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View Full Version : Ported vs. PR for my application



gckless
04-12-2013, 09:11 PM
So, thinking about doing PSI PR's with my 3HP's. I know I have seen that rule of thumb is have double the Vd in your PR's as you do in your powered drivers, but how much wiggle room is there? Can I get away with less? And there's no problem with doing different sized PR's in the same box, right? From what I understand, I just need to make sure each weighs what it should based on the tuning I want.

I'm also looking for info on ported vs. PR in the sound arena (I understand the immediate positive of space savings). How do they sound different? What stuck in my head when I was reading was "the sound of a sealed box, with the output of a ported box." I know this can't be entirely true. Was looking to see how they act at low/high tuning under power. I read they roll off at 28dB (PR) vs. 24dB (ported) under tuning.

So here is my ported box design:

http://i723.photobucket.com/albums/ww236/gckless/Custom%20Green%203HP%2015s/GilbertKless2nd2custom3hp15skerfportedxray_zps0bc3 d5bc.png (http://s723.photobucket.com/user/gckless/media/Custom%20Green%203HP%2015s/GilbertKless2nd2custom3hp15skerfportedxray_zps0bc3 d5bc.png.html)

Two 15" 3HP's run off a DC 5k. This box is tuned just under 30Hz. Would probably tune around 27Hz or lower with PR's. Most amount of Sd I could fit here is a 15" and two 12" PR's, but not sure that would be enough.

Reason I'm thinking about this, is that I'm trying for a great sounding decently loud setup, but the focus is on sounding good.

TaylorFade I know you've played with PR's, what you got for me? ciaonzo keep_hope_alive

ciaonzo
04-12-2013, 09:38 PM
You can definitely make a vented or PR setup sound like sealed but with far more output. As loud as the same driver tuned to some feggish high midbass tuning? No, lol. But certainly much more than the same driver in a sealed design (provided the driver was suited for both sealed and vented in the first place). I will work on some models for comparison and make some points on this. Might not get around to it tonight or this weekend. It's my birfday!

As far as PR area, it's all about how loud you intend to get. You can use 1:1 but you will lock up if you try to dump tons of power into the driver. Example, if you had an EPIC 12" and wanted to use a single 12" TC VMP, you would be fine because the VMP has for more excursion capability than the EPIC12". I wouldn't suggest the same for the AXIS 12", I would use a minimum of a single 15" VMP or two 12" VMP's. For you, because I thik you intend to get decently loud, I would go 2:1.

So can you fit six 15" cones in your ride? lol

gckless
04-12-2013, 09:45 PM
You can definitely make a vented or PR setup sound like sealed but with far more output. As loud as the same driver tuned to some feggish high midbass tuning? No, lol. But certainly much more than the same driver in a sealed design (provided the driver was suited for both sealed and vented in the first place). I will work on some models for comparison and make some points on this. Might not get around to it tonight or this weekend. It's my birfday!

As far as PR area, it's all about how loud you intend to get. You can use 1:1 but you will lock up if you try to dump tons of power into the driver. Example, if you had an EPIC 12" and wanted to use a single 12" TC VMP, you would be fine because the VMP has for more excursion capability than the EPIC12". I wouldn't suggest the same for the AXIS 12", I would use a minimum of a single 15" VMP or two 12" VMP's. For you, because I thik you intend to get decently loud, I would go 2:1.

So can you fit six 15" cones in your ride? lol

Happy Birthday bro! Take your time with the models. Lookin forward to them though.

And yeah, what you explained about the excursion/surface area is what I had understood. At lower volumes/power levels it's not as important, but once you get into bigger setups, double the Vd in the PR's is rule of thumb. I do plan on getting pretty loud (Two 3HP's off a DC 5k), so I was pretty much thinking I would, but hoping I wouldn't, need more PR than I can fit :(

mat3833
04-12-2013, 09:51 PM
ive played with PR's a bit in HT enclosures. the best ratio i have found(in general, and keep in mind this is HT) is step up one size and go for more excursion. so if you have an 8" sub use a 10 PR with at least the same or higher excursion. in your situation it might be hard to get enough cone area and excursion for a PR settup to really shine.

the best PR settup i ever did was for a friend. he has a Epic 10 and wanted to be able to "bring the house down" ended up using 2 10" PRs with 1.5X the excursion, and tuned them to 20hz(tuned being a loosely defining word. more like weighted them, lol). i may not be good at theory or explaining things, but when given the resources i can make magic. lol

Matt

ciaonzo
04-12-2013, 10:01 PM
Happy Birthday bro! Take your time with the models. Lookin forward to them though.

