Sealed vs Ported graphs - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 21 Old 09-07-2018, 08:19 PM - Thread Starter
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Sealed vs Ported graphs

What do you guys think? I'm losing 7dB @ 20Hz from ported to sealed. Gaining 4.5dB @ 10Hz from sealed to ported. Gaining 15dB @ 4Hz from sealed to ported.


If you were me which situation would you pick?
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post #2 of 21 Old 09-07-2018, 08:55 PM
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You are also gaining a lot of distortion going to sealed because ported uses less Xmax from 15 -30hz. Around tuning sealed distortion will jump >300%
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post #3 of 21 Old 09-07-2018, 09:03 PM
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Another thing to consider is how useful is that 85dB at 10Hz or 65dB at 4Hz ?

From my readings so far, you need at least 100dB @10Hz, preferably 110dB to notice the effect, way way more for 4Hz. If those values in the graph are the max those subs can achieve, you probably will not notice the advantage the sealed shows in the graph.

The advantage that the ported shows at 20Hz is high enough, and large enough that you would notice that much more.

Now if that sealed sub has the headroom for even way more SPL below 10Hz, or you can afford to stack enough of them to raise that low range in the 100+dB, you may be happier with a sealed setup if low extension is what you are after.

With a single or couple of subs, if it is low frequency you are after, my bets are on ported, tuned between 10Hz-20Hz depending on what you are working with, and what works best for you

EDIT: Lol, just learned 'at' 20HZ is not a good thing to type, apparently there is a member named '20Hz', so it would count as a mention. Wondering how many mentions he has accumulated so far.
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post #4 of 21 Old 09-07-2018, 10:30 PM
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My question is what you're ultimately concerned with frequency wise. From what I recall you have wire a potent system with sealed regardless. Are you bottoming @ 10hz at regular listening levels?
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post #5 of 21 Old 09-07-2018, 11:09 PM
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The graph shows the difference in attenuation. Ported attenuates around -24 dB per octave. While sealed attenuates at around -12 dB. Ported is more efficient before the tuning frequency.

Ported alignments will always have higher distortion compared to sealed. The size of the diameter of the ports, the length of the port, and amount of ports create a port resonance that can interfere with the quality of the sound. Also, the chuffing sound that the air creates increases distortion. The benefits of high loudness over sound quality is the compromise when going with ported compared to sealed.

What sounds good to you is better than debating which one has a better bass extension versus higher loudness. Probably a better question which alignment can reproduce the musical instrument that you heard in person.
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post #6 of 21 Old 09-08-2018, 04:05 AM
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Instead of going ported have considered adding a radiator speaker to your box, effectively increasing your area of air movement and give similar results to a port without some of its issues.

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post #7 of 21 Old 09-08-2018, 09:26 AM
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When in doubt, go ported.
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post #8 of 21 Old 09-08-2018, 01:00 PM
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Quote:
Originally Posted by DaBateman View Post
What do you guys think? I'm losing 7dB @ 20Hz from ported to sealed. Gaining 4.5dB @ 10Hz from sealed to ported. Gaining 15dB @ 4Hz from sealed to ported.


If you were me which situation would you pick?
Is that both subs in the same location and no EQ? If so and the sealed has enough power/xmax to get it flat or even slightly rise down to say 10-15hz that will make quite a bit of a difference in the sound and "feel" of the sealed.

I have an old graph comparing a sealed um18 to a Kappa Pro 18 ported and I preferred the Kappa for most music(30hz+) but it drops off after 20-30hz so with lower content the UM18 sounds and feels more impressive.

The best of both worlds was running the two together but it takes quite a bit of experimenting with crossover/delays etc to optimize everything to get smooth FR and sound good across the FR.
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post #9 of 21 Old 09-08-2018, 07:57 PM - Thread Starter
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Yeah should’ve added more info, they are in the same location, I probably had YPAO on but I believe only one filter is on (250 +3dB).

After doing some WinISD graphs it seems that Xmas is through the rough at <30Hz so it appears I’ll be sticking w/ ported. I enjoy my ported setup very much but, it only extended, barely, to 8Hz I wanted to get a feel of what the ULF is like. Seems as if I’ll be left to add another ULF only sub to the mix. I purchased a UM15 but, have yet to decide on the enclosure.

Another aspect to remember is my room only being ~1000cufr.

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post #10 of 21 Old 09-09-2018, 04:42 AM
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Quote:
Originally Posted by tecknurd View Post
The graph shows the difference in attenuation. Ported attenuates around -24 dB per octave. While sealed attenuates at around -12 dB. Ported is more efficient before the tuning frequency.

