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Discussion Starter · #1 ·


That would be the front of the car, hopefully my wonderful image makes some sense. ;)

The tweeters (25NFA) will be in the A-pillars, aimed slightly toward the windshield. The green lines are on-axis.

As you can see, the listener is almost 90 degrees off-axis from the tweeter on his side (red line)

It is generally recommended to use the straight line from the speaker to the listener to calculate the required time correction, but wouldn't it make sense in this case to use the reflected blue lines, which are presumably more representative of the distance travelled by most audio waves? Or is the first wave reaching the listener always the point of reference for time correction?

Thanks in advance, figuring out all that stuff is a lot of fun. :)
 

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Would like more info on this as well.....but i do have different idea about how it works....sound waves are not straight lines, sure on axis is, but speakers have a dispersion characteristic, and what sets up a soundstage is the sum of each side, plus all the reflections off of the windshield, so there is every degree b/w on axis and 90 degrees being thrown at you at the same time. As the windshield reflects the sound thrown towards it. So i'm not sure if you should truely worry about the on axis response....or if the off axis is more important for a A-pillar install.

But as you have drawn in your pic say 30degrees on each side of the axis, you have to also think about the 50 or 60 degree offaxis reflecting back towards you off of the windshield as well. I may be wrong though, very intresting would also like to know alot more about this as well.

I read a article by Werewolf awhile back about imaging and pathlenghts, i remember n=2n IIRC n= pathlength from source, 2n is the pathlength from source to reflected surface to listener) i don't remember much of it though, mabey he'll chime in and speak :)
 

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You're not going to need time alignment for treble frequencies, and in fact it won't make any difference at all. I think your main concern would be getting your left and right side frequency response matching... which should include early, high amplitude reflections.
 

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Ok dang that means alot, But any way you could put "Early High Amplitude Reflections" into laymens terms.

I have noticed some differnces using TA/not using TA on my tweets. Soundstage seems much wider not using TA, but i feel like i'm missing the center image by not using it, but by using the TA on my midbasses i can get a firm midbass/midrange image in the center of my dash, but not for both seats, as if i take the TA off my midbasses it sounds very one sided, and that may be the problem with going 2way and having good imaging, as the midrange and midbass need to be either in/out of phase or vise versa to get the best sound for each seat. I'm sure i'd need someone who actually knows what there listening for to sit in my car and tell me if its any good or not. I mean i think it sounds awesome, from a tonality standpoint, but just the imaging throws me off sometimes on whats supposed to be right and wrong. Would like to have both front seats sound really good, not just the drivers or passengers, as if i was demoing the car, there passenger seat would sound like ass and he drivers be completely awesome.....would rather have both be aweosme.
 

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TA should always be considered a band aid approach to only be used when nothing else fixes the problem.

The most I have ever used was a tiny bit on a R mid, in one install, temp situation at that.

Rick
 

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I'm not exactly sure how to get a firm center image as if i flip the phase on one of my midbasses the midrange sounds very hollow and distant, though there seems to be a little more midbass and it seems more centered. But its a game of tradeoffs.....i guess thats just what happens when you go a 2way up front, having problems with phasing b/w midrange/midbass when the same driver plays both.

But neway back to the tweeter ideas.
 

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lawnboy, i see a critical flaw in your idea. You want the left tweeter to bounce off the window and door to go to your right ear. I'm sure the left ear will still be able to hear the left tweeter and defeat the imaging. With that said, you have L/R reversed after reflecting, but you can still hear the L/R before reflecting... Also depending on how deadend your door, and the trim level on your car, the characteristics of reflection might not even go that far...
 

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Discussion Starter · #8 ·
I don't "want" the left tweeter output to bounce off the window and reach the right ear, it's simply a consequence of mounting the tweeter there. It's the only location that doesn't require a lot of fabrication and AFAIK it's a not a bad place to mount a tweeter.
 

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demon2091tb said:
I'm not exactly sure how to get a firm center image as if i flip the phase on one of my midbasses the midrange sounds very hollow and distant, though there seems to be a little more midbass and it seems more centered.
How even are the lengths between mids? If its sounding hollow and distant, its out of phase, but may sound more centered only because when in phase the driver's side one is going to be louder if it's closer normally.

-aaron
 

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Lets say 38"-L and 55"-R IIRC, to drivers head. mounted in factory places IB. Tweets on the A-pillar, same lengths to sources. 38"-L, 54"-R. When flipped out of phase it does sound hollow but it dosent seem like its from one being louder than the other....it just seems to miss out on a full sound, very hollow type.
 

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raamaudio said:
TA should always be considered a band aid approach to only be used when nothing else fixes the problem.

The most I have ever used was a tiny bit on a R mid, in one install, temp situation at that.

Rick

Could you explain why you view it as a band aid approach?

It was my understanding that the only fix for this problem would be to get the speakers to equal pathlengths, and since most car environments do not allow for this time alignment seems like the next best thing. Or are there disadvantages to this?
 

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mikemcus said:
Could you explain why you view it as a band aid approach?

It was my understanding that the only fix for this problem would be to get the speakers to equal pathlengths, and since most car environments do not allow for this time alignment seems like the next best thing. Or are there disadvantages to this?

I'm sure Rick will have a more in-depth answer, but I think the biggest problem with T/A is that it is a compromise. You can't align the car for both seats, (driver's and passenger's,) to have the same soundstage, so you always end up compromising one side for the other.

If you can get pathlengths equal, then you'd have the ideal setting, with both passenger and driver getting the correct staging.

Just my 2 cents,

-Ben
 

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ahhhh, thanks for the explanition Ben. That makes sense.

So are the majority of people here tuning the car for both passenger and driver? Perhaps a processor like the h701 with multiple presets for time alignment would be the best solution. That way you could set the car up to sound pretty good from both seats, and then tweak it further with time alignment for when you are riding alone.... maybe
 

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Mike,

Not sure how most people on here are tuning. For competition, I believe that it is judged from both sides now, (back when I used to compete, it was only driver's side.)

A processor like the 701 seems like a good idea, I'm actually looking into that myself if the Behringer piece that everyone loves doesn't get a working power supply soon.
 

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Imo time alignment isn't really a band-aid, it's just not a complete solution. Having the right pathlengths not only insures correct time arrival, but gives you better left / right frequency response and amplitude matching as well.

As far as "time aligning" for both the passenger and driver, well honestly Imho you can never have the perfect stage for both the passenger and driver... unless you have one speaker in the middle of the dash.
 

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demon2091tb said:
Ok dang that means alot, But any way you could put "Early High Amplitude Reflections" into laymens terms.

I have noticed some differnces using TA/not using TA on my tweets. Soundstage seems much wider not using TA, but i feel like i'm missing the center image by not using it, but by using the TA on my midbasses i can get a firm midbass/midrange image in the center of my dash, but not for both seats, as if i take the TA off my midbasses it sounds very one sided, and that may be the problem with going 2way and having good imaging, as the midrange and midbass need to be either in/out of phase or vise versa to get the best sound for each seat. I'm sure i'd need someone who actually knows what there listening for to sit in my car and tell me if its any good or not. I mean i think it sounds awesome, from a tonality standpoint, but just the imaging throws me off sometimes on whats supposed to be right and wrong. Would like to have both front seats sound really good, not just the drivers or passengers, as if i was demoing the car, there passenger seat would sound like ass and he drivers be completely awesome.....would rather have both be aweosme.
When you measure the frequency response in the car, make sure to include early reflections that are pretty "loud". Your ear tends to lump those into the original signal which affect tonality.
 
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