What Subwoofer Phase?
 

What phase are you running your spare tire mounted subwoofer in? I'm undecided whether I prefer normal or reverse so I'm interested in what other people have gone with. Obviously different crossover points etc will effect results, but I'm still keen to hear what people have chosen...

When you say reverse do you just.mean 180deg out of phase (as in wiring the sub "backward")? Only special setups should do this (which will not include our cars). Destructive interference will start cancelling bass if you do this.

Exactly - 180deg out of phase with the front speakers. Using pink noise and an RTA reversing the phase gives me a better curve, but I'm not convinced it sounds better than in normal phase. I'm leaning towards sticking with the normal phase, but I'm interested in whether anyone else has found reversed better.

The slope of your crossover will affect our phase. Both the LP of your sub, AND the HP of your woofers/mids combined. They both play together. A 24db slope is the most common because it presents the least amount of phase issues. Time Alignment also comes into play here as well. A LP with a 12db slope is 90 out of phase... add to that a HP of 12db on your woofers....180 out. a 24db LP is 180 out.. add to that a 24db HP.. 360 (back in phase)
Just go with whatever sounds best to your ears.

I'm using 24db for both at the moment but also have a fair bit of overlap between the sub and woofers. Might play with the crossover points to see if it achieves any improvements.

Yep. Everyone's ears are different. What sounds good to me might not sound so good to you.

A lot of people get too wrapped up in the numbers (especially when it comes to cars, which are about the crappiest environments for sound reproduction you can find). It's all about what sounds good to your ears in your car.

:iagree:

Turn some "knobs" and see what you like

me too...thats what I did.

Typically not necessary (or wise) for low freq. drivers. Overlap can cause cancellations of certain frequencies. Try gapping your xovers between Sub and Woofers...
Example: 63hz LP on Sub, 80hz HP on woofers. No freq or crossover is set in stone. your vehicle may display gains or dips anywhere on the spectrum. keep tweaking little bits at a time until you find what works for you.
If you have the capability to do so, I like to save my Base tune to one preset, copy that to a second preset, and tweak on the second. Once I feel Im satisfied with tune #2, switch back to the base and compare what improved/what got worse, ect.

Thanks mate, this was very good advice! I'd previously increased the overlap to try and correct a dip in some frequencies, which looks like it actually did more harm then good. Re-adjusting the crossovers has done the trick!

Glad to hear it.