Log in

View Full Version : Poor Performance with Polk 5 1/4 inch speakers-- Why ???


James
January 27th 07, 03:15 PM
Ok, maybe some of you guys can give me some hints as to why I am not
satisfied with the new front speakers in my 1997 Jeep Wrangler.

Let me start from the beginning. Several months ago I installed a new HU,
the Alpine 9857. This set is rated at 18 watts per channel, but many folks
consider that a very conservative rating on this particular HU. I am not
running an amp.

I purchased an adaptor so that I could replace the front 4 X 6 speakers
with the Polk Audio DB5250, 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. 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 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).

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

I guess there are several possibilities:


1. Bad HU, causing distortion in the highs.

2. Bad crossovers.

3. Bad tweeters on these brand new speakers.

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

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

The speakers in the rollbar are very old , and basically "blown." I plan
to order new speakers for them soon. I know that if I had speakers in the
rollbar, I could make some comparisons. Yet, I hate to choose speakers for
them until I get better satisfaction out of the front Polks. I had thought
of similar Polks for the rollbar.

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 ?

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.


--James--

X-OvrDistortion
January 27th 07, 04:22 PM
First off, HU power is not enough to run a set of components properly.

Second, to much poly can reduce performance.

Make sure that you have the tweeters hooked up right again.

If you have the money, get yourself a cheap amp that will do 50x2 (that
will be sufficient) and run the speakers off of that. I guarantee that
you will be happier going that route.


--
X-OvrDistortion

D.Kreft
January 28th 07, 12:13 AM
On Jan 27, 8:22 am, X-OvrDistortion <X-OvrDistortion.2l2...@no-
mx.forum.carstereos.org> wrote:

> First off, HU power is not enough to run a set of components properly.

That's kind of a generalization, isn't it?

> If you have the money, get yourself a cheap amp that will do 50x2 (that
> will be sufficient) and run the speakers off of that. I guarantee that
> you will be happier going that route.

Not even a thousand-watt amp is going to help with LF response if the
backwave is not kept from canceling-out the front wave of the speaker.
In order to get the best out of your speakers, you need to make sure
that there is absolutely no path from the back to the front of the
speaker. Unless you can guarantee that, you're doomed to substandard
performance.

-dan

BigBob
January 28th 07, 08:04 AM
Could you be a bit more specific please?
Thanks
Bob
"D.Kreft" > wrote in message
ps.com...
> On Jan 27, 8:22 am, X-OvrDistortion <X-OvrDistortion.2l2...@no-
> mx.forum.carstereos.org> wrote:
>
>> First off, HU power is not enough to run a set of components properly.
>
> That's kind of a generalization, isn't it?
>
>> If you have the money, get yourself a cheap amp that will do 50x2 (that
>> will be sufficient) and run the speakers off of that. I guarantee that
>> you will be happier going that route.
>
> Not even a thousand-watt amp is going to help with LF response if the
> backwave is not kept from canceling-out the front wave of the speaker.
> In order to get the best out of your speakers, you need to make sure
> that there is absolutely no path from the back to the front of the
> speaker. Unless you can guarantee that, you're doomed to substandard
> performance.
>
> -dan
>

Matt Ion
January 28th 07, 07:05 PM
BigBob wrote:
> Could you be a bit more specific please?
> Thanks
> Bob

http://www.decware.com/secrets3.htm

http://www.raysmith.co.uk/lets_make_bass.php

> "D.Kreft" > wrote in message
> ps.com...
>
>>On Jan 27, 8:22 am, X-OvrDistortion <X-OvrDistortion.2l2...@no-
>>mx.forum.carstereos.org> wrote:
>>
>>
>>>First off, HU power is not enough to run a set of components properly.
>>
>>That's kind of a generalization, isn't it?
>>
>>
>>>If you have the money, get yourself a cheap amp that will do 50x2 (that
>>>will be sufficient) and run the speakers off of that. I guarantee that
>>>you will be happier going that route.
>>
>>Not even a thousand-watt amp is going to help with LF response if the
>>backwave is not kept from canceling-out the front wave of the speaker.
>>In order to get the best out of your speakers, you need to make sure
>>that there is absolutely no path from the back to the front of the
>>speaker. Unless you can guarantee that, you're doomed to substandard
>>performance.
>>
>>-dan
>>
>
>
>

D.Kreft
January 28th 07, 10:20 PM
On Jan 28, 12:04 am, "BigBob" > wrote:

> Could you be a bit more specific please?

I already have...in this thread:

http://groups.google.com/group/rec.audio.car/browse_frm/thread/
a21dbf97ff381c45/1bce3cf3198b504e?lnk=gst&q=infinite+baffle+free+air
+backwave&rnum=1#1bce3cf3198b504e

-dan

GregS
January 29th 07, 03:26 PM
In article >, "James" > wrote:
>
>
>Ok, maybe some of you guys can give me some hints as to why I am not
>satisfied with the new front speakers in my 1997 Jeep Wrangler.
>
>Let me start from the beginning. Several months ago I installed a new HU,
>the Alpine 9857. This set is rated at 18 watts per channel, but many folks
>consider that a very conservative rating on this particular HU. I am not
>running an amp.

Most head units have the same power, and 18 watts is pushing the rating.

>I purchased an adaptor so that I could replace the front 4 X 6 speakers
>with the Polk Audio DB5250, 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. 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.

Oem speakers can sometimes create a lot of bass by having a high QTS.

When you start to install stuff, you basically need to know all. From my
experiance with coaxial speakers, I would doubt any would meet my creteria
for any kind of quality. To know what to do with crossovers, you need to know
that driver. Drivers spec sheets is always nice, and most of the time
absolutely necessary. A frequency response plot on and off axis as well
as the Z plot is necessary. if you don't have these things, then you
need to measure.

greg