noah katz said:
Noah,
I guess we should just listen to sine waves at Fb=0 , so we can't hear the difference. Maybe there's no sonic difference at that frequency. I never bothered to test it. Ports and PRs are a great shortcut to higher SPL, but eventually we all grow out of that in the search for better bass.
I very much share this view. One way to demonstrate this that will make things plain as day and night is to look at the group delay.
Sure there's a huge peak in group delay at resonance, but that's all the way down at 16hz and for music, there really wont be any effect(unless of course your music contains strong infrasonic output).
But even in the case where there is output that low and it suffers a large amount of group delay we must realize how insensitive the ear is to such low frequencys. Then you got to figure how noticeable a ~50ms delay is for things to start vibrating.
For HT the soundtrack is going with video and as I understand the human eye doesnt descriminate beyond 16frames per second which corresponds to one frame every .0625seconds. If you see the dinasaur's foot stomp down and one frame later(.05seconds corresponding to 50ms of group delay) you feel the impact it will probably seem pretty accurate.
Bass,
Do yourself a favor and make the thing ported. Play some music with the port open and with it stuffed. Then come back and tell us there's no difference. You've been brainwashed by theory. In the real world there's a difference.
The designer of your particular driver used to have specific recommendations on their site regarding different ported alignments for their drivers and guess what? Big low tuned enclosures were recommended strictly for HT use and not music. Why? Could it be because there is a significant audible difference? Of course there is.
Do yourself a favor and make the thing ported. Play some music with the port open and with it stuffed. Then come back and tell us there's no difference. You've been brainwashed by theory. In the real world there's a difference.
The designer of your particular driver used to have specific recommendations on their site regarding different ported alignments for their drivers and guess what? Big low tuned enclosures were recommended strictly for HT use and not music. Why? Could it be because there is a significant audible difference? Of course there is.
You're stating in plain that sealed is better and provide no proofs at all.
When I state in plain that ported is better and providing no proofs, you get frustrated, that's was exactly what I was looking for, what would you do if I do the same thing as you did hehe!
Don't bitch Canada engineering, it's not that bad. We do have many pure physics courses and maths courses. It's about half and half. So we do two years of physics+maths and two years of engineering, with a few not useful courses in the way like everywhere.
Now, IMO, ported is better because the frequency response of a EBS tuned enclosure is flat in room. To achieve the same FR, you need to EQ the sealed enclosure quite hard, so you get almost the same group delay and you need way more power so might exceed the powerhandling of the driver. You'll also get way more distortion because the driver must work really hard to get on par with the EBS enclosure.
When tuned low with EBS (<18 Hz), the group delay at 20 Hz is usually under 25 ms (half a cycle behind), if you tune <16 Hz, then you get under 20 ms at 20 Hz. So that means you're about 0.02 second late on that 20 Hz tone which you'll feel more than you'll hear it. It's also about 2/5 cycles behind, it's not that bad. Then if you aim for 14 Hz tuning, you get under 15 ms, so that's less than 1/3 cycle behind at 20 Hz.
Of course a linkwitz transform for example would yield lower group delay, but at what cost? Seriously compromised SPL, way higher distortion, lots of wasted amplifier power, higher cost, etc.
So, in the end, IMO SQ is better for a ported enclosure versus a sealed enclosure at the same loudness.
Anyway, we have all a different opinion because this is audio, subjectivity rules! Who is right, who is wrong? Would it matter anyway? Play the music the way you like it!
When I state in plain that ported is better and providing no proofs, you get frustrated, that's was exactly what I was looking for, what would you do if I do the same thing as you did hehe!
Don't bitch Canada engineering, it's not that bad. We do have many pure physics courses and maths courses. It's about half and half. So we do two years of physics+maths and two years of engineering, with a few not useful courses in the way like everywhere.
Now, IMO, ported is better because the frequency response of a EBS tuned enclosure is flat in room. To achieve the same FR, you need to EQ the sealed enclosure quite hard, so you get almost the same group delay and you need way more power so might exceed the powerhandling of the driver. You'll also get way more distortion because the driver must work really hard to get on par with the EBS enclosure.
