Hey guys, this is my first time posting here, but i've been a big fan of the site ever since i got my sentra a year ago. i got a custom made sealed sub box with two 12" subs from transparence and a rockford fosgate amp installed in my car just recently, powered by an alpine deck with the built in amp (to power the speakers). anyways, i bought the amp and sub together from a friend of mine who had it in his honda accord. it sounded out of this world in his car, your entire body vibrated from the inside and there was never any rattle at all. i want to recreate this effect in mine, but i cant seem to get the configurations right.

the sub volume is always set to maximum (the scale goes from 1 to 15) and i need to have the volume go as high as 20 (which is very loud, volume maxes out at 33) for the sub to start banging away. otherwise, if i have the volume at anything under that, you only hear dry thumps and the sound doesn't "invade" your body the way it does at a club.

i was wondering if this problem was attributable to the setup or to the speakers. since im still using the stock speakers, i went to see an audio expert that i trust who told me that the speakers were at fault. im not technical at all, so forgive the very amateurish explanation. he told me something to the tune of "your speakers are artifically loud, they seem to be modified to put out a lot, when in reality it distorts too much at high volumes and isnt meant to peak". something like that. anyways, i cant figure out a way to have the speakers not so blaring loud whilst still being able to hear and feel the subs in the back.

do you guys have any idea what might be causing this problem? ill give any extra information you guys need to determine the problem, though i understand it must be difficult to diagnose this online with no hands-on feedback. any help would be much appreciated. thanks in advance!!

is the sub wired out of phase

have yo uset the gains on the sub amp sounds like they need to ocme up.

that or the crossover is set wrond what is the crossover set at?

Did you check to see if the subs are out of phase (wired backwards from each other). To do this unplug one of the subs, if you get more bass with one sub, change the other one and hook it up.
Is all the gear the same, sub, amp, box wires etc?
How did you ground the amp, and is your power wire connected solidly to your battery (bad connections can cause power loss)

did you measure head unit preout voltage? also does your amp get really hot?

man, lotsa replies, looks like you guys are gonna be able to help m eout. ok, first off, the gains are set to max. i know this risks blowing up the sub, but since its not pushing anything significant at this point, im not afraid of blowing them up. also, i didnt do the install myself and i know nothing about electricals (im a politics major, heh how useless is that?) so i couldnt tell you about the ground wiring and all that.

the amp doesnt get hot, no.

i have a total of 4 wires going into the sub box, so ill try disconnecting and reconnecting them back into different ports, see if that helps. keep the tips coming guys, and thanks!!

edit: here's a pic of the amo config in case that helps any.. http://us.f1f.yahoofs.com/bc/30009d9...6WvgABObZ6zC0j

[ April 18, 2004, 03:33 PM: Message edited by: spacehog ]

ok, checked some settings on the deck:
HPF: it was at 160hz, i set it to 80 -- no change
LPF: it was at 80, i left it there
Bass: the level range was -8 to +8, bandwidth went from 1 to 4, and i could adjust frequency from 50-160 (in the end, i left this at 0 on all bandwidths and at 80 on the frequency option)
Treble: frequency was set at 17.5k, i left it there.

hope some of this can help. there were no other settings i could fiddle with except turning v-drive on and off (the built in amp for the speakers) and adjusting sub level from 0 to +15 (its always been set at +15 and reducing it affects the sub performance only a bit, so this isnt where lies the problem). thanks again!

you say no change when you change the lpf to 80, you should notice something.
What kind of amp is it? and what are the settings on the amp set to(hpf etc.)

i do notice a little change, when it goes from flat to 80hz, but not substantial. it's a rockford fosgate 500 mono "punch" series amp, one of the older ones. i just set the amp to low pass filtering and the x-over is at 24db.

I usually dont like my body to be "invaded" by anything, ESPECIALLY large speakers, but....why not take it back to the shop that installed it for you?

the shop is in montreal and im in kingston for another 2 weeks. i wanted to try figuring this out sooner rather than later...

check that the RCAs are plugged in securely to the deck and the amp.

Other than that the only other problem it could be is electrical. Is your wire guage radically different from the guy you bought it off of? If he was using 1/0 guage and you're using something like 8 then that could make a difference.

If that's not it, it has to be an installation problem. I agree with Orion - chill out for 2 weeks and take it back to the shop.

And on this whole invasion of one's body thing. Make sure you choose your music wisely and consider protection. There are a lot of tracks out there recorded at low bit rates, most of which are classless fodder. I don't know about you but I won't let myself be penetrated by anything less than 192 kbps and even then I expect to be romanced and cuddled after its all over... [img]tongue.gif[/img]

probably not the case....and probably stupid, but is there a chance that the wiring from the amp to the sub is wrong? (I don't know what type of VC those subs are running) maybe the impedance is screwed.

Ok...lets start by disconnecting the subs from the amp at the speaker-out terminals. Then get a normal 1.5V AA battery and touch each speaker wire on the positive and negative ends of the battery. When you switch the wires from end-to-end on the battery, the cone of the sub should make a small pop and move either inwards or outwards. The speaker wire touching the positive end of the battery when the speaker cone pushes outwards is the positive wire, 100% guaranteed. It's important to eliminate possible incorrect wiring, who knows the positive wire might be incorrectly connected to the negative terminal inside the sub box.

Now, what is the rating on the subs, 2, 4 , or 8 Ohm? I'm pretty sure the Punch series amps can handle a 2 ohm mono load (please check this first, anyone know?) and if so, odds are your subs are 4 ohms each. Wire both VERIFIED positive speaker wires from each sub to the positive speaker out terminal indicated by the label on the amp marked "Bridged or Mono +" and the negative wires to the "Negative Bridged terminal. If you still have a problem, it's definately not the wiring to the subs.

What kind of RCA out-put voltage does your deck provide?...and what brand and model number is your deck? And more info on the subs...

Let's start there....

[ April 21, 2004, 01:03 PM: Message edited by: islandphile ]

ok, my deck just stopped turning on today. nothing i can do to the deck itself will turn it on, so eithe ri screwed up big time somewhere, or my deck picked the right time to crap out. either way, ill be going to a pro shop i trust, but i want to thank you guys for all the great advice you shared. ill definitely save what you guys said and share it with the shop pros to give them some ideas on what can be wrong, though theyll probably be able to figure it out themselves. thanks again guys!

Let us know how it turns out.

I'm gonna say, if you don't know what you're doing, then take it back ot the ppl who installed it and say "WTF IS THIS CRAP?? FIX IT!!!" and don't take any BS, hold out till they do the job right