# Symptons of not enough power on sub?



## ImK'ed (Aug 12, 2013)

Hi im running a jl 900/5 in my car with w12gti sub in sealed 1 cubic foot enclosure with polyfill as per jbl spec. Most of the time it sounds brilliant but on some bass heavy music it sounds like the sub doesnt have enough power as it will sound loud then abit muddy if that makes sense, ive used -5db test tones to set gain on sub. Increasing volume doesnt make a difference i think the amp starts clipping if i turn it up more than few clicks above the volume i tuned at on hu


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## Bloodyjames (Dec 7, 2013)

Sadly, you are underpowering your sub. Considering you amp only produces 500(4ohm) watts and you sub requires 700(6ohm) watts. Keep in mind as well that sealed enclosures may require more power vs. ported.

My opinion, your sub will only clip when you want to demand more from it as you said so yourself. The lower the notes the more power required to drive them. You should upgrade your amps. Maybe a 4 channel and mono for the sub? Anything around 700-1000 watts should be enough for the sub.


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## syc0path (Jan 23, 2013)

What does the power supply voltage to the amp look like? If the amp can't get enough power from the car's electrical system, then it will clip before it reaches its real max output. It could be that the car can't keep up, the wiring needs to be upgraded, there are poor connections, etc. In such a case, adding a bigger amp won't fix the problem.

If the input voltage remains strong even under heavy bass, then check the voltage at the sub output. Does it appear to be clipping? It could be that the gains are set too high or that the bass freqs are boosted too much. Or it could be that the amp simply doesn't have enough power for your taste.

Another consideration is that this is a physical issue. Check the box for air leaks -- that could allow the cone to travel farther than it should. Panels of the box could slapping against each other. The box could be flexing. The dust cap, surround, or spider of the sub may be failing.


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## BlueAc (May 19, 2007)

syc0path said:


> What does the power supply voltage to the amp look like? If the amp can't get enough power from the car's electrical system, then it will clip before it reaches its real max output. It could be that the car can't keep up, the wiring needs to be upgraded, there are poor connections, etc. In such a case, adding a bigger amp won't fix the problem.
> 
> If the input voltage remains strong even under heavy bass, then check the voltage at the sub output. Does it appear to be clipping? It could be that the gains are set too high or that the bass freqs are boosted too much. Or it could be that the amp simply doesn't have enough power for your taste.
> 
> Another consideration is that this is a physical issue. Check the box for air leaks -- that could allow the cone to travel farther than it should. Panels of the box could slapping against each other. The box could be flexing. The dust cap, surround, or spider of the sub may be failing.



I agree... I called JL a while back because I thought I had a bad 900/5. After trouble shooting with the tech he advised me the problem could be my battery. He said it's common for the sub channel to clip or not even power up when the voltage was low. I knew my battery was already bad but didnt think it would cause just the sub channel to clip. I got a new battery and haven't had that problem. 


Sent from my iPhone using Tapatalk


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## ImK'ed (Aug 12, 2013)

I'll do some voltage measurements at amp this weekend. I do think that it is the lack of power though, i thought i could be happy with 500rms but not happening!


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## qwertydude (Dec 22, 2008)

It's also that the WGTi just doesn't do all that well sealed, Sure you could use it but I can guarantee you it will sound a lot better in the spec ported box. Pretty much everyone on here who owns one and went from sealed to ported say the difference is night and day and the output greatly increases in the deeper bass registers. To the point where you could try getting a 2000 watt amp and still run sealed or just run a ported box and your 500 watts. The output would be almost the same.


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## ImK'ed (Aug 12, 2013)

Hmmm think i should build a ported enclosure then


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## Bloodyjames (Dec 7, 2013)

What car do you have this system in if I may ask?


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## ImK'ed (Aug 12, 2013)

Civic 3 door hatch


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## Bloodyjames (Dec 7, 2013)

Then it is most likely the lack of power from your car like syc0path mentioned. Civics carry small alternators. About 80 amps if am correct.

Best check those voltage drops. Have you done the big 3?


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