Passive System Time/Alignment

Here are some of my "methods", and if you are a tuner for a car that competes against a Nizzle car, feel free to not read this and make a run to Taco Bell or something...LOL!

FIrst lets talk about a passive set-up only and that way I can keep focus. There are several configs you can have for a passive front stage...2way passives and active sub, 3 way passives/active sub, individual custom passives w/active sub, any of the above with passive sub. Hell you can even have a 2-way and run free-air 10s as subs and midbass and use horns from 800Hz up (like a certain Bimmer we all should know). He's running active tho, so forget that I brought it up. You can also run passives AND dedicated amp channels on each speaker too, thus you "technically" have a passive x/o, but the ability to signal process actively. Confused yet? I am.
Anyways, I start by looking at the actual speaker locations...what speaker is closest to the driver? Which one is furthest? A way I use to establish distances is I set my RTA micstand in the drivers' seat with the seat all the way back (listening position) and adjusted to roughly ear level. I use a tape measure to plot the distances from the tip of the stand to each speaker's APPROXIMATE voice coil location, and jot down the measurements. THis is less crucial to our passive setup, but helpful nonetheless. Next step is reference all your measurements to zero, meaning the CLOSEST driver to your head becomes "zero inches", and the remaining speakers distances are all converted to the DIFFERENCE in inches compared to the zero speaker.
Lost? Picture this...left midbass is closest to you at 40", left mid measured 47", left tweet 42", rt mid 56" rt midbass 50" rt tweet 53". THe resulting values are lt midbass zero, lt mid 7", lt tweet 2", rt mid 16", rt midbass 10", rt tweet 13". GOt it? Good.
I dont worry about the sub until last, so turn it off/unplug the amp. Since we are passive up front, we need to then establish the best phase relationship for the speakers in each channel. I do this first, right after gain-matching (you DID already adjust your amp gains to identical levels between left and right channels using your trusty test-tones disc and an A/C voltmeter, didnt you?????) OK, so phase relationship...first, disconnect the right channel from the amp, or unplug the right rca. Next, listen to an acoustic track with no amplified instruments. THe less complex the better you can focus on the placement of said instruments. A good vocal is a plus. What you want to listen for is the music coming from the exact same or nearest the exact same spot, both left to right and top to bottom. You will find that most of the time both tweeters and door-mounted midbasses will get you the best result of this test when in reverse polarity. THe reason is the mechanical delay you introduce in the impulses going to those drivers actually brings them into closer arrival time with the midrange, which hopefully is the furthest speaker from you. THis delay is freq dependant, and is only the mechanical phase, not the absolute phase (which is a monster in and of itself, and better left out of this for now) When I do this polarity wiring, I look for the wiring scheme that best takes the music and pinpoints the location as high as possible. You can also do this with test tones or even pink noise, but who the hell wants to listen to pink noise, eh?

Repeat this step for the right channel, unplugging the left. Once you have established that you have the best wiring scheme for each individual channel, connect both channels. Remember, this is a PASSIVE system, so therefore we can NOT align individual drivers, we have to do individual CHANNELS. So, this means we are only concerned with left vs. right, and since the left side is closer to our listening position, we know we will be needing to DELAY the left channel to correct the arrival time difference. THe measurement difference between our two mids ( from above it was 16") will serve as a good starting point. Grab a track with acoustic instruments and a really strong, focussed center vocal for this step.

Play the track, focussing on center vocal location from left to right, adjusting the delay on the left channel to get the best possible center vocal placement. If the vocalist is very low or seems diffusely large and or unrealistic, then your install is suspect and you need to check speaker placement, mounting, damping, all of which I am assuming have already been addressed in yer rides.

Now, about these processors that do T/A....they are all different. THe Sony I use in the civic will apply a delay to a channel based on the distance difference measurement of the OPPOSITE channel...picture this> by entering zero for my left channel /mid location, I would simply then enter 16" for the right channel, and the processor applies the appropriate left delay in milliseconds based on the measurement difference. Alpines are the opposite...you have to input the 16" difference on the LEFT channel so it will apply the appropriate delay to the left channel. I cant recall if the 9255 is like the Alp or not, but I think it is. My Pioneer 8000 is like the sony...I tell it the rt mid is 16" further away that the left, and it adds appropriate delay to the left. THe p9 however, if my mem serves me correctly, is like the Alp, you gotta tell it how many inches/millisecond of delay you want on the channel. If your processor does not allow for measurements in inches, then look in the 700/701 Alpine manual (pdf) for the conversion of inches to milliseconds. If your processor does cm distances, then do the inches-to-cm conversion.

Damn I am longwinded. Back to the system...Once I find the sweetspot of left-to-right center image placement, it is time to bring in the subs. If the sub is in front, but not further away that the other drivers, I add small steps of delay to it until I get the most dynamic and coherent bass response overall, meaning the subs and misbasses are blending well and there is no "out-of-phase" cancellation occuring. I also try to get the bass sounding as far out front as possible. IF the sub is in the firewall, thus further from you than the mids, THEN you need to set the sub to zero and add EQUAL DELAY to the left and right channels, this will have to be done by ear until the best bass response occurs. If the subs are behind you, they will likely be closer to you than the 56" measurement of the right mid we had above, so measure from the v.c. location to the location of the drivers' head/mic stand and jot down the measurement. if multiple subs, I measure from a central point between them all. Add delay accordingly until you no longer can tell the subs are behind you. SOmetimes, simply revering the polarity can help, sometimes both a polarity reversal AND delay must be used. THe goal is to 1) not have the sub gain too high 2) get the bass to sound like it is part of the front soundstage 3) find the best bass response setting of the subwoofer t/a adjustment.

Now, stage height, width, depth, tonality, transparency, etc...ALL of this is dependant on speaker location, install techniques, reflections, damping, EQ, x/o point selection, x/o slope, cancellations, etc etc etc! All we did was get the imaging where it should be. Adjustements to tweeter levels using the passives will affect most of these. Some passives actually have midbass level too. EQ and x/o points will affect apparent height as well as tonality. It's all a synergism, and in no way have I covered all possible aspects of it. THis was simply my method of setting T/A on a passive system. Next installment shall be ACTIVE! WOOHOO!!!!