Crap, when you ask those kind of questions , I have no idea what you are talking about.
I was talking about Xmax, measured distrotion was still very low. In the other thread I mentioned this, but I am placing the mike at the MLP.RE audio XXX 18" drivers. I have them in an infinite baffle setup.
Dave I still have you beat by a driver...
You have the better room and mains though.
LOL, did you just dare me?
Maybe I should add those 4 LMS ultra 18" to the equation?Crap, I think I caught your disease.
LOL, did you just dare me?
Crap, I think I caught your disease.
Pics please, or video @ 5hz
vacuphile,
A typical horn is only 1/4 wavelength but even that is huge and impractical inside anything smaller than a stadium. I myself have never seen an 18" speaker that was rated at 5hz or even close to that. So what is going on here, are they in a closed box with augmented low frequency electrical eq to force them this low?
JapanDave,
The Xmax is the normal maximum excursion rating of a speaker at 10% distortion, and Xmech would be the ultimate mechanical limitation of the device before self destruction, such as having the voicecoil completely leaving the gap or physically being limited by the surround or spider before things start to tear or reach their physical limit such as a surround that only can stretch so far. Another problem with many 18" speakers is the voicecoil will hit the back plate and then they are toast. Without adding mass to the cone or electrically extending the low frequency output I don't see how you are doing what you say you are?
A typical horn is only 1/4 wavelength but even that is huge and impractical inside anything smaller than a stadium. I myself have never seen an 18" speaker that was rated at 5hz or even close to that. So what is going on here, are they in a closed box with augmented low frequency electrical eq to force them this low?
JapanDave,
The Xmax is the normal maximum excursion rating of a speaker at 10% distortion, and Xmech would be the ultimate mechanical limitation of the device before self destruction, such as having the voicecoil completely leaving the gap or physically being limited by the surround or spider before things start to tear or reach their physical limit such as a surround that only can stretch so far. Another problem with many 18" speakers is the voicecoil will hit the back plate and then they are toast. Without adding mass to the cone or electrically extending the low frequency output I don't see how you are doing what you say you are?
Something like this is simple actually. In a normal domestic sized space frequencies below 20hz are huge relative to the boundaries and get heavily reinforced same as in a car cabin or a closet just less strongly. You use a sealed system or IB arrangement due to the shallow 12dB octave roll off and predictable excursion profile vs frequency. Then you select electronics which do not have dc blocking filters until as low as possible (3-8Hz is not uncommon). From there it is a matter of LT or shelf boosting the low end shape to where you want it and scaling the system (power/driver displacement capability)to a size capable of producing the output levels required. The electronics roll off determines the bottom limit at that point.
Once you have 25-50L of driver displacement and the power to use it, you can accomplish quite a bit and with over 100L of potential displacement (>3.5 cubic feet) headroom becomes a complete non issue.
Dave and I have somewhat similar HT bass systems using the same drivers and similar power but his is IB and mine is a sealed alignment, so I can assure you this type of thing is possible. Home theater guys have been doing this for years.
Once you have 25-50L of driver displacement and the power to use it, you can accomplish quite a bit and with over 100L of potential displacement (>3.5 cubic feet) headroom becomes a complete non issue.
Dave and I have somewhat similar HT bass systems using the same drivers and similar power but his is IB and mine is a sealed alignment, so I can assure you this type of thing is possible. Home theater guys have been doing this for years.
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Josh,
I follow you here you are in effect using the room loading to extend the bottom end. But you must be limiting the excursion at the same time, and what are you doing to tune out the fs of the device. I remember the papers from years ago on using electronics to use a speaker below its free air resonance in a seal box. but that was long ago and wasn't very well accepted at the time.
I follow you here you are in effect using the room loading to extend the bottom end. But you must be limiting the excursion at the same time, and what are you doing to tune out the fs of the device. I remember the papers from years ago on using electronics to use a speaker below its free air resonance in a seal box. but that was long ago and wasn't very well accepted at the time.
The resonance of a system is largely irrelevant here. The system will still respond to inputs of frequencies below that point just not as strongly. Electronic manipulation of the signal input is used to reach the desired final response shape and behavior (extending the response very deep in frequency to the point that the electronics themselves roll off due to DC blocking filters). In this case shelf or Linkwitz transform boosting of frequencies on the low end in combination with the gain from the acoustic space the system is in are used to accomplish this. To be clear this does not modify the amount of maximum headroom available from the system which is set by the subwoofer alignment, amplifier power and room acoustics. This is why multiple long stroke large diameter drivers and loads of power are typically used.
