How to SEAL...?

[Din61]

Ayubowan!

Friends, this query is not about that far-gone "Sealed vs Ported" topic, everybody knows the basics to know by now, I just prefer the bass accuracy of sealed enclosures due to their dominance upon the driver, and that dominance in turn makes the sealed require more and more things over the ported in terms of driver and enclosure characteristics, I know.

Now, my living room under construction is L shaped, 20*20 + 10*10 ft. (room is massive for "acoustic suspension"), I'm planning on a diy 2-way stereo + sub in the large portion, need my sub to low down to 20hz (with my active crossover I intend to low-pass @ 50hz) with a desirable spl (not much of a concern). I emphasize no space limitations for me.

How possible with 12TBX100 @ 1000w (should I be nearfield or what if not that TBX or two subs of that TBX or higher TBX like 18" or any other than TBX or bigger box or more power or whatever, suggest me everything)...?

Thanks...

 

[Verdinut]

Well, you don't seem to know much about the real facts about the specifics of either a sealed or a ported woofer or subwoofer.

The ported subwoofer, while being more efficient down to infrasonic frequencies than the sealed one, will also have a more linear excursion and perform with much lower distortion than if it was sealed. You have the space to use a bigger enclosure, there is no argument in favor of the sealed box.

See the following threads:

Sealed vs Ported Loudspeakers: Which is Better?

Sealed vs ported loudspeaker designs, which one is better? This article provides a historical perspective and attempts to answer this age old question.

www.audioholics.com

Sealed vs ported

"Overall system performance is a function of the driver’s Thiele/Small parameters and enclosure volume, which together will determine system Q and the system’s resonant frequency. Below the resonant frequency, sealed subwoofers typically feature a shallow roll-off of 12dB/octave, which also...

forums.audioholics.com

 

[Din61]

Well, you don't seem to know much about the real facts about the specifics of either a sealed or a ported woofer or subwoofer.

The ported subwoofer, while being more efficient down to infrasonic frequencies than the sealed one, will also have a more linear excursion and perform with much lower distortion than if it was sealed. You have the space to use a bigger enclosure, there is no argument in favor of the sealed box.

See the following threads:

Sealed vs Ported Loudspeakers: Which is Better?

Sealed vs ported loudspeaker designs, which one is better? This article provides a historical perspective and attempts to answer this age old question.

www.audioholics.com

Sealed vs ported

"Overall system performance is a function of the driver’s Thiele/Small parameters and enclosure volume, which together will determine system Q and the system’s resonant frequency. Below the resonant frequency, sealed subwoofers typically feature a shallow roll-off of 12dB/octave, which also...

forums.audioholics.com

But, as fas as I've learnt from a plenty of online resources (not in practice though), a sealed enclosure tends to present great transient response, low group delay, smooth roll-off, no over-excursion (when properly damped) and audiophile quality with natural harmonics (the reason why top-of-the-line hi-fi stereo built inside of sealed cabs), am I missing something here...???

 

[lovinthehd]

I think you're reading some of the old myths about subs (and yes many "audiophile" sites still propagate such nonsense)....that list of reasons sounds like something you'd pick up on one. Such "audiophiles" barely know what to do with a sub for the most part.

Is this the driver you're thinking about using? https://www.bcspeakers.com/en/products/lf-driver/12-0/8/12tbx100

 

[Din61]

I think you're reading some of the old myths about subs (and yes many "audiophile" sites still propagate such nonsense)....that list of reasons sounds like something you'd pick up on one. Such "audiophiles" barely know what to do with a sub for the most part.



Is this the driver you're thinking about using? https://www.bcspeakers.com/en/products/lf-driver/12-0/8/12tbx100

I think we've met before at another thread, so welcome back...

Yep, that's the driver.

How about a parallel 6th order bandpass then (if you suggest me not to care a lot about transients)?

And what do you think of this?

Sealed is Not Acoustic Suspension in Loudspeakers

Some vented speakers offer port plugs for sealing the cabinet and making them act like sealed speakers. This does not result in a true acoustic suspension. What's the difference? Read on to find out.

www.audioholics.com

 

[lovinthehd]

Okay, hello again?! Might have to look that up....or is it in the acoustic suspension thread? Sealed is a type of acoustic suspension, but not the type discussed in that article.

I'd suggest you find a subwoofer driver first before planning a sub, tho. B&C makes more appropriate drivers I'm sure.