When tuned low with EBS (<18 Hz), the group delay at 20 Hz is usually under 25 ms (half a cycle behind), if you tune <16 Hz, then you get under 20 ms at 20 Hz. So that means you're about 0.02 second late on that 20 Hz tone which you'll feel more than you'll hear it. It's also about 2/5 cycles behind, it's not that bad. Then if you aim for 14 Hz tuning, you get under 15 ms, so that's less than 1/3 cycle behind at 20 Hz.
Of course a linkwitz transform for example would yield lower group delay, but at what cost? Seriously compromised SPL, way higher distortion, lots of wasted amplifier power, higher cost, etc.
So, in the end, IMO SQ is better for a ported enclosure versus a sealed enclosure at the same loudness.
Anyway, we have all a different opinion because this is audio, subjectivity rules! Who is right, who is wrong? Would it matter anyway? Play the music the way you like it!
Simon5,
I'm sorry, I wasn't bashing Canadian engineering. It was more a poke at Costa Rica Computer Engineering, where they don't take ANY basic engineering courses. No physics and almost no electronics, so I don't understand how they can use the term engineering. Your curriculum sounds like it makes more sense to me and you won't end up a glorified programmer.
I'm not going to get into a sealed vs ported debate. I've moved on from both except in my HT where I still use an EBS Maeltrom, which is fine for HT and fine for music with the ports stuffed and the difference isn't what I would consider subtle in the bass region.
If you like an EBS sub for music, maybe you listen to music that contains a lot of very low frequency content, so the added low end is welcome. Have you even done any critical listening to compare the ports open and closed?
Noah made the point that GD effects are not audible. GD may not be the culprit. If not, then what is? Since ported helps control cone movement, maybe it is the forces inside the box that help control excursion that are detrimental to SQ. It's not my imagination and I don't think it's a matter of personal preference once someone critically listens and hears the difference.
Another thing supporting Noah's point is that dipoles don't exhibit this problem and it would make sense that the rear wave would be detrimental to SQ if GD is. The difference is that with dipole the cone operates freely vs more forces inside the box affecting cone movement with ported than with sealed.
I'm sorry, I wasn't bashing Canadian engineering. It was more a poke at Costa Rica Computer Engineering, where they don't take ANY basic engineering courses. No physics and almost no electronics, so I don't understand how they can use the term engineering. Your curriculum sounds like it makes more sense to me and you won't end up a glorified programmer.
I'm not going to get into a sealed vs ported debate. I've moved on from both except in my HT where I still use an EBS Maeltrom, which is fine for HT and fine for music with the ports stuffed and the difference isn't what I would consider subtle in the bass region.
If you like an EBS sub for music, maybe you listen to music that contains a lot of very low frequency content, so the added low end is welcome. Have you even done any critical listening to compare the ports open and closed?
Noah made the point that GD effects are not audible. GD may not be the culprit. If not, then what is? Since ported helps control cone movement, maybe it is the forces inside the box that help control excursion that are detrimental to SQ. It's not my imagination and I don't think it's a matter of personal preference once someone critically listens and hears the difference.
Another thing supporting Noah's point is that dipoles don't exhibit this problem and it would make sense that the rear wave would be detrimental to SQ if GD is. The difference is that with dipole the cone operates freely vs more forces inside the box affecting cone movement with ported than with sealed.
"GD may not be the culprit. If not, then what is?"
Have you compared the obvious - freq response?
It could be the differing responses of the ported vs. sealed, and/or that the ported version has more output at a room mode freq, which is a much bigger determinant of bass SQ than the difference between ported and sealed.
I'd sum the whole thing up this way: In any situation where you need more than moderate low bass output levels, a competently designed ported system will sound better.
The debatable disadvantage of more GD is nothing compared to a driver driven into nonlinearity and/or overload.
Have you compared the obvious - freq response?
It could be the differing responses of the ported vs. sealed, and/or that the ported version has more output at a room mode freq, which is a much bigger determinant of bass SQ than the difference between ported and sealed.
I'd sum the whole thing up this way: In any situation where you need more than moderate low bass output levels, a competently designed ported system will sound better.
