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Car Forum / Driving, Maintenance, Tuning / Car Audio / May 2008

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New Sound System in 1997  Jeep Wrangler /  Sounds bad !!!!!!!!!!

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James - 27 Apr 2008 03:45 GMT
Perhaps some of you experienced guys can give me some ideas as to why I am
not
satisfied with my updated HU and front/rear speakers in my 1997 Jeep
Wrangler.

My  HU is the Alpine 9857.   This radio is rated at 18 watts per channel,
but many folks
consider that a very conservative rating on this particular HU.  I am not
yet running an amp, although I  plan to install one, probably a 4 channel
amp of at least
70 watts per channel.  But, I don't want to install an amp until I
understand why I am not
getting anywhere near "decent" sound with what I now have.

Please note that I am an older gent, and I am not trying to play music for
someone
a mile away to enjoy.  I just want a decent stereo in this particular Jeep.

FRONT SPEAKERS:

I purchased an adaptor so that I could replace the front 4 X 6  speakers
with the   Polk Audio DB5250s, which is a   5  1/4 inch speaker with a
separate tweeter and crossover unit.     Before choosing this speaker, I
read  **many**  reviews that rated these speakers very very highly.   Yes,
the reviews pointed out that this size speaker doesn't produce  HUGE  bass,
but of course that couldn't be expected from any speaker this size.   But,
every review that I read said that these speakers perform way beyond their
size, and are fantastic.

I also installed polyfill in the front dash, in the area above, below,
behind, and all sides of these front speakers.  I did this because many
folks
reported that  this improves the bass response.

RESULTS--   these speakers really seem dull, and dead.  I don't know any
better way to explain it.   To be more specific, they seem to have  **almost
no** bass response.  Once again, I know that they cannot have huge bass, but
I have heard other speakers of this size that have three times the bass
response.

Equally puzzling, the tweeters themselves (separates)  actually distort the
music.
When  I say distorted, I mean fairly strong distortion, on some music
passages.
They don't seem to distort all the time, but they are significantly
distorted.   ( some users say these tweeters are a bit too "bright", and I
have cut down on the treble to account for this).

I have double-checked the hookup wiring, including the phasing, etc etc.
As far as I can tell, I have everything right,  left and right.   (The two
sides seem to perform the same).

Now here is the most weird part........... the sound  (I will review the
rear
speakers below)    the sound is so bad.......... it actually sounds so tinny
that
it gives me a headache.   The entire sound is so tinny and
distorted-sounding,
It is very very hard to explain... it just sounds BAD.

REAR SPEAKERS IN ROLL BAR:

I installed  Polk  5  1/4  inch coaxial speakers in the rollbar. (Model
MMC525s)
There is rubber type material in the rollbar, so I  didn't want to try to
remove that to put
polyfill in like I did in the front.    Just like the front, there is  NO
bass in these speakers, and
in general they sound awful.  If I play at just barely a decent volume level
(Not Loud) they
distort terribly.

OK,  PLEASE NOTE:    I am  100% aware that this is a JEEP, and that these
are not
large speakers.   But, the entire sound in this Jeep with   four     5   1/4
inch speakers is
just rotten, to the point of giving me headaches.  I can't stand to listen
for more than about
ten minutes.    I have a 2000 Jeep Grand Cherokee with an Infinity sound
system, and it
sounds  ten times better, seriously.  I can listen to it all day.   I also
know that I will never
get equal sound from a Jeep Wrangler, but I should be able to get
**decent**  sound with
what I have installed, or so I thought.

---------------------------------------

I guess there are several possibilities:

1. Bad HU, causing distortion in the highs and lows.

2. Bad crossovers.

3.  Bad tweeters on these brand new speakers, front and rear.

4.  Too much polyfill in the front,  not allowing speakers to push enough
air, thus
restricting the bass.

--------------------------------------

Can you guys give me some advice, and/or comments ?     Any other
possibilities other than the 4 items that I have listed above ?

Yes, I know that any good speaker system will sound better with an amp.
But, nearly all of the user-reviews that I have read, indicate that these
speakers will do a fine job with  18 watts per channel.     Also, I think
that the improvement from an amp would be mainly in the bass and mids/   but
not sound from the tweeters, right ?    I clearly don't mind installing the
amp
next, but it seems crazy for me to move forward at this point until I have
the
basic system sounding decent.

Thank you very much for any additional thoughts or ideas.  I want decent,
good-quality sound, that I can play medium-loud.  I am an older gent, and
don't listen to rap , rock, or other extremely loud music.   But, I do know
decent sound when I hear it, and at this point, these speakers don't even
come near what I had hoped for.

HELP PLEASE    !!!!!!!!!!!!!!!!!!

--James--
Matt Ion - 27 Apr 2008 19:59 GMT
I left all that intact because I was too lazy to decide what to trim...

In any case, polyfill is not an answer in itself... the trick to getting
bass out of ANY speaker is that the front and back sides of the cone
MUST be isolated from each other, and that means an enclosure, PERIOD.

You don't note how you have the roll-bar speakers mounted - are they in
boxes of any kind?  Same with the dash speakers - I haven't worked on a
Jeep that new, but if they're anything like the late-80s/early-90s ones,
there is no enclosure of any sort behind the dash speakers; there are
just cutouts in the front of the dash and the backwave can easily leak
around under the dash.

The problem here is the sound wave from the back of the speaker is 180
degrees out of phase with that from the front, and with lower
frequencies being non-directional, the bass wave from the back of the
speaker literally cancels out the bass from the front.

Stuffing soft material in behind the speaker will help a bit, but not a
lot - there's no substitute for a proper box.

> Perhaps some of you experienced guys can give me some ideas as to why I am
> not
[quoted text clipped - 120 lines]
>
> --James--
Ender W - 02 May 2008 11:33 GMT
> Perhaps some of you experienced guys can give me some ideas as to why I am
> not
[quoted text clipped - 131 lines]
>
> --James--

Hello James
Have you checked to make sure all the speakers are in phase?
Just having 1 speaker out of phase will have a canceling effect on the rest
of the speakers.
The most noticeable is in the bass response.
The speaker(s) out of phase could be connected wrong at the speaker or the
radio
try fading front to back and see if one set sounds better than the other.
you can also try fade and balance to 1 speaker and see if just one sounds
better.

I believe these are the speaker colors and polarity in your vehicle
Right Rear Spkr (-) Blue w/ Orange Stripe
Right Rear Spkr (+) Blue w/ White Stripe
Left Front Spkr (-) Brown w/ Red Stripe
Left Front Spkr (+) Green
Left Rear Spkr (-) Brown w/ Blue Stripe
Left Rear Spkr (+) Brown w/ Yellow Stripe
Right Front Spkr (-) Blue w/ Red Stripe
Right Front Spkr (+) Purple
James - 02 May 2008 21:03 GMT
Thank you Ender for this advice.  I will check all of this out as soon as I
get a chance.

This had really been a frustrating experience for me.

I welcome other comments on this problem.

Thanks  !!

James

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