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View Full Version : Sealed vs Ported vs Passive Radiator



jockhater2
03-02-2013, 04:40 PM
I found this when I searched it. Can someone help me understand it a little better. Basically dumb it down for me. I guess my big question is. Passive radiator vs Ported. What are some pro and cons.

This is what I found when I googled it.
"From another sealed vs ported discussion

The design choice depends on $$$/driver/footprint and power available.

The important differences are .

1. Ported designs need less power to produce output down to their tuning point.
2. Ported designs have better output at their tuning frequency then sealed design when driver/amp are similar.
3. Sealed designs have more output below and above the tuning of a ported design.
4. Sealed designs can inherently protect the driver from over excursion if the box is small enough. Ported designs need a SubSonicFilter to protect the driver.
5. Sealed designs need far greater power to achieve high SPL down low because there is a HUGE boost down low to get output.
6. Audiophile myths like tighter bass are not worthy of any science discussion. Of course a port introduces more noise into the design.



The difference between ported and Passive Radiator is pretty simple.

1. PR allows for a smaller box with same tuning point.
2. PR offers less noise (NO port chuffing, etc).
3. PR costs a little more $$$ vs ported
4. Ported box will have a little higher max SPL vs same amp/driver in a PR design."


pro-rabbit ; double 07 ;
TaylorFade ; keep_hope_alive ;

n8skow
03-02-2013, 05:38 PM
Those statements all look pretty accurate.
What is your asking exactly?

neo_styles
03-02-2013, 05:42 PM
Those statements all look pretty accurate.
What is your asking exactly?

According to the OP, Basically dumb it down for me. Think he needs the layman's version of what they're trying to say.

n8skow
03-02-2013, 06:37 PM
...like with pictures and stuff?
:D
I tease, I tease...

Sealed - good frequency range, good cone control (e.g. ability to handle power), enclosures can be fairly small.

Ported - basically twice the output at tuning frequency over sealed, sacrificing cone control below tuning (which is where the subsonic filter on your amp comes in - to reduce the signal output from the amp to the woofer below a certain threshold). Downside - quite a bit larger than sealed enclosure.

Passive Radiator - similar properties to ported box without losing enclosure volume to accommodate the displacement of the port (not 'quite' as loud as ported, but louder than sealed, again around tuning). Downside, the extra cost, and trial-and-error of tuning it (by adding or removing weights from the cone).


According to the OP, Basically dumb it down for me. Think he needs the layman's version of what they're trying to say.

neo_styles
03-02-2013, 06:39 PM
...like with pictures and stuff?
:D

I guess? I think he just wants a better explanation of why the facts at the beginning are what they are.

n8skow
03-02-2013, 06:57 PM
*Edited my post above to expand on the 'whats'.
To get into the 'whys' would definitely get more technical than the points he's already covered though - and some of it probably way over my head.
=)

keep_hope_alive
03-03-2013, 12:47 AM
that all seems pretty straight-forward to me...

jockhater2
03-03-2013, 09:56 AM
...like with pictures and stuff?
:D
I tease, I tease...

Sealed - good frequency range, good cone control (e.g. ability to handle power), enclosures can be fairly small.

Ported - basically twice the output at tuning frequency over sealed, sacrificing cone control below tuning (which is where the subsonic filter on your amp comes in - to reduce the signal output from the amp to the woofer below a certain threshold). Downside - quite a bit larger than sealed enclosure.

Passive Radiator - similar properties to ported box without losing enclosure volume to accommodate the displacement of the port (not 'quite' as loud as ported, but louder than sealed, again around tuning). Downside, the extra cost, and trial-and-error of tuning it (by adding or removing weights from the cone).

Perfect. Thank you for this.
So a passive radiator set up is a bit difficult to get right? but is basically a best of both worlds minus the output?

Oh. Ok. So that is why you set your subsonic filter. 5 hertz below yours ports tuning correct?

ciaonzo
03-03-2013, 10:01 AM
...like with pictures and stuff?
:D
I tease, I tease...

Sealed - good frequency range, good cone control (e.g. ability to handle power), enclosures can be fairly small.

Ported - basically twice the output at tuning frequency over sealed, sacrificing cone control below tuning (which is where the subsonic filter on your amp comes in - to reduce the signal output from the amp to the woofer below a certain threshold). Downside - quite a bit larger than sealed enclosure.

Passive Radiator - similar properties to ported box without losing enclosure volume to accommodate the displacement of the port (not 'quite' as loud as ported, but louder than sealed, again around tuning). Downside, the extra cost, and trial-and-error of tuning it (by adding or removing weights from the cone).Good job.

TaylorFade
03-03-2013, 12:18 PM
PR's ARE ports. Essentially. They're just huge and use moving mass instead of a volume of air. You actually calculate the weight of the air in a port the size of your PR's diameter to figure out how much mass you need to add. PR's also unload like a bish below tuning so I suggest tuning them lower than you would a standard port if there's a chance you'll play below that.