And yeah, what you explained about the excursion/surface area is what I had understood. At lower volumes/power levels it's not as important, but once you get into bigger setups, double the Vd in the PR's is rule of thumb. I do plan on getting pretty loud (Two 3HP's off a DC 5k), so I was pretty much thinking I would, but hoping I wouldn't, need more PR than I can fit :(Thanks, man. :)

Might want to stick with a huuuuuuge vent, lol.

gckless
04-12-2013, 10:01 PM
ive played with PR's a bit in HT enclosures. the best ratio i have found(in general, and keep in mind this is HT) is step up one size and go for more excursion. so if you have an 8" sub use a 10 PR with at least the same or higher excursion. in your situation it might be hard to get enough cone area and excursion for a PR settup to really shine.

the best PR settup i ever did was for a friend. he has a Epic 10 and wanted to be able to "bring the house down" ended up using 2 10" PRs with 1.5X the excursion, and tuned them to 20hz(tuned being a loosely defining word. more like weighted them, lol). i may not be good at theory or explaining things, but when given the resources i can make magic. lol

Matt

Yeah, that's what I meant by double the Vd. Vd is volume displaced, which is surface area (Sd) multiplied by Xmax. Don't mean to patronize you, just clarifying. Unfortunately I don't have the space to fit twice the amount. So at this point I guess I'm looking for deeper information than people typically get. Or experiences, so thanks man!

mat3833
04-12-2013, 10:07 PM
Yeah, that's what I meant by double the Vd. Vd is volume displaced, which is surface area (Sd) multiplied by Xmax. Don't mean to patronize you, just clarifying. Unfortunately I don't have the space to fit twice the amount. So at this point I guess I'm looking for deeper information than people typically get. Or experiences, so thanks man!

not a problem. IF you can find really high excursion PR's you should be able to get away with 3 12" PRs. you would have ~the same(slightly more depending) "cone" area, but if you can get 1.5X or more excursion you should be ok. :-)

Matt

jockhater2
04-12-2013, 10:10 PM
Thanks, man. :)

Might want to stick with a huuuuuuge vent, lol.

Happy Birthday shane!

ciaonzo
04-12-2013, 10:16 PM
Happy Birthday shane! Thanks, guys! :toast:

gckless
04-12-2013, 10:19 PM
Thanks, man. :)

Might want to stick with a huuuuuuge vent, lol.

Yeah the box design I showed above has a pretty large port. Wanted to tune lower, but this was the lowest I could go due to space.


not a problem. IF you can find really high excursion PR's you should be able to get away with 3 12" PRs. you would have ~the same(slightly more depending) "cone" area, but if you can get 1.5X or more excursion you should be ok. :-)

Matt

Yeah, in my first post I said that I could fit one 15" and two 12" PR's. Would give me a bit more surface area than my two 15" powered drivers, but not sure about double the Xmax. The PSI PR's have about 3" usable Xmax according to their site, so it might be alright.

mat3833
04-12-2013, 10:26 PM
ive never tried using different sized PRs, would be a first. lol

Matt

ciaonzo
04-12-2013, 10:33 PM
Bro, with your cone area, excursion, and power...I would have gone medium sealed and EQ'd the low end to taste. You would easily be in the 'teens for extension.

I once had a single 10" LMS on 900w and with a little EQ bump at 20hz it absolutely murdered everything from 40hz to 15hz.

gckless
04-12-2013, 10:46 PM
Bro, with your cone area, excursion, and power...I would have gone medium sealed and EQ'd the low end to taste. You would easily be in the 'teens for extension.

I once had a single 10" LMS on 900w and with a little EQ bump at 20hz it absolutely murdered everything from 40hz to 15hz.

****, more to think about! Sure would help the low end extension. Guess I'm just trying to wring all the output I can out of these beasts. But, maybe that is the way I should go.

gckless
04-12-2013, 10:53 PM
Bro, with your cone area, excursion, and power...I would have gone medium sealed and EQ'd the low end to taste. You would easily be in the 'teens for extension.

I once had a single 10" LMS on 900w and with a little EQ bump at 20hz it absolutely murdered everything from 40hz to 15hz.

Here's T/S:

http://i723.photobucket.com/albums/ww236/gckless/Custom%20Green%203HP%2015s/photo_zpse9a44782.jpg (http://s723.photobucket.com/user/gckless/media/Custom%20Green%203HP%2015s/photo_zpse9a44782.jpg.html)

Think they would do better in sealed or ported? From what I can gather, they would do decent in either.

hispls
04-13-2013, 12:05 AM
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.

gckless
04-13-2013, 12:14 AM
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
04-13-2013, 08:23 AM
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
04-13-2013, 12:27 PM
Here's what WinISD says for graphs:

http://i723.photobucket.com/albums/ww236/gckless/Custom%20Green%203HP%2015s/Boxplots_zps414e7d3f.png (http://s723.photobucket.com/user/gckless/media/Custom%20Green%203HP%2015s/Boxplots_zps414e7d3f.png.html)

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
04-13-2013, 01:05 PM
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
04-13-2013, 04:54 PM
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
04-13-2013, 06:03 PM
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
04-13-2013, 06:42 PM
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
04-13-2013, 06:51 PM
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
04-13-2013, 06:58 PM
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
04-13-2013, 07:04 PM
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
04-13-2013, 07:08 PM
what are the dimensions of that side?

