Sealed vs Vented Enclosures

[bradley]

I've been lurking and learning for a while here, searched the topic, learned quite a bit, but am still left in some doubt about.. vented or sealed? I know that convention seems to maintain sealed subwoofers as best suited to "musical" apps, and vented enclosures to higher spl, helicopters and thunderclaps home theater, etc. This is practically axiomatic to most discussions. But the few contrarians out there seem passionate, and often persuasive. The (apparent) majority of manufactured higher end subwoofers, small monitors, and full range speakers using tuned porting would also seem to say something on its own, but I'm not exactly sure what. Is there stronger consensus out there on this subject than I seem able to find so far?
I want to begin building some projects, including subwoofers. I don't yet have the expertise or software to get very involved with passive radiators, transmission lines, folded horns, etc. I'd love to hear more thoughts on this.
Thanks a lot.
brad w

 

[mikee12345]

I want to begin building some projects, including subwoofers

see the SHIVA from adireaudio.com and assocated subwoofer plate amp,always a solid start.Very popular.

to see how to design subwoofer enclosures-diysubwoofers.org
www.linearteam.dk

Personally for me
Ported comes out on-top

----Quick version as i need to go sleep ----

I need output,i want low distortion I dont mind if i have higher GD at tuning.

It comes down to making choices and knowing the pros/cons of each

Sealed doesnt have the output or loading that i want.

I like it how the port loads the cone,providing output(depending on the alignment,maybe rather pure,or not < boomy or overdamped responses > )at the low frequencies where you want the loading.

Also sealed boxes resonate at a higher frequency than the Fs naturally,and below Fs woofers distort more,,so why raise it!

Also- a ported box can have very similar sound to a sealed box if the responses are similar(which if they are then the ported box wil be smaller providing the ports fit) but ofcourse-the objective is MORE bass,not the SAME bass in a smaller box,so we extend the low frequencies.....losing quality.

The port tuning can be near the woofers Fs- where you want low cone movement to prevent BL distortion from turning the output to custard.

So really it comes down to 'you dont get something for nothing' and ported box EBS etc are just ONE of the ways to get the lows,at a cost.

However!
If i could buy 2 or 4 high excursion low distortion 15"s for sealed operation to give me 115db at listening position,i would buy them (and the associated huge amplifiers)

Oneday i will arrange a listening test with a Pi aligned ported box,or other overdamped alignment vs a sealed box..and compare qualities-but it must be a thought out test,no use comparying apples with oranges-or atleast do it 'fairly'

Cheers!
http://homepages.paradise.net.nz/quadroph

 

[sreten]

The bottom line is reflex is more cost effective, hence its popularity.

sreten.

 

[Jimmy154]

The (apparent) majority of manufactured higher end subwoofers, small monitors, and full range speakers using tuned porting would also seem to say something on its own, but I'm not exactly sure what.

To me the apparent majority of high end subs are sealed. But all I can think of is Velodyne, Paradigm, Revel, and Bob Carver Subs, and on half of those I'm not sure.

I know that I hate the sound of ported anything. Although the loudness of the port is very tempting. Also I like 15" subs. Did you listen to any subwoofers?

 

[roddyama]

The design of a driver for low frequency reproduction is a series trade-offs. Everyone would like to get the driver to:
1.) Be low cost
2.) Be efficient
3.) Have a wide bandwidth
4.) Have high output
5.) Have low distortion
6.) And be a reasonable size.
Dollar for dollar, a ported system can give you better results for 2, 3, 4, or 6, and 5 is debatable, but theoretically, 5 as well. The trick is you can’t have them all. You really need to know what you want as your priorities.

 

[amo]

The (apparent) majority of manufactured higher end subwoofers, small monitors, and full range speakers using tuned porting would also seem to say something on its own, but I'm not exactly sure what.

PROFIT PROFIT PROFIT PROF.....


I guess I should clarify..... Given unlimeted resources, including cost, size, weight, heat, etc. perhaps we would not have ported designes. This is just my openion, but... If you could have a speaker of any size, and an amp capable of any power, I am not too sure why you would choose ported. But when you have to compromize, then you get creative, and find ways to "improve efficiency".....

