sub not cranking fully

red_rocket · Post by **red_rocket** » Fri Jul 23, 2010 12:31 am

ok i need some advice so here is the low down.
in my rex i have front speakers running off my 4ch amp.
my back 2 run into where the front speakers used to be on the back of the deck(so i can fade it still but its just opposite)
i have now added a sub to the equation and took the wires straight from sub to deck(bridged them)
ok.
i only have one rca outlet in my deck...so i have added the rca adapter to give me another two upon the already 2 i have. so i can run all 4 channels...im pretty sure.
see pic below(the best i could get without taking the seat out again)

now the sub just doesnt seem to want to fully fire, some voice and minimal base is coming out of her but not what should be coming out.

anybody have any experiences with this? could it be that im trying to run 2 outputs on 1rca output(the adapter might be stuffing it up????)

any help is great, dont want to get ripped off by taking to audio place just yet

thanks

Mr Top Hat · Post by **Mr Top Hat** » Fri Jul 23, 2010 1:13 am

ok well im happy to help but i need to see a photo of the cross over settings for all channels

and i also need to know:

sub wattage, coil resistance, 1 voice coil or 2?
amp specs watts per channel, watts bridged, cable size being fed to it, fuse ratings on the amp

the one rca on the head unit what is the voltage?
and what is the line voltage limits for the amp? ie 200mv - 5V

Post by **Alex** » Fri Jul 23, 2010 9:59 am

you need to hit the LPF switch.

red_rocket · Post by **red_rocket** » Fri Jul 23, 2010 10:56 am

hey alex what is the lpf switch?
And mr top hat maybe i could swing around on sat and you could have a look for me. In exchange for beers or whatever your currency may be

Post by **Alex** » Fri Jul 23, 2010 11:05 am

for the rear speakers its proabably set to high pass, ie, it only lets the higher frequencys through. (good for running splits), then youll have a middle setting which is no filter usually, letting all the frequencys through. The low pass filter only allows lower frequencys through to the sub, which is what you want. on your amp it looks like its set high pass (HP) for your front speakers, which is correct. I cant see the switch for the rear channels which you have bridged to the sub. It needs to be set to low pass (LP) and a frequency of about 80hz is a good number. You may also need to crank up the gain abit.

best way is to get someone who knows what theyre looking at to tune it for you, but its all pretty easy to grasp once you know it haha.

there may also be settings in the deck which is preventing it from doing the correct thing for ya.

alex

red_rocket · Post by **red_rocket** » Fri Jul 23, 2010 12:13 pm

ok that makes sense. ill give that a crack and i think the rear is on hp also.
if no go after that i may take it to someone to check out. the deck is a pretty basic deck also so it has no sub control or anything

thanks mate

Post by **Alex** » Fri Jul 23, 2010 12:42 pm

if the rear is on HP, i'll bet my left nut thats what it is

alex

red_rocket · Post by **red_rocket** » Fri Jul 23, 2010 2:51 pm

um. Got it working.
Changed from hp to lp and adjusted the gain and freq down to around 80ish and she is now shaking the boot(which i dont really want but no it has some get up). Will just reduce the gain.
Thanks 4 the help and you get to keep your left nut since you win

Post by **Alex** » Mon Jul 26, 2010 12:36 pm

good stuff mate.