PR's are kind tricky though. The rule of thumb is at least 1.5-2x cone area or xmax. It's tough to find a PR with double the xmax of our subs, so it's got to be 1.5-2x cone area. Like, a 12" PR for a 10" sub or (2) 10" PR's. Say you use a 12" PR. Well... that's basically a 12" port. Say your 10 needs a 1.5cf box. A 12" port in 1.5 cubes for 30hz needs to be, wait for it.... 218" long. Hello. So... the volume of a 12" port that's 218" long is 14.5 cubic feet. Air weighs ~ .08lbs per cube. .08lbs x 14.5cf is 1.16lbs. That's your moving mass.

Or you can use this "quick" formula...

http://i848.photobucket.com/albums/ab45/taylorfade/Builds-boxes/f89e063d.jpg

jockhater2
03-03-2013, 01:03 PM
PR's ARE ports. Essentially. They're just huge and use moving mass instead of a volume of air. You actually calculate the weight of the air in a port the size of your PR's diameter to figure out how much mass you need to add. PR's also unload like a bish below tuning so I suggest tuning them lower than you would a standard port if there's a chance you'll play below that.

PR's are kind tricky though. The rule of thumb is at least 1.5-2x cone area or xmax. It's tough to find a PR with double the xmax of our subs, so it's got to be 1.5-2x cone area. Like, a 12" PR for a 10" sub or (2) 10" PR's. Say you use a 12" PR. Well... that's basically a 12" port. Say your 10 needs a 1.5cf box. A 12" port in 1.5 cubes for 30hz needs to be, wait for it.... 218" long. Hello. So... the volume of a 12" port that's 218" long is 14.5 cubic feet. Air weighs ~ .08lbs per cube. .08lbs x 14.5cf is 1.16lbs. That's your moving mass.

Or you can use this "quick" formula...

http://i848.photobucket.com/albums/ab45/taylorfade/Builds-boxes/f89e063d.jpg

wow. Really good stuff here. Thank you for this. What do you prefer? PR's, ported or sealed? I have only done sealed and ported. I don't know anyone with PR's.

Also. What is unloading?

TaylorFade
03-03-2013, 01:11 PM
wow. Really good stuff here. Thank you for this. What do you prefer? PR's, ported or sealed? I have only done sealed and ported. I don't know anyone with PR's.

Also. What is unloading?

I love my PR's. Super easy. Cut a hole and drop it in. Done. And they sound great. Ported box output without the hassle.

Unloading is when your subs just flap in the wind like they weren't even in a box. Slap, chuff, slap, chuff, slap, wocka wocka wocka... hello back plate.

TaylorFade
03-03-2013, 01:12 PM
http://i848.photobucket.com/albums/ab45/taylorfade/Builds-boxes/05d9fa37.jpg

http://i848.photobucket.com/albums/ab45/taylorfade/Builds-boxes/03c68aa9.jpg

http://i848.photobucket.com/albums/ab45/taylorfade/Builds-boxes/36950B3B-689C-4A53-BA69-A5C4AC1783DF-12030-00000808D63968EC.jpg

http://i848.photobucket.com/albums/ab45/taylorfade/Builds-boxes/14DE45DD-2E7A-4D3A-9C86-E1AD65F0EFD9-16131-000007C0923B455D.jpg

jockhater2
03-03-2013, 01:20 PM
http://i848.photobucket.com/albums/ab45/taylorfade/Builds-boxes/05d9fa37.jpg

http://i848.photobucket.com/albums/ab45/taylorfade/Builds-boxes/03c68aa9.jpg

http://i848.photobucket.com/albums/ab45/taylorfade/Builds-boxes/36950B3B-689C-4A53-BA69-A5C4AC1783DF-12030-00000808D63968EC.jpg

http://i848.photobucket.com/albums/ab45/taylorfade/Builds-boxes/14DE45DD-2E7A-4D3A-9C86-E1AD65F0EFD9-16131-000007C0923B455D.jpg

Oh wow. Does it save you a lot of box space? How much bigger would your box be if it was ported?
How hard was it for you to get your box to sound right? without the subs unloading.

How much were your PRs?

TaylorFade
03-03-2013, 01:24 PM
Oh wow. Does it save you a lot of box space? How much bigger would your box be if it was ported?
How hard was it for you to get your box to sound right? without the subs unloading.

How much were your PRs?

I think I paid $80/ea. They're custom ones made with the same basket and soft parts as my Tantric MD's. Murph made them for me.

Calculate port volume and wood involved to find the saved space.

Tuning isn't difficult. You can really just do it by "ear" and watching the subs while you play tones. Start super low (like 20hz) and track up until the sub(s) move the least. That's where it's tuned.

jockhater2
03-03-2013, 01:34 PM
I think I paid $80/ea. They're custom ones made with the same basket and soft parts as my Tantric MD's. Murph made them for me.

