Setting Phase on an amp

[Wigzter]

Hey everybody, it's me again Ken to bother ya'll with another noob question.

When you are adjusting Phase, does it affect your subs at all? Like when I hear it get loud when tuning Phase, is it adding more power from the amp to the subs? Or does it change the direction of the sound wave or how does that work?

I just want to know so that when I adjust it, I know whether or not I should be turning down the gain when I hear it get louder? I already made the mistake of blowing one Ti212D4 and really don't want to do it again.

In a nutshell, what is Phase and how does it work?

All I know about it is from what it say in the Ti21300.1 user manual, but it doesn't really say how it works.

Thanks again in advanced

[vwdude]

So when you connect the + together and the - together then your subs are in phase. If you swap the + and - on one sub then they are out of phase. Another way to look at it is on your amp, if you swap the - and + as compared to the sub, that's swapping the phase. You don't have to do that on your amp as the knob does it.

So your sub puts waves. They reverberate off different surfaces in your car and they might come back on themselves canceling itself out. If you adjust the phase you can shift the wave slightly, and the wave won't cancel itself out, which is where you hear it getting louder. It's not adding any power, it's just shifting the wave itself.

For the experts...I'm not about to get into a physics lesson, this is the idea behind phase without getting into all of the physics....if you choose to correct me then have at it.

[Wigzter]

Awesome, that def helps me out a lot! Thanks man. I'll def be checking the Phase on the amp again tomorrow. If anyone else has anything to add to help explain it to me as well, feel free to throw in your two cents.

Much thanks again vwdude!

[Bfowler]

vw pretty much nailed it. it just alters where the wave hits surfaces and in some cases changes where in the wavelength you notice the notes. there is no wrong or right setting. just which you like better

this isnt only limited to sub either. swapping the phase of one or both mid or high drivers can change the sound stage level or perceived depth/output too.

[Eric D]

If you just put a sub in a vehicle and had no other speakers installed, adjusting the phase would do nothing. No matter where you place the knob, it would sound the same.

The point of adjusting the phase is to get the sub to match with the other speakers in the vehicle. If you have a sub and component speakers as well, they will have different distances from their centers to your ears. When you turn the phase and hear it get louder, this is the point where the waves from the sub and the waves from the component speakers are hitting your ears at the same time, and adding their acoustic powers. If you turn the knob and the sound is quieter, then that is were the waves are starting to cancel each other at your ears.

Technically there is a correct setting on the phase control, but the problem is if you move your head 4 inches in one direction, the adjustment may no longer be correct. So, the best you can do is get this setting "in the ballpark" and live with it there.

You can use things like a Radioshack SPL meter, or JL Audio's iPhone app with SPL to properly set the phase. You would place the meter at your ear locations, and using tones around the chosen crossover frequency you can turn the phase control until the signal is highest.

[Wigzter]

Alright cool. So I guess I have one last question about Phase then. I was doing more research as well and on the Steve Meade forums someone said that Phase changes the polarity of your sub as well..

So set at 0 the subs fire forwards and at 180 they fire inwards. I haven't had a chance to test it yet today but if this is true, you'll get the most excursion at 0 fire forward and as you adjust it back, you almost lessen the excursion when you start turning the dial?

I'm just throwing educated guesses here lol

[Eric D]

If you have a knob for phase which is 0 to 180 deg, then at 0 it would be normal polarity, and at 180 it would be reversed polarity.

Music is AC, so having a sub wired forward or backward makes no difference on its excursion, nor does it make any difference on how it sounds.

[ttocs]

A neat example of cancellations and phase is if you take a box that especially if its not separated internally but even if it is, wire one sub backwards. For every mm one sub goes up, the other goes(at least if they are matched) down the exact same amount. You will see the subs moving all crazy and they will look as if they are pounding, but the net sound is either 0 or very very low. We would have customers come in with this problem and would tell them the solution, and normally they would not believe us. I won $5 from one customer(he was a regular) that one of the subs was backwards as he he wired them correctly, and he checked them as well. I knew his amp was wired in stereo so I walked out, unplugged one rca and boom boom boom the one sub started pounding, I held out my hand....

[Wigzter]

Alright so I think I'm getting this Phase thing down. I just have it at 0 right now.

I use my stock receiver with a line out converter for RCA's.

Running a Ti21300.1 to push 2 Ti212D4's at 1 ohm.

I'm going to play around with it some more when I have a friend to help me turn the dial at the amp while I listen up in the drivers seat. Hopefully I'll get this set optimally today.

Just want to give a big thank you shout out to everyone's input!!

Being new to car audio is kind of tough especially with little electronic principles knowledge.

[Eric D]

Go here...

http://www.bcae1.com/

That is above and beyond the best place to learn, as everything is broken down into simple terms anyone can relate too.

[Wigzter]

Thanks Eric!! This is exactly what I need!