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]

Originally posted by bradley
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]

Originally posted by bradley
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





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]

Originally posted by 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

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.