keith77

Id do 4 cubes tuned to 30 hz. Sub facing up, the port facing back. and 64sqin of port. Just wondering does your back window rattle bad, my buddy has a blazer and the back window sounds horrible.

01 Tahoe, its about 22 square inches of port area per cubic Right now its sub up port back, port on the passanger side. and the box is diangle loading up on the passanger side (give it some more room until i move my batteries) Your port is way too big. 14 sqin per cuft is about what you want. It took me a lot of trial and error before i got my BTLs to sound like I wanted them to.

I recently upgraded to 2 BTL 15s from a 2 Qs. In a nutshell im having the same problems that i was having with the Qs, Overexcursion. I am running a MTX TA81001 to each sub, only 1500 watts. The total volume of the box after displacements is 8.5 cubes, port is around 100sq inches and is tuned to 32hz. SSF is set at 30hz, HPF is set at 150hz, Bass boost is set at 0, and volt meter reads 38 volts which should make the amp put out 1500 watts. I went to my local shop (Pure Pressure Audio) where everyone who works there runs FI. They said i need 6 or more cubes for each speaker, and my box is causing them to move as much as they are. I built the box to FIs specs and it doesnt sound right. Can anyone help me.

Ive decided to build a new box. This time im going to tune at 30hz with a lot bigger port area, maybe this will fix some of the problems im running into. I think speakers facing forward sound the best also but i would lose about 2cuft of airspace to give the subs clearance. I appreciate everyones help and i will keep you posted as to how it goes. Thanks, Keith

The frequency where it starts sounding sloppy is around 30 hz, but When i am sitting inside with the trunk closed it sounds good. the speakers are about 5 inches from the lid. Should i try a new box with more port area?

I finally got some time to mess with the port. I tuned it down to 32hz like it was before. It sounds like the speakers are bottoming out, but I got another shop to look at them and they said it is not overexcursion, just distortion. He turned down the Xover to 80hz and he turned the gain down and it sounds a little better. The dustcaps have never got hot or smelly, the speakers just sound really distorted when i listen to them with the trunk open at 25- 30hz. When i sit inside the car it all sounds musical, 30hz is loudest (really loud) and the higher the frequency goes the weaker the bass is (60hz being not very loud). 30hz tones dont have as much excursion as the higher tones but they sound like they could be damaging the speaker. Higher tones 35-50hz sound much cleaner and have hardly any distortion. I have had audiobahn eternal 15s and Kicker L7s in a jeep cherokee and they never sounded like this, even with the back door open. Is this how they should sound. I dont want to keep playing them like this if something is wrong. Now for the the box setup. The speakers and port are facing straight up towards the trunk lid. I know everyone says to face them back, but my last box was facing back, forward, and up and i didnt notice much of a diference. So i wanted to maximize my trunk space and have the box as big as possible. The external dimensions are H23xW24xL38 and the wood is .75" thick which makes the internal volume 10.22cuft before displacements. About .5cuft for both the speakers and .1cuft for bracing. My port is a straight slot port 4"x 22.5" with a 18" length, So that makes the port displacement 1.11cuft. The total box volume is 8.5cuft after displacements (4.25 for each speaker). The only thing that might have messed me up is carstereo.com, the calculator i used to get my tuning. Scott, Nick, or anyone who has had similar issues, if you could please look over my calculations and help me resolve this issue im having, i would greatly appreciate it.

But this was a 4cuft box tuned to 32hz on half the power that everyones running. Do i need to keep tuning lower to get it to handle the music im feeding it. The other shop i went to said it sounds fine, that its just how the speaker sounds.

I feel really stupid for posting this and im sorry for wasting everyones time. I went up to the shop and they told me there is no way btls could bottom out with that power. They said they are bottoming out because i am listening to them with the trunk open and there is no pressure coming from the trunk lid. This is the first system ive ever had in a car and i felt like an idiot when i realized how much sense it made. the inside of the car sounds rediculous and these are some of the best speakers ive ever heard. I appreciate everyones input.

