Z1NONLY

iTrader: (2)

After repairing an ancient Rockford 12" and installing it in a ported enclosure in my daughter's car recently, I found myself missing the low end extension that ported boxes provide. (I was running a .75-cube sealed enclosure I built years ago with a JL 10WX sub.)

So I started playing with designs and found that I couldn't fit a round port into any of the designs. So I decided to try my first slot port.

~1.3 cube box that ends up around 1.1 once the port is subtracted.

The port is 1.25 X 8 X 25.5" (~29Hz)

The 1.25 slot support was giving me fits when I tried to drill them in place so

I recruited my retired custom cabinet maker father-in-law to help with the delicate port.

Here's how it went together....
First, the short end of the port.



After he helped with the delicate stuff, I took the project home to finish. I wanted to keep it as shallow as possible in case I ever upgrade to a W6. By using 1/4" MDF(for the top of the slot port), I was able to maintain a little over 8" mounting depth. Here is the completed slot port. (Finished before I brought it home)



Minimal fill.


Ready for carpet.


Ta-da!


Old Vs new.


Installed. (Wire clean-up tomorrow)



I really wish I had done this sooner. The response is flat way into the deep end, and it's considerably louder than the sealed box.

My software said I would gain 5db @50Hz. In real life, I think Bass Box Pro wasn't kidding.

Wow! This is the cheapest sub JL offers with ~120w and it's now about as loud or louder than the 10W3v2 I run in my work vehicle in a sealed box @180w. (And the WX plays lower)

kno

iTrader: (22)

wow thats nice, i would like to make one like this for the cubby behind the driver's seat

Mcutali

iTrader: (10)

woa really cool dude, id like to upgrade to this from my stealth zenclosure

My LT Won

not trying to be rude and i see it's your first shot at a ported enclosure but that's awful. you aren't even at the minimum amount of port area per cube. you should shoot for a minimum of 12sq inches per cube. also don't forget to subtract sub displacement. which obviously isn't much on that 10" driver. also why didn't you just make the port the full height of the box? instead of doing that goofy "tunnel" style port? it's obvious your not looking for much bass so i'm sure it's fine in your application but do some research for future boxes.

good to see people making there own boxes though.

Z1NONLY

iTrader: (2)

"Goofy tunnel"? Seriously? It's a slot port. You act as though you've never heard of it.

Not my first ported box. My first slot port. I've been doing car audio since the late 80's. I've done countless enclosures sealed, ported, bandpass, isobaric, IB...

The slot exits where it does because I wanted it on the same plane as the sub.

12" per cube? Really?

First, the maximum outside dimensions of the box were 22.5 X 14.5 X 10. (~1.3 cubic ft internal after the .032 driver displacement is subtracted, before the port.)

12" per cube > 15 sq port area. In order to get a tuning fq of ~30Hz (nice flat response) the port would have to be 46" long.

Where exactly would you like to put that port in this box?

Second, Vent air velocity isn't an issue with the 8 X 1.25 port until I get cone displacement over 15mm. The WX isn't capable of that. Even if I upgrade to a W6, I will have to hit it with about 700 watts @20Hz to make that happen in this enclosure. (And that's not going to happen either)

I'm sure "12 sq inches per cube" is a nice safe rule of thumb for you. If that's what you are comfortable with, fine. But it's prohibitive within the design specs I am working with, and totally unnecessary for my application. (If not most applications)

You obviously have no understanding of how this enclosure performs.

You have the outer dimensions of my box. I have practical reasons for both the width and depth, while the height was stopped at the top of the strut tower for aesthetics.

22.5 X 14.5 X 10, 8" mounting depth ....3/4 MDF.

Go dig up your list of one-size-fits-most generalities, you seem to use like a security blanket, and then tell me what design you would have used....

ntwillie1

iTrader: (3)

subscribed.

OP, nice work.

