a friend of mine recently bought JL audios 500/1 amp and a custom box with two 8" JL subs (each in seperate enclosure) fired upward into a bandpass enclosure (box fills the trunk pit). the dual coils are in series (8 ohms per sub) and the speaker terminals are in parallel (4 ohm load altogether). it's $800 of stereo just for the low end,500 watts RMS at one channel seems like more than enough,the box is very thick,it wieghs around 85 lbs with subs. for some reason it still sounds distorted and everytime I get it to sound good,it deteriorates and needs to be re-adjusted as if the speakers are fatigued . this is all hooked up to an alpine head unit with 4v rca's. it seems as if most of the bass is artificially recreated from the subs,it just "thumps" and sounds the same and hurts my ears,in other words : it sounds as if it were bought from K-mart! should this guy,return the JL stuff or keep the amp and change the subs/box setup? the polk ex 6x9s are in boxes and don't sound that good either,those are powered by an alpine V12 75x2rms (great amp) this car had better all around sound quality and bass response with the kenwood 6x9s in the trunk cover (using the trunk pit as a resonant cabinet) powered by just the V12 amp,all we want is more bass without compromising sound quality.......this can be done right?
I'm disapointed in myself,I've always been happy with my installs,I'd like to blame this on the equipment
thanks for putting up with my bitch'n,any suggestions??

 

it is more likely the box is not designed right for the subs. jl is known for very nice sounding subbass. my 10w6 sound tight and hit very hard. also your amp could be way out of adjustment. jl amps have many eq freatured built in and you could have it tuned wrong.
what is your x over on the amp set at?
bass boost?
q boost and center freq?

 

It sounds like the subs might be wired wrong. Are you sure they are wired properly?

I would try wiring each sub's dual coils as a parallel load onto each channel of the amp. This way, you would get 2 -- 2Ohm loads on the amp (this is assuming the amp can handle this load)

I once had a dual 8" bandpass box wired up improperly (by accident of course) and because one speaker was wired out of phase, it made it sound horrible.

Just a thought .........

Good luck!

Thomas.

 

It also may be that the bandpass box is not designed for these subs. I'm the biggest fan of sealed boxes, so I never think that a bandpass box sounds good. Just my opinion though. I would also verify that the subs are wired correctly.

Chris

 

thanks,I'll check it out tomorrow. I might try to parallel the coils (2 ohm) then do those in series (4 ohms). even though it's 4 ohms now,the coils in series are 8 ohms. I'm not absolutly sure of this,but,two 2ohm loads might allow better current flow,therfore better bass response than two 8ohm loads.

I'll measure the enclosures,the box actually has three chambers,two sealed cabinets for the subs(side by side) and a larger bandpass section with a plexiglass plate & two 3"(approx.) ports over the subs.

I set the x-over to 80Hz
the Q all the way down
center freq. at 40Hz
bass boost is at 1/3 cw
the infrasonic filter is off
the input sens. is about half way
input voltage is set to "low"

thans for the help,I'll post results on monday. thanks

 

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