DiyMobileAudio.com Car Stereo Forum banner

21 - 40 of 40 Posts

·
Premium Member
Joined
·
4,128 Posts
exactly, you need to make sure when making your 2.5cft box that you add to the overall size the amount of space the port will consume. so its 2.5 PLUS port volume when building.

Have you considered doing a slot port?
A slot port will still be taking up volume, and often the slots have more area than a round port... hence sloted ports gobble is more volume than a cylindrical port. There are only two solutions that gobble up no volume.
 

·
Registered
Joined
·
6,593 Posts
A slot port will still be taking up volume, and often the slots have more area than a round port... hence sloted ports gobble is more volume than a cylindrical port. There are only two solutions that gobble up no volume.
really? a slot port takes up room in the box? Thanks for the heads up;)

Yes it does take up space, but in a different way. The problem i run into with an aero port is the flange is so big inside the box that it generally in some way hits the basket or the magnet or the side of the box. Slot ports are just way easier for me anyway to design around.

And yes we know you love passive radiators, but they have problems too. You can't expect to just use 1 12" passive with a 12" driver. It generally takes 2 passives, and that adds a lot to the cost, plus you also run into the same real estate problem as you do with aero ports. how do you locate 3 12 in drivers in a 2.5 cuft box.

Maybe i'm missing something but slot ports seem easier to me.
 

·
Premium Member
Joined
·
4,128 Posts
really? a slot port takes up room in the box? Thanks for the heads up;)

Yes it does take up space, but in a different way. The problem i run into with an aero port is the flange is so big inside the box that it generally in some way hits the basket or the magnet or the side of the box. Slot ports are just way easier for me anyway to design around.

And yes we know you love passive radiators, but they have problems too. You can't expect to just use 1 12" passive with a 12" driver. It generally takes 2 passives, and that adds a lot to the cost, plus you also run into the same real estate problem as you do with aero ports. how do you locate 3 12 in drivers in a 2.5 cuft box.

Maybe i'm missing something but slot ports seem easier to me.
Well I admit I like passives.
That 12M that I had posted earlier has something like 4" of excursion... and therefore is rated as only needing a single unit for a 12" sub.

The "total box" is going to be fatter with a slotted... The port volume need to exist somewhere. (Whereas with a PR the air mass become steel mass, which is way denser than air, and hence the volume it ~nil.)
If realestate is precious, as it seems to be in the OP's case, then some serious consideration as to whether a PR makes sense seems warranted.

If he/she has the room for a slotted, then that is definitely cheaper.

There is something unattractive (IMHO) with a leaf blower looking sub... )although I may end up doing that myself... which is for a slightly different (but related) reason.)
 

·
Registered
Joined
·
2,743 Posts
Well I admit I like passives.
That 12M that I had posted earlier has something like 4" of excursion... and therefore is rated as only needing a single unit for a 12" sub.

The "total box" is going to be fatter with a slotted... The port volume need to exist somewhere. (Whereas with a PR the air mass become steel mass, which is way denser than air, and hence the volume it ~nil.)
If realestate is precious, as it seems to be in the OP's case, then some serious consideration as to whether a PR makes sense seems warranted.

If he/she has the room for a slotted, then that is definitely cheaper. ....
While those are all valid points, there are a number of additional considerations WRT PRs and their application. Unfortunately, there does not seem to be a wealth of detailed information from first-hand experience; and to that extent, the uninitiated are sort of on their own.
 

·
Premium Member
Joined
·
4,128 Posts
What's not to like? :D
Stihl ^That^ one is an exception.:D


While those are all valid points, there are a number of additional considerations WRT PRs and their application. Unfortunately, there does not seem to be a wealth of detailed information from first-hand experience; and to that extent, the uninitiated are sort of on their own.
There may not be a lot, first hand experience, but a lot of that may be that it is because it is not how a sub is supposed to look in a car.

And what is to know about the PR? Pick your Port freq, and it works like any port. If one later changes their mind, then they just change the port frequency with some weights. The physics is exactly the same as an hollow round or slotted port.

Many manufactures make them (Seas, SB, etc), but the SLAMS one is a super long extension.

And it is easy to cutting (another) round hole with a jig saw, and add mounting screw holes. The plumbing fittings shown on page one, take additions skillz to use.
 

