Subwoofer phase issue. Is this normal?

[gamehawk55 10+ year member]

Ok, the issue I have is simply this. With my subwoofer phase on "normal" I hear more low end bass (50hz and down) but my top end (60hz+) lacks or generally cancels out. With the phase on reverse it brings that 60hz+ range back into play but the really low bass starts to get cancelled out a little bit. Also the sub seems to be a little bit more localized when on the reverse setting. Is this normal to have cancellation at opposite ends of the crossover point when switching phase? Or should I be able to hear the entire spectrum up to my Xover point (60hz)? It's rather frustrating sometimes because at the right frequencies and volume level I get alot of cancellation and so have to switch the phase on the deck to get it back.

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[keep_hope_alive Premium Member]

try reversing polarity of your speakers and that should resolve the top end cancellation.

 

[gamehawk55 10+ year member]

try reversing polarity of your speakers and that should resolve the top end cancellation.

I tried that and it didn't really sound right to me :/ But really...Shouldn't reversing the phase on the sub essentially do the exact same thing as reversing phase of the speakers? At first I thought it was because I recently re-enabled the rear deck speakers/sub of the stock system. But regardless of running fronts only or all I still get the same cancellation issue :/

 

[Jeffdachef 5,000+ posts]

I tried that and it didn't really sound right to me :/ But really...Shouldn't reversing the phase on the sub essentially do the exact same thing as reversing phase of the speakers? At first I thought it was because I recently re-enabled the rear deck speakers/sub of the stock system. But regardless of running fronts only or all I still get the same cancellation issue :/

let me get this right, are you running extra subs along with the stock sub?

 

[Umbra]

I tried that and it didn't really sound right to me :/ But really...Shouldn't reversing the phase on the sub essentially do the exact same thing as reversing phase of the speakers? At first I thought it was because I recently re-enabled the rear deck speakers/sub of the stock system. But regardless of running fronts only or all I still get the same cancellation issue :/

I'd like to know this too. I understand the basics of how phasing works, but I thought a 180 degree phase shift and swapping the polarity achieved the same result.

 

[gamehawk55 10+ year member]

let me get this right, are you running extra subs along with the stock sub?

K here's the story lol. I have a pair of SA-8v2's in the back and a set of Focal PS-165's up front. For the longest time I had my rear stage(stock) disabled. The rear stage consists of 2 6x9's and a hidden "sub" that runs off it's own dedicated amp (that isn't configurable). So one day I figured I would try re-tuning the system to allow the rear stage to be present as well to "lift and boost" the front stage a bit. It sounds great to my ear, I just happened to noticed the sub cancellation happening. But I think it's un-related because I seem to get the upper bass cancellation regardless of rear stage being active or not.

That being said. At lower volumes with the subs on reverse polarity the "low" frequencies get cancelled out by the stock sub. But that gets corrected by simply turning it up a couple notches and the SA-8s overpower the weak stock subs sound waves and push through. I just don't know why I'm getting the upper bass cancellation. Is it the cabin of the vehicle cancelling them out perhaps?

 

[Jeffdachef 5,000+ posts]

K here's the story lol. I have a pair of SA-8v2's in the back and a set of Focal PS-165's up front. For the longest time I had my rear stage(stock) disabled. The rear stage consists of 2 6x9's and a hidden "sub" that runs off it's own dedicated amp (that isn't configurable). So one day I figured I would try re-tuning the system to allow the rear stage to be present as well to "lift and boost" the front stage a bit. It sounds great to my ear, I just happened to noticed the sub cancellation happening. But I think it's un-related because I seem to get the upper bass cancellation regardless of rear stage being active or not.
That being said. At lower volumes with the subs on reverse polarity the "low" frequencies get cancelled out by the stock sub. But that gets corrected by simply turning it up a couple notches and the SA-8s overpower the weak stock subs sound waves and push through. I just don't know why I'm getting the upper bass cancellation. Is it the cabin of the vehicle cancelling them out perhaps?

Turn off/get rid of that that stock sub, its the main culprit here. You dont want multiple types of subs going at once, thats cancellation hell right there.

 

[gamehawk55 10+ year member]

Turn off/get rid of that that stock sub, its the main culprit here. You dont want multiple types of subs going at once, thats cancellation hell right there.

