Ported vs. Sealed

[dieselpower1966]

ok this is totally hypothetical but here it goes.
If I have a 1700 cubic foot room and I have 2 styles of subs:

1 ported
1 sealed

and everything being equal such as 300 watt and frequency and crossovers the same including box dimensions, which one would give the best results?

as I said just hypothetical but interesting to me.
thanks
John

[mojomike]

One question, John: Is the room closed or open to another area?

If is closed, a room gain in a small clased area will offset the natural roll off of a sealed sub and give you something close to a flat response in the lower frequencies.

Tf the room is open, the sub effectively "sees" a larger space and there will be less room gain in the deeper frequencies. A good ported sub may might do better in this case for the deeper frequencies.

[thxgoon]

A ported sub will give you more output down to it's tuning frequency and then drop like a rock from there. A sealed sub will have a gradual roll off as frequency decreases. There are really too many other variables to answer this question correctly. ie - what type of driver, how big is the box, what tuning frequency, port size etc... all play a roll in output, extension and distortion for a particular design.

[dieselpower1966]

first off thank you Mojo and Thxgoon for joining in.
once again this is all hypothetical, let's assume that the room is closed off. let's also assume that the room is 14'x15'x8' that's 1680 cubic feet of volume. (which is the actual size of my room) kinda coincidental...
let's also assume that both the ported sub and the sealed sub are 18"hx12"wx14"d, (this is the actual size of my current sub) both have 300 watt amps, the same exact crossover, (you can even choose the crossover if you wish), both have 2- 8" front firing drivers, the port on the sub let's say is 4", also ported to the front and they are both tuned from 25-120hz and let's say that the distortion is 3% (remember hyperthetically).
so I would love to read both your opinions, and hypothesies on this.
by the way if you want to give your theater a real work out with lots of eye and ear cand,
you must watch Transformers. your theater will love it

John

[Mike P.]

All things being equal, the ported would have more low end output.

[mojomike]

A box that size would be a little smallish for a ported sub with 2 x 8" drivers. This of course depends on the woofer specs, but sealed might be a better choice if that is your only size option.

[imbeaujp]

For movies, the ported sub should give you a better experience. But for stereo audio, the sealed sub will be more accurate.

For my system, i use 2 sub with pasive radiators. This is a good compromise between ported and sealed.

JP

[dieselpower1966]

Thank you Mike and Mojo for the feedback.
and that is my actual sub, it's an older Yamaha yst-sw150 the 2 front facing woofers measure 8" across, from side to side of basket, so I guess that makes the woofers actually 7.5" and the 4" port is also located on the front. so let me mention the subs that I'm thinking of and you guys tell me what you think.

1. Emotiva DRS-1 (this is a dual subwoofer set up each with 2 12" woofers and a shared 600 watt amp, these are sealed and are due out in January) $999
2. Outlaw audio LFM-1 (again this would be a dual sub setup each with 1 12" ported, down
firing woofer and 350 rms with 1300 peak rms $1098
3. SVS PB12-Plus/2 down firing 12" woofer w/ 4 ports 900 watt amp w/EQ $1099

I'm not sure about the down firing vs. the front firing. (I want to feel the bass in my face and shaking the windows) also the Emotiva won't be out till January
so I have to wait for that review. The choice of the Outlaw and SVS is based on many reviews that I've read. right now my room is only 14'x15'x8 which is 1680cu. ft, but this is not permanent I do plan on a much larger room somewhere around 17'x20'x8' which is 2720 cu. ft (give or take a foot). so if I go the dual sub route, I could put one away for now. The SVS would only be a single sub at that price.
so many subs, so many options, too small a bank account.
John

[SteveCallas]

But for stereo audio, the sealed sub will be more accurate.

Different people must have different definitions of the word accurate. Ported will maintain a flatter FR while extending deeper, have less distortion, and more headroom. With the type of sub the OP is describing however, I wouldn't even bother to go ported.

[dieselpower1966]

ok Steve,
let's try to get this straight. you said a ported sub will have a flatter frequency, extend deeper, have less distortion, and higher headroom.. buy you wouldn't bother with a ported sub? isn't that a contradiction? I'm also not sure who or what the OP is, can you explain?
thanks John

[SteveCallas]

OP = original poster, which is you. I wouldn't bother because you want to use two 8" drivers in a small enclosure.....ported or sealed, performance isn't going to be all that great. For the cost of two 8"s, I'd get one 12" instead so you could build something a little more capable.

