Can someone please tell me why my Subs sound like a$$

Systems

i recently put in 2 mm120 subs in a sealed box. Each sub has a JL 500/1 amp hooked up to it. It is getting plenty of power and i thought that it would knock my socks off....
instead, i am very dissapointed that it sounds like ****.. the bass is very weak and if turned up too much, they just distort and make some sort of internal flapping sound...
i dont know if its because they havnt been broken in yet, but im sure it shouldnt make that much of a difference. and im not going to have my car on for 30 hrs just to break in the subs.

Please help... i really had a lot of pride and faith in these subs before i installed it. But the two subs can barely hit 100db. i think i can scream louder then them....

if i can get direction as to what is goign on w/ them, i would appreciate it. Thanks everyone.

PoweredByDodge

well dude.... i dunno.... but, i'm thinkin any of the following...

1 - the amps - i know the jl 500.1's are regulated and they also match impedance loads -- so they'll put out their rated power at any impedance... but is that matching simply for 2 ohms or less or is it all the way up to 4? if its not, then you may only be getting 250 watts per sub instead of 500... also, check your gains (although you've probably done that already).

2- head unit - what is your preamp output voltage rated at... if you dont have at least a 2 volt preamp output to each amp, you may be in trouble (two 2 volt outputs or a single 4 volt split to 2 amps would be fine... if you've got that, then this is not the problem).

3- power cable - you need at least a 4 gauge line for each of those amps... or a single 2 gauge line split to the two of them, thinner wire would mean they amps may be "starved" for power.

4- box size -- a momo 12 sealed needs 0.88 cubic feet per sub -- anything from 0.75 stuffed w/ polyfill to 1 cube should be allright. anything bigger or smaller will cause trouble.

5- phase -- if both amps are hooked up that the + of the amp goes to the + on the woofer and the - amp to the - woofer, make sure that this is so, and that one of them is not + to - instead of + to +... if they are both as they should be, then try to switch one of them and see what happens... once in a great while, something odd happens and people actually have to run woofers out of phase to get the "right" sound. its rare but it does happen.

6- leaks in the box -- if you're box is not bulletproof airtight, then you're going to have trouble. even the slightest air leak can cause havok.

7- defective speakers - the first wave of momo 10's and 12's let go on the market this past year had a problem with the glue on the surround... it was defective and caused the speakers to "flap" or "****", and just in general sound and perform like crap -- they were recalled by polk corporation and new subs with the problem "fixed" were sent out.

other than that, i can't think of anything off hand other than the direction of the speakers... where / how you point them is very important... if they're in a trunk, point them toward the rear of the car and push them as far forward as posisble in the trunk... in a cabin (like in a truck or suv) downfiring is usually best and "fool proof"...if you dont downfire you will have to experiment with forard, backward, left, right, or straight up -- believe it or not the same two subs firing up or forward in my truck sounded like crap... but when you downfire / rear fire them they sounded VASTLY better. many others have had the same experience with their gear.

good luck dude

Systems

WEll i have them facing forward torwads the cabin so that might be a problem. But they also distort at high volumes so i dont understand that. I assumed it might be the box, but the cubic volume is about right but maybe its leaking cause its been used w/ other subs.
they are running 4 gauge wire and my headunit is the pioneer avx-p7300 dvd, so i dont believe thats the problem.
JL amps are digital w/ internal crossover or something lik that so they feed 500w rms from 1.5ohm-4ohm.
neg. is in the neg. and pos. is in the pos.
they arnt the new mm12 w/ the yellow momo.. but i bought them 8 months ago and installed them 1 month ago... does anythign happen to them from sitting unused for too long....


how can i break in my subs outside my car.. like take them out and plug them into a wall power source and home stereo system to bump them for a few hours... is this possible?
thanks


oh yeah.. i dont have my seriel number for them so i cant join! are they on the subs or what? i dont have my reciepts or anything anymore...

Systems

How are your gains set. Sounds too me they are not set properly and thats why your getting the noise at louder volumes. Also..what bass enhancers do you have enabled?

1) WHAT volume is the box per sub? You cant just guess and expect great bass... a box good for brand "X" sub may not bee good for brand "Y" sub
Are the subs single chambered..or each have thier own?

2) any leaks comming from the box itself will cause poor perfomance from the sub.

3) Check to see what your xover is set too..etc... on the amps. and they should be identicle.

Couple things to check out

Systems

How are your gains set. Sounds too me they are not set properly and thats why your getting the noise at louder volumes. Also..what bass enhancers do you have enabled?

1) WHAT volume is the box per sub? You cant just guess and expect great bass... a box good for brand "X" sub may not bee good for brand "Y" sub
Are the subs single chambered..or each have thier own?

2) any leaks comming from the box itself will cause poor perfomance from the sub.

3) Check to see what your xover is set too..etc... on the amps. and they should be identicle.

Couple things to check out