Matt

gckless
04-13-2013, 07:11 PM
what are the dimensions of that side?

Matt

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

mat3833
04-13-2013, 07:13 PM
hmm, thats a tough one. you cant make ANY side at least 20 inchesX20 inches?

Matt

gckless
04-13-2013, 07:16 PM
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
04-13-2013, 07:26 PM
wait, are you going to use the 18" PRs or 15" PRs?

Matt

gckless
04-13-2013, 07:28 PM
wait, are you going to use the 18" PRs or 15" PRs?

Matt

18". They have a 16.75" cutout diameter.

mat3833
04-13-2013, 07:30 PM
how the hell does that work? they would only have the cone area of a 15"PR....

Matt

gckless
04-13-2013, 07:36 PM
how the hell does that work? they would only have the cone area of a 15"PR....

Matt

Cutout diameter is the hole you have to cut to fit it in the box. Always smaller than the rated size on any sub. Overall diameter is 18.5" with gasket.

mat3833
04-13-2013, 07:53 PM
-_- i feel stupid now. i was thinking OD not cutout. hell the cutout on my 8's is 7.3", lol

Matt

gckless
04-13-2013, 08:17 PM
-_- i feel stupid now. i was thinking OD not cutout. hell the cutout on my 8's is 7.3", lol

Matt

Yeah my 15's are like 14.125. But those 18's should fit in there with some cutting of one of my upper top baffle. Not a whole lot though.

gckless
04-14-2013, 12:00 AM
Bump for opinions/information on PR's. Do I go PR or no??

gckless
04-14-2013, 11:19 PM
ciaonzo I was promised info! :)
I'm sure you are still recovering from the bday though lol.

I think PR's are in my future.

ciaonzo
04-14-2013, 11:24 PM
ciaonzo I was promised info! :)
I'm sure you are still recovering from the bday though lol.

I think PR's are in my future.Haven't worked on the models if that's what you're after. Go for the PR's, though! Throw 'em in, do a little tweaking to find the tuning you like, and enjoy. :)

jockhater2
04-14-2013, 11:44 PM
I hope with shane's help that PR's are in my future too.

gckless
04-14-2013, 11:55 PM
I hope with shane's help that PR's are in my future too.

Ya know, with as popular as they are in home theater, I'm surprised I don't see more. I know they cost more, but everyone is always trying to save space, sooooooo...

What you plannin bro?

gckless
04-18-2013, 10:12 PM
So, talking with PSI now about the PRs. It's lookin like he will take care of me for a decent price :)
Anyway, here's what I sketched up for the box changes. Unfortunately, Buck is not in the best of health, so he's not available at the moment. Hope he's doing well. In his absence, I gave it a try. Only sketched what I would change.

Original:

http://i723.photobucket.com/albums/ww236/gckless/Custom%20Green%203HP%2015s/GilbertKless2nd2custom3hp15skerfportedxray_zps0bc3 d5bc.png

Changes:

http://i723.photobucket.com/albums/ww236/gckless/Custom%20Green%203HP%2015s/PRFace_zpsd6116878.png

These things will JUST fit.

gckless
04-23-2013, 05:29 PM
Well just paid for my PSI passive radiators. Was kinda just a thought before, but I'm committed now. A pair of 18" PR's, upgraded high-roll surround for 3.5" p-p, dual spiders to handle the power, carbon fiber dustcap, built and shipped in a week, for $350. I'm happy with it as of now. We'll see if I feel that way when I get them :)

gckless
04-25-2013, 05:54 PM
Just want to say PSI has the fastest turnaround ever. Paid for my passive radiators Tuesday afternoon, and just received tracking info. They weren't standard either, got a couple upgrades.

mlstrass
04-26-2013, 02:55 AM
Interested to see how this turns out...

gckless
04-28-2013, 05:13 PM
Got the box design done:

http://i723.photobucket.com/albums/ww236/gckless/Custom%20Green%203HP%2015s/PRBox_zps51fd5ce0.png

And just got my PRs in too:

http://i723.photobucket.com/albums/ww236/gckless/PSI%2018%20Passive%20Radiators/DSC_5027_zps3bb31da6.jpg

http://www.caraudio.com/forums/subwoofers/574605-psi-18-passive-radiators.html#post8381753

