[dflee]

Lets say you have two speakers that both go down to 20 hz, one ported and one sealed. In theory or sound which would have the better bass? I exclude open baffled cause I'm not sure they can do it.

Later
Don

[Æ]

Even if you have two woofers that go down to 20Hz, it all changes once you've installed them in an enclosure. There is no absolute "best" alignment. A sealed enclosure is analogous to a second order high pass filter while a vented enclosure is analogous to a fourth order high pass filter. Typically you'll get better transient response from a lower order alignment. Lots of other things to take into consideration though, such as the actual size of the enclosure and the final efficiency.

[Bob in St. Louis]

Yea....I think I'd like to follow this one. Looks to be interesting. 

[Æ]

Yea....I think I'd like to follow this one. Looks to be interesting. 

When it comes to bass, what is best? It's all subjective. In some ways a bass reflex alignment is better and in other ways a sealed alignment is better. It just depends. Thiele/Small delved into it extensively. If you want to know more, that is where you should start.

http://en.wikipedia.org/wiki/Thiele/Small

Theoretically a sealed alignment is probably better, but that is just my opinion.

[cujobob]

My opinion is that a sealed alignment is best and also easiest to integrate with a subwoofer.

[JLM]

In general, I'd say sealed too.  But there are many variables.  Without playing circuit games, pure ported designs have a faster roll off versus pure sealed designs.  At 20 Hz cut off you're typically working with subwoofers and they normally have circuits to limit really low output to avoid nasty room/equipment feedback.

What one designer calls "down to 20 Hz" can be different than another (anechoic chamber versus "in-room", - 3 dB versus - 10 dB, etc.).

And it's not uncommon for designs (rock monitors) that roll off around say 50 Hz to have a bump up around 60 Hz to seem like they "have more bass" (mistaken for deeper bass) which does extend bass response, but not as much as they'd like to advertise.

[JohnR]

I would be inclined to pick sealed over ported for music applications in typical home listening rooms. If those were the only choices........

With regard to OB, there are some tricks. Like anything (e.g. headphones), you can make them flat to 20 Hz. But, whether this is a good aim is not so clear. I'd suggest that good impact down to the mid-30s is a good target, and below that is a juggling game between all kinds of tradeoffs. If you think you have good "flat to 20 Hz" performance, I'd really like to see your decay plots.

[Duke]

All else being equal, the sealed box is superior.

Now here is one reason why all else may not be equal:  The elephant in the room is... the room.  Perceptually, the room and the loudspeaker are a system, at long wavelengths anyway; that is, you cannot hear the loudspeaker apart from the room's effects. 

So, I would favor the system whose in-room response is the best.  Usually that will be a sealed-box system, because (painting with a broad brush here) the relatively gentle rolloff of a sealed box synergizes better with typical room gain.  But in my opinion, it is possible to design a vented box system whose rolloff is an even better match for typical room gain.  Both types could be said to "go down to 20 Hz", but done right, imho a vented box can be better.   Unfortunately most vented boxes are tuned for "impressive in a brief audition" bass, which translates to "over-emphasized". 

[dflee]

Duke
Thanks for the honesty but now I feel like Lou asking who's on first. I am so confused.
Is that why some don't use the sound proof room approach for speaker design.
Does the sealed enclosure remove the room effects? And if so why would anyone go with OBs and have all the trouble of trying to remove that factor. Or are they using the room as part of the enclosure to get sound they wouldn't get otherwise?

[Æ]

Does the sealed enclosure remove the room effects?

There is no enclosure that removes the room effects. The room effects are there regardless if you have loudspeakers or not. When you have a problematic room, you have to treat the room. Placement will only get you so much, a series of compromises.

[JLM]

Some "serious" vendors advertise that their speakers are "placement friendly," (lifestyle) like Amphion and TBI while others promote constant directivity like Audiokinesis, Geddes, and Pi.  Most of these use waveguides.  The constant directivity designs design with multiple subs, bipoles, and 45 degree/corner placements.

