Originally Posted by bosso
To try to answer your question, why would a person need a subwoofer at all if he's cost conscious and listens to the music you refer to?
This baffles me, as you really seem to be forgetting that there is a range of bass frequencies greater than single digits, and when it comes to music, the ovewhelming majority of it has bass that does not dip below 30hz. That's precisely why someone would need a subwoofer if they listen to music, be it classical, instumental, rock, pop, jazz, rap, etc. Let's get one thing straight, I'm by no means against single digit extension - the more extension the better - however, to give it the type of priority you do, at the cost of higher frequency performance (which whether you want to admit it or not, will happen, even with quad 15" sealed drivers), when it is rarely if ever observed in music, and is more of a novelty in movies, comes off as an exercise in futility.
Then why are you commenting as though it matters what you think?
The discussion is about bass performance, and a large ported subwoofer will offer greater performance compared to sealed over at least 75% of the bass range based on where the majority of bass in real media falls.
Yeah, so your answer is that you would have to build a PR
version, or that the driver can't be ported? Because, you know, that would sort of blow your 'driver for driver' spiel. It's YOU who has no ported version to compare it with, and your answer should be that you are mistaken when you say that 'driver for driver, ported is better'. You need to rephrase that statement or continue to sound ill-informed.
My answer is neither, I simply stated that it's easy to look good with no competition, and that is precisely the reason you mentioned that sub. You continue to ignore the perfect comparison that is the TC2k ported vs TC2k sealed. An oddball driver here or there, especially one that costs what the LMS did, was available for as short a period of time as it was, and was specially developed and optimized for the sole purpose of working well in a small, sealed enclosure, is definitely not something that would cause me to change my view.
You don't have a point. That's the fundamental flaw in your posts.
You're oblivious to the point, that's why you can't grasp it.
Originally Posted by Thomas
I'm star-struck watching a "Professional Genius" in action....
Thanks. Signed autograph is $30 if you are interested.
Originally Posted by Looneybomber
Well technology is always going to extend our sound reproduction capabilities. You make it sound that we must be able to reproduce 3hz with 100db of output. That is rediculous to me knowing just how much that will cost. You make it sound like a person with a $500 budget may as well forget the subwoofer because it wont be flat to below what an elephant can hear.
I don't even look at this as a matter of budget. If the goal is to be able to better recreate bass in music that you will actually be able to differentiate, then digging into single digits wouldn't seem to add anything - lowering distortion and increaisng headroom in the more audible ranges is a better goal. Again, I have proposed an experiment that can prove/disprove this. If the goal is to achieve extra rumble 5% of the time from certian types of movies after all headroom and distortion concerns have been met, then by all means, have at it. The furthering of the notion that extension to 3hz adds to the musical experience - without any facts, proof, or logic - is viewed as eccentric and perhaps even wasteful.
Originally Posted by augerpro
versus a 300L @ 13Hz box with 6" port
OTOH even with a 6" inch port the first resonance is showing up at around 170Hz
Which is why a LLT requirement is for the first port resonance to be no lower than 190hz, preferably much higher in fact. People have built ports as long as 36" for a ~188hz first resonance with no offensive audible effect, though I personally would tend to error on the side of caution.
Originally Posted by bosso
To correct you, 30Hz+ is better achieved and cheaper in a sealed sub, for many reasons.
Umm, not really. If one is only interested in 30hz+, they could just build a ported sub optimized for a ~25hz tune.
Originally Posted by Stealthdude
Just look at JL Audio and Dynaudio for example... Commercial offerings and companies who have the R&D to make any type of speaker or sub they choose to make.
Both of their top shelf sub alignments are sealed.... there has to be a reason for it.
Yeah, there definitely is a reason for it. Because a top shelf ported alignment would be similar in size to the LLT subs you see many people building nowadays. The logistics of designing a manufacturing operation and handling the shipping for such large subs would be a nightmare for all but the most dedicated. I'm really quite surprised Epic went as large as they did with the Conquest, yet it still falls a little short in my eyes in regards to proper porting and achieveing the best balance of performance with the selected tune. It's much easier for a manufacturer to dump a bunch of money into a smaller sealed design.