But... just think what a great sales pitch this is though: this speaker is TEN TIMES SMALLER then this one, but gets just as loud.....


Ok I need sleep

 

[mikee12345]

I know that I hate the sound of ported anything. Although the loudness of the port is very tempting. Also I like 15" subs. Did you listen to any subwoofers?

I dont hate the sound of ported at all. a nice overdamped response sounds great.

Perhaps the alignments you heard were flat-anechoic but boomy in room.

i like 15" subs too

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Depending on the alignment (Just like sealed box Qtc,) ported boxes can have excess resonant energy at port tuning, resulting in a 'high qtc-like' sound.

the question is=with an overdamped response, what is the transient response like NOW when measured at tuning good?

I see measurements at linkwitzlab.com on sealed boxes,but no ported comparison.
I expect it to be better.

Cheers!

 

[amo]

Here is a good experiment for begginers: Download WINisd. Now model a bass driver in a sealed enclosure, and the same driver in a ported. Take a look at the gain and SPL pages.... ported looks pretty good. Now click on the group delay tab

 

[mikee12345]

Download WINisd. Now model a bass driver in a sealed enclosure, and the same driver in a ported. Take a look at the gain and SPL pages.... ported looks pretty good. Now click on the group delay tab

you forgot this step

Build each of those enclosures
-Decide if ~20ms of GD at 22hz tuning *typical shiva tune* actualy sounds that bad compared to sealed

Listen outside to ensure the room doesnt interfere.Becaue the ported box can have more low output,room gain can cause it to have too much output down low in certain rooms..and then theres room modes..

 

[Stephen D]

Here is a good experiment for begginers: Download WINisd. Now model a bass driver in a sealed enclosure, and the same driver in a ported. Take a look at the gain and SPL pages.... ported looks pretty good. Now click on the group delay tab

Yep, & that about sums the main sonic +/- that each has compared to the other. One thing to keep in mind though on the group delay advantage of sealed.... at such low freq typical of subwoofer application it's most often a moot point as room resonant delay acoustics generally dominate & over ride any sonic difference (provided the ported design is decent to begin with).

The max SPL curves will usually show you that for the bottom octave & more of the ported enclosure it would take more than a couple of the same driver in a sealed to achieve the same SPL.

The simplicity of sealed I think can often be a better choice for mid/upper bass where SPL differences aren't as great & ported carries the added concern for being driven to severe over excursion from infrasonics below the port tuning if not filtered.

I use either depending on the requirements of the application.

 

[planet10]

Me, i like push-push t-lines (or aperiodic if it has to be smaller). Ported does little for me, and sealed boxes have their own problems, but i'd take a low Q sealed box over a ported box.

dave

 

[wintermute]

Here is a good experiment for begginers: Download WINisd. Now model a bass driver in a sealed enclosure, and the same driver in a ported. Take a look at the gain and SPL pages.... ported looks pretty good. Now click on the group delay tab

Yes as said by others, compromise is the key here...... Is there any point having low group delay at say 30Hz if the output is down say 15db compared to a ported design with the same driver???? Also look at the difference in linear (ie xmax)power handling of the ported vs sealed enclosure (at least until you get to the box resonant freq) and you will see that the ported has a few advantages on it's side, depends on what your priorities are.

above figures pulled out of the air. I did the comparison you mentioned about a week ago and yeah below about 50 or 60 hz (I think) the ported boxes group delay was worse than the sealed (above from memory it was about the same), worst group delay was around 30hz and was about 17ms.

This was with a Vifa M26WR-09-08....

Tony.

 

[OMNIFEX]

The max SPL curves will usually show you that for the bottom octave & more of the ported enclosure it would take more than a couple of the same driver in a sealed to achieve the same SPL.

And, this is why reflex cabs are more popular. With todays
electronic music, you generally need a design that will offer
alot of low bass. While some people perfer tight punchy
bass, others perfer low extended bass. It's a matter of preference.

 

[chris ma]

And, this is why reflex cabs are more popular. With todays
electronic music, you generally need a design that will offer
alot of low bass. While some people perfer tight punchy
bass, others perfer low extended bass. It's a matter of preference.

