Correct, just understand this means the vent/terminus is either right next to each other or has the same path-length to your ears.
I don't know what you mean
"The distance between the radiating side of the driver diaphragm and the port outlet is specified using the acoustic path length parameter. The acoustic path length is the length of the shortest acoustic path between the two outputs ) assumed to be point sources"
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If I sim the similar 500l BR in TL mode to add a little Filling I get this
Gd is around 33ms in this sim at 20hz and 8ms at 30hz in this sim without filling.
OK now that we can see that it is looking in the ball park...Something like this could be used in a TMM with a xo of 350hz to a large horn, using the 18h+.
What do you guys think?
Gd is around 33ms in this sim at 20hz and 8ms at 30hz in this sim without filling.
OK now that we can see that it is looking in the ball park...Something like this could be used in a TMM with a xo of 350hz to a large horn, using the 18h+.
What do you guys think?
Given that 20 Hz is largely felt rather than heard - below 20 Hz the average human being is unable to distinguish pitch, I don't think GD doesn't matter much unless it's very high.
If you compare some of the sims I posted before (2x12" in BR cabs) to this (B&C 15TBX100 in 180l closed) you'll see that GD is only marginally lower at infrasonic frequencies. At the same time, the output at these frequencies is substantially higher for the BR. Simply put, the B&C/sealed actually hardly delivers any meaningful output below 40 Hz. 'Sealed freaks' will argue that the GD is lower above 40 Hz, which is of course true. But as I have stated before, imho, the difference doesn't outweigh the disadvantages.
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The feeling can be delayed from the hearing (higher frequency), in time...The ear can hear the rest of the event. In nature there is a GD in bass too, is there not? Lightning is an example of this or no??? Distance acts as a high pass filter? Still if we are pushing the "feeling" too far removed from the original material, I suspect there is still a detachable difference at some point. Efficiency still wins, but the route to get their, might vary....
The point of diminishing returns seemed to be based around headroom, so that does leave options. But if I want to achieve 123db down to 20hz, with what I got, I'd need more drivers or to try a vented enclosure.
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Largely true, but there might be some unique individuals who could hear the pitch at VLF.
This was interesting one, quick search gives explanation that seems reasonable: sound comes from explosion as air turns into plasma all the way the lightning struck, the other end being on the clouds somewhere. First crack is the sound from closest point of the strike, somewhere close to you and then comes the rest, perhaps several kilometers of sound fading into rumble. Distance works as low pass filter 🙂
Air over long distances is a LP filter. That's why we can't hear very high, because little in nature - at distances - goes that high (>15kHz, maybe even 10.) And that's why cats have such very good HF hearing - their world is much smaller, shorter distances to prey. Our senses adapt to what works best in our environment.
I'd go with "more drivers".
Whats challenging me is how the heck they are hitting 123db peaks with no distortion at plus ft.....I really wonna see whats behind that screen.
Have you looked at cinema subwoofer specsheets? Some list the sensitivity using multiple drivers/boxes. You can get crazy SPL's using multiple subs. Don't forget about mutual coupling. Look at one vs 4 in the specsheet.
Rob 🙂
Hello
The question was SPL capability not GD. I don't see GD as an issue below 80Hz. There is so much going on with the room in that range I just don't see GD as an issue in subwoofer territory. How would you separate any audible GD from room modes?? I think it's waste of time. If you look at the spec sheet max SPL goes up to 140 dB using multiples aided by mutual coupling. It's not at all hard to see how you could hit 120+ db. All it takes is sd and horsepower.
Rob 🙂
Did you buy 2 or 4 TD18H's?
Because 4 should do. 2x a pair in a 500l BR cab, tuned to 25 Hz.
2241Hs are also used in 2 way systems (with a 2360 above), but I'm sure a TD18H sounds better in the low mids.
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John Janowitz (Acoustic Elegance):
"IMO the vented box is really the way to go vs a sealed. They have high motor strength designed to be able to work very well in vented cabinets. I've done this demo with TD18's and B&C 18TBX100's side by side in identical enclosures and the difference was amazing.
The one way Xmax on these drivers is 14mm. The actual suspension will do 23mm one way. This was the longest travel 18" surround I could find. The spider really is good to 30mm+ so the surround is the limiting factor. In any case there is a good 60% extra travel beyond Xmax before damage."
MTM with BMS 4594ND + SEOS-24 crossed @ 450 Hz:
...“The result is an incredible speaker that can extend down to 20hz and can reach levels as high as 130db from 25-20,000hz at the seats if called upon."
Some people are critical of the resulting EBS alignment when the TD18H is simmed in a large cab, tuned low, but those folks have probably never listened to such cabs. Personally, I'm a proponent of EBS, even more so after listening to the Fleetwood Devilles.
"IMO the vented box is really the way to go vs a sealed. They have high motor strength designed to be able to work very well in vented cabinets. I've done this demo with TD18's and B&C 18TBX100's side by side in identical enclosures and the difference was amazing.
The one way Xmax on these drivers is 14mm. The actual suspension will do 23mm one way. This was the longest travel 18" surround I could find. The spider really is good to 30mm+ so the surround is the limiting factor. In any case there is a good 60% extra travel beyond Xmax before damage."
MTM with BMS 4594ND + SEOS-24 crossed @ 450 Hz:
...“The result is an incredible speaker that can extend down to 20hz and can reach levels as high as 130db from 25-20,000hz at the seats if called upon."
Some people are critical of the resulting EBS alignment when the TD18H is simmed in a large cab, tuned low, but those folks have probably never listened to such cabs. Personally, I'm a proponent of EBS, even more so after listening to the Fleetwood Devilles.
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