Originally Posted by Mark Seaton
Of course now I'm going to have to listen to Steve go on about how big boxes are the only way to go. Of course the largest, most efficient box is still a waste if it's in a very inefficient location to drive the room.
Absolutely. And the story you went on to tell about using a small sealed subwoofer to test for the best position in room of a large ported subwoofer is something I have suggested to many LLT owners while in the planning stages. If you are going to go DIY, you may as well tailor it to perform the best it can in your listening environment.
Originally Posted by cluelessngr
what happens when after hitting a substantially loud low bass note resulting in a displacement of air out of the enclosure via the port, logic would have it that for a brief period of time the enclosure is in a negative pressure situation
Remember that the driver is still moving - the moving mass of air is only sucked back into the port when the driver is told to move again in the opposite direction. The driver is the dog that wags the movement of air in the port, not the other way around, as the driver is receiving the signal from the amplifier and initiates all the action. The air in the port is just a slave.
Add to this that if the driver it asked to produce another large burst of sound before the enclosure/port has replaced the air from the first burst we have a situation in which we have the port both exhaling and inhaling introducing resistance to the second burst at the same time. It would seem to me that this effect, along with any noise that occurs from the re-stabilization of air volume has to add a level of distortion not found in the sealed design (which it appears has other distortion issues not so prevalent in the ported design).
Again, the moving mass of air in the port responds to the motion of the driver. Assuming an at least somewhat well thought out design with no EQ around tuning, this scenario can not and will not take place.
Keep in mind that the port involvement is minimal a couple octaves above tuning and gradually becomes more pronounced as you approach tuning. Also, remember that the frequency being reproduced means that the driver is moving in that many cycles per second, so this whole scenario of action/reaction between the driver and port is happening extremely quickly, even with infrasonic tuning.
The only way in which this act can result in added distortion (as compared to say sealed trying to reproduce the same frequency) is if the port is undersized or underflared for the application, resulting in turbulent air flow and "chuffing", or a swooshing sound. A competent design uses large diameter ports and flaring to avoid this, and thus, the benefits of porting (when combined with a low tune) are achieved with minimal to no negativelu audible side effects. Since the driver moves so little at tuning, distortion is actually improved dramatically.
Originally Posted by Jack
I'm thinking the compression of the air in the box by the port has to be fairly considerable at high SPL if it's actually what's damping the motion of the driver. Is that the case, or am I thinking about it the wrong way (again)?
Think of the amount of air being displaced to recreate a 20hz sine wave at 120db from 1 meter ground plane, ignoring the driver, alignment, and enclosure. It's a significant amount of displacement. Now imagine we are displacing that amount of air with a single 18" driver using ~60mm of total travel continuously. Now place that 18" driver moving back and forth a total of 60mm inside a small, sealed enclosure. The amount of air being displaced by the driver forces the small volume or air inside the enclosure to compress. This results in a very high pressure.
Now place that 18" driver in a humongous sealed enlcosure. You're still displacing the same amount of air, but since there is far greater volume for that force to be diffused upon internally, the increase in pressure is nowhere near the same. When you add a port and approach tuning, you're simply trading movement of the driver for movement of the port, so the internal pressure created is the same, and it is still far less than a small sealed enclosure.
Originally Posted by dae3dae3
IMO the whole ported vs sealed basically comes down to budget. People that have more money than god will throw a ton of money at the solution and end up with a high number of sealed subs. (SteveC will then jump in and tell them they could have had more performance if they had ported the subs.)
Correct. It's not about the size of the budget, it's about the amount of performance you want at any budget. Performance-orientated, ported wins. Size-orientated, sealed wins.
Originally Posted by Stealthdude
I would be dissapointed with JL and Dynaudio is the only reason they made a sealed sub was to keep the size down.
Prepare to be disappointed
Surely they didn't have low distortion, FR linearity, and headroom as top priorities for their budget when they decided to build a small, sealed enclosure. Ultimately, in the end, they may have built subs that achieve great performance in those areas generally speaking compared to other subs, but, it cost them a lot more to get there than it would have to have gone ported and achieved better results.