 

[William Lemmerhirt]

Bandpass boxes are usually limited to a smaller frequency range, and generally one note wonders. Not sure where you think HD said transients aren’t important. Bandpass won’t help, and sealed won’t either. I agree with them both.
You have plenty of room(although dimensions that are the same, or multiples of each other are not usually good a acoustically speaking), so why bother with sealed. Group delay? Nah. In a quality ported sub, it’s well below the point of audibility. And in a sealed sub, the added dsp and eq to make it play flat to 20 or below can add group delay that could be higher, as well as adding more distortion. And yes you can drive them to over excursion. The driver HD linked has a very high FS and imo, would have limited output in a room that size. Especially in a sealed enclosure. Plus 9mm xmax? I don’t see that thing doing 20hz with any authority at all.
So I’m not sure about your opening paragraph. Seems the sealed vs ported topic isn’t that far gone at all! Lol

 

[Verdinut]

I think we've met before at another thread, so welcome back...

Yep, that's the driver.

How about a parallel 6th order bandpass then (if you suggest me not to care a lot about transients)?

And what do you think of this?

Sealed is Not Acoustic Suspension in Loudspeakers

Some vented speakers offer port plugs for sealing the cabinet and making them act like sealed speakers. This does not result in a true acoustic suspension. What's the difference? Read on to find out.

www.audioholics.com

What sub do you intend to use?

That woofer you are referring to is just a limited woofer for a 12 inch driver. Having a high Fs of 42 Hz it cannot dip efficiently below 40 Hz and, and because of its low Q, is designed to be ported. The manufacturer states its frequency response as 40-1000 Hz. Actually, for hi-fi use, it's a lousy woofer. That woofer has more of the characteristics of a pro audio driver and is not designed for low frequency room shaking duty. As a matter of fact, I have built enclosures using 6 inch woofers with which I could get an adequate response down to 35 Hz.

 

[lovinthehd]

FWIW you might review some of the reviews involving B&C drivers in both diy and commercial configurations at data-bass.com

 

[Verdinut]

But, as fas as I've learnt from a plenty of online resources (not in practice though), a sealed enclosure tends to present great transient response, low group delay, smooth roll-off, no over-excursion (when properly damped) and audiophile quality with natural harmonics (the reason why top-of-the-line hi-fi stereo built inside of sealed cabs), am I missing something here...???

Subwoofers with a Q of 0.45 or less are designed to operate in a vented enclosure. When they are driven with a solid state amp in a properly tuned cabinet, they have an excellent transient response.
But don't drive them with a tube amp, or one of those McIntosh amps that use a transformer at the output stage, then there is a possibility of getting a poor transient response.

 

[Din61]

Okay, hello again?! Might have to look that up....or is it in the acoustic suspension thread? Sealed is a type of acoustic suspension, but not the type discussed in that article.

I'd suggest you find a subwoofer driver first before planning a sub, tho. B&C makes more appropriate drivers I'm sure.

No, I've posted my first thread prior to this, there we met before.

I guess the article I linked was trying to imply (in addition to the factor that port-plugging isn't acoustic suspension) how nice a perfectly-built acoustic suspension enclosure is, what a smart concept of Mr. Villchur to utilize AIR as a suspension technique that excelled the AR speakers back in the 60's, how their low Q drivers still win in low-freqs over extremely sophisticated ones available now, as critics in that era acclaimed how clean & tight the bass response in a truly SEALED box is and that today's people have ignored the GROUP-DELAY argument Mr. Mitchell was highlighting.

Yes, 12TBX100 is the driver, but that article further explains that a few of today's low-freq transducers claiming they fit in both SEALED and PORTED is just ridiculous, so that I have to simply give up the particular driver (and most probably all B&Cs).

 

[Din61]

Bandpass boxes are usually limited to a smaller frequency range, and generally one note wonders. Not sure where you think HD said transients aren’t important. Bandpass won’t help, and sealed won’t either. I agree with them both.
You have plenty of room(although dimensions that are the same, or multiples of each other are not usually good a acoustically speaking), so why bother with sealed. Group delay? Nah. In a quality ported sub, it’s well below the point of audibility. And in a sealed sub, the added dsp and eq to make it play flat to 20 or below can add group delay that could be higher, as well as adding more distortion. And yes you can drive them to over excursion. The driver HD linked has a very high FS and imo, would have limited output in a room that size. Especially in a sealed enclosure. Plus 9mm xmax? I don’t see that thing doing 20hz with any authority at all.
So I’m not sure about your opening paragraph. Seems the sealed vs ported topic isn’t that far gone at all! Lol

How about a 4th order (one SEALED one PORTED), better than PORTED for hi-fi listening (I know it's way better than 6th order in "one note wonder" thing)...?

No, I thought he was implying such, my bad I think...

Yes, as I've mentioned in the post my room is big, honestly I'm still uncertain if SEALED would fit my room, but I really like the TAMED bass (kind of obsessed nah?), so was enquiring if 20hz is achievable with multiples of SEALED in a 4000 cu. ft. room (instead of just EQing).

