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#1
Posted to rec.audio.car
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problem with subwoofers thumping out of control!
I just replaced my 400w sub amp with a used 800w sub amp and I'm having
some wierd problems... First, the setup is the rear-output of the headunit running to the input of the amp (the amp does not have seperate rear/front inputs). From there I have the right-low output and left-low output running to the subs. The amp is set on low-pass with the crossover all the way over to the low end. When I have the amp powered on the subs just produce a steady pounding. It kind of sounds like the beat of house music at about 120-130BPM. It does not matter if the headunit is even plugged into the amp - it still thumps. I'm hoping the wiring in the amp isn't screwed up - can anyone think of anything that stands out as troubleshooting tips? |
#2
Posted to rec.audio.car
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problem with subwoofers thumping out of control!
It sounds like a phasing issue or some kind of feedback problem. Here are
some things to try, first and foremost, make sure your subs (you indicate more than one) are wired in-phase. If your subs are wired out of phase, it might DEFINITELY produce problems like you are describing. Also, try summing the left and right channels BEFORE they go into the amp. In other words, combine the left and right channels into one, then run that into the amp. Actually, most amps when you run them in bridged mode are designed to only accept one channel of input. But if yours does accept two inputs even in bridged mode, try running them in mono. Another thing to check is to make sure you have the amp bridged correctly. Not all amps bridge the same way. Some have switches that must be engaged while others do not (it's just how you wire it). DOUBLE CHECK YOUR WIRING. Check the manufacturer's instructions for bridging. MOSFET wrote in message oups.com... I just replaced my 400w sub amp with a used 800w sub amp and I'm having some wierd problems... First, the setup is the rear-output of the headunit running to the input of the amp (the amp does not have seperate rear/front inputs). From there I have the right-low output and left-low output running to the subs. The amp is set on low-pass with the crossover all the way over to the low end. When I have the amp powered on the subs just produce a steady pounding. It kind of sounds like the beat of house music at about 120-130BPM. It does not matter if the headunit is even plugged into the amp - it still thumps. I'm hoping the wiring in the amp isn't screwed up - can anyone think of anything that stands out as troubleshooting tips? |
#3
Posted to rec.audio.car
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problem with subwoofers thumping out of control!
it's a ground problem, there are a few possibilities, but the most common
would be a broken/loose ground pin on the amplifiers rca connector.. also possibly a burnt ground trace at either or both ends (amp or HU), or with luck, a poor ground to chassis which is yet to cause that damage.. you'd be real lucky for that one.. anyway, not an expensive fix generally no matter which.. wrote in message oups.com... I just replaced my 400w sub amp with a used 800w sub amp and I'm having some wierd problems... First, the setup is the rear-output of the headunit running to the input of the amp (the amp does not have seperate rear/front inputs). From there I have the right-low output and left-low output running to the subs. The amp is set on low-pass with the crossover all the way over to the low end. When I have the amp powered on the subs just produce a steady pounding. It kind of sounds like the beat of house music at about 120-130BPM. It does not matter if the headunit is even plugged into the amp - it still thumps. I'm hoping the wiring in the amp isn't screwed up - can anyone think of anything that stands out as troubleshooting tips? |
#4
Posted to rec.audio.car
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problem with subwoofers thumping out of control!
"Dark1" wrote in message . .. it's a ground problem, there are a few possibilities, but the most common would be a broken/loose ground pin on the amplifiers rca connector.. also possibly a burnt ground trace at either or both ends (amp or HU), or with luck, a poor ground to chassis which is yet to cause that damage.. you'd be real lucky for that one.. anyway, not an expensive fix generally no matter which.. apologies, I guess I skimmed over the "doesn't matter if the HU is plugged in to it or not" part.. well, first, don't plug it in as you could damage your HU, and that narrows it down pretty well to either a bad chassis ground, or a broken trace/connection in the amp... wrote in message oups.com... I just replaced my 400w sub amp with a used 800w sub amp and I'm having some wierd problems... First, the setup is the rear-output of the headunit running to the input of the amp (the amp does not have seperate rear/front inputs). From there I have the right-low output and left-low output running to the subs. The amp is set on low-pass with the crossover all the way over to the low end. When I have the amp powered on the subs just produce a steady pounding. It kind of sounds like the beat of house music at about 120-130BPM. It does not matter if the headunit is even plugged into the amp - it still thumps. I'm hoping the wiring in the amp isn't screwed up - can anyone think of anything that stands out as troubleshooting tips? |
#5
Posted to rec.audio.car
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problem with subwoofers thumping out of control!
I, too, failed to notice that the problem occurs whether the HU is plugged
in or not so obviously you can ignore my advice to sum the left and right channels. But I would double check to make sure that your subs are wired in phase (and wired correctly to the amp) and checking the grounds wouldn't hurt. But I agree it very well may be a problem with the amp such as a broken trace. MOSFET "Dark1" wrote in message .. . "Dark1" wrote in message . .. it's a ground problem, there are a few possibilities, but the most common would be a broken/loose ground pin on the amplifiers rca connector.. also possibly a burnt ground trace at either or both ends (amp or HU), or with luck, a poor ground to chassis which is yet to cause that damage.. you'd be real lucky for that one.. anyway, not an expensive fix generally no matter which.. apologies, I guess I skimmed over the "doesn't matter if the HU is plugged in to it or not" part.. well, first, don't plug it in as you could damage your HU, and that narrows it down pretty well to either a bad chassis ground, or a broken trace/connection in the amp... wrote in message oups.com... I just replaced my 400w sub amp with a used 800w sub amp and I'm having some wierd problems... First, the setup is the rear-output of the headunit running to the input of the amp (the amp does not have seperate rear/front inputs). From there I have the right-low output and left-low output running to the subs. The amp is set on low-pass with the crossover all the way over to the low end. When I have the amp powered on the subs just produce a steady pounding. It kind of sounds like the beat of house music at about 120-130BPM. It does not matter if the headunit is even plugged into the amp - it still thumps. I'm hoping the wiring in the amp isn't screwed up - can anyone think of anything that stands out as troubleshooting tips? |
#6
Posted to rec.audio.car
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problem with subwoofers thumping out of control!
thanks for the tips guys, I've done a bit more testing and this is what
I've found: I tried running the connection to the amp to each of the subs in the box (the box has connectors for each subwoofer individually) - I did it one at a time to make sure the problem happened with each speaker being plugged in alone. It did. If I plug both subs in together (a set of cables running to each speaker) - it produces the same problem. When I got the box I noticed the positive jack on one speaker, and the negative jack on another speaker were "unscrewed" - making it look like the last person to use the box had run one wire to each speaker and they were bridged internally. I gave this a try and had no luck - no sound was produced at all, not even the thumping. I'll double check all my grounds but I don't think that's a problem (unless it's a problem inside the amp itself) because when I hook my old amp back up and then plug in the new 2-speaker box, I have no problems and it sounds ok playing music. |
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