[dieselpower1966]

Steve, thanks for responding again,
There may be a little confusion, it may be on my part but maybe not.
I did not imply that I wanted another sub with 2 8" woofers that is what I have now. It was merely a hyperthetical what if... compared to the same exact enclosed sub with no ports.
If you go back to the postings and the replies that I got from other great shackers, those are what led me to my 3 final choices between the Outlaw, SVS and Emotiva Subs which are all much more substantial than the one I now own.
please feel free to reply again.
John

[SteveCallas]

I see. Assuming the dimensions you listed allow for enough volume to properly port the sub, ported will always yield more performance when using the same driver(s) and amplification.

[Mike P.]

John, a perfect example of what Steve said would be to compare the results of 2 subs recently tested by Ikka. Look at the response graph of the SVS PB13-Ultra tuned to 15hz,

http://www.hometheatershack.com/foru...-tune-new.html

and compare that to the response graph of the SVS PB13-Ultra sealed.

http://www.hometheatershack.com/foru...ealed-new.html

[warpdrive]

Some of the best sounding subs are sealed, so it's not a matter of ported vs sealed being better, they both have their own tradeoffs depending on what the designer is compromising. There are examples of great subs from either type. If you look at some of the larger sealed subs, they have little to apologize for in terms of output and extension. The ported subs can dig deeper but they may do so at the expense of other parameters in the mid band or elsewhere.

[SteveCallas]

Some of the best sounding subs are sealed

Different people prefer different sonic characteristics, but if we are talking about accuracy or performance, ported will always be better assuming the same driver(s) and amplification.

The ported subs can dig deeper but they may do so at the expense of other parameters in the mid band or elsewhere.

Please give an example as to what you are referring to.

[warpdrive]

SteveCallas wrote:

Different people prefer different sonic characteristics, but if we are talking about accuracy or performance, ported will always be better assuming the same driver(s) and amplification.

First, I'm not what you mean by ported is more accurate. Ported enclosures can be subject to ringing, transient response problems, intermodulation distortion etc.

This whole thread is kind of a red herring. You can't say "using the same driver" because the best drivers optimized for a ported enclosure may not perform as well in a sealed enclosure due to the mechanical compliance differences and excursion capabilities of the driver. That's why SVS themselves said that they will never use their Ultra driver in a "SB13-Ultra" model because that driver was designed to work best in a ported configuration. Running it in sealed mode is not going to be optimal. For that reason you can't take the "sealed mode" numbers in the tests (by plugging all the ports) and say that the sealed mode is inferior. If one was to design a ported sub of that size, you wouldn't choose the Ultra driver. The Plus driver was designed with both ported/sealed modes in mind, but it walks the middle ground in its design.

[SteveCallas]

Ported enclosures can be subject to ringing, transient response problems, intermodulation distortion etc.

Sure, if the design is executed poorly, but that can be said for any alignment. You can see that the issues you bring up are really non issues from Ilkka's testing of DIY subs. The perfect example is his testing of a sealed TC2k and a ported TC2k.

As for accuracy, having a deep extending, flat FR with low distortion and ample headroom is *required for any type of accurate bass reproduction.

[dieselpower1966]

O.k. enough of the philosophical design debate, this all started with a hyperthetical question anyway.
I will definitely wait to see if the Emotiva DRS-1 gets reviewed here on the shack. HOPEFULLY it does I would love to see how they fair against the Outlaw LFM-1 and the SVS PBS 12 plus 2.
Do any of you have first hand experience with the sub Outlaw or the Svs mentioned above?
Also a small note, for the price of the single SVS mentioned, I could get 2 of the Outlaws or the Dual Emotiva set up.
This has been very interesting reading,
thank you gentlemen.
Happy Hollidays
John

[mojomike]

Different subwoofer alignments can work better or worse than others in different environments. Using the 13Ultra as an example, even though ground plane test show far superior results in 15 and 20hz modes, there are many folks out there who prefer the sound of the 13Ultra in sealed mode. That may have very much to do with the way the sub performs in a particular room.

[dieselpower1966]

Mojo,
I am definietly leaning towards another portes sub, basically because the supposedly play flatter down to their lowest frequency, and I would try it with the port open and blocked to see which way it integrated with my system the best.
does anyone have first hand knowledge with the Outlaw audio LFM-1ex?