SuperBlack350z

iTrader: (59)

Good job, work looks classy

My LT Won

i was saying mainly for future builds. i love the stuff people post on here and then pretend they are experts in car audio. just because you have been doing something for a long time or worked at a stereo shop means nothing. i wouldn't let any local audio shop touch my car with a 10ft pole.

also people build tLines when they have a long port in a short box. look into it.

running 120watts on that sub in that enclosure i'm sure it's hard to hear the bass over the road noise in the car. so yes i know those other factors wouldn't help much. i think your confusing "flat response" with zero bass.

cool to see you doing your own work and box looks fine on the outside, but please don't pretend to have lots of box building knowledge.

Z1NONLY

iTrader: (2)

If I build anything in the future for this car it will be in the confines I already laid out and none of the crap you brought up will improve on the design I chose.

That's exactly what I was thinking when I read your first post.

Multiple successful installs, as well as many failed experiments, mean I know enough to discern the the difference between useful, application-specific, design elements and useless "rule of thumb" generalities.

"The minimum amount of port area per cube." That's cute, but utterly useless and irrelevant in my application.


So you're saying you really don't have a better idea? A wave guide in this application? Seriously.


You really have no clue.

I have enough experience with box building to know that the BS you wrote in your first post here is useless and even counterproductive in this application.

Bullitt5339

There's a lot of back and forth in this thread, but as an IDBL and NSPL Former World record holder, and a rep from one of the most successful car audio companies in DB Drag, NSPL and Bassrace in the past 5 years, I have to back dude up.

12 square inches of port per cubic ft. is widely recognized as being the minimum acceptable port area for slot port boxes. That's recognized across the industry, he's not just talking out his ***. 15 square inches per cubic ft. is where I like to start at when designing a box for music to be honest, and I will go down to 12 if needed for space concerns.

I'm not getting into a pissing match with anyone on here about car audio, because frankly, I've built way too many award winning cars in every series to waste my time.

Z1NONLY

iTrader: (2)

I never said he pulled the number out of his ***. I simply pointed out that such a number would have been detrimental in my application so his regurgitation of said number is useless.

The tire industry "widely recognizes" that tires should be replaced once they are down to the wear bars but, because I understand why that's the standard, I wouldn't be dumb enough to tell one of the guys at the track that they shouldn't race on such tires on a dry day.

I would be pissed if I built a ported enclosure with port area so small that it produced audible turbulence. 12 cubic inches per cube would sure help me avoid that problem in this application, but it would create far more problems. (Higher tuning fq, bumpy frequency response, less sub clearance for future upgrades)

I was careful enough to use enough port area to avoid the problem with this sub and a wide range of higher end subs at higher power levels.

I don't care if the audio industry would "accept" my port diameter any more than I care if the tire industry would accept me running my tires past the wear bars on a dry run at the track.

I understand the benefits of more port area and the downsides to less. But I had other design considerations and found port dimensions that allowed me to get the response I wanted in the space I had with the equipment I want to use, with no port flutter.

Bullitt5339

Again, I understand why you did what you did. Most of the time in car audio, especially working in a relatively small space, there are compromises you have to make.

Congrats on taking the effort, and as long as you're happy with the way it sounds, that's all that really matters in the end, isn't it?

Z1NONLY

iTrader: (2)

True, but if others read this thread and assume that bad things automatically happen if your port area goes bellow a "standard" number, it could make other DIY's lives' needlessly difficult.

If they can keep the vent air velocity safely bellow 33m/sec, they shouldn't have problems with port flutter. If they don't have the time to bother with a vent air speed formula (and don't have/can't calculate the sub's reference efficiency) or have access to software that calculates it for them, then the 12 sq in/cube standard is great.