Regarding that B&C I have a little story, in our country we don't have a single designer (in the engineering perspective) to simulate a sub, plenty of builders though who clone originals, exactly the reason why I'm here, on the other hand we don't have any home audio diy stuff, only car audio and pa sort of like B&C, so the only choices I have is either B&C (the only recognizable brand) or car woofers (genuines are there but good for home use???).

Okay, whether or not far-gone, "Sealed vs Ported" is a long debate, agree.

 

[Din61]

What sub do you intend to use?

That woofer you are referring to is just a limited woofer for a 12 inch driver. Having a high Fs of 42 Hz it cannot dip efficiently below 40 Hz and, and because of its low Q, is designed to be ported. The manufacturer states its frequency response as 40-1000 Hz. Actually, for hi-fi use, it's a lousy woofer. That woofer has more of the characteristics of a pro audio driver and is not designed for low frequency room shaking duty. As a matter of fact, I have built enclosures using 6 inch woofers with which I could get an adequate response down to 35 Hz.

True, B&C is pro stuff, loud above 40 outdoor, unfortunately then car audio is plan B (reason explained above), but I heard that car audio speakers (sub) aren't for home right?

 

[Din61]

FWIW you might review some of the reviews involving B&C drivers in both diy and commercial configurations at data-bass.com

Sure, I will...

 

[lovinthehd]

You don't need designers in your country, you can model your own with appropriate software, or just borrow designs posted up in this and other audio fora/groups. There are "car" subs that can work in a home sub, I've done so (Infinity 1262Ws in my case) and there are others. I used larger multiple sealed diy subs in my main setup in a larger volume space than yours but the driver I used isn't available even here any longer (SI HT18D2s). I built sealed because they were easier to move around and was a beginning woodworker too.....thought initially about ported but thought I'd start out simpler.

 

[Verdinut]

Yes, as I've mentioned in the post my room is big, honestly I'm still uncertain if SEALED would fit my room, but I really like the TAMED bass (kind of obsessed nah?), so was enquiring if 20hz is achievable with multiples of SEALED in a 4000 cu. ft. room (instead of just EQing).

It's impossible to reach down to 20 Hz with sealed subs without any EQing. In addition, that would require powerful amplification as every 3 dB boost means doubling of amp power. To produce a frequency one octave lower than at 40 Hz, the cone displacement has to quadruple. Infrasonic frequency production requires a lot of air displacement and this where the ported design has the real advantage.

I would suggest that you try having hold of a subwoofer having a Qts of 0.40 to 0.45 and a Fs around 20 Hz, with which you could build at its recommended box volume, the proper enclosure.
With the good driver in a properly tuned ported cabinet , you shouldn't expect any poor transient response. You need to have adequate knowledge about the complexity of building speaker enclosures. The following books are good starting guides:

Designing, Building, and Testing Your Own Speaker System with Projects: Weems, David: 9780070694293: Amazon.com: Books

Designing, Building, and Testing Your Own Speaker System with Projects [Weems, David] on Amazon.com. *FREE* shipping on qualifying offers. Designing, Building, and Testing Your Own Speaker System with Projects

www.amazon.com

Speaker Building 201: Ray Alden: 9781882580453: Amazon.com: Books

Speaker Building 201 [Ray Alden] on Amazon.com. *FREE* shipping on qualifying offers. Speaker Building 201

www.amazon.com

Also, some online stores sell kits including the appropriate cabinet where you have no calculations to do, just assembling.

 

[Pogre]

Ported designs are a better design than sealed by almost every measure. There's 1 reason to consider sealed and that's if it absolutely has to be as small as possible. That's it, full stop. You've been reading uneducated, subjective accounts on this. Go with a ported design.

 

[highfigh]

Ported designs are a better design than sealed by almost every measure. There's 1 reason to consider sealed and that's if it absolutely has to be as small as possible. That's it, full stop. You've been reading uneducated, subjective accounts on this. Go with a ported design.

One caveat is that in a ported design, the port tuning frequency needs to be low enough and the signal can't extend below the port tuning frequency- that means a small ported box needs a long port and that can become very awkward. Also, the Qts needs to be low enough to avoid it being a one note wonder.

 

[Pogre]

One caveat is that in a ported design, the port tuning frequency needs to be low enough and the signal can't extend below the port tuning frequency- that means a small ported box needs a long port and that can become very awkward. Also, the Qts needs to be low enough to avoid it being a one note wonder.

I did say "almost" every measure, but of course I also mean a competent design using the appropriate driver/Qts/box, port tuning, etc.

 

[Verdinut]

One caveat is that in a ported design, the port tuning frequency needs to be low enough and the signal can't extend below the port tuning frequency- that means a small ported box needs a long port and that can become very awkward. Also, the Qts needs to be low enough to avoid it being a one note wonder.

The Qts has to be limited to 0.45 but shouldn't be below 0.35 for sure, because that would make it more difficult for a sub to efficiently reach infrasonic frequencies.