So we can not have them both? Isn't that what sub-woofers are supposed to give the extended low to supplement the main speakers tight bass?
Can we build them both to cover it all or they will cancel out each other?

Chris

 

[wintermute]

Good question, but I think that is more dependent on the driver The comparison between reflex and sealed (at least IMO) is probably only really relevant for a particular driver. Some drivers will perform better in one or other of the enclosures.

If You get a suitable driver in a sealed cabinet, then you can get it to outperform a different driver in a vented one, howerver there will most likely be other tradeoff's. Like size, power needed to drive it etc..... Again it comes down to prefference ...... not everyone has room for a 200L cabinet with an 18" driver (once again totally fictitious numbers pulled out of the air)....

Everything I have read about ported enclosures says they are much more difficult to get "right" than sealed enclosures, which is I suspect why a lot of people don't like them....... Could be they have tried ported and it didn't sound good/right, then tried sealed and it did. I haven't tried sealed yet (but I'm planning to in my next project), yeah my ported boxes have some problems, but I put that more down to poor cabinet construction than anything else. edit: I'm sure that they would sound even worse if they were sealed, due to the number of leaks!!!!!!!

It's all swings and roundabouts.......

Tony.

 

[Peter M]

Hi Brad,

If you decide to go with a sealed sub because it's more "musical," why not look into a dipole sub? Construction can be as easy as you need it to be, and you can get great results with even cheap drivers. The search function should bring up more than enough threads to get you started.

Hope this helps,
Peter

 

[OMNIFEX]

wintermute

I have to agree with you 100%

One of the problems most people do when designing a
sub, is pay no attention what the TS Parameters really
mean. They buy the woofer because their buddy has it
and/or they heard great raves about it.

They never take the time to understand that only if they
are using the same cabinet size, same amplification, same
room dimensions, and, the same music, they are going to
get the same response.

Sealed cabs is what I call, you can't mess up kind of design.
No matter what, your going to a decent to fantastic sound.

But for reflex, you need to know that if you're off by half an
inch in your tuning, you're not going to get the sound you
were destined for.

Another thing is cabinet size. Reflex are generally better
when you are limited in space. If you have more than
enough room, build a cabinet the size of your refridgerator.

Bottom line to produce Low Bass, you need a large box.
If you can't acomodate such a beast, Reflex is the next
best alternative.

 

[planet10]

While some people perfer tight punchy
bass, others perfer low extended bass.

The problem with many designs is that they are designed anechoically flat, and you put them into a real room and then it isn't low extended bass you are getting, but big lump bass.

A real-world sub should start rolling off where the room gain starts kicking in.

dave

 

[amo]

Hi Brad,

If you decide to go with a sealed sub because it's more "musical," why not look into a dipole sub? Construction can be as easy as you need it to be, and you can get great results with even cheap drivers. The search function should bring up more than enough threads to get you started.

Hope this helps,
Peter

To me this is the ultimate configuration, but it will take more space, drivers, amplification, electronics to get the same SPL as sealed, and much much much more to get the same as ported. It just depends how much bass you want and how pure you want it to be. Dont miss understand me... you may be perfectly happy with a sub that has a passive radiator on every wall.... if that is the case, why waste money and time on something else. By the way, Dave raises an interesting point. There are a few less popular configurations that you may want to study. For example, the Tapered Line is sometimes described as a "non-reasonant ported enclosure" which seems to resolve some problems of the standard port. The push pull configuration can also benefit many setups.


Like I said above, to me the ultimate sub will have many dozens of 15 inch drivers in a dipole configuration, as per S. Linkwitz. But untill I am a rich man and can afford such obsenity, my personal compromise has to be a large sealed sub with a Linkwitz transform to increase low output, and digital room correction, to make it sound more like a dipole....

 

[mikee12345]

interesting
Im glad we have some thinkers.

like i said- nothing comes for free

want more low end? port ur box and get higher GD

but will it matter?

OR

EQ your sealed box,increasing GD also..

2 ways to skin a cat..many more also

my jbl response is like this ...and i like it! overdamped ported =

Find the reference material that shows Effects of port ringing with various alignments and tunings..and compare to sealed.

im wanting to build the 30hz expo horn soon anyway,, 400Litres
Cheers!