Bandpasses in Modified classes

Hey Im new to usaci but I have competed for many years mostly when I lived in Florida I used to run Iasca and DBDrag classes..Since moving back to Texas all I see is ported walls..I know they work but was wondering if there is anyone running a 4th order in the Mod classes??

Team tiny. In street beat

Ya I should have elaborated more for SPL..

He is street beating a 160 with it. That's splish lol.
Haven't ver remember any at finals in mod.

Just out of curiousity, is there a name for Danny Hays' "box in a box in a box" style?

Quasi-4th order?

I'm sure others have attempted it... but it's pretty innovative (yet simple). Car is relatively sealed. A wall is used to manage the "cab" vs "trunk" dynamics. The sub is placed at the opposite corner to the port.

I guess the theory is to use the sub to generate a local pressure source, and unload safely. The resonance of the rear chamber causes maximum pressure at the port... which resonates the front chamber (Bernoulli flute style).

I'd rock a similar design in mod, but that's just me. Walls have less parameters to juggle (neither is easy to get loud), but I like elegant solutions.

Youll see some soon. Beau boran has one. As well as a couple in the works. We atarted one for 0-1 last year but things changed. Definitely go for it

Hmmm. I guess if you wanted to take it 1 step further, you could look at where the losses occur in that type of setup.

My guess is the rear chamber could be re-thought, since the front area is well-defined in the rules. A sealed horn enclosure (basically a Port Wars box) seems like the ideal choice for maximizing woofer control and the energy delivered to the front chamber. Transmission line and various tapped horns would be slightly more efficient, but it would add complexity without the guarantee of cone control.

This train of thought is leading to very expensive ideas (like when I built a CRX shaped shell inside of my RAV4...)

What elements make up the perfect port wars box?

I have always used ported walls but Im using a Bandpass now for 2 18s in my 2 door blazer..The shell is huge and practically takes up the whole truck..The design I have I have tried 4 18s but did not work it sounded incredible and had a very wide pass band but sucked on the meter..With the 2 it was right off the bat 3 DB louder than 4...After finals down here going to rebuild the entire truck..

So the four failed? Man, it looked promising.

Found this old thread with some example pictures for 4th and 6th order.

LINK

They suggested that 6th order, with both partitions on the same side may be the loudest. Alot of experience crammed in that thread.

It seems like a relatively small box + lots of room for the front-wave to expand = efficient power transfer to the B-pillar. Obviously, box size should be dictated by woofer excursion limits and minimum impedance rise for amp turn-on. Start small and make it as big as possible.

My main question is how to tune the B-pillar port. Ballpark figures... will be slightly below the cabin gain peak?

chapdawg1971 wrote:

So the four failed? Man, it looked promising.

Ya it was doing a 157 at 30 hertz so it wasnt meter friendly..I have been messing with the 2 subs again and its looking pretty promising..

4th orders are kind of tricky...but once u figure out how to tune them they are easy....i build tons of them...mostly in cut threws....4 10s is one of my favorites....most of them are on lower pwer so only doing mid 150s....as for tinys its 4 15s in a wall...still needs to be tuned but its pretty loud SB 160s and burps 163 on lower power its self.....only down fall to a bandpass that if drops when opening a door...but overall....u need big power and a solid box and alot of time to tune it.

When I competed in Iasca Bass boxing it was a 3 round average..First round sealed second 1 door open 3rd round both doors open..The ported walls would do well sealed up and than 1 door open but would lose their ass with both doors open..All the winners in that class all use 4th orders they would maintain their higher avaerage..Here its 1 door open so Im trying to be loud with a bandpass instead of the usual ported wall...

i did bassboxiung this year!lol came in second in lightweight with 2 12's.lol but you are right all the middleweight and heavyweight guys run 4th orders who are at the top flat walls fall on their face both doors open but a properly tuned 4th order with keep subs from unloading. moonie you should check out steve mick's van its the nastiest 4th order ive ever seen 161+avg sealed up 30 sec 162+ avg 1 door open and 158 or so both doors open for 3 rounds just nasty and jarod gibsons jeep is not far behind he still falls off a good bit both doors open but is def louder 1 door open. use to be diff when they had blockers but now with no blockers and doors wide open lots of people findin out their setup wasnt as good as they thought.lol

Interesting. Did you ever run across people who tried to tune for both occasions? I would imagine that you'd get some creative designs.