·
Registered
Joined
·
1,506 Posts
IMHO 6,5 aero is over the top for one 12" driver.
If you calculate port lenght without aeroport endings, later when you add them you will need to shorten your pipe lenght for 1/2 of height of EACH aeroport ending used. Lets say your aeroport ending is 3 inches in height, so if you are using aeroport on both ends you should shorten your port pipe for 3 inches to maintain desired tuning of the box. When using aeroport endings your port may be a bit shorter compared to standard straight pipe.
For me aeroports are easier to set up and to retune if needed compared to slots.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #28
IMHO 6,5 aero is over the top for one 12" driver.
If you calculate port lenght without aeroport endings, later when you add them you will need to shorten your pipe lenght for 1/2 of height of EACH aeroport ending used. Lets say your aeroport ending is 3 inches in height, so if you are using aeroport on both ends you should shorten your port pipe for 3 inches to maintain desired tuning of the box. When using aeroport endings your port may be a bit shorter compared to standard straight pipe.
For me aeroports are easier to set up and to retune if needed compared to slots.
Thanks. This measures from the outside of the flare, top to bottom? This would be more like 8" at each end, given the added height from the flare.


I am going to tune this also by ear. I will do the math first, test it, then make modifications if necessary. I will try to tune it in the front seat, though, so i don't have to drop it in the "hole" behind the seats multiple times. that's a pain in the booty.

good catch, several posts back, about the port subtracting volume from the 2.5 ft^3 box. I actually miscalculated the cut dimensions, so the total volume will be 2.7 ft^3- this will offset the lost space from the port.

the last few times i've set out to work on the box, shit came up. i had meetings last week, i set the stuff up monday at work, but the manager came back, etc. today, however, i am going to cut the holes for the sub and hopefully the port too. i want to have this bumpin by the weekend
 

·
Registered
Joined
·
2,743 Posts
To be clear, the flared port lengths indicated in my earlier posts (as per Products Menu ) are for the full assembled port length including both flared ends (which will of course be longer than a non-flared counterpart of the same area or diameter).
 

·
Registered
Joined
·
1,506 Posts
When I competed in SPL back in the day I used to have molded one aeroport ending to the MDF board with poyester resine and fiberglass (only resine without mat is britle and a piece of it may find its way to the cooling hole and from there to the Voice coil where severe damage may accour to the driver). That board was later secured with screws directly to the box with a piece of neoprene in between to maintain air tight bond...always worked like a champ.
You have also option to mold a piece of port pipe to the MDF board and fix that to the box. You will also know exactly how much space it takes from the box. remember, ported box must be airtight the "only hole" is the port opening.



this are my Aeroports - 8" diameter,....you can see aeroport flare molded to the MDF board (lower right aeroport)
This way you also have an option to elevate the whole port by just adding MDF plates under the plate that hold aeroport ending - this has also impact on the SPL result.....in my case it was 0,8" that helped me with result.
 

·
Registered
Joined
·
2,743 Posts
IMHO 6,5 aero is over the top for one 12" driver.
If you calculate port lenght without aeroport endings, later when you add them you will need to shorten your pipe lenght for 1/2 of height of EACH aeroport ending used. Lets say your aeroport ending is 3 inches in height, so if you are using aeroport on both ends you should shorten your port pipe for 3 inches to maintain desired tuning of the box. When using aeroport endings your port may be a bit shorter compared to standard straight pipe.
For me aeroports are easier to set up and to retune if needed compared to slots.
Cone area is of little or no use in determining adequate port area. Input power, cabinet volume and tuning frequency are far greater determining factors.
 

·
Registered
Joined
·
10 Posts
Discussion Starter #33
Sup y'all, I got an update. Last night, the mechanic and I cut the baffles and glued them together. The sub fits perfectly- this is a good sign- I've made so many mistakes with woodworking.

My next step is cutting the holes for the port and figuring out the correct length. If I need to make it longer, I will make spacers with MDF like @LBaudio. Last night I cut several practice holes and practiced sanding them until the port fit snugly. When I started this project, I underestimated the skill necessary for woodworking. I want to get better at it, and have been practicing by cutting scrap pieces. I have to tell myself to slow down too- I rush and make mistakes.

After I complete this project and the oppressive texas heat cools down, I want to build a box for my gf's subs. I installed 2 kicker L7's she bought at a pawn shop and they're suffocating for air. They're in a tiny sealed prefab box- the front box is literally the area of the 2 subs next to each other. She doesn't know the difference, but we have to turn the volume up too high to get loud.


Anyway, I did the math to get an estimate for the length. The precision port seems like good quality. I attached the instructions in case anyone wants to see what it comes with.



My goal is to bump by this weekend
 

·
Premium Member
Joined
·
4,128 Posts
...
... Last night I cut several practice holes and practiced sanding them until the port fit snugly. When I started this project, I underestimated the skill necessary for woodworking.
...
Of course a skill craftsman doesn't blame his toools... but there is no dishonour in using a hole saw, and there are also jig saws with circle work accessories.
 

·
Registered
Joined
·
1,506 Posts
You can use duct tape or aluminium tape on your port pipe. If you gonna glue it together and later needed to change the lenght of port you will have hard time.
I used to compete in dBDrag with this (first 8"aero in the world - 15+ years ago with a couple of world records in street B) 8" aeroport and this way of port assembly was the way to go, and it was also safe (not even one time port pipe fell off of the aeroport ending. If you test a lot than version like pictured - lower right aeroport is the way to go - secure it with T-nuts and screws - this way you won't damage your box and aeroport - you can assemble/disassemble it 10000 times.