You would not try this with any system other than sealed or IB as excursion gets wildly out of control, distortion skyrockets and output drops off a cliff below the corner in any resonant assisted alignment plus they get HUGE attempting to push the corner down below 15-20Hz range. Also this would be pointless and or dangerous to your equipments health to attempt to run a setup like this with just a couple of 12" drivers for example which would typically be maybe 3 to 5 liters of displacement.
You would not try this with any system other than sealed or IB as excursion gets wildly out of control, distortion skyrockets and output drops off a cliff below the corner in any resonant assisted alignment plus they get HUGE attempting to push the corner down below 15-20Hz range. Also this would be pointless and or dangerous to your equipments health to attempt to run a setup like this with just a couple of 12" drivers for example which would typically be maybe 3 to 5 liters of displacement.
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Josh,
I follow you here. we are really doing what was done long ago. Long excursion designs with massive amounts of power to drive the devices with electronic shelving below the resonant frequency of the drivers in a sealed box. I follow that completely. At one time this was a patented process and so it wasn't adopted by the industry as it was not allowed. A diy device is not going to fall into the category of an infringing consumer manufacturer. I read about this in an early AES paper many years ago and I think it was included in the speaker compendium going back to Webster and up to what was current when the volume was put out.
I follow you here. we are really doing what was done long ago. Long excursion designs with massive amounts of power to drive the devices with electronic shelving below the resonant frequency of the drivers in a sealed box. I follow that completely. At one time this was a patented process and so it wasn't adopted by the industry as it was not allowed. A diy device is not going to fall into the category of an infringing consumer manufacturer. I read about this in an early AES paper many years ago and I think it was included in the speaker compendium going back to Webster and up to what was current when the volume was put out.
I haven't read this entire thread, and won't bother to, but here's the easiest way I've found to accomplish experiencing this:
Some vehicles resonate wildly with one of the windows down while cruising the highway. A friend's Dodge Nitro is one of the worst I've noted. It's shaped like a rectangular box, I'm sure there are plenty of other vehicles that will do similar. I'm usually in the backseat and let down the window while it's going down the highway, and the 5-10 Hz resonance will cause substantial ear pain in a matter of seconds. Anyone else in the car abruptly demands and begs for me to stop and let the window up.. I just enjoy it for a moment, usually while watching the headliner flap to the frequency, and then give in and proceed to let the window back up when the pain becomes too irritating. Enjoy.
Some vehicles resonate wildly with one of the windows down while cruising the highway. A friend's Dodge Nitro is one of the worst I've noted. It's shaped like a rectangular box, I'm sure there are plenty of other vehicles that will do similar. I'm usually in the backseat and let down the window while it's going down the highway, and the 5-10 Hz resonance will cause substantial ear pain in a matter of seconds. Anyone else in the car abruptly demands and begs for me to stop and let the window up.. I just enjoy it for a moment, usually while watching the headliner flap to the frequency, and then give in and proceed to let the window back up when the pain becomes too irritating. Enjoy.
BHTX.
I have experienced that sensation many times with a sun roof open to a certain amount and it drives me crazy while others seem to be oblivious to the very low frequency buffeting. I just can't imagine trying to make such low frequency output myself, I find it terrible to have that affect. Not unlike needing to pop your ears when changing elevation. I have made some extreme double 18" bass horns that put out plenty of low bass but not that low as we used them for PA use outdoors and below a certain frequency you are going to have low frequency feedback for sure, so the very low frequencies are actually cut with a filter. Except for the body sensation which you can get at much higher frequency than 5hz I just don't see the point and I imagine that there are others like me that can't stand that. I would walk out of the room, this would not be an enjoyable experience for me at all. I guess I have better sensitivity to this than some, I pick up on it instantly.
I have experienced that sensation many times with a sun roof open to a certain amount and it drives me crazy while others seem to be oblivious to the very low frequency buffeting. I just can't imagine trying to make such low frequency output myself, I find it terrible to have that affect. Not unlike needing to pop your ears when changing elevation. I have made some extreme double 18" bass horns that put out plenty of low bass but not that low as we used them for PA use outdoors and below a certain frequency you are going to have low frequency feedback for sure, so the very low frequencies are actually cut with a filter. Except for the body sensation which you can get at much higher frequency than 5hz I just don't see the point and I imagine that there are others like me that can't stand that. I would walk out of the room, this would not be an enjoyable experience for me at all. I guess I have better sensitivity to this than some, I pick up on it instantly.