The debatable disadvantage of more GD is nothing compared to a driver driven into nonlinearity and/or overload.
It's really hard to really compare ported vs. sealed because they are so different.
IMO, you would need to compare a sealed LT and a EBS, then I think EBS would win if the sealed LT is designed to have the same frequency response in room. Distortion would be way lower. The box could be much bigger, of course.
IMO, you would need to compare a sealed LT and a EBS, then I think EBS would win if the sealed LT is designed to have the same frequency response in room. Distortion would be way lower. The box could be much bigger, of course.
"It's really hard to really compare ported vs. sealed because they are so different."
Seems to me that makes comparisons a lot easier.
Anyway, GD is always mentioned as the reason ported is inferior, so to test that both should be EQ'd to the same freq resp to eliminate that variable.
Also, for most people the room will be a bigger determinant of bass SQ than the sub (ring times much longer than even a mediocre sub), so anyone who's halfway serious ought to have EQ.
Seems to me that makes comparisons a lot easier.
Anyway, GD is always mentioned as the reason ported is inferior, so to test that both should be EQ'd to the same freq resp to eliminate that variable.
Also, for most people the room will be a bigger determinant of bass SQ than the sub (ring times much longer than even a mediocre sub), so anyone who's halfway serious ought to have EQ.
noah katz said:
Bass management processing is just a bandaid that masks the problem somewhat. It doesn't correct the problem. Anyone who's more than halfway serious ought to have physical bass treatments in their room. That why I constructed my room so that 50% of the walls and 100% of the ceiling are panel bass traps tuned to different frequencies and the long side wall of bass traps forms one very low tuned bass trap using the sealed airspace and wall behind that.
Using the rock music that I usually listen to, I think the EBS sub I used, which is tuned to 16hz if I recall correctly, has a pretty comparable response sealed or ported from 40hz up to the 80hz cutoff I use on the HT rig and that music doesn't have much content below that. Just because computer modelling predicts an equal response doesn't mean they sound the same.
John.... one question I have is this, Where is your first port resonance.
EBS enclosures Typically have LONG ports especially if it happens to be a smaller box with a larger driver(which is definately the case for Tumult). The high excursion of the sub only makes it worse because the cross section of the port has to be larger making it even longer for such a low tuning.
When you get a first port resonance at 80hz, even if you cross over at 40hz 24db/octave the port is probably going to muddy things up a bit at 80hz from the port. If you cross higher, the problem gets ALOT worse. As I understand passive radiators negate these effects, one reason why I opted to use them.
EBS enclosures Typically have LONG ports especially if it happens to be a smaller box with a larger driver(which is definately the case for Tumult). The high excursion of the sub only makes it worse because the cross section of the port has to be larger making it even longer for such a low tuning.
When you get a first port resonance at 80hz, even if you cross over at 40hz 24db/octave the port is probably going to muddy things up a bit at 80hz from the port. If you cross higher, the problem gets ALOT worse. As I understand passive radiators negate these effects, one reason why I opted to use them.
Bass,
I'm not into ported enclosures and built the thing 2 years ago. Going from memory it's 360 litres (maybe 320L) with dual 4" x 17" ports. I think the straight parts are 15" and both ends are flared.
It's not a resonance or room modes. It's the alignment. I really can't believe that you guys really can't hear the difference.
I'm not into ported enclosures and built the thing 2 years ago. Going from memory it's 360 litres (maybe 320L) with dual 4" x 17" ports. I think the straight parts are 15" and both ends are flared.
It's not a resonance or room modes. It's the alignment. I really can't believe that you guys really can't hear the difference.
where are you crossing at dude?
Having extremis midwoofers in my mains puts me down to about 42hz f3 and crossing below that isnt seriously detrimental. The sub's band is very small for music. Either it's not a critical portion of the frequency spectrum, or my ears suck, because I cant tell a difference(except in the intensity of infrasounds)
Having extremis midwoofers in my mains puts me down to about 42hz f3 and crossing below that isnt seriously detrimental. The sub's band is very small for music. Either it's not a critical portion of the frequency spectrum, or my ears suck, because I cant tell a difference(except in the intensity of infrasounds)
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