Down the rabbit hole I go:
I like to think about boxes from a "lumped capacitance" perspective. Simplify things, and convert them into a physical system or circuit. Air that never leaves the speaker box is effectively a spring (capacitor). Air that moves through the port is a mass (inductor). Losses such as heat and cancellation are considered dampers (resistors).

SPL boxes are typically smallish, with lots of port, tuned high. In car terms, that's a Mazda RX-7 ... stiffly sprung, low weight, and (given its weight) inefficient. SQ boxes are larger, with modest sized ports, tuned low. That's a Chrysler 300 ... soft springs, heavy, (given it's weight) fairly efficient.

For the Bass Boxing example, you're tuning the bandpass to operate well on the track (sealed) ... then driving a little slower on the street (outlaw). Progressive springs, MR dampers, and adjustable ride height allow cars to be great in both environments.

Similarly, I imagine loading walls are progressive springs. Multiple port tunings (and diameters) are MR dampers. Competition rules don't allow us to modify the setup similar to ride height adjustments.

How well have ABC boxes, 6th order, 8th order, and other multiple-tuning setups succeeded in Bass Boxing?

moonie is right on his last parts you def need lots of time and knowledge to get it right i got alot of friends that run them and most of them that are loud now took a good year or so to get it where it is.lol i know steve has rebuilt that van he has so many times he knows everything about it hell even his team does.lol same with jarod has done alot of stuff to that jeep over the years to get it where it is

thre are not alot of them man you way over analize stuff.lol all the top guys have 4th orders not many have 6th orders for bassboxing. i know steve plays 3 diff songs for his bb and bb is all 3 rds mic on the dash you just get 1 dr open second rd and 2 dr open 3rd rd. i did sb and bb at finals this year and just ended up using my sb cd because i couldnt find something to work good for bassboxing without modifying my setup for sb which i didnt wanna do at the time

basically its all out for the first 2 rounds in all classes then trying not to launch subs in teh final round.lol

here are all of micks bb rounds at finals.lol

https://www.youtube.com/watch?v=KELLAYoyvWc

https://www.youtube.com/watch?v=QDKVATq4vOE

https://www.youtube.com/watch?v=j21-lI_WKeg

and just for fun here is his 142.2 pnp 30 sec avg 6ft outside the window.lol
https://www.youtube.com/watch?v=_vdtu3OPZcY

and my bb run for fun.lol
https://www.youtube.com/watch?v=_3ULgJcY5D0

Good stuff. I'll check the links once I'm out from behind the firewall.

I definitely overanalyze things, but audio is a great outlet for creativity.

Sounds like the track car analogy is right on. Drive your Formula D RX-7 on the track... then an autox... then in rallyx. You'll be buying alot of parts if you don't slow down.

random thought: Progressive spiders on a passive radiator might get the job done... if you have way too much $$ and free time.

BP has to be HUGE to reach good efficiency on a wall setup, and once you get there you have the advantage of a 100% "recyclable" setup. You can easily change sub size, quantity, etc.

i know there will be quite a few in usaci this year.lol

muriloalvares wrote:

BP has to be HUGE to reach good efficiency on a wall setup, and once you get there you have the advantage of a 100% "recyclable" setup. You can easily change sub size, quantity, etc.

I agree I love them..

muriloalvares wrote:

BP has to be HUGE to reach good efficiency on a wall setup, and once you get there you have the advantage of a 100% "recyclable" setup. You can easily change sub size, quantity, etc.

Should be good room in the astro huh?

Astro I'd do a floor cut and build as wide and tall as possible. It really has to be huge, you must be able to walk inside the box, sit down and have a coffee.

Well cant cut the floor lol. Id consider beau boran having good luck. Maybe not full bandpass potienta.but decent. 10 incriminator 40.1 and 5 15s was over 170 in.ss 5+ in his toyata. But i figure about 55+ cubes available in the astro. Not quite tall enough to stand though

you drag guys and your floor cuts.lol thats a nono in usaci.lol

oh nevermind then, I'd stick to a regular wall.

Hmm. I really figured even though its not the potential of a full floor cut that even the 55+ cubes in an astro would still be better than a wall. Was thinking 6 18s lol

has to be wide and tall, the depth isn't really super important (unless you build for music)