Might not post a whole lot in this thread anymore, I'll be starting a build log soon. I will direct to that though, and I'll try to come back and update this when I finally get these in and start tuning. Gonna be a while though, still have all my electrical to buy and cash is tight right now :(

gckless
04-28-2013, 09:49 PM
ciaonzo you got models fo me? :nerd:

04murdalanche
04-29-2013, 12:42 AM
In

ciaonzo
04-29-2013, 04:08 PM
ciaonzo you got models fo me? :nerd:You see any, yet? lol

Sorry, man. Right when we were having that discussion I began a new position at work which means a relocation for me. I've been home once since then and that was to ship out the drivers I sold. I'm staying at my lady's house until the move is complete. I was basically going to post a comparison of the various plots between a sealed alignment and a vented alignment that illustrate a very similar roll off but with the vented alignment hanging in for a lower F3, obviously. It would have been more in depth but you get the idea...

gckless
04-29-2013, 07:22 PM
You see any, yet? lol

Sorry, man. Right when we were having that discussion I began a new position at work which means a relocation for me. I've been home once since then and that was to ship out the drivers I sold. I'm staying at my lady's house until the move is complete. I was basically going to post a comparison of the various plots between a sealed alignment and a vented alignment that illustrate a very similar roll off but with the vented alignment hanging in for a lower F3, obviously. It would have been more in depth but you get the idea...

Oh ok man, it's all good. Got to take care of yourself first. Hope it all works out for ya.

And I've seen a couple plots, enough to where I got a decent feel for what it will look like. So I guess it's not super important if that's what you were gonna throw at me. Thanks for all the info anyway!

ciaonzo
04-29-2013, 07:32 PM
Oh ok man, it's all good. Got to take care of yourself first. Hope it all works out for ya.

And I've seen a couple plots, enough to where I got a decent feel for what it will look like. So I guess it's not super important if that's what you were gonna throw at me. Thanks for all the info anyway!I will be useful at some point, lol. It's pretty stressful right now but I like to log on here and there and laugh at/with you clowns. I think you are gonna love this PR setup, those turned out nice.

gckless
04-29-2013, 07:40 PM
I will be useful at some point, lol. It's pretty stressful right now but I like to log on here and there and laugh at/with you clowns. I think you are gonna love this PR setup, those turned out nice.

Probably laugh AT us, but it's all good :)

And dude, I'm really excited to do this. I have never seen a PR setup on higher power than like 2k. I'm not saying it hasn't been done, but I have not seen it anywhere. I like being different :)
Just really irks me that I won't be done with this build until about August.

And these are beautiful. I can't say enough about PSI. Dude built these in 2 days, I had them in my hands 4 days after I paid. Dave was in contact with me the whole time, answered my stupid questions, said he built them himself, and even threw in a shirt and some stickers. Much respect for that man and his business.

gckless
05-20-2013, 08:00 PM
Soooooooooo, made a really stupid mistake when I reworked the box for PR before. I removed the port, which was over 2 cubes, but didn't cut down any outside dimensions. So, here is the final redesigned box, Buck approved :):

http://i723.photobucket.com/albums/ww236/gckless/Custom%20Green%203HP%2015s/PRBoxXray_zpsd52792ad.png

Much better. 9 cubes gross, with displacements should bring me down to right around 8.5 net. I'm going to mount inverted, and being a bit bigger leaves me room to mount normally if I need/want to. It also will fit right in between the wheel wells, no building over the wells bullshit. About 6" from the hatch. More than likely getting it built next month.

REALLY glad I caught this. Would have been SO pissed.

gckless
06-01-2013, 06:18 PM
Finally started a build log, this is where I'll be posting any updates: http://www.caraudio.com/forums/car-audio-build-logs-cars-trucks-suvs/578701-1999-chevrolet-blazer.html#post8406268

Might come back here in a couple months after I get things installed to update on tuning discoveries and things like that, if for nothing more than thread closure.

gckless
08-19-2013, 08:23 PM
Bumpin this back up.

Finally got everything installed. Levi took a dump, but that's of no concern in this thread.

http://i723.photobucket.com/albums/ww236/gckless/1999%20Chevrolet%20Blazer/45DD0596-040B-460F-ACFD-FBBFF6698EE3-5225-0000034C385AC92A_zps73d0dbca.jpg (http://s723.photobucket.com/user/gckless/media/1999%20Chevrolet%20Blazer/45DD0596-040B-460F-ACFD-FBBFF6698EE3-5225-0000034C385AC92A_zps73d0dbca.jpg.html)

Took a quick video (Can't embed here?):

System - Day 1 - YouTube (http://youtu.be/Kmx3um-pEjs)

Found my tuning as of now to be at 35Hz. Here's a quick video on finding tuning without math:

How to Find Passive Radiator Tuning - YouTube (http://youtu.be/QKYn6e1QIb8)