Hi all,

I'm working on a design for 3 18" BTL's for a jeep grand Cherokee, the hard part about this is that he wants to run the vehicle in the "no wall" class for db drag, meaning that you cant have any part of the audio above the window line. so this creates a space issue. he also is going to be using about 6 Power master D3100 batteries. so that takes up some of the space. the space we have to work with is 66" deep x 43.25" wide x 18" or under tall. now the batteries (which will be connected with buss bars) will be in front of the box. this will take about 14 inches of the depth, so that leaves us with 52 inches. now if you try to port firing backwards that takes away another 10-15 inches for the hatch to not block the port or act as an extension of some type. so thats where i came up with if we can port upwards we will gain that extra 10-15 inches back and can get more internal volume for the box. now im basically asking the box designers out there, "what would you do?". i will be working on getting a 3d model/drawing completed here in the next hour or so, i just wanted to post this before i started working on it.

Thank you for your time,

Anton Miller

hmm... subs up port back always tends to be the typical best for suvs.

You can run as little as a few inches from the door, doesnt have to be a foot or more back.

Also, if u still prefer not to do that, when porting up, make sure it's all the way at the back of the box and pretty f'in wide!

You may also wanna attach some pvc to it so u can flare the port.

I just did the math on the box size.. it's not large enough for 3 18s to be efficient for competition.

However... if u line all the batts down the side, depth-wise, you will gain almost 3 full cuft!

I recommend doin that then staggering the subs up top so they fit.

ok, it took me longer than expected to try to fit these bad boys in there, but in the end of all this, i got 14.5 cu ft tuned to about 34.25 hz, after all displacements.

the port is 5" x 41.25" x 18.26", we will be using 1" mdf (could we use .75"?) double baffle on top (2"). the 3 subs will be equally spaced in a triangular fashion, on a 19" diameter "bolt circle".

now my questions are, how big of a difference will porting up be compared to porting back? what would/could be effected?

if i missed some info please let me know.

You could try CRX style box, i'm not quite sure how it would work in an SUV

u would want at least 18cuft net to work well.. otherwise, u gonna want to run 12kw or more because the space u have to work in isn't all that big.

Besides.. why tune so low? this is for competition, not daily.

u would want at least 18cuft net to work well.. otherwise, u gonna want to run 12kw or more because the space u have to work in isn't all that big.

Besides.. why tune so low? this is for competition, not daily.

mainly daily, just wants to compete in the no wall class when there is a comp. not too many competitions around here in mn, maybe 3 a year for db drag. and i think he peaked low, like 38-40 hz some where in there, so maybe tuning low wont hurt that much? we do need to figure out where he peaks though. and hes going to be using either the AQ20K or 3 AQ 3500.1D (new style)

i recommend 3 of the smaller ones.

easier to sell

Anyways, it's not normal to peak that low, something's wrong there.

Most suvs peak in the high 40s. Get a sealed box in there and find out what his peak is.

It'd be better to find his cabin gain throughout the entire legal metered frequency range because the car's peak isn't the only frequency u can get loud with.

i recommend 3 of the smaller ones.

easier to sell

Anyways, it's not normal to peak that low, something's wrong there.

Most suvs peak in the high 40s. Get a sealed box in there and find out what his peak is.

It'd be better to find his cabin gain throughout the entire legal metered frequency range because the car's peak isn't the only frequency u can get loud with.

the only thing i dont like about running the smaller ones is that you would almost have to match the gains wouldnt you? or put each sub in its own chamber so they dont get any sort of cancellation. but i agree about the resale factor. ok could you possible draw a picture or somthing about how you where thinking about doing the batteries (along the side) cause im not seeing it gaining 3 cu ft, so im thinking that i dont have it visualized correctly.

just do the math man, trust me, it gains volume. Subtract 14" from the width and max the depth out, WALA!

If u dont know how to gain match their amps, here's an easy way-

Hookup ALL 3 remote gain controllers and keep them plugged in for obvious reasons below-

turn the gains on all 3 amps up ALL THE WAY.

Keep the gain on the remote controls on all 3 amps all the way DOWN.

Now in sync, start by slowly turning up all 3 amp's remote gain knobs on a test tone until they all clip at the same time.

that's an easy way for you to gain match them close enough.

just do the math man, trust me, it gains volume. Subtract 14" from the width and max the depth out, WALA!

If u dont know how to gain match their amps, here's an easy way-

Hookup ALL 3 remote gain controllers and keep them plugged in for obvious reasons below-

turn the gains on all 3 amps up ALL THE WAY.

