Phasing with different X-over slopes?
Thread Starter
Race Director
Joined: Dec 2003
Posts: 12,599
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From: Texas
Phasing with different X-over slopes?
It is my understanding that when a X-over point is set at 12 DB an octave that one of the meeting slopes needs to be put out of phase with the other so that they are actually in phase at the 3 DB down point. Does this sound right??
If so, I have found that the closest meeting slopes on my signal processor is 18 DB per octave slopes. What should the phasing be (if any) in order to keep the 3 DB down point in phase? Would 24 DB on the slope not need any phase adjustments? Does the X-over affect phasing when done in the digital stage? My head is an older P1R, supposed to have digital X-overs, but I swear they are out of phase on the 12 DB octave settings.
If so, I have found that the closest meeting slopes on my signal processor is 18 DB per octave slopes. What should the phasing be (if any) in order to keep the 3 DB down point in phase? Would 24 DB on the slope not need any phase adjustments? Does the X-over affect phasing when done in the digital stage? My head is an older P1R, supposed to have digital X-overs, but I swear they are out of phase on the 12 DB octave settings.
Drifting
Joined: Sep 2004
Posts: 1,961
Likes: 2
From: Fort Knox
I guess you're not geting reply's because you're taking your soundstage a bit too serious. There are all sorts of weird phase modes inside of a car that sort of make a moot point out of you worring weather digital and analog phasing attributes. Especially in a vette, which isnt exactly a great soundstaging model in the first place, but really, what car is (assuming you are at least mostly using your stock locations).
Ive seen some people so fanatical about staging that they fabbed their own pylon midbass and tweeter componants as if it was bookshelf speakers, or even studio monitors.
About your questions, do you have some significant dead/flat portion in the fequency range you are wishing to produce when sampling with an RTA? Also, im kinda interested in what signal processor you are using, since ya didnt mention it. And I dont know what a PR1 is offhand. I know ive not helped any.
Ive seen some people so fanatical about staging that they fabbed their own pylon midbass and tweeter componants as if it was bookshelf speakers, or even studio monitors.
About your questions, do you have some significant dead/flat portion in the fequency range you are wishing to produce when sampling with an RTA? Also, im kinda interested in what signal processor you are using, since ya didnt mention it. And I dont know what a PR1 is offhand. I know ive not helped any.
Race Director
Joined: May 2003
Posts: 14,137
Likes: 2,985
From: Iowa
St. Jude Donor '03 thru '26
P1R (Pioneers Reference Units)
very nice unit but was out of my budget back them. I can see how you would be concerned. This is how it goes: 6db equals 90 degrees of phase, 12db 180 degrees, 18 db 270 degrees, 24db 0 degrees, 36db 180 degrees, etc.
In a car, speakers are sometimes put out of phase on purpose. It is done because you have speakers facing each other can cause cancelations. Your best bet is what snoopdan kind of recommends.
You need to hit a audio shop with a RTA. They might charge $50 an hour but it will be money well spent. It will show where you have those cancelations and you can mess with phases to see if they are causing your sound problem. If the phases are not your problem, the RTA will show you what you need to do in forms of equalization. And remember, it is usally better to cut than gain on a eq.
Jay
very nice unit but was out of my budget back them. I can see how you would be concerned. This is how it goes: 6db equals 90 degrees of phase, 12db 180 degrees, 18 db 270 degrees, 24db 0 degrees, 36db 180 degrees, etc.
In a car, speakers are sometimes put out of phase on purpose. It is done because you have speakers facing each other can cause cancelations. Your best bet is what snoopdan kind of recommends.
You need to hit a audio shop with a RTA. They might charge $50 an hour but it will be money well spent. It will show where you have those cancelations and you can mess with phases to see if they are causing your sound problem. If the phases are not your problem, the RTA will show you what you need to do in forms of equalization. And remember, it is usally better to cut than gain on a eq.
Jay
Thread Starter
Race Director
Joined: Dec 2003
Posts: 12,599
Likes: 1
From: Texas
Originally Posted by snoopdan
I guess you're not geting reply's because you're taking your soundstage a bit too serious. There are all sorts of weird phase modes inside of a car that sort of make a moot point out of you worring weather digital and analog phasing attributes. Especially in a vette...
I do appreciate the reply though
the speaker placement in my C5 is infinitely better than my C4 but still lacks the stage depth that my custom kick panels in my Jimmy had. Still, I have hope 
