haemphyst wrote:
No. The high pass section has a +360 degree shift, and the low pass section has a -360 degree phase shift, so the speakers are in phase with one another AT THE CROSSOVER POINT. Due to the location of the headrest speakers, and how close to your ears they are, it will be quite difficult to adjust any time delay on the doors. Also, if you are running ALL of the speakers off two channels of amplification, you will not be ABLE to adjust the TD for the door speakers. To do this, discrete amplification channels (a dedicated channel to EACH driver compliment) are demanded. |
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So, it's not a problem that the tweeter is 720deg ahead of the woofer? I guess ideally with the tweeter closer to your head you would want it to be delayed behind the woofer, but you're right, I can't delay that.
I have the door components hooked up to the front two channels, and the left and right headrest speakers on the left and right rear channels respectively. Going off of the owner's manual for the Alpine, I don't see why it'd be so difficult to set it up so at least the headrest speakers and door components as a whole are delayed correctly with respect to each other.
I took some measurements, and the headrest speakers are both about .127m away from my ears, so those are like the two rear speakers. I chose points on the door panels that were about equidistant from the woofers and tweeters, and on the left that's .889m from my head, and on the right it's 1.194m (I originally measured in inches, but the manual does the calculations in meters, so those are converted.) So if we take the right door speaker minus the left door it's .305m different. According to Alpine, .305/343x1000 (343 being speed of sound in m/sec) means the front left should have a .88 millisecond delay (.9 is the closest I can get).
Then the headrest speakers get the same delay since there's one on each side of the headrests that are the same distance from my head. The 1.194m front right distance minus the .127m gives 1.067m. 1.067/343x1000 gives a 3.1 millisecond delay for those. Is all of this about right? So the FL should get .9ms delay and both rears should get 3.1ms?
Thanks for the help on the subsonic filter too, but maybe I have a misconception about what it's supposed to do. It's my understanding that it's there so that the amplifier doesn't waste any of its power generating tones that the speakers its driving won't be able to play anyway, and it can use the power saved to drive the speakers to a higher volume without clipping, but does it really save the amp any work the higher it's turned up?