playa6tnine

iTrader: (5)

i uninstalled and reinstalled my system this past weekend to do some sound dampening. when i put everything back together, i noticed this problem:

the sub will play normal, and it will do the low steady frequencies fine. like "booooooooooooooooom". those notes are fine.

but when it is supposed to "hit", the sub gets quieter, instead of "hitting". this only happens on the hard hitting quick notes, like the notes you would make if you hit your fist on a desk to make a beat.

lol does this explanation make sense? did i hook something up wrong? reverse polarity or something?

StreetOC192

iTrader: (7)

2 of the most common problems that would cause the symptoms you are describing would be reverse polarity wiring or air leak.

VO...

iTrader: (25)

+1

VO(knows from experience)

playa6tnine

iTrader: (5)

so if the polarity is reversed, that would mean i would have to switch the positive and negatives?

and by air leak, you mean like something as small as a screw hole or larger? or dont think i have any leaks, but i will check

StreetOC192

iTrader: (7)

Correct

Correct.....it only takes a very small air leak to cause a problem.

VO...

iTrader: (25)

Yes & yes.

Polarity reversal is pretty obvious though. When the sub hits, it'll suck inward instead of outward. That's polarity reversal...

doug

iTrader: (5)

well if its an air leak.. this would be a perfect opportunity to get rid of those JL's i'm suprised you even put it in your sig

playa6tnine

iTrader: (5)

cool guys, thanks for your help! i have some investigating to do.

as for doug, i'm not sure where you're getting at, and if my JL system is a positive or negative thing lol

clarkemtp

I read your thread. School of Hard Knocks. Life's best teacher (and lessons not soon forgotten).

VO...

iTrader: (25)

You think that's bad. Read this thread. Start on post #4

https://my350z.com/forum/brakes-and-suspension/241538-squeaking-new-rotors-with-brakes.html

str8dum1

iTrader: (11)

reversed polarity only matters if you have 2 subs, which the OP used the word "sub" so i assume that means 1. out of phase subs with the highs would have nothing to do with the situation that the OP is describing.

StreetOC192

iTrader: (7)

Not true necessarily. If you have your mid woofers crossed over low enough and are overlapping frequencies between mid woofers and sub, you will get cancellation if the sub is wired with a reverse polarity. As the OP describes the sub will hit the low notes, but not the punchier notes in the higher subwoofer spectrum. Since I am not there to analyze the issue myself to rule anything out I included it in my remote synopsis. It takes 25 seconds to prove this out. Better to be too thorough than not thorough enough.

clarkemtp

Damn. Your car modding would make a great country song. A couple of steel guitars twangin' away and chorus about "...it it weren't for bad luck I'd have no luck at all...".

Don't feel bad though, I just got rid of a C6 Vette that I drove for two years. I bought it with the Z51 performance package and those brakes, even stock, squealed like a stuck pig. I was always just freakin' PUMPED to pull up at a light, step on the brakes... and have everyone WHIP their head around to see what fuggin' POS was makin' all that racket.

A change to ceramic pads was a widely known "fix" in the Vette community, but damn it... if I'd wanted crappier than stock braking, I wouldn't have popped for the Z51 in the first place. lol

/back-to-your-regulary-scheduled-thread-already-in-progress

doug

iTrader: (5)

OMG.. i changed to ceramic pads unaware of the performance issue.. i can't tell how many times i almost/did run a stop sign

clarkemtp

I detect a note of sarcasm in your post.



Sorry guys, I wasn't implying that ANY pad of ceramic, or other origin, was any better or worse than any other pad in this application. Being a new owner, I know *squat* about the popular brake pads for the 350z.

All I meant was the GM ceramic pads that everyone used to "cure" the squealing Z51 brakes were a definite performance compromise over the stock compound pads.

That being said, you might try stepping on the pedal sooner and you won't run that big red sign.

playa6tnine

iTrader: (5)

lol this thread went from a subwoofer issue, to ceramic brakes. thanks guys!

Z1NONLY

iTrader: (2)

I just skimmed through all the replies. The polarity could be an issue if another driver (large midrange?) in the car is trying to reproduce the same "hit" FQ's as the sub and is out of phase.

But, I wonder if you might have changed the X-over FQ on the amp or other crossover device when you reinstalled the equipment. If the sub is crossed over at 40hz, it might have the effect you are describing. (I don't know if your head unit has a built in sub crossover but if it does, I would check that too. -maybe it defaults to some setting you don’t want.)

Also, a ported box that is incorrectly tuned will do this also.

Sorry if any of this has already been covered.

doug

iTrader: (5)

I was not being sarcastic.. i was being real... i bought ceramic pads.. and i was driving with my brother.. hit full boost.. came to a stop sign and the car wouldn't stop.. so i got back on the gas and made a left turn and kept going..

i could have braked earlier... however i didn't know that ceramic pads needed more time to stop.. my prior brakes held better and stopped quicker

clarkemtp

One of the hazards of giving up "face to face" communication, it's harder to tell when someone is being genuine vs. "just f'kin with ya". My bad, although I'd say no harm no foul. I'm not easily offended. I guess that comes from many years of posting in the Off-Topic section of CorvetteForum.com. You develop a THICK skin, quickly.

Anyway, again, I'm no brake pad expert as they relate to our Z cars, but in the Vettes it was a common swap for whiney Z51 owners that should've never bought the option in the first place. The GM ceramic pads squealed less and dusted less.

Let's see... No squeal? No dust? No bite. No brakes. You traded ultimate braking performance for a quiet car with nice clean wheels. Yeah, ummm, no thanks. I kept the stockers... just got rid of the car. hahaha

doug

iTrader: (5)

to be honest.. i bought them because i ignorantly thought they were better for performance.. NEVER AGAIN.. i would rather clean my rims everyday than live through that horror