12w3 poppy noise when turn up gain

[ThunderOne 10+ year member]

I have a JL 12w3 and an Alpine MRP-M50 300 watt amp. When I turn the gain up past 50% I get this weird poppy sound from the sub. My friend said my box was too big but I am pretty sure it's smaller than the sealed specs that JL recommends. This sub can handle up to 500 watts. The box doesn't have any leaks. Is there anything else I can look for? If I turn it to about 40% the popping goes away but it's only getting minimum RMS wattage.

Box is 27" length, 12.5" tall, bottom depth 12", top depth 8.5"

Thanks

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[AnthonyO 10+ year member]

Your recommended enclosure by JL is 1.195 before speaker displacement and 1.125 after displacement. You are sitting at approximately 1.35^cu.ft after displacement. So your box is a little big. That popping sound could be the sub bottoming out due to the enclosure being too big. Its hard to say over the internet without seeing and hearing it in person.

 

[ThunderOne 10+ year member]

What can I do to make the box smaller? I am a box noob, I bought mine.

 

[pickup1 5,000+ posts]

How old is the sub?

 

[ThunderOne 10+ year member]

About two months.

 

[ThunderOne 10+ year member]

If I cut the width down to 23 inches that will put me right where I need to be. Any suggestions on if that's a good idea and how to go about cutting it?

 

[AnthonyO 10+ year member]

You can add mass to the interior of the box. By building a 7"x7"x7" cube and and sealing it to the internal of the enclosure should bring the net volume down to 1.15^cu.ft after displacement. Someone correct me if I am wrong.

 

[ThunderOne 10+ year member]

I just figured it would be more straightforward to just cut some of each side off. Or is that a bad idea?

 

[cdc351jeferson 10+ year member]

Subwoofer Enclosure Calculators, Fraction to Decimal, Parallel, Series, Port Length and Volume Calculators

 

[AnthonyO 10+ year member]

I just figured it would be more straightforward to just cut some of each side off. Or is that a bad idea?

Not a bad idea. But if its carpeted and you don't wanna cut it up, thats why I posted the other method.

Also if you cut it down to 23 it WOULD be the perfect size according to JL.

 

[ThatChevyGuy 5,000+ posts]

dont turn your gain up either, its not a volume knob

 

[ThunderOne 10+ year member]

Not a bad idea. But if its carpeted and you don't wanna cut it up, thats why I posted the other method.
Also if you cut it down to 23 it WOULD be the perfect size according to JL.

I don't mind redoing the carpet, I just have to figure out how to cleanly cut it and make it look all pretty again. The wood is recessed on the sides by about a half inch.

 

[Wingman0121 10+ year member]

Well is the popping sound a mechanical noise? Look at the woofer when it's doing that, it may be bottoming out.

If that's the case then you need a smaller box and/or a lower tuning frequency, and back off the gain a bit.

btw the easiest way to reduce the internal volume of a box is to add pre-measured bags of sand, much easier than trying to cut the box and redo it.

 

[psych0ticnemes1 5,000+ posts]

Set your gain properly and go from there.

 

[2012ScionTC 10+ year member]

Easier test, take the speaker out and just add a board inside to cut down the internal vol... Piece of 2x4 or a MDF board should do nicely. I seriously doubt it's the size of your enclosure. I had a 10W3, look on JL's website for it's optimal recommend RMS power range, 300 Watts. 500+ is in the red. Don't be concerned about turning the gain up past 1/2, the gain is used to match the signal input to the amp and speaker. If your setting the gain too high then that is the cause of the popping noise. I now have a 10W6 and a JL 500/1 and my gain is set just past the 1/2 mark conservatively. If I go up too high on the gain I get into clipping, distortion, delayed bass, Loose and boomy on some frequencies, better to be safe and not damage your equipment. If your not getting enough bass then look at possibly going to a ported enclosure custom tuned, high end sub, more power... I ran my 10w3 in a ported enclosure before getting the 10W6 and it was excellent... but upgrading to the 10W6 with the custom ported enclosure was big improvement!