Kindhornman, I know exactly what you mean with the open roof. The point you make about extreme bass is absolutely correct. The speakers I listen to now go into the high thirties - 3dB, and even then it may sometimes get uncomfortable for the random low rumble you have in much audio material. I am in the proces of designing an analog xover for this speaker, and it will have shelving high pass filter at the extreme low end to tune it to the room and the program material.
Kindhornman, I know what you are saying, a 5hz sine wave in my room can give you an unpleasant sensation if played for too long (Not that I regularly play 5hz sine waves). But , in the real world when experiencing 5hz in a movie it is a whole different feeling, not to mention it is usually only for a few seconds at most in any given movie that 'actually' has 5hz content.
In the movies I have heard, the ultra LF signals used are always used to convey an "unpleasant sensation", whether it is supposed to be real (earthquakes, explosions, car crashes etc.) or psychological (ghosts, alien influence, mind games).
Either way, I find it does not take a whole lot of level to get the message across.
I truly believe that you are exaggerating the frequency response in a movie theater. First the majority of theaters are using JBL sound systems behind the screen, leaving out any side wall or rear wall speakers as they could not produce these low frequency waves, and I don't remember them ever specifying such low frequency output of 5hz. Second fact would be that in a multiplex, the majority of theaters these days, you could never contain those low frequencies, everyone in the next theater over would hear all that sound bleeding into the other theaters and this would include just about every other screen in the theater, not just the adjacent screen. I have built bass horns that were used in a club and people down the block were complaining about the sub harmonics that were rearing their ugly head in a different building through conduction in the ground. It is next to impossible to isolate these sounds, this is a problem even in anechoic chambers and recording studios even with floating foundations. You do not have to hit 5hz to feel the impact of an earthquake and other low frequency illusions. Not necessary.
Kindhornman,
So far, you are the only person that has mentioned commercial theater systems which certainly don't go as low as the home theater systems Josh or Dave have.
Even my moderate 2x12" home theater sub goes well below the THX standard, though not as loud.
You are correct that a speaker system does not have to hit 5hz to feel the impact of an earthquake and other low frequency illusions, but one that can is more accurate reproducing a recording containing those frequencies than one that can't, whether "needed" or not.
Art
Art,
What I see now happening in the commercial theaters is they are now adding shakers to the seating to give the illusion of those very low frequencies, not through the air but through actual vibration transfer into your butt. In a home I would worry about things vibrating off of shelves and you would sure find out quickly if your wife or girlfriend was dusting well as it starts to fall from places you never thought of before! I had that experience in a famous club here in Los Angeles when we brought in some low frequency horns and proceeded to cover everyone with the dust accumulated on the exposed ducting above the audience. Those got shut down rather quickly!
What I see now happening in the commercial theaters is they are now adding shakers to the seating to give the illusion of those very low frequencies, not through the air but through actual vibration transfer into your butt. In a home I would worry about things vibrating off of shelves and you would sure find out quickly if your wife or girlfriend was dusting well as it starts to fall from places you never thought of before! I had that experience in a famous club here in Los Angeles when we brought in some low frequency horns and proceeded to cover everyone with the dust accumulated on the exposed ducting above the audience. Those got shut down rather quickly!
I have sat in quite a few of those theaters with the tactile transducers in the seats.
I can also tell you my infinite baffle subwoofer creates the same effect, but BETTER. It's better because it's reproducing the whole range of sound, smoothly and without distortion.
And please people, unless you have experienced a movie with ULF material played on a system capable of decent volumes down near 5hz... stop saying how useless or uncomfortable or worthless it is.
My IB system absolutely floors everyone who hears/feels it. That, of course, is the ULF part, the part that pressurizes the room and shakes the floor. It adds a LOT to movies and music that have it. After all, it's the artist's intent.
The more subtle part of an IB is the clairity of the sound. Subwoofer have got a bad rap from audiphiles because of the distortion. IB subs have very little.
And another bone of contention with many of the comments in this thread, describing the huge amounts of money and drivers needed to experience ULF. In a normal sized home theater, room gain makes those needs much smaller.
My sealed 1700 cubic foot room is easily filled by four 18" FiCar IB3 drivers in dual manifolds with 500 watts going to each driver. About $1500 (U.S.) total.
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