Thanks for all your help, ill keep playing with it untill i figure something out.

Im not sure what clamped means. I played a 50hz test tone at 0dbs when i set it with a meter. I cut about 6 inches off the port to see what would happen and it only made the problem worse (higher excursion on a 30 hz tone). It seems like the lower the tuning the less it moves on lows. should i try tuning at 30hz.

Yes, low pass filter. No, they dont have a scope. none of the shops have a scope, they all told me to use a volt meter.

Ive got 2 BTL 15s and i wanted to make sure my calculations were correct before i started building. The total room i have to work with is h=23 w=24 l=39inches. Total internal volume is 10.5 cubes, and after all displacements i have 8.65 cubes. the port dimensions are h=22.5 w=4.5 l=18.4 which should make the box tuned to 33hz. can someone check this for me to make sure i didnt make any errors. Thanks Keith

Theres a formula but its kind of confusing. I went to carstereo.com, they've got port lenght calculator. Just plug in numbers and it will tell you how long your port should be for the tuning you want. I dont know if its accurate, thats why im tryin to get some help from the pros.

Everyone says Excessive Amperage is one of the best but theyre expensive. I was quoted $500 for a 300 amp alternator, but you never hear bad things about them. You can go to excessiveamperage.com or realmofexcursion.com where they have a forum.

I could care less about mid bass also. i do like a sub that can get loud at both 30hz and 60hz, wich is what ive seen from the BTL. Most music doesnt get recorded at 20 - 30hz unless its chopped and screwed, and thats where the Qs shine the most.

Im not putting down the Q by any means. Ive got 2 Q15s w/BP powered by 2 MTX 81001s (1500 watts each) and its too much for them. The problem i ran into is overexcursion and for me they didnt get as loud as i wanted them to. They do hit lower than most speakers ive heard but they lack on the higher notes. Why not get the full potential out of your amp and get the BL or the BTL. If you do get the Q ask if they will make it with a stiffer spider to keep it from bottoming out.

Both the Qs and the BLs could handle that amp, its 4000 watts to 4 speakers (1000 watts for each). I think the 4 BL 12s would be the loudest and they would sound better than the 2 BTL 15s. The Qs would sound the best but would not be as loud as the other 2 choices.

If you buy the FI Q you will be making a $400 mistake that u will regret. You want to go with the BL or the BTL. Im not just running my mouth, im speaking from experience.

Dont get the Q's, you will be disappointed. They still get loud and drop really low but 1500 watts for a Q is too much. Ive never heard the bl's but i heard 2 btl 18s on 1500 watts each and they were way louder than my Q15's on the same power. I dont know what DBs they were hitting but it was really uncomfortable to sit in for too long.

After hearing a BTL for the first time yesterday i have decided that i want one, really bad. I will only be pushing 2000 watts to each sub in a daily setup (no comps). Is there any point in getting the high XMax coil, does this loosen up the suspension for better SQ. the BTL that I saw was only getting 1500 watts and didnt seem to flex much so im not sure if the high xmax coil would really do anything. Thanks, Keith

Thanks for the help, putting in the order right now!

what about the third slug, would that have any effect on the speaker.

Hi, i currently own the Q15s w/BP. The SQ is exellent but i would like more output. I have heard BLs dont get a lot louder than the Qs and the BTLs are way louder than both. My question is... Would the BTLs get louder than the BLs on 1500 watts. I dont see anyone running a BTL on 1500 watts. Also, the amps im running are MTX TA8001 1500 watts at 1 ohm (birthsheet says around 1900 watts at 14.4 volts so im might be getting around 1700-1800. Thanks Keith

Maybe ill mess around with the box a little bit before i go sellin them. Ill let ya know how it turns out. Thanks everyone.

Box is around 3.4 cubes for each sub tuned to 29 hz. I have to keep the amps turned down to avoid popping from over excursion. I did have them tuned to 32hz but the lows wern't hiting like i wanted them to.