Calculate port volume and wood involved to find the saved space.

Tuning isn't difficult. You can really just do it by "ear" and watching the subs while you play tones. Start super low (like 20hz) and track up until the sub(s) move the least. That's where it's tuned.

so you need 2x the cone area in PRs vs. your active subs?
I don't understand the last part. How do you tune it by ear? and you want which subs to move the least?

So for a PR set up. You build the box to the specs of a sealed enclosure. and then introduce the PRs?

TaylorFade
03-03-2013, 02:00 PM
so you need 2x the cone area in PRs vs. your active subs?
I don't understand the last part. How do you tune it by ear? and you want which subs to move the least?

So for a PR set up. You build the box to the specs of a sealed enclosure. and then introduce the PRs?

Yes. 1.5-2x. A 12" PR is good for a 10. A 15" for a 12 and so on. Or just double it up.

The actual sub. It will move the least at system resonance. If you are tuned at 30hz, the sub will barely be vibrating at 30hz. It will move a lot below tuning, so track up on the tones until it stops flopping around. Add wieght until it is barely moving while it's playing the note you want to tune it at. I should make a vid of that, I guess.

You can do it that way if you like, but I usually stick to recommended ported box specs.

jockhater2
03-03-2013, 02:11 PM
Yes. 1.5-2x. A 12" PR is good for a 10. A 15" for a 12 and so on. Or just double it up.

The actual sub. It will move the least at system resonance. If you are tuned at 30hz, the sub will barely be vibrating at 30hz. It will move a lot below tuning, so track up on the tones until it stops flopping around. Add wieght until it is barely moving while it's playing the note you want to tune it at. I should make a vid of that, I guess.

You can do it that way if you like, but I usually stick to recommended ported box specs.

Ok. Just curious. I was more just asking about it because I think it would be a set up I would like to run some day. The tuning part I don't necessarily understand. But I could always have someone help me. It is just an interesting way to run a sub stage.

Beatin'
03-03-2013, 08:04 PM
Yes. 1.5-2x. A 12" PR is good for a 10. A 15" for a 12 and so on. Or just double it up.


I don't think you MUST have 1.5-2x the cone area for the PR. It can be for example 15" for 15" but the PR must possibly have less weight or more excursion, etc, something.

TaylorFade
03-06-2013, 09:22 AM
I don't think you MUST have 1.5-2x the cone area for the PR. It can be for example 15" for 15" but the PR must possibly have less weight or more excursion, etc, something.

Hence why I said it's either cone or xmax.

You don't HAVE to have any of it. But if you'd rather not have your PR slapping around and bottoming out, I suggest you follow those guidlines.

jockhater2
03-06-2013, 03:54 PM
Hence why I said it's either cone or xmax.

You don't HAVE to have any of it. But if you'd rather not have your PR slapping around and bottoming out, I suggest you follow those guidlines.

Can you break a PR from over excursion or anything like that?

ciaonzo
03-06-2013, 04:02 PM
Indeed, you can.

n8skow
03-06-2013, 04:14 PM
Could potentially damage the suspension.

jockhater2
03-06-2013, 04:18 PM
Could potentially damage the suspension.

Oh ok. Wanna do me a favor...What exactly is the "suspension" on a sub?
What is the coils? That pole in the middle of the sub?
I don't even get how the current from the tinsel leads...traveling to wherever they go...make the speaker play.

n8skow
03-06-2013, 04:24 PM
Suspension - referring to the surround and spider.
A passive radiator is basically the woofer without a magnet or voice coil.

http://4.bp.blogspot.com/_z11ySfEYTPk/TPQ9HP8RqHI/AAAAAAAAAe0/-fjLwg_S-SY/s1600/speaker-anatomy.gif

jockhater2
03-06-2013, 10:16 PM
Suspension - referring to the surround and spider.
A passive radiator is basically the woofer without a magnet or voice coil.

http://4.bp.blogspot.com/_z11ySfEYTPk/TPQ9HP8RqHI/AAAAAAAAAe0/-fjLwg_S-SY/s1600/speaker-anatomy.gif

OH...that's what the spider is. That yellow/orange ripple looking stuff. What exactly does the spider and voice coil do?

bubbagumper6
03-06-2013, 10:25 PM
Voicecoil is what is energized by the amp creating a magnetic field which pushes/pulls the cone assembly through the motor's magnetic field (the large magnet on the bottom). The spider is what actually supports the cone and keeps it from tearing apart.

jockhater2
03-06-2013, 10:33 PM
Voicecoil is what is energized by the amp creating a magnetic field which pushes/pulls the cone assembly through the motor's magnetic field (the large magnet on the bottom). The spider is what actually supports the cone and keeps it from tearing apart.

And now I know. Thank you!

Beatin'
03-07-2013, 12:39 AM
And now I know. Thank you!

:laugh:

jockhater2
03-07-2013, 03:49 PM
:laugh:

:fro: