Amp Tuned incorrectly??? JL sub BARELY hits...

[pssst]

I just finished a fiberglass box in my girlfriends Scion XB.

The XB is running the FACTORY head unit to a 12" JLW3 to an Alpine MRP-M650. Now in theory, this combo should hit pretty hard.

I had searched and found a few threads and sites on how to correctly tune your sub amp. After trying 3 separate instructions for tuning the amp, the sub is still VERY VERY quite. Finally I had the Gain practically all the way up, and still, the JL barely barely moves, even when I turn up the bass on the head unit EQ.

Since the XB has the stock head unit, I'm not sure if the Line-out converter has anything to do with it. I have done many installs before using a Line-out converter, and was able to get the car to hit extremely hard.

Now when I had this exact sub and amp in my 300 with an Alpine VMA-200 head unit plugged into the Sub RCAs, I had to have the Sub setting on head unit ALL the way up.

Only thing I can think is that the amp doesn't have the power to push the sub, which I find hard to beleive.

Can it be that the STOCK head unit doe not have the power??? I have no idea. I have used LOCs before on STOCK stereos in numerous vehicles and have had excellent results.

So if anyone can give me some insight, that would be great. Again the equitment I'm running is:

-Stock head unit with Line-out converter

-12" JLW3 sub

-Alpine MRP-M650 amp

Thanks

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[tc3k101 5,000+ posts]

how big of a box? u check to see what the voltage you are getting out of ur loc?

im running a loc right now and my ish gets decently loud

 

[bean burrito 10+ year member]

try turning the lows up on the cd player. I had to do this with a focus one time.

 

[tc3k101 5,000+ posts]

try turning the lows up on the cd player. I had to do this with a focus one time.

you are endofdays lol:crap:

 

[bean burrito 10+ year member]

you are endofdays lol:crap:

yeah, but i am being serious. i had to do it to a focus and a crx before, and it worked.

 

[pssst]

Not exactly sure the Cubic size of the box. I have not checked the voltage coming off the LOC, how exactly is that done??? I have a voltage meter.

Any other ideas of what might be wrong? Thanks for the replies

 

[tc3k101 5,000+ posts]

Not exactly sure the Cubic size of the box. I have not checked the voltage coming off the LOC, how exactly is that done??? I have a voltage meter.
Any other ideas of what might be wrong? Thanks for the replies

well ur box could be too small

 

[johnecon2001 5,000+ posts]

What type of box is it? Sealed or ported? I'd guess a bad LOC or you have your Front to Rear fader on one or the other.

I've run LOC's with stock Head units before and had no problems with minimal gain. Another option is to try a different amplifier. The Alpine could have an internal issue and just won't perform.

 

[gunz4me 10+ year member]

Make sure you didn't wire your LOC out of phase! An easy way to test this would be to set your balance full left or full right. If you have bass on full left or full right but it disappears when you center the balance, your LOC is wired out of phase.

I hate to break it to you, but JL Audio's recommendation for a sealed box is less than ideal for ultimate sub bass performance //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

ETA: You normally have to build your sealed box much bigger and it usually needs to be around the same size they recommend for a ported box. You don't even want to know how the ported box models in WinISD or Bass Box Pro.

 

[Fiercetimbo17 10+ year member]

Dont worry about the out of phase wiring, that being the only sub in the car nothing can be out of phase with it, depending on where you have it crossed.

But make sure the amp has he lowpass filter on and set to the 80ish range, gain is up, do whatever with bass boost, id leave it off but thats your call.

Next go to the headunit, if its a pioneer it might have a highpass filter setting that is not allowing the lower signal keeping you from getting anything from your LOC.

If those dont work its most likely a signal problem, where did you tap the LOC? If you tapped a signal for a speaker that has a highpass then that would be your problem.

Depending on the year XB you might even have RCA preouts on the back of the unit.

 

[gunz4me 10+ year member]

Dont worry about the out of phase wiring, that being the only sub in the car nothing can be out of phase with it, depending on where you have it crossed.

I beg to differ. If you wire your LOC out of phase between the left and right channel inputs and your amp utilizes both inputs, you will have problems due to cancellation! I once had a car delivered to me where the professional installer wired the LOC out of phase and I had NO sub bass output for a basic sub addon to the factory system. Hell, that is what got me back into working on my own cars again. Gotta love incompetent "professionals" that charge top dollar for half-*** work:verymad:

 

[m3dia_lab 10+ year member]

try tapping your loc to another set of speakers. in my mazda 3 i first had my sub LOC to my front speakers and i was not getting the low notes 35hz and below i would say.... hooked it up to the rear and bam! i was good to go

 

[pssst]

The enclosure is sealed. The LOC is wired correctly to the rear speakers, along with the RCAs to Left and Right. Just made sure everything was correct one more time. Anymore help would be great. Thanks

Here are a couple pictures of the install after I finished.