So why are sealed boxes so unpopular? - diyAudio
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Old 5th May 2005, 10:49 AM   #1
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Default So why are sealed boxes so unpopular?

Vented boxes are more complex, produce excessive excursion below resonance (especially important in HT), greater group delay (poorer transient response), produce chuffing and other noise, need bigger boxes, reduce baffle strength (due to extra hole), and integrate poorly with room gain. Can someone remind me as to why they're so popular?
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Old 5th May 2005, 10:56 AM   #2
Vikash is offline Vikash  United Kingdom
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oh o. I feel a sealed vs ported vibe...

I think it's just easier for the average DIYer to get output at those lower Hz via the ported route.
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Old 5th May 2005, 10:57 AM   #3
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Vented enclosures are far more efficient.
This is very important when you aren't running massive amounts of amplifier power.
Measurements aside, some think they simply sound better.
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Old 5th May 2005, 11:24 AM   #4
Shaun is offline Shaun  South Africa
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Default It's the designer's choice

You as the designer have control over all of the factors you mention. A sealed box (for a given driver) is the safe (read easy) option, and it inherently has quite good sonic quality. But it also yields less low frequency output. In this region the BR box is more efficient. Above resonance it has less distortion (in fact, at resonance it has quite low excursion).

But the overall result is in the hands of the designer. You must decide the alignment (LF response). If you give it maximal flat response, group delay will be high, and room gain will cause the bass to be exaggerated (unless you listen in a massive room); you may have to place it away from any boundaries.

A BR box can give you a nice tight bass sound, but it requires a bit more work, and is also much more prone to boundary reinforcement effects.

I don't believe it is a black-and-white issue. Sealed enclosures can sound bad, too. It all hinges on what alignment you choose.

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Old 5th May 2005, 11:49 AM   #5
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I didnt think that sealed were unpopular in the DIY sector, lots of people seem to use them or say they are going to.

In the consumer market lots of it is about whose goes deepest and loudest so ported makes good marketing sense. Its funny however that all sealed speakers, in reviews, are always given really good reports on how good their bass is.
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Old 5th May 2005, 01:30 PM   #6
RJ is offline RJ  United States
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Order of preference using 2 Dayton 8" Classic woofers;
1. ML-TL - smooth & tight bass, really clear & clean sounding. Doesn't sound like a $22.00 speaker and it had punch!!!
2. Dual-Chambered Ported Enclosure. Deep Bass with lots of Growl. Most excellent for Rock, Dance & Hip-Hop. Lots of punch. As diysubwoofers state this box is great for low Xmax woofers and no fears of below resonance cone destruction.
3. Closed box. Sounded OK but just not deep enough & no punch
4. 4th order Bandpass - Drums sounded great but no punch and sound quality was a little muddy.
5. And last, a ported enclosure. Musicians sounded like they were playing in a cave.
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Old 5th May 2005, 02:27 PM   #7
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Order of preference using 2 Dayton 8" Classic woofers;
Remember not all types of enclosures prefer the same sort of T/S-parameters.
So as this might say something about the enclosures tested, it says definitly something about the 2 Dayton 8" Classic woofers.

Mvg Johan
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Old 5th May 2005, 03:09 PM   #8
simon5 is offline simon5  Canada
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Default Re: So why are sealed boxes so unpopular?

Originally posted by David Gatti
Vented boxes are more complex,]
True, you need to drill one more hole, but I think it's not that much more complex.

produce excessive excursion below resonance (especially important in HT),]
True, but you can tune below 20 Hz to bypass this problem.

greater group delay (poorer transient response),]
Same as above.

produce chuffing and other noise,]
Same as above and also with vent speed under 17 m/s, not noticeable.

need bigger boxes,]
IMHO, not true, to achieve the same deep bass, the sealed box would need to be way bigger than the vented box.

reduce baffle strength (due to extra hole),]
True, but negligeable.

and integrate poorly with room gain.]
The sealed box rolloff is always too fast versus room gain, unless you're in a car. You can easily tune the rolloff of a vented box to integrate perfectly with room gain.

Can someone remind me as to why they're so popular? [/B]
All of the above and also like people said, the high efficiency.
I would like to add the deep bass you get by tuning under 20 Hz is better in HT also. LoTR and the like will never be the same.

There's the FR curve of a ported subwoofer I built, in a room. It's not at maximum power (but near) and it's not in a corner. The person I sold this to will make me soon a new curve with the subwoofer corner loaded at maximum power.
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Old 5th May 2005, 03:18 PM   #9
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A sealed box integrates much better with 'room gain'.

A ported enclosure rolls-off at 24dB per octave, a sealed box rolls off-at a much gentler 12dB per octave.
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Old 5th May 2005, 03:48 PM   #10
woodman is offline woodman  United States
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Originally posted by RJ
5. And last, a ported enclosure. Musicians sounded like they were playing in a cave.
I've never heard a ported loudspeaker that allowed the bass player to sound like he/she was playing in the same room as the rest of the band. There always seems to be a disconnect between the perspective of the low frequencies and the mids/highs.

There was one speaker that I had that did seem to get it right though - Dahlquist DQ-16. This was a ported enclosure that was sopposed to have a quasi-bessel alignment that allowed the bass to roll off at 6dB per octave like a sealed box. Additionally, the speaker was sopposed to look like a purely resistive load to the amplifier. Wish I could figure out what the designer (Carl Marschiotti (sp)) did.

Thanks RJ, now I'm gonna have to build a stuffed TL just to hear how it compares to AS speakers
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