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Old 16th December 2009, 06:51 PM   #1481
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Originally Posted by gedlee View Post
Those woofers all get their low fs with massive cones - and resulting very low sensitivity. I'm not sure where this is going, but I think that your post proves my main point that low frequencies mean low efficiency. I doubt that I would ever consider using any one of those drivers so I guess thats why I never noticed them. As I said, none of the companies that I would consider using ever get down that low in Fs.
The best example of a reliable low Fs driver is Exodus Audio's (diycable.com) Maelstrom 18" driver DIYCable.com : Intro Home Exodus Subwoofers

17 Hz, 32 mm xmax, 88 dB SPL

And Kevin Haskins tells it like it is, no fudged specs.

Driver sag in mm = 248/[(Fs)^2], i.e. .9 mm for this driver, hardly an issue.

As for the whole issue of low freq efficiency, all efforts using a box are doomed to the same result because even if the driver has 100% electrical to mechanical transduction efficiency, it takes the same amount of energy to compress a given air volume a given amount, and that energy is lost, at least with current technology.

Earl, speaking of transduction efficiency, which would depend only on the motor design and not be a function of Cms or Mms, do you have any idea of what the range is for drivers?
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Old 16th December 2009, 08:04 PM   #1482
tinitus is offline tinitus  Europe
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Originally Posted by pjpoes View Post
Neither of those are anywhere near that price. The B&C is in the 700's and the BMS in the 400's.

I'm not sure your point here Tinitus, just wanted to bash on the examples I gave, or was this something constructive?

What would be your better choices for less money?
Ah, no I never just "bash", no way
I always try to be straight and fair, and constructive
But I do make mistakes
I thought you were thinking about the latest BMS with very low Fs a big Xmax, genuine sub driver, and a bit rare in pro world, and that one really is that expencive
Im sorry about the B&C, I was mistakenly thinking about the latest Beyma woofers, and those really are that expencive as well, but really not low Fs
Obviously I dont read too good

How about the "old" 21" Beyma
Right now Im looking at a PrecisonDevices 15" neo, looks fine down to 30-35hz in BR, full 97db
Shouldnt take much EQ to make it straight all the way to 30hz

The bigger PD 21" and 24" looks good too, but also expencive
And their very low 0.2 Qts means they need a lot of "help" to get below even 50hz, pure 100db pro woofer, roll off like a stone

Just looked at B&C 21"
Theres one at 500EUR, and two at 649 and 789EUR
Cheapest 21" B&C I could find, multiply by 1.5 and you have it in USD

Last edited by tinitus; 16th December 2009 at 08:11 PM.
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Old 16th December 2009, 08:07 PM   #1483
pjpoes is offline pjpoes  United States
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We have probably let this go into the wrong direction and I'm wondering if this wouldn't be a better topic on it's own in the loudspeaker section instead of Dr. Geddes speaker news pages.
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Old 16th December 2009, 08:10 PM   #1484
pjpoes is offline pjpoes  United States
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Tinitus we are talking about the same driver I think from BMS. The model I was thinking about, the BMS 18N860 is their newest 18" driver, low fs, huge xmax, and the price I was quoted was not that much. I believe Assistance said they could order me one for in the 4-500 range. Beyma's new 21" drivers are listed on US Speakers in the 4-500 range, as is 18 sounds. As has been mentioned, these are commodity products, and the prices shift quickly. I think they have come down a lot lately.
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Old 16th December 2009, 08:25 PM   #1485
tinitus is offline tinitus  Europe
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Yeah, I have heard you US guys can get last years Honda VFR800 at something 8.000 USD
Around here it still cost like 30.000USD, or more
You can get the brand new 1200VFR at about 16.000 USD
Around here it will cost 60.000USD
In rest of EU about half as much

Its about you pay less taxes, if any
And its about huge quantities, which can make the prices drop like a stone

Strange
Here the prices are going up, because they are "hungry" and not selling much
At your place its the opposite, because they import in huge numbers, and are getting huge stocks, not selling, prices go down
Totally upside down