Ported alignments will always have higher distortion compared to sealed. The size of the diameter of the ports, the length of the port, and amount of ports create a port resonance that can interfere with the quality of the sound. Also, the chuffing sound that the air creates increases distortion. The benefits of high loudness over sound quality is the compromise when going with ported compared to sealed.

What sounds good to you is better than debating which one has a better bass extension versus higher loudness. Probably a better question which alignment can reproduce the musical instrument that you heard in person.
A good ported design will have LOWER distortion than it's sealed counterpart. A large enough and well designed port will not have any audible noise and not compress under common listening conditions, add the reduced driver excursion compared to sealed for the same spl, and greater heat dissipation resulting in less heat build-up in the coil and so less distortion, all mean ported will have overall less distortion than sealed. Port resonance can usually be modelled to be above the crossover frequency so it isn't audible also. Unless chasing single digits or if space is a concern, I can't see any reason not to go ported! Regarding your last point about musical instruments, any live concert that requires amplification will use ported subs, no doubt about it, and some live systems sound incredible with amazing power and slam!

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post #11 of 21 Old 09-09-2018, 10:58 AM
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Quote:
Originally Posted by DaBateman View Post
Yeah should’ve added more info, they are in the same location, I probably had YPAO on but I believe only one filter is on (250 +3dB).

After doing some WinISD graphs it seems that Xmas is through the rough at <30Hz so it appears I’ll be sticking w/ ported. I enjoy my ported setup very much but, it only extended, barely, to 8Hz I wanted to get a feel of what the ULF is like. Seems as if I’ll be left to add another ULF only sub to the mix. I purchased a UM15 but, have yet to decide on the enclosure.

Another aspect to remember is my room only being ~1000cufr.
What kind of driver and enclosure are you using that Xmax is already maxed out at 30hz in a sealed enclosure?

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post #12 of 21 Old 09-09-2018, 06:14 PM
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I am not a charts and graphs guy, so forgive the dumb question. What is the massive dip at 60 Hz and 110 Hz? Are those the kinds of things DSP is supposed to correct?


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post #13 of 21 Old 09-09-2018, 06:52 PM
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Quote:
Originally Posted by tecknurd View Post
Ported alignments will always have higher distortion compared to sealed. The size of the diameter of the ports, the length of the port, and amount of ports create a port resonance that can interfere with the quality of the sound. Also, the chuffing sound that the air creates increases distortion. The benefits of high loudness over sound quality is the compromise when going with ported compared to sealed.
Data-bass has subs tested that can be run ported or sealed and all ported alignments are lower distortion than sealed for the same sub. Look at the results of the SVS subs for proof:

https://data-bass.com/data?page=system&id=55

Ports interfere with the quality of the sound? If the output is less distorted, it is truer to the original signal. Lower distortion is not interfering with quality.
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post #14 of 21 Old 09-09-2018, 07:51 PM - Thread Starter
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Originally Posted by bscool View Post
What kind of driver and enclosure are you using that Xmax is already maxed out at 30hz in a sealed enclosure?
Dayton 390ho 3.75cuft. I believe I modeled 800wts

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I am not a charts and graphs guy, so forgive the dumb question. What is the massive dip at 60 Hz and 110 Hz? Are those the kinds of things DSP is supposed to correct?
Room modes. Pointless to eq them, a 5dB boost only nets .5-1dB rise in FR.
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post #15 of 21 Old 09-09-2018, 10:08 PM
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Quote:
Originally Posted by DaBateman View Post

Room modes. Pointless to eq them, a 5dB boost only nets .5-1dB rise in FR.

In my ignorance I wouldn't boost the dips, I would lower the peaks. I've read that boosting any point more than 3 db puts a lot of stress on the amp.


I have a couple of Umax 15's with an Inuke 3000 w/dsp. I've played with the DSP but all I've managed to do is make muddy bass. Despite all I've read it's clear I have no earthly idea what I'm doing.
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post #16 of 21 Old 09-10-2018, 12:22 AM
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monty6400 and SpinMonster both of you reading way too much into distortion. When does low distortion matter for sound quality? It doesn't. I know that low distortion doesn't always mean better sound quality. I should have been more specific. I did state how does each alignment sound. This means how well does it replicate the sound of the instrument like it's played in person.