Keep the gain on the remote controls on all 3 amps all the way DOWN.

Now in sync, start by slowly turning up all 3 amp's remote gain knobs on a test tone until they all clip at the same time.

that's an easy way for you to gain match them close enough.

is there a way to use one knob for all three? and i have an o scope, would that be better for doing it then using the clip light on the amp?

also that still doesnt make any sence, if you take away 14 inches for 66 inches compared to 14 inches for 43.25 inches, the 66 inches is going to be a greater displacement than the 43.25. without batteries its:29.734 cuft outside dims, with batteries up front its:23.427 cuft outside dims, with the batteries on the side its: 20.109 cu ft outside dims.

another way to try to squeez every last cu ft out of this, could we use 3/4" mdf instead of 1" mdf? just trying to get within Fi's specs of 5-10 cu ft per sub.

dang this is just a mind teaser.

here is the false floor that he built, it has the dims on it and everything. but its 18" high is the tallest from what he tells me, i havent actually gone back to take a board and see if the subwooferes surround is at window line or not.

also i told him to put the batteries where the back seat persons feet would be, but he didnt like that idea for some odd reason.

couldn't you install the batteries under the rear seats? the D3100's aren't too tall.

you could try to squeeze some extra space out of that

or try the Sundown Audio Nightshades as they prefer 4-5cuft boxes per sub for the 18's

couldn't you install the batteries under the rear seats? the D3100's aren't too tall.

you could try to squeeze some extra space out of that

or try the Sundown Audio Nightshades as they prefer 4-5cuft boxes per sub for the 18's

rear seats are gone, and hes set on the BTL's, i told him to try out the smd's when they come out or the 21" wardens. but he wants a btl. which i dont blame him, cuz i want one too. lol

he could make an underbody battery rack like smd did

he could make an underbody battery rack like smd did

he mentioned that, but i dont believe we posses the skills to fabricate such a structure, and in mn we get some pretty nasty snow and rain, and the government likes to put salt down which might corrode the battery terminals or the rack itself. just so many possible solutions, ill have to consult with him later and see what he likes best for a solution. thanks for all your suggestions. keep them coming.

sorry man, you're right, i subtracted only 4 instead of 14 when i was thinking of batts on the side... oops!

how bout this!!

Put the batts in front of the box like planned... but side to side, width-wise.

You will only be able to fit 3 side by side... so he will have to build a rigid battery rack to hold the other 3 on top of the bottom 3.

this will still keep him below the 18" mark as well!

The width of the batts would be the depth and that displaces 7" so lets say 8"

so that would be 58"x43.25"x18".

Using DOUBLE layered wood 3\4" thick for both sides, front, rear and top(bottom single layer), i come up with- 20.17cuft GROSS

There's your extra 3cuft.

sorry man, you're right, i subtracted only 4 instead of 14 when i was thinking of batts on the side... oops!

how bout this!!

Put the batts in front of the box like planned... but side to side, width-wise.

You will only be able to fit 3 side by side... so he will have to build a rigid battery rack to hold the other 3 on top of the bottom 3.

this will still keep him below the 18" mark as well!

The width of the batts would be the depth and that displaces 7" so lets say 8"

so that would be 58"x43.25"x18".

Using DOUBLE layered wood 3\4" thick for both sides, front, rear and top(bottom single layer), i come up with- 20.17cuft GROSS

There's your extra 3cuft.

i like this one alot! all ill have to do is tell him to use wires instead of buss bars to connect the batteries (which i dont think would effect anything voltage wise). and ill have to take a trip up that way once he rips everything out of the truck to start the rebuild and see how much MORE room we can squeeze out of this thing. im going to update my model and see where the new dimension puts us at with the port and all in there and ill post the new results. again thanks alot.

just thought of this if he still want to use buss bars, if we lay them on there side and stack them on top of each other i think we would gain some room as well. ill have to look up the width height and depth of the batteries to find out how much.

i would ONLY suggest using buss bars IF you already have them...

If you do not, just use wire! It's a LOT cheaper, trust me!

I just spent over $100 on 3ft of copper bar that's rated @1,750A continuous.

Plus u have to use anti-oxidant grease on all connections, that's more money...

Unless you are trying to run more than 19 connections, he doesnt need buss bars.

those D3100s can accept up to 6 ring terminals per post.

i would ONLY suggest using buss bars IF you already have them...

If you do not, just use wire! It's a LOT cheaper, trust me!

I just spent over $100 on 3ft of copper bar that's rated @1,750A continuous.

