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Discussion Starter #1
Does anyone know if there is any time alignment going on in the gen 3 JBL system? I'm looking at the distances involved between the various speakers in the vehicle and if my calculations are right (which they may not be) if all the speakers are in phase and not time aligned, there would be fairly significant destructive phase interference around 60-75 Hz right about at the driver's seat. The drop in perceived bass would seem to match that. Also I tried listening in the driver's side second row seat and the bass sounded much more solid. If my calculations are right (again, they may not be), I think that switching the polarity on the sub would make things better for the driver's position. Has anyone tried this?

I'm very tempted to set up a few microphones and take some measurements to see if there's any delay in the speakers. If I do I will post what I find--but if anyone's done this or knows if there's any time alignment going on, I'd be very interested in that info.

Thanks!
 

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Lol, I have called JBL! Recently in fact. They are not as informed as you may think!!! Yoy get someone who knows how to answer a phone and look up information thats already available to you. I love that you seem to have taken my response personally. Lol. "Kid"😉. The OP has a legitimate question and your response is "hey call the manufacturer. 🤣🤣. Maybe this is a question that can be asked in an audio section in this forum rather than here? Calling people names and answering questions with ridiculous answers sounds more like an a$$hole move to me👍😉



lol? yeah, lol alright. first off, i ain't calling them and asking them "did you design your system incorrectly", and that is NOT what the op wants to know anyway. so fell free to run that answer down yourself, kid.

second, don't bother to lie to us by stating you have called jbl to ask about time alignment in your hl jbl system (or any other question you can make up), and just admit you have absolutely NO idea what jbl will or will not tell anyone that calls them with questions.

finally, YOU would be surprised what can be learned by picking up the phone and calling a company or manufacturer and asking them a few questions, while not acting like a$$hole.
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Discussion Starter #5
So, I made some measurements. I placed microphones about 1” from the sub, 2nd row drivers side door and driver’s side front row door speakers. I then ran an 80hz test tone through the system while recording the three mics.

There appears to be no delay between the front and 2nd row drivers side speakers. There’s about a three ft distance between each speaker and my head, so that’s good. The system appears to delay the sub channel by about 5 ms.
319950

This looks like it puts the sub almost 180 degrees out of phase with the front/2nd row seats.

But, the sound from the sub takes about 8ms to cover the 8ft from the tailgate to the driver’s seat and the sound from the front and second row door speakers takes about 3ms to cover the 3ft from the speakers to the driver’s ear. Factoring those distances in it looks more like this:
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The sub signal looks about 90 degrees out of phase here.

So, at least at 80 hz it seems like it’s not great but not as bad as it could be. It also means that reversing the sub’s polarity won’t make anything better, at least at 80hz anyway. And then there’s the effect of being in a closed space, etc. At least we know that there is some time alignment going on, though I’m not sure what is actually being aligned with what.

In addition, I also measured the L/R delays. It looks like the front passenger speaker is delayed 3ms from the front drivers side. Interestingly, the second row drivers side is delayed by about 2ms from the second row passenger’s side. I’m not quite sure what that achieves, but it is definitely there.

So one takeaway is that, assuming the tile alignment is done in the amp and not the head unit, buying an aftermarket head unit with time alignment makes sense only if you’re also planning on replacing the amp. If you’re planning on using the JBL amp, you’re probably better off with making sure you have a good EQ in the head unit.

Interesting stuff.
 

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Lol, I have called JBL! Recently in fact. They are not as informed as you may think!!! Yoy get someone who knows how to answer a phone and look up information thats already available to you. I love that you seem to have taken my response personally. Lol. "Kid"😉. The OP has a legitimate question and your response is "hey call the manufacturer. 🤣🤣. Maybe this is a question that can be asked in an audio section in this forum rather than here? Calling people names and answering questions with ridiculous answers sounds more like an a$$hole move to me👍😉
rude personal remark deleted.
Infraction served.
Please, stay civil and respectful of other posters.
 

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Out of curiosity. Do you have an oscilloscope that could record frequency sweeps or just a series of static frequency plots. This would be a great way to determine if channels are outputting full range signals. I’m thinking about tapping a signal from my rr door to put a small sub under the passenger seat.

My background is more scientific (not audio) and I would think a scope tapped into the speaker terminals giving electrical signal plots would be the way to do this since the speakers certainly wouldn’t give a linear profile down to 20Hz or so.
 

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Discussion Starter #8
I don’t have an oscilloscope but I could do another mic setup with a different mic that’s better at low end. I’m certain the rear door speakers’ response will fall off. If we get down into the 30hz range I would be shocked. That’s actually pretty deep as small full range speakers gi.
 

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All this information is great. I do not have the JBL system, but I've added the tailgate speakers and am using audison amplifiers to adjust everything. I know I do not have them perfect, but it still sounds pretty good, but I got some more adjusting to do. My problem area would be the second row. It doesnt have as much bass like the front or 3rd row.
 
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