I have unmounted my Dayton Audio Ultimax 10 inch from the 1.25 cu. ft. and replaced it with a Peerless SDF-250F75PR01-06. The Peerless woofer is able to reproduce the sounds of the instruments more accurately and clearer than the Ultimax woofer. The amplifier stayed the same and no bass boost. The amplifier that I am using is Bash 300S from Parts Express.
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post #17 of 21 Old 09-10-2018, 07:19 AM
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Quote:
Originally Posted by tecknurd View Post
monty6400 and SpinMonster both of you reading way too much into distortion. When does low distortion matter for sound quality? It doesn't. I know that low distortion doesn't always mean better sound quality. I should have been more specific. I did state how does each alignment sound. This means how well does it replicate the sound of the instrument like it's played in person.

I have unmounted my Dayton Audio Ultimax 10 inch from the 1.25 cu. ft. and replaced it with a Peerless SDF-250F75PR01-06. The Peerless woofer is able to reproduce the sounds of the instruments more accurately and clearer than the Ultimax woofer. The amplifier stayed the same and no bass boost. The amplifier that I am using is Bash 300S from Parts Express.

Correlation is not causation. You state low distortion does not matter for sound quality, which is false.



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  • Sensitivity89.39 dB 2.83V/1m
Ultimax 10


  • Sensitivity84.8 dB 2.83V/1m
These numbers are pulled from the data sheets at parts express, but does not represent the deep bass sensitivity from the T/S parameters and the box type / alignment.



In the upper bass, the Peerless will have a 4.59 dB advantage with the same voltage applied. You need more voltage for the Ultimax to equal the output.

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post #18 of 21 Old 09-10-2018, 02:30 PM
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Quote:
Originally Posted by tecknurd View Post
monty6400 and SpinMonster both of you reading way too much into distortion. When does low distortion matter for sound quality? It doesn't. I know that low distortion doesn't always mean better sound quality. I should have been more specific. I did state how does each alignment sound. This means how well does it replicate the sound of the instrument like it's played in person.

I have unmounted my Dayton Audio Ultimax 10 inch from the 1.25 cu. ft. and replaced it with a Peerless SDF-250F75PR01-06. The Peerless woofer is able to reproduce the sounds of the instruments more accurately and clearer than the Ultimax woofer. The amplifier stayed the same and no bass boost. The amplifier that I am using is Bash 300S from Parts Express.
Don't even know how to reply to the statement that low distortion doesn't matter for sound quality. Who on earth enjoys listening to driver distortion? And how does lower driver distortion not mean better sound quality? IT does. Also your statements about distortion in each alignment were false, that's why we felt the need to correct you, as false info is useless info. Based on your other posts on these forums it's clear you have a set frame of mind in terms of sound quality and ported and sealed and that's fine, but don't portray it as dogma and don't give false information that could be misleading to others, that is all.

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post #19 of 21 Old 09-11-2018, 10:42 PM
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Originally Posted by DaBateman View Post
What do you guys think? I'm losing 7dB @ 20Hz from ported to sealed. Gaining 4.5dB @ 10Hz from sealed to ported. Gaining 15dB @ 4Hz from sealed to ported.
I'll kindly presume this is not a joke. Gaining at 4 Hz would presume the port is tuned that low, which probably means it is the size of a house. The lowest/longest organ pipes are 8 Hz, so unless you are playing elephant recordings this 4 Hz I think is meaningless (note: I haven't checked the data base for movie sounds).

I am only superficially familiar with WinISD. How does it model impedance? Because unless it has a complex, and drive-voltage-dependent model driven from real imported impedance data, the simulations should not be taken too literally.

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Another thing to consider is how useful is that 85dB at 10Hz or 65dB at 4Hz ?
Not at all I'm pretty sure. Reference *Fielder, Louis D.; Benjamin, Eric M. "Subwoofer Performance for Accurate Reproduction of Music" JAES Volume 36 Issue 6 pp. 443-456; June 1988 or purchase from
http://www.aes.org/e-lib/browse.cfm?elib=5147
Essentially, they make the point that due to human hearing's insensitivity, subwoofers must generate a quite tremendous SPL at very low frequencies, or you will not even hear what they are putting out. Google "Fletcher Munson" also.
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post #20 of 21 Old 09-12-2018, 08:54 AM
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I believe he typed that wrong as the graph clearly shows the sealed gaining down low and not ported. The ported advantage is 15-30hz.

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post #21 of 21 Old 09-12-2018, 09:59 AM
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IMO no reason to go sealed here unless space is a concern or you subjectively "like" the sound better.

There's nothing in those graphs that show sealed gives you anything more than ported. You are not going to hear/feel anything under 15 Hz at those levels. 15 Hz and up, ported wins, so go with ported.
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