Plus u have to use anti-oxidant grease on all connections, that's more money...

Unless you are trying to run more than 19 connections, he doesnt need buss bars.

those D3100s can accept up to 6 ring terminals per post.

he does already have buss bars, iirc they are .5" thk aluminum ones.

alright, i updated my model, i used 57 inches for the depth. i ended up with 16.35 cuft after displacements tuned to ~35hz. giving us 5.45 cuft per sub. port changed from 5" wide by 41.25 to 5.5" wide by 40.25 to accommodate the box size change and wall thickness change. i did what you said shizzzon and did double wall 3/4" mdf all around except for bottom and port outside wall are single layer.

just do the math man, trust me, it gains volume. Subtract 14" from the width and max the depth out, WALA!

If u dont know how to gain match their amps, here's an easy way-

Hookup ALL 3 remote gain controllers and keep them plugged in for obvious reasons below-

turn the gains on all 3 amps up ALL THE WAY.

Keep the gain on the remote controls on all 3 amps all the way DOWN.

Now in sync, start by slowly turning up all 3 amp's remote gain knobs on a test tone until they all clip at the same time.

that's an easy way for you to gain match them close enough.

A dmm is cheap and safer alternative to gain matching by following the clip led.

OP : I've seen the setup implemented before in a Grand. IIRC it peaked low. He is going to fight against the odds if he wants big numbers together with a low tune. Try and implement some port inserts to be able to tune higher when needed

On those aluminum bars-

if it's 3" wide or more, those bars are capable of at least 1150A continuous using typical aluminum alloy.

If it's 2" wide, expect rating to be somewhere in the lower 800A continuous.

On those aluminum bars-

if it's 3" wide or more, those bars are capable of at least 1150A continuous using typical aluminum alloy.

If it's 2" wide, expect rating to be somewhere in the lower 800A continuous.

First off I would like to thank you and Anton for helping me out because this is my build.

Also right now my buss bar is .5'' thick x 2 inchs wide. But my new ones for the powermaster will be 3inchs wide x 1inch thick

Btw the alum flat bar for 3x1 cost me only $30

Edited February 15, 201015 yr by 08 Jeep Grand Cherokee

just do the math man, trust me, it gains volume. Subtract 14" from the width and max the depth out, WALA!

If u dont know how to gain match their amps, here's an easy way-

Hookup ALL 3 remote gain controllers and keep them plugged in for obvious reasons below-

turn the gains on all 3 amps up ALL THE WAY.

Keep the gain on the remote controls on all 3 amps all the way DOWN.

Now in sync, start by slowly turning up all 3 amp's remote gain knobs on a test tone until they all clip at the same time.

that's an easy way for you to gain match them close enough.

A dmm is cheap and safer alternative to gain matching by following the clip led.

OP : I've seen the setup implemented before in a Grand. IIRC it peaked low. He is going to fight against the odds if he wants big numbers together with a low tune. Try and implement some port inserts to be able to tune higher when needed

What year was that jeep. Each one is different. Even with the same year some will peak higher or lower then others. Just by 1 bad weld spot all the way to a lose bolt can change everything.

hmm... subs up port back always tends to be the typical best for suvs.

You can run as little as a few inches from the door, doesnt have to be a foot or more back.

Also, if u still prefer not to do that, when porting up, make sure it's all the way at the back of the box and pretty f'in wide!

You may also wanna attach some pvc to it so u can flare the port.

I just did the math on the box size.. it's not large enough for 3 18s to be efficient for competition.

However... if u line all the batts down the side, depth-wise, you will gain almost 3 full cuft!

I recommend doin that then staggering the subs up top so they fit.

iv tryed this. moved my subs up port back box from 5 inchs away to 12inchs and was away louder.

yea buddy like we said next step is to find out where you peak, gotta turn that box of yours into a sealed box and figure it out. that place down in mankato may have a TL that we could use till i get mine. im going to look into it.

also we could move the subs around to find out where the best placement for the subs would be and try to optimize the design, this may take building a sealed box for one of the 15's you have...

Edited February 16, 201015 yr by Anton Miller

yea buddy like we said next step is to find out where you peak, gotta turn that box of yours into a sealed box and figure it out. that place down in mankato may have a TL that we could use till i get mine. im going to look into it.

also we could move the subs around to find out where the best placement for the subs would be and try to optimize the design, this may take building a sealed box for one of the 15's you have...

sounds good. 1 problem though. That amp was my buddys and I just installed his system yesterday