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#1
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Amp ok until motor is started
I installed a subwoofer amp, at the moment I am using the high level input
on the amp. That means I'm running wires from left and right speakers to the amp input connector. So I have the rear speakers in parallel with the sub amp inputs. All works fine when the ignition is turned on, but when the motor is started one of two things happens. 1) The volume goes way down on the sub woofer. When #1 happens the rear speaker volume is also very low. 2) or the subwoofer starts a low frequency rumble. Once the car is started I can disconnect the subwoofer input then plug it back in and all works well again. What do you think could be the problem? Thanks, Mike |
#2
Posted to rec.audio.tech
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Amp ok until motor is started
"amdx" wrote in message ... I installed a subwoofer amp, at the moment I am using the high level input on the amp. That means I'm running wires from left and right speakers to the amp input connector. So I have the rear speakers in parallel with the sub amp inputs. All works fine when the ignition is turned on, but when the motor is started one of two things happens. 1) The volume goes way down on the sub woofer. When #1 happens the rear speaker volume is also very low. 2) or the subwoofer starts a low frequency rumble. Once the car is started I can disconnect the subwoofer input then plug it back in and all works well again. What do you think could be the problem? Thanks, Mike The sub amp is probably a big draw on the battery. When logic components, i.e. the IC's which control the subwoofer amp, get low voltage they can do weird weird things. Try wiring the power source direct to the battery with an in-line fuse on the (+), bypassing the car's electrical system entirely. Or, realize that it's an issue, and don't turn it on until the car is running. Or, buy a separate battery to run it and modify your charging system with a battery isolator to properly charge the two parallel batteries. |
#3
Posted to rec.audio.tech
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Amp ok until motor is started
"Dave" wrote in message news:kMDsj.21455$w57.3801@edtnps90... "amdx" wrote in message ... I installed a subwoofer amp, at the moment I am using the high level input on the amp. That means I'm running wires from left and right speakers to the amp input connector. So I have the rear speakers in parallel with the sub amp inputs. All works fine when the ignition is turned on, but when the motor is started one of two things happens. 1) The volume goes way down on the sub woofer. When #1 happens the rear speaker volume is also very low. 2) or the subwoofer starts a low frequency rumble. Once the car is started I can disconnect the subwoofer input then plug it back in and all works well again. What do you think could be the problem? Thanks, Mike The sub amp is probably a big draw on the battery. When logic components, i.e. the IC's which control the subwoofer amp, get low voltage they can do weird weird things. Try wiring the power source direct to the battery with an in-line fuse on the (+), bypassing the car's electrical system entirely. Or, realize that it's an issue, and don't turn it on until the car is running. Or, buy a separate battery to run it and modify your charging system with a battery isolator to properly charge the two parallel batteries. The amp is hardwired to the battery, It has a remote input that gets a signal from the radio when it it turned on. So even when starting the car then tuning on the radio that energizes the amp the problem occurs. Thanks, Mike |
#4
Posted to rec.audio.tech
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Amp ok until motor is started
"amdx" wrote ...
The amp is hardwired to the battery, It has a remote input that gets a signal from the radio when it it turned on. So even when starting the car then tuning on the radio that energizes the amp the problem occurs. But there are lots of different ways of "hardwiring". Specific discussion of where to attach, what guage of wire to use for the distance and current draw, those extra mega-capacitors they use, etc. are the things that are specifically discussed in car audio forums, and rarely here. You didn't even mention what the voltage supply at the amplifier is with the engine off vs. running (much less while cranking). If you can't put numbers to the problem, you could be chasing it around for months. |
#5
Posted to rec.audio.tech
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Amp ok until motor is started
On Tue, 12 Feb 2008 11:32:06 -0600, amdx wrote:
I installed a subwoofer amp, at the moment I am using the high level input on the amp. That means I'm running wires from left and right speakers to the amp input connector. So I have the rear speakers in parallel with the sub amp inputs. All works fine when the ignition is turned on, but when the motor is started one of two things happens. 1) The volume goes way down on the sub woofer. When #1 happens the rear speaker volume is also very low. 2) or the subwoofer starts a low frequency rumble. Once the car is started I can disconnect the subwoofer input then plug it back in and all works well again. What do you think could be the problem? Check the battery voltage at the amp between the amps + and - temrinals. You may have a bad ground to the trunk. Also check the control line with a meter. Try the RCA inputs of the sub w/ the line levels disconnnected -- drive it with a walkman/xpod and see what happens. That would let you isolate the problem from the signal inputs. |
#6
Posted to rec.audio.tech
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Amp ok until motor is started
In article ,
"amdx" wrote: I installed a subwoofer amp, at the moment I am using the high level input on the amp. That means I'm running wires from left and right speakers to the amp input connector. So I have the rear speakers in parallel with the sub amp inputs. All works fine when the ignition is turned on, but when the motor is started one of two things happens. 1) The volume goes way down on the sub woofer. When #1 happens the rear speaker volume is also very low. 2) or the subwoofer starts a low frequency rumble. Once the car is started I can disconnect the subwoofer input then plug it back in and all works well again. What do you think could be the problem? Thanks, Mike My guess is that you're engaging a crowbar or clamp protector on the sub's input. Case #1 would be both leads and case #2 would be one lead. When you crank your engine, your headunit and sub preamp might be running at completely different voltages for a moment. That could trigger input overload protection. It remaining in overload mode sounds like a total design screwup somewhere. See what happens if you put 4 Ohm resistors in line with all speaker leads to the sub. Most car audio equipment is crap because people want it cheap. -- I don't read Google's spam. Reply with another service. |
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