Hi there all, i have just upgraded the stereo in my BA Falcon. I have replaced the front and rear speakers with Polk Momo MMC570, added a Rockford Fosgate P4004 amplifier and an LC6 to interconnect the factory icc. The problem i am having is that when the fader is in the rear position, i have much more bass than when it is set to the centre position. Even moving it to the front position gives me more bass than having all four speakers. Moving the fad-er two bars off the centre position towards the rear has a significant effect. I this due to bass cancellation?? I must say, although i am using the same speakers all round the rear have much more bass, most probably because of boot space?? The front speakers also sound a lot more "middy"

Any suggestions would be of great help, as this is the only real let down because moving the fader seems to spoil the sound stage. Please help.....

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[color="#3333ff"]Thanks Jim

its cancellation coz one or more speakers is out of phase.....

basically on one or more speakers, then the + and - are round the wrong way.....

id say that both front speakers a right, but both the rears are wrong.....so switch the terminals, and see how you go

I have check that and all is ok. When you move the ballance to either side it sounds the same. ie phasing is ok.. It almost sounds as if the front speakers are cancelling the rears.

ok then, check at the amp......

What should i be looking for at the amp??

making sure that the wires are right....if they look right at the speakers, they may not be wired right at the amp...

you said when you go from left to right it sounds the same?? is that meaning there is cancellation?? therefore its a phasing issue between the front and the rear

How can there be a phasing problem, between front and rear if individual channels are in phase??

ok, if the front speakers are right, ie pos to pos, neg to neg, then there isnt any cancelaation probs when its faded al the way to the fron

if both back speakers are backwards, ie neg to pos, pos to neg, then there isnt any cancellation when its faded all the way to the rear, as they are in phase with each other....

so when its in the middle, it will cancel.....

so when you have the fade center, but you adjust the balance between left and right, then there will still be cancellation, coz the front and rear are cancelling on each side....

I will have a look, but it isn't as bad as when speakers are out of phase. You know that real tinny sound. This sounds like a frequency issue.

and thats what being out of phse is...its a frequncy issue.....

when they are out of phase, they are playing the same thing, but 180 degreeas out, so when a wave peak meets a wave trough they cancell......

That makes sense. Thanks.

Checked all wiring and all is ok. What i ment before about a frequency issue was that the fronts don't seem to have as low a bass output as the rear. When you move in to the rear of the car, the bass is still there with the fader in the centre position. It is only when sitting in the front this phenomenon occurs.

ok, you need to deaden and seal the doors....

Biggest mistake i made was not doing that. What product do you recommend?? Dynamat or something similar to this .

dynamt, stinger roadkill, they are the two best ones...

there other dodgy ones, like brown bread from jaycar or flashtac from bunnings, but they are cheap dodgy alternantives, and if you are gunna do it, do it right the first time....

some cars have the outer door panel just far enough away from the speaker to cause annoying resonances over a specific, highly audible range.

Sound diffusing tile (in the style of dynaxorb) should do the trick too. Just mount it directly opposite the speaker on the outer skin.

Try reversing the pos and neg on either the front speakers or the rear speakers.
Cheers

proclass...read the whole thread........

and see how many times i told him to do that......

not flaming, it just annoys me to no end when ppl reply without readng the whole thread

this thread is out of phase and become heated.............zion

I read the whole thread. The suggestion to wire either the rear or front speakers out of phase will determine if the phase issue is electrical or acoustical. Two very different things.

The problem must have been acoustic. I added a Soundstream PQ7 Eq and added 3db of 60HZ to the front channels and problem fixed. I will still add Dnynamat as i think there is some huge losses through these doors. Anyway thanks for all the suggestions.

Keep analyzing your setup dude , often it takes a few test seesions to really get a good feel of what is happening.............zion