weird sub problem

tisguy

New Member
okay, i probably should've posted this earlier and i think i know what the problem is, but i wanan get some input before i dump money into fixing it.
2 JL 10w6 hooked up into a Q-logic sealed enclosure.
powered by 600W phoenix gold amp and 1fd cap.

here's the problem, once i turn up the amp's sensitivity or the subwoofer setting on the deck, at low bass the sub will rumble. the right side continues to hit properly, but the left one will just vibrate and sound all distorted... kind of like a rapid farting sound.

i think the problem is the air volume in the enclosure (i've tried another same model sub and still resulted in the same problem).
 

TegSox

Super Duper Moderator
I seriously doubt it's a problem with the airspace. The problem is either the amp itself, or the signal, either from the deck to the amp or the amp to the sub. Here's some troubleshooting steps you can take to isolate the problem:
-Swap the RCA plugs, see if the problem goes from one sub to the other. If it does, you'll know the amp is OK, the probem is either in the deck or the RCA cables (they may be pinched and grounding out).
-If the problem doesn't move from one sub to the other, swap the sub wires. If the problem moves to the other sub, the amp is the problem.
-If you swap the RCA's and the sub wires back and forth, and the same sub keeps acting up, the sub is the problem. But it looks like you've ruled that out.

btw, how are your sub's wired? These troubleshooting steps will only work if their wired in stereo off the amp. Does each sub have its own terminal cup on the outside of the box, in other words. Or is there one terminal cup, and the 2 subs are wired to each other internally.
 

tisguy

New Member
from the fuse block 1-8ga leads to cap, then cap to amp. and 1-8ga from block to amp directly. the amp is a mono, and the subs are wired in parallel. the sub only starts acting up when the music demands for some hard hitting. but i'll try checking the rca's tomorrow.
 

TegSox

Super Duper Moderator
So your amp is bridged to 1 channel? Both subs are running off the same channel?
 


tisguy

New Member
yea, does that affect the performance? the amp had 2 outputs on it that said that it was already made parallel internally.
 

TegSox

Super Duper Moderator
Anytime you bridge an amp, it drops the impedance in half. The amp will put out twice the power, but it also will run hotter (and s/n ratio increases, but for subs that not an issue, you won't hear any difference). Amps have a minimum impedance they can tolerate, drop the impedance too low and you'll fry it.

But concerning the problem your having, none of that matters.
If both of your subs are recieving the same signal, and one sub is distorting at high volume while the other is perfectly fine, then the problem has to be the sub.

What's your amps minimal impedance?
What's the impedance of your subs? single or dual voice coil?
 

tisguy

New Member
can someone explain to me how the resistance of the sub affects performance? right now both subs are wired in 1.5ohm (parallel-parallel), the other option makes it at 6ohms. does running at 1.5ohm going to blow the sub? just wonder, i'm planning to redo the wiring on the subs this weekend...
 

TegSox

Super Duper Moderator
tisguy said:
does running at 1.5ohm going to blow the sub?
Click to expand...
No, but it will blow your amp if it isn't made to operate at 1.5 ohms.

I tried opening that manual link, and my computer had a damn seizure trying to do it, I have dial up.

The only thing sub impedance affects is the amp. 2 ohm subs vs. 4 ohm sub vs. 6 or 8 ohms subs make no difference in how the sub will sound.
 

tisguy

New Member
cool. im gonna try to fix my sub problem tomorrow. some songs the bass sounds really clean, and then other songs the sub just goes nuts =T.
 

B18TEG

BLACK DA
check the settings on the amp as well. it could be that the sub is working outside of the range that the amp is set to. i had that problem once i adjusted the db level of the amp it never happened again.
 
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