Yeah eventually I will dig into it and disable it completely. But like I said it's hidden under the rear deck somewhere. The wires for it aren't even visible. But as I have said. The upper bass cancellation exists regardless of rear stage being enabled or not while the subwoofer phase is set to "normal".

 

[T3mpest 10+ year member]

The correct setting should be whatever makes you blend better up top. Use the setting that gives you more output up top. Neat thing about phase, if a speaker is only playing by itself changing phase does NOTHING audible at all. Phase only effects how speakers play relative to one another, so if they arent' overlapping ranges, you can't hear a change in phase..

How does that matter to you, you ask? If means the cancellation your getting down low with your phase "backwards" will go away when you remove your stock sub, because at that point it'll be the only speaker playing low bass and will have it's normal frequency response down low regardless of which way you have it setup. The only difference at that point will be the extra upper end bass.

Also, KHA had a good suggestion as well. If the sub has more upper bass out of phase run it that way, and also try flipping just one of your midbasses and see if that continues to improve the situation. If you flip BOTH midbasses, you havent' done anything for your midbass subbass transion that couldnt' have been done by simply flipping the sub, it's all relative, so a flip of your midbasses vs flipping your sub does the same thing, except for what is going on up top where the mid mates to the tweet, but that isnt' very phase depenent, so you likely wont' hear that much. A single midbass flip though is a change all on it's own and can be combined with a sub flip to create a new combination.

 

[bbeljefe]

If your subwoofer amp has a variable phase pot you could also try shifting the sub stage 90°. But regardless, you don't need the factory sub in the mix.

 

[keep_hope_alive Premium Member]

I tried that and it didn't really sound right to me :/ But really...Shouldn't reversing the phase on the sub essentially do the exact same thing as reversing phase of the speakers? At first I thought it was because I recently re-enabled the rear deck speakers/sub of the stock system. But regardless of running fronts only or all I still get the same cancellation issue :/

since you prefer the low end with sub phase at normal, the upper end cancellation is happening due to phase issues with the speakers. swapping polarity on the speakers should resolve the phase interference at midbass frequencies while letting you keep the low end response also.

t3mpest is right that phase matters where speakers overlap in response. crossovers introduce phase shifts, then we react to those phase shifts with adjustments to polarity. 12dB/oct and 18dB/oct are 180 deg and 270 deg phase shifts, respectively, and result of both are like reversing polarity.

so you start by considering the phase shifts caused by crossovers.

then you consider the phase differences caused by different arrival times.

1. adjust crossover slopes (if capable)

2. adjust time alignment (if present)

3. adjust polarity

 

[gamehawk55 10+ year member]

since you prefer the low end with sub phase at normal, the upper end cancellation is happening due to phase issues with the speakers. swapping polarity on the speakers should resolve the phase interference at midbass frequencies while letting you keep the low end response also.
t3mpest is right that phase matters where speakers overlap in response. crossovers introduce phase shifts, then we react to those phase shifts with adjustments to polarity. 12dB/oct and 18dB/oct are 180 deg and 270 deg phase shifts, respectively, and result of both are like reversing polarity.

so you start by considering the phase shifts caused by crossovers.

then you consider the phase differences caused by different arrival times.

1. adjust crossover slopes (if capable)

2. adjust time alignment (if present)

3. adjust polarity

Ok I think I got it fixed. I discovered that the crossover for the "front" section on my head unit also affected the rear stage speakers. So all I did was open up my xovers on both amps and controlled it from the HU instead. Set the xovers on the HU for front and sub to 60hz and now I'm pretty sure it sounds normal on "normal" phase. And the bass is now more "up front" and the sub in the upper range sounds like it's reinforcing the mids now and the higher frequencies are no longer heavily localized to the rear of the vehicle. Still doing more testing but I think this did the trick.

 

[gamehawk55 10+ year member]

Also I will say it sounds "weird" with the sub set to reverse now too and way too localized.

 

[gamehawk55 10+ year member]

So I'm happy to report that what I did completely fixed the problem and now my subs, mids and rears have absolutely NO cancellation anymore //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif I feel like somehow I always had cancellation problems up until now because I was never able to listen to hard style's reverse bass lines before and have them sound good. It always felt like there was some sort of delay in the sound and something just didn't sound quite right. I put on some hard style tonight and holy cr*p what a difference. Was a perfect blend to the mids and I could hear every inflection in the bass note //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif Hooray for no cancellation, it's like I'm hearing my system for the first time haha (and I've been running it for over a year)