Both camps are trying to take the room out of the equation.

Overall room gain can balance natural bass drop off.

Dipoles (including open baffles) load the room differently.

Most recommend keeping reflected sound paths at least 11 feet longer than direct sound paths.

[Æ]

Most recommend keeping reflected sound paths at least 11 feet longer than direct sound paths.

Haas Effect.

[Bob in St. Louis]

I see the room as an ally, not an enemy.

Moderately treated, a room with IB/OB can .......... oh......... wait......

We excluded all but ported and sealed, sorry. My mistake. Bye.

[Letitroll98]

I see the room as an ally, not an enemy.

Moderately treated, a room with IB/OB can .......... oh......... wait......

We excluded all but ported and sealed, sorry. My mistake. Bye.

Well, to be exactly correct, the OP intimated they could be discussed if they reach down to 20hz.  Your play.

Actually I was wondering when the bass master Bob was going to kick in with a thought or two.

[Æ]

I see the room as an ally, not an enemy.

Yeah, especially on a cold night like this one.

[Bob in St. Louis]

  Well Letitroll, it was a bit of a kick in the groin for him to discount them, right off the bat. That's why I made the comment I made. All in good fun of course, I don't take much seriously.

Regarding OB reaching 20?
No. Not with much "omphf" remaining anyway.
IB ...... not much explanation needed there. My IB curve is still rising as it comes down nearing 20.

Regarding his comment about "better" bass. Is he talking about best quality for a home situation, most accurate to real life, most 'punch', what?

Regarding what dflee said, "why would anyone go with OBs and have all the trouble of trying to remove that {room] factor"
As I said earlier, I use the room to my advantage. That's what OB is all about. Unless you're in freshly plowed Nebraskian corn field, the room will always be part of the equation. In my opinion, OB can complement the room, and visa versa.. No need for the two to fight each other. Mine is "moderately" treated, and I feel those treatments and OB complement each other nicely.

Regarding your original question, I've had ported <20Hz in the room (2 15" drivers mounted in a Decware Housewrecker) and I've had OB/IB (too much to list here). And there is zero comparison. The OB/IB is the cleanest, clearest, non-muddy/boomy bass I've ever heard.

Right now I'm listening to Ahmad Jamal After Fajir, Topsy Turvy, and the bass through two 15" woofers in OB is pure, clean, crisp, and accurate. I couldn't ask for more. The IB isn't even on. That's for another genre altogether.

So there's my thought or two Letitroll. 
Thanks for the "bass master" name, I'm flattered. But I'm not worthy.

Next?

Bob

[Æ]

I think the best way to compare the two is with a graph, explain it graphically. I took the liberty of hand drawing a crude graph. Red area represents where bass reflex is superior. Blue area represents where a sealed enclosure is better. The graph is not absolutely accurate but is sufficient enough for illustrative purposes.

[JohnR]

The bass master is correct 

Look, it's a pointless question (no offense to the OP). Duke's post nailed it - what you get in room is what counts. That means not just FR but also decay times. Do you really want down to 20 Hz (whatever it means) for music? I bet almost everybody who does has never had it. (Prove me wrong  )

[Bob in St. Louis]

The bass master is correct 

Thank you John.

20Hz for music is uncomfortable. Plain and simple. It's annoying for the family members in the rest of the house (despite having taken a LOT of precautions when building my room to avoid that). It's great for home theater, it's great when my friends come over to impress them, and it's great for the occasional jam session when the family isn't home and I've had a couple glasses of wine.

Other than that, 20 Hz is over rated and unnecessary for most people. Of course, all those pipe organ fans will have differing opinions

As far as which is "better".....I would say it's much like asking which of these is better:
Doing 200mph in a Ferrari, or doing 200mph in a Lamborghini?


Bob

[Æ]

As far as which is "better".....I would say it's much like asking which of these is better:
Doing 200mph in a Ferrari, or doing 200mph in a Lamborghini?

Doing 200mph in a Porsche!