which btw, I have seen far more basic and obvious questions answered in this group). Ben "Mark Zarella" wrote in message ... Tell me o wise one, what might a 'professional' do that I have not? I thought this group was supposed to be helpful. Anyone else have some constructive insight? Ok then don't. Just keep in mind which one of us is in here asking newbie questions. I hear your question all the damned time, and 95% of the time it turns out to be solvable by an experienced installer. Oh yeah, did you try messing with your HU ground? Probably not... |
#8
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Possible amp repair? Please help...
No, I did not try messing with the head unit ground, thank you for
suggesting it. What about the head unit ground would make the noise thru RCA's but not hi-level inputs, even when the engine is off? A ground loop? As I said in my first post, any info is appreciated. Ground loops are funny sometimes. The addition of the RCA's could actually cause the ground loop, your HU could be attempting to use those as a ground. Or you could have bad RCAs with a break in the cable somewhere. Try the HU ground and try a different set of cables. Pay attention to the results of each and then in combination, that way if it doesn't work you can tell us what exactly happened. Les |
#9
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Possible amp repair? Please help...
No, I did not try messing with the head unit ground, thank you for
suggesting it. What about the head unit ground would make the noise thru RCA's but not hi-level inputs, even when the engine is off? A ground loop? As I said in my first post, any info is appreciated. This group is full of DIY'ers. If you are that experienced, please use it to help us, not disrespect our newbie questions (which btw, I have seen far more basic and obvious questions answered in this group). I gave you my best recommendation. You rejected it. Instead, I'll suggest that you make sure that the problem is with the amplifier first by trying a different low-level source. A portable cd or mp3 player perhaps? Although the evidence so far points to the amp, you need to explore all avenues first as most repair shops charge you just to look at an amp. |
#10
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Possible amp repair? Please help...
I think he's assuming the cables are fine because the other amp worked with
it. Not an unreasonable assumption. But I've seen stranger things happen. It's not at all uncommon to get noise out of a perfecty working amplifier or signal processor, even when plugging in another type gets rid of the noise. "Soundfreak03" wrote in message ... No, I did not try messing with the head unit ground, thank you for suggesting it. What about the head unit ground would make the noise thru RCA's but not hi-level inputs, even when the engine is off? A ground loop? As I said in my first post, any info is appreciated. Ground loops are funny sometimes. The addition of the RCA's could actually cause the ground loop, your HU could be attempting to use those as a ground. Or you could have bad RCAs with a break in the cable somewhere. Try the HU ground and try a different set of cables. Pay attention to the results of each and then in combination, that way if it doesn't work you can tell us what exactly happened. Les |
#11
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Possible amp repair? Please help...
Mark,
Why is it not uncommon to get noise out of a perfecty working amplifier or signal processor, even when plugging in another type gets rid of the noise? Thanks, Shane "Mark Zarella" wrote in message ... I think he's assuming the cables are fine because the other amp worked with it. Not an unreasonable assumption. But I've seen stranger things happen. It's not at all uncommon to get noise out of a perfecty working amplifier or signal processor, even when plugging in another type gets rid of the noise. "Soundfreak03" wrote in message ... No, I did not try messing with the head unit ground, thank you for suggesting it. What about the head unit ground would make the noise thru RCA's but not hi-level inputs, even when the engine is off? A ground loop? As I said in my first post, any info is appreciated. Ground loops are funny sometimes. The addition of the RCA's could actually cause the ground loop, your HU could be attempting to use those as a ground. Or you could have bad RCAs with a break in the cable somewhere. Try the HU ground and try a different set of cables. Pay attention to the results of each and then in combination, that way if it doesn't work you can tell us what exactly happened. Les |
#12
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Possible amp repair? Please help...
Why is it not uncommon to get noise out of a perfecty working amplifier or
signal processor, even when plugging in another type gets rid of the noise? Some pieces are more susceptible to ground loops and other types of noise sources than other pieces. |
#13
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Possible amp repair? Please help...
Ok Thanks!
"Mark Zarella" wrote in message ... Why is it not uncommon to get noise out of a perfecty working amplifier or signal processor, even when plugging in another type gets rid of the noise? Some pieces are more susceptible to ground loops and other types of noise sources than other pieces. |
#14
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Possible amp repair? Please help...
A portable cd player plugged into the amp resulted in no noise, so I guess
the amp is fine. Once I get time this weekend, I will play with the head unit ground. Do I have to ground the HU at the same point as the amp, or will a good ground up front suffice? couple random questions: Do the power lines to the HU sometimes give noise like a bad ground would? Do power filters, ground loop isolators, noise supressors, etc work? How? (I plan on fixing the real problem before trying one of these band-aids, but am just curious) Thanks for all the replies! Ben "Mark Zarella" wrote in message ... No, I did not try messing with the head unit ground, thank you for suggesting it. What about the head unit ground would make the noise thru RCA's but not hi-level inputs, even when the engine is off? A ground loop? As I said in my first post, any info is appreciated. This group is full of DIY'ers. If you are that experienced, please use it to help us, not disrespect our newbie questions (which btw, I have seen far more basic and obvious questions answered in this group). I gave you my best recommendation. You rejected it. Instead, I'll suggest that you make sure that the problem is with the amplifier first by trying a different low-level source. A portable cd or mp3 player perhaps? Although the evidence so far points to the amp, you need to explore all avenues first as most repair shops charge you just to look at an amp. |
#15
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Possible amp repair? Please help...
A portable cd player plugged into the amp resulted in no noise, so I guess
the amp is fine. Once I get time this weekend, I will play with the head unit ground. Do I have to ground the HU at the same point as the amp, or will a good ground up front suffice? No, just aim for a good ground. As you may have heard before, eliminating noise is more of an art than a science, so I wish you luck. Some cars and some equipment is more difficult than others. That's what I meant when I suggested you had a professional look at it. Not that you're incompetent or that you couldn't figure it out. But rather, it can be a real pain in the ass to finally figure out and they don't charge extra to do it. couple random questions: Do the power lines to the HU sometimes give noise like a bad ground would? No. Do power filters, ground loop isolators, noise supressors, etc work? How? They can. They work by isolating grounds. |
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