mikee72

I noticed something today that I thought might be interesting to people wishing to upgrade their SC Pioneer/Premium system. I was playing with the fader while listening to a Jean Luc Ponte tune that has a very pronounced and punchy kick drum. It is quite apparent that despite the fact that the front and rear speakers are identical, the rears would go ~3dB louder than the fronts before distorting. Unless there is a difference in the cutoff frequency between front and rear, it would certainly seem like the stockers "prefer" the sealed trunk to the probable infinite baffle door mounting. I haven't taken the door panel apart yet, but it certainly would seem that some improvement in response could be gained by building some sort of solid enclosure for the speaker to sit in. (Not a foam baffle) After A/B-ing the front and rear, it's easy to understand why people think the rears are 6 1/2's.

FireCode

iTrader: (1)

Um.... the rear speakers are not sealed. They are free air, I.B. the front speakers are in there own ported enclosures.

mikee72

Um...the rear speakers in *my* car are inclosed by a trunk. Do you not have a trunk lid?

Granted, the enclosure is huge, but there obviously is some acoustic suspension effect going on, at least with the sub. If the front enclosures were more effective than the rear setup, how do account for the difference in frequency response?

FireCode

iTrader: (1)

Your missing the point here man...You can dial down the sarcasm a little bit. The rear 4 inch speakers are installed in a free air setup. When people want to replace the stock 10 by using the factory locatio, what do they look for? In most cases it is the JL Ib4 (infiite baffle) The same applies for the 4 inch speakers in the rear deck. The front speakers are in there own enclosure that Lexus thought would be better suited for the front stage. What accounts for the frequency response? Obviously it is the enclusure or lack thereof( if you want to call the trunk as a whole an eclosure then go ahead) I wold assume it would be similar to installing say a DD 9514 in a huge ported box versus a small sealed box. The difference would be crazy loud low bass for the ported to not as loud at all and tight bass for the sealed. I havent taken a look at each 4 inch speaker for an exteded period of time but perhaps they could have also been built just a little bit differently

FireCode

iTrader: (1)

one more thing. when listening to your radio lean your head down to about the shifter area when it is in park and see if there is a difference. You will see what I am talking about. Placement and aiming of the speaker is not optimal for the fronts.

mikee72

I understand your point, that the setup is commonly referred to an infinite baffle, but given that the sub's output (and threshold of distortion) is effected by whether the trunk is open or closed, I thought that it's worth noting that that there's more going on here than just an IB. Now, I just did the fade test with the trunk open, and it appears that we were both correct. The rear mids seem unaffected by whether the trunk is open or closed, but the sub is substantially effected. Back to your "speaker construction" theory. My issue is, I have never read anything that suggests that the front and rear speakers aren't identical. The other obvious question is, if the 4's work better in an IB setup, why did they not choose to go a different (less effective) route in the front?

mikee72

I agree, but the early distorsion threshold is still there.

FireCode

iTrader: (1)

I have to fix a mistake first, I meant to say Digital Designs 9515 not 14.. Anyways, the sub will also be louder with the winndows down rather than up. Another weird thing about sound waves that is way too technical for me. I also have never read anything about the build beinng different, I just thought that they may have changed up the T/S parameters for the fronnts a little. It could be a possibility but unlikely. As for why Lexus didnt try to do something similar in the doors is an easy question. When you take off your door panel you will see that what they did with their enclosure is really nice. I dont think it was a possibility to make the door speakers in an IB setup. Not enough airspace and too much sheet metal around.

mikee72

Well, the reason why the sub is louder with the windows down is because you're reducing the pressure that the sub has to work against. This wasn't a variable in my tests, since I had the doors and windows closed when opening and closing the truck.
I have been studying the pics that RSTspeed took for his thread up top, and I have a pretty good idea of what the sheet metal looks like. It's the enclosure itself that I'm having a hard time with. It's difficult for me to see what he did to seal up the sides of the modded enclosure, since he only has a pic of the front and the back. I have always wanted a/d/s 346is's in the front, but 1. I'm not sure if I can effectively seal the two sides of the cone from each other, and 2. I don't know if the huge crossovers will fit in the doors. I know Dynaudio is the "Preferred" brand here, but I've never heard them, and the 346is's blew me away when I heard them.

FireCode

iTrader: (1)

Yea I too am having a hard time figurig out his re-work. The factory enclosure is 2 halfs as you know. He took off the top part. However there is a problem. The back peice of the enclosure is not flat. Say you had a basketball and cut in half, you now have 2 perfectly flat peices right. Well this isnt the case for the stock box. If looking at it from the side, it looks something like this

------\
lllllllll\
llllllllll\
lllllllllll\
llllllllll/
lllllllll/
lllllllll
lllllllll

simply laying a peice of wood ontop for your new baffle wont work. So yea, I would like to know more about how he sealed it up and such. And also you have to be real careful or the new speakers you just installed will probably hit against the door panel adding stress. I myself installed 5 1/4 oz speakers in the doors and as of now it is ghetto rigged. due to the fact that I wasnnt working with a flat surface. I will redo them very soo becuase 1. its ghetto rigged and 2. they are hitting my door panel. The best bet for you would be to go ahead and take off your panel and it will clear up some confusion. RSTspeed didnt show you the top part of the stock enclosure.

mikee72

I'm glad I'm not the only one who has pondered this issue. Search "6.5**" and you'll find some interesting posts, like this one from LexLuthor.:

https://www.clublexus.com/forums/sho...t=6.5%2A%2A%2A

..and...

https://www.clublexus.com/forums/sho...t=6.5%2A%2A%2A
https://www.clublexus.com/forums/sho...t=6.5%2A%2A%2A
https://www.clublexus.com/forums/sho...t=6.5%2A%2A%2A