Ported vs. PR for my application

[gckless 5,000+ posts]

You can't get a pair of 18" PR's on that box?
I expect when the new Sundown cones/spiders/frames come out those would make a good platform for super excursion PR, at the moment I'm not sure what'll have more throw than Ti basket with 10" spider to do 1:1 area and get away with throwing that kind of power at them.

Also if your goal is music you can probably get away with a bit less port area especially with flared ends if you're trying to get tuning down.

It would take some work cutting it just right. The box is 19" OD high including double baffle, so it would take some work. So question is, would it be worth the extra work/cost?

The ported box is good to go as the design in the first post. Just wondering if PR would be worth it.

 

[hispls 5,000+ posts]

It would take some work cutting it just right. The box is 19" OD high including double baffle, so it would take some work. So question is, would it be worth the extra work/cost?
The ported box is good to go as the design in the first post. Just wondering if PR would be worth it.

Well you could easily free up a couple cubes of volume and have the ability to modify tuning easily (assuming it's a decent PR with a good way to add and remove mass). If you want to tune really low and space is an issue it's the way to go IMO. I think the only reason you don't see them used a lot more is the price.

 

[gckless 5,000+ posts]

Here's what WinISD says for graphs:



Blue is my current box design (as shown in OP), red is a vented tuned to 24Hz (this is my PR for the graph), and yellow is sealed.

 

[mat3833 10+ year member]

in my experiance PRs dont actually perform as modeled. they have always performed better. BUT if you can get the 2 18" PR's in there you would be golden. the thing i like most about PRs if you can essentially change tuning freely. i had a PR box in my HT for awhile. and i had the PR inverse mounted so i could simply remove or add weights when i wanted. listening to music? remove weight to get ~34hz tuning. watching movies with buildings falling and explosions? add weight to your hearts desire. im sure either way you go you will end up being happy, but with PRs you will be unique(somewhat).

Matt

 

[gckless 5,000+ posts]

in my experiance PRs dont actually perform as modeled. they have always performed better. BUT if you can get the 2 18" PR's in there you would be golden. the thing i like most about PRs if you can essentially change tuning freely. i had a PR box in my HT for awhile. and i had the PR inverse mounted so i could simply remove or add weights when i wanted. listening to music? remove weight to get ~34hz tuning. watching movies with buildings falling and explosions? add weight to your hearts desire. im sure either way you go you will end up being happy, but with PRs you will be unique(somewhat).
Matt

Yeah dude, I'm leanin towards them. Gonna play with my box design in a bit and do some math and see what I can do as far as fitting those 18" PSI PR's.

 

[gckless 5,000+ posts]

So playing around a little, and tuning to 24Hz with two 18" PR's in 8 cubes will require an additional 400g of weight on each PR (that's if my math is right, probably way off). That's a lot of weight, and not sure how group delay and things like that are affected when weight gets big like that. Can anyone school me on sonic qualities?

 

[mat3833 10+ year member]

dont quote me on this since ive always just followed the formulas and not really gotten into theory. the weight on the PR is there to simulate the port. to find the weight you find port volume and multiply by the weight of air. essentially a PR is just another stylr of "ported" enclosure. the only problem you can run into is if you have heavy PRs they NEED to be counter-balanced. put one on each side of the enclosure if you can. having nearly a pound of weight moving on one side of the enclosure can cause it to rock and even tip over(please dont ask me how i know this...). ill check ur math in a few min once i dig up my spreadsheet. group delay should be bettter than ported and slightly below sealed. below tuning frequency GD is worse than ported.

Matt

 

[gckless 5,000+ posts]

dont quote me on this since ive always just followed the formulas and not really gotten into theory. the weight on the PR is there to simulate the port. to find the weight you find port volume and multiply by the weight of air. essentially a PR is just another stylr of "ported" enclosure. the only problem you can run into is if you have heavy PRs they NEED to be counter-balanced. put one on each side of the enclosure if you can. having nearly a pound of weight moving on one side of the enclosure can cause it to rock and even tip over(please dont ask me how i know this...). ill check ur math in a few min once i dig up my spreadsheet. group delay should be bettter than ported and slightly below sealed. below tuning frequency GD is worse than ported.
Matt

Appreciate it. Total weight would be like 801g for each PR, and mms is 420g for each with no weight on them. So that's 3.5lbs moving on the one side of the box. Mounting one on each side is out of the question, so I would just have to secure it well I guess.

 

[mat3833 10+ year member]

how do you plan on having the box laid out? if its like the picture you can get away with moving the subs to the front top and the PRs to the back Side.

Matt

 

[gckless 5,000+ posts]

how do you plan on having the box laid out? if its like the picture you can get away with moving the subs to the front top and the PRs to the back Side.
Matt

Yep, same design, just will shave the sides to make up for the space addition from removing the port. Probably center the subs. PR's will be rear-facing, on the same face as the port is now.

 

[mat3833 10+ year member]

what are the dimensions of that side?

Matt

 

[gckless 5,000+ posts]

what are the dimensions of that side?
Matt

Rear side? 40x16.75" ID if I shave the left and right sides.

 

[mat3833 10+ year member]

hmm, thats a tough one. you cant make ANY side at least 20 inchesX20 inches?

Matt

 

[gckless 5,000+ posts]

hmm, thats a tough one. you cant make ANY side at least 20 inchesX20 inches?
Matt

Well the PR's will fit on the rear face, the dimensions I just listed. They have a 16.75 cutout diameter. When I said JUST fit before, I wasn't joking lol.

 

[mat3833 10+ year member]

wait, are you going to use the 18" PRs or 15" PRs?

Matt