My LT Won

no people will come here and see your garbage and think it's a good box and use your build as a refference then wonder why their stereo sounds like crap.

i do however preffer lots of output and that's how i build my boxes. i also don't run over priced jl garbage. i am also finding it hard to believe someone could be satisfied with your setup? can you even hear the bass over the road noise say on the freeway? i have heard a few setups like yours in multiple cars and it's a waste of space in my opinion.

not to mention that box internaly looks like a 5yr old built it. lucky for you the carpet hide the looks but it won't hide the sound coming from it to someone who has a clue about stereos.

Z1NONLY

iTrader: (2)

It sounds great and has considerably more output and flatter response than the .75 cube sealed enclosure I ran before I switched to this.

Now, unless you are suggesting that I couldn't build a basic sealed enclosure properly or that I can't tell the basic differences in response and output between the two, the fact that this ported enclosure plays louder and lower (with no port flutter) than the sealed enclosure means the port design worked as expected.

Then build a burp box and brag about SPL numbers. Two aluminum garbage can lids, banged together repeatedly, are loud, but that's not what I was shooting for.

The sub cost 70 bucks. It's worth 70 bucks.


I find it hard to believe that anyone can be this ignorant.

So you still don't have a better design do you?

My LT Won

i said nothing about a burp box. i like loud daily setups. i have 2 12" fi btl's in my z. tuned @34hz. still plays loud and low.

why would i offer and new design? you pretend to know it all or your "bass box pro" seems to have all your answers. do you have the first clue how to build a box without that program doing it all for you?

i have heard quite a few setups like yours that sound ok at a idle or with music playing with the car off but when road noise is factored in they sound awful and really leave much to be desired.

this section really is just for a good laugh on this site. that's why i continue to add fuel to the fire. it helps pass the time.

i'd love too see some more of your boxes that you have built. i might ask for your wisdom on my next box design.

Z1NONLY

iTrader: (2)

You're the one that said my design was "awful." and implied you could do it better. I gave you the design constraints and you have produced nothing.

I used pencil, paper, and formulas for years. BBP cuts design time way down and allows me to explore different ideas without investing too much time on each. I could dig up the old formulas and do it the hard way if I had too, but this software has nailed it every time, to the point where I trust it enough to "thread the needle" on things like vent air velocity. Better still, I can "see" the subs reference response over its entire envelope. Graphing that stuff long hand is a PITA.

I'm perplexed by this angle you are taking. If the systems "like mine" that you have listened to couldn't absolutely bury road noise, I can tell you they weren't "like mine." In fact, it's been a long time since I've heard a 10" sub setup that weak.

This single entry-level 10" with ~120w isn't the 138db pair of 12's I ran in the mid 90's, (sealed, 400w, in the trunk of a Sentra no less) but it's strong.

Don't have many pics of the different setups, but here's a few of the Sentra. (system was already old when these were taken, but it held up well)

My LT Won

well enjoy your setup.

138db? i could talk over that at fult tilt. esspecialy on the old super inflated numbers the old mics read vs new termlab.

i guess were just very far apart on are thoughts on how things sound.

Z1NONLY

iTrader: (2)

I'm sure the same setup would be louder in a small hatchback. Louder still with a larger ported enclosure, in a hatchback.

But inflated numbers? Talk over it? You know not of what you speak.

Bullitt5339

The inflated numbers he speaks of are the difference between the old Standard AudioControl microphones that were used up until the mid-90's vs. the Termlab, which is today's standard DB Measuring tool in car audio. The Audiocontrol typically would read 10-12db higher than the new Termlab because of the way they measure pressure, with the general consensus being that the Termlab is closer to reading true decibel levels than the AudioControl.

Nice old school equipment BTW. I absolutely love the old Orion HCCA amps and ran a 225HCCA before Autotek paid me to run their new (at the time) 7050XX. I did stick run those subwoofers as well for a long time and made the switch (reluctantly) to the old Kicker Comps in 1991. With all the advances in subwoofer and processor technology, nothing beats the old REAL Class A amplifiers with unregulated power supplies from the late 80's, early 90's.