 

·
Registered
Joined
·
2,743 Posts
Here's a neat trick:

Determining tuning frequency of a cabinet using garbanzo beans (or peas, rice, etc.).


Note: the principle is the same for both passive radiator and vented/ported - i.e. driver cone moves least at Fb (tuning frequency).
 

·
Registered
Joined
·
10 Posts
Discussion Starter #39
EDIT: Please open this album so my post makes sense
https://imgur.com/a/p0e8bas

Alright, y'all, I got a big update:

I woke up saturday morning and my gf was moody and irritable, so I tried placating her, but that didn't work, so I set out to finish my project. The mantra for the weekend was "just do it" and get the bass going in my truck. Before I started, I returned another tool to harbor freight. This time a jigsaw- it wasn't terrible, except the trigger lock feature would jam occasionally. I also tried returning a 6 month old warrior drill that succumbed to its premature death, but they only accept returns for 90 days. For the people outside of the US, harbor freight is a discount tool supply place that sells tools made in china. The store smells like the interior of a shipping container, and they have signs in the store that tell you shop anywhere else, you're overspending.

People like this store, because they sell cheap tools and repeat the same thing: "I only need the tool once, why should I spend more at a retail hardware store?" I don't understand this thought process- the tenth project is no different than the first qualitatively. The tool can either do it's job correctly or not, regardless of what project you're on, and its performance will influence the first project or the tenth. I've spent over $2,000 there in the last year and have decided I won't buy anything major there, unless it's small, like tape or a screwdriver. I still haven't returned a straight-edge clamp that moves a 1/8" to one side when locking. I now see why the mechanics at my job don't shop there- It was hard to miss an irate customer was yelling at the cashier for charging a 20 percent restocking fee for a broken generator.

Next, I went to home depot, it's a US hardware chain. I spent an hour looking at the different tool "systems" and decided on their store brand, Rigid.

Quality tools made the project easier and more enjoyable.

It's a handsome orange drill (photo) and impact set- I won't go into detail, but having these tools made assembling the box a breeze and even enjoyable. I hate to admit how down I was over this project, given my initial woodworking mistakes and the shop that didn't make the cuts. Anyway, onto the project:

These photos were taken after gluing all of the panels together. I assembled the side panel with the port last- I managed to get a great, tight cut by cutting the hole with a 15 degree angle, then sanded it down to fit the port.





And finally, this guy's getting a home:


After applying the clamps, I called it a night. Sunday morning, I went to home depot to get a drill bit and more corner braces. When I got home, I sealed the box with nails, wired the sub and put it in the box, and put the top on the box. I was careful to put the top panel on when the box was lying on its back, so the glue wouldn't drip on the sub


I had one issue when drilling the sub into the baffle- There were a couple screws where the baffle was too wide, so they didn't go into the wood! I used the cardboard template while cutting, so i don't know what happened. Underneath the sub's rubber bezel are 3 little indented circles, so I tried drilling through another one, but the bit wouldn't go through, and my drill was sliding. I got scared that I would slip again and put a hole in the sub, so I left it alone. I was able to pick up the whole assemblage by the back of the sub, which showed me it's in there tight. If it comes out by vibration, I can take the sub out and attach another baffle, but I doubt this will happen.


My girlfriend helped me load the sub into the truck, then I went to my job to install it. They have all the tools I needed and more. I already had RCA's and a remote wire running from my previous install, so all I had to do was install the power cable and connect the amp. I installed the big 3 last month, and all i gotta say is damn, I am impressed. No dimming at all thanks to a 350 amp alternator.


I was playing trance, but got impatient waiting for the drop, so I changed to a rap station. I thought it was cool, the garage doors in the shop were vibrating, but it wasn't as loud as my 2 kicker l7 10's. Whatever, I figured it needed time to break in. Then, on my way home from the gym, I connected my phone and played a trap mix. Holy hell, I thought my truck was going to come apart! The whole interior of the cabin flexed! I had a big, stupid smile on my face. Now I see why people go through the hassle of building boxes themselves. It sounds full and amazing!

Here's the mix I played:
 

·
Registered
Joined
·
10 Posts
Discussion Starter #40 (Edited)
For some reason, the images are not showing. Here's another post with the images:
Here's a link to the album.

Big thank you to everyone who helped me with this!!! You guys know your stuff. I am going to read around the forum to educate myself. Good call on the precision port too. I am going to get my stuff back from the wood shop and reengineer the box for 2 12's to accommodate an aero port. The aero port was fun to work with. I can only imagine how hard 2 of these would pound in a regular cab. The single 12 vibrates the whole cabin









 
21 - 40 of 40 Posts
Top