Just checked, BMS 18N860 cost 600EUR, or like 1000USD, and shipping could be another 150-200USD
Seems like we have very different terms, I forgot
Forget about it, please go on

Eh, I may afford the B&C 18PS100, which looks ok too
But I need it to be good at 500hz too, but all B&C are peaked, different story

Last edited by tinitus; 16th December 2009 at 08:55 PM.
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Old 16th December 2009, 10:55 PM   #1486
pjpoes is offline pjpoes  United States
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Quote:
Originally Posted by noah katz View Post
The best example of a reliable low Fs driver is Exodus Audio's (diycable.com) Maelstrom 18" driver DIYCable.com : Intro Home Exodus Subwoofers
Noah that driver, even though it has a much lower FS, performs quite similarly, in my models, to the BMS and B&C drivers. The prices are all similar as well. Conversely, there is a disadvantage to the driver above 50hz, but since none of them would likely be used by us above that range, to me at least, it just seems like a toss up.
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Old 16th December 2009, 11:18 PM   #1487
gedlee is offline gedlee  United States
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Originally Posted by pjpoes View Post
greater mms doesn't seem to increase LF sensitivity, it just lower the higher bass sensitivity so that the lower bass sensitivity is higher relative to that level.
This is absolutely the case and why I say that bass extension has to come at the sake of efficiency unless you use more drivers. And if you are going to use more drivers then spread them out. This is precisely how I came up with the idea of multiple subs, It solves a couple of problems at the same time.
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Old 16th December 2009, 11:20 PM   #1488
gedlee is offline gedlee  United States
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Originally Posted by pjpoes View Post
We have probably let this go into the wrong direction and I'm wondering if this wouldn't be a better topic on it's own in the loudspeaker section instead of Dr. Geddes speaker news pages.
Whatever - these threads always wander. Its not a problem. I sell subs so its pertinent to understand why I do what I do.
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Old 16th December 2009, 11:24 PM   #1489
gedlee is offline gedlee  United States
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Originally Posted by tinitus View Post
Just checked, BMS 18N860 cost 600EUR, or like 1000USD, and shipping could be another 150-200USD
Seems like we have very different terms, I forgot
Forget about it, please go on
I was trying to get drivers for my kits sent directly from the EU. I found out how much markup is normal there and it was a crime. These kinds of markups would never survive in the US. Its the system there that has a stranglehold on the distribution and rips off the customer as a result.
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Old 16th December 2009, 11:33 PM   #1490
pjpoes is offline pjpoes  United States
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Related to that, I've come to another conclusion that I believe you reached a while. Namely, bass extension between a ported vs sealed box, in room, at these really low frequencies, seems to be pretty similar. however, ported boxes seem to cause more "smoothness" problems in that I often find a bit of a peak around the tuning frequency in my room response. It seems like your better off using a sealed alignment or 4th order alignment since in room bass response will be similar, but integration will be easier. It's less of an issue if you aren't integrating to another speaker, such as the ULF sub, but it seems to be a major issue for the main speakers and broad band subs. I am guessing this is why you did what you did.

My only exception to this at all is if you make a ported box with a very low tuning and enclosure size that would net, if sealed, like a .7 qts for the design. This gives a far more gradual roll off for the sub, akin to sealed, but does offer that excursion control at the port tuning frequency. You called that a leaky box though, I guess it probably is, but I was pretty excited when i realized that benefit.

In the ULF range, it seems, as you mentioned, that lots of subs is the best option if you need more bass down there, well that or larger diameter drivers, but a 21" driver is really big. Your talking about an enclosure that's probably at least 25" wide and will need a good 10 cubic feet of internal volume. I think multiple 18's or even 15's would be easier to hide. What I'm wondering is, based on your comments before, if only talking in the sub 50hz range, would multiple subs be best stacked or is there still benefit in that range to spreading the subs around? I thought you had indicated once that the primary benefit was in the area of greatest modal density, which is above that 50hz range, right?
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