I'm not really operating below Fs the way Bag End does it. My alignment is more of an EBS (Extended Bass Shelf). If you look at the response of a typical EBS system you'll see that it droops a bit, and depending on tuning it will have a flat section before rolling off.
If you went for a QB3 alignment with my drivers, you'd end up with 8 cubic feet tuned to 28 Hz. This would give you an F3 of 35 Hz. My enclosure is 8.5 cubic feet tuned to 24 Hz. Without EQ, this gives pretty close to a 12 dB/octave rolloff from 40 Hz down to 20, with a 24 dB/octave drop below. If the room gain matched theory, no EQ would be required for flat in room response to 20 Hz.
My room has a set of French doors, windows and a large opening to the rest of the house, so I don't get full theoretical room gain. I use an adjustable Q second order 20 Hz high pass filter to compensate for the missing room gain. For Flat anechoic response I'd need 10 db of gain, and would have an F3 of 19 Hz. I ended up with about 5 dB of gain to get flat in room response.
If you look at the response modeled in WinISD you might think I really don't have a subwoofer if you forget about room gain. That is exactly the point - you probably don't need flat anechoic response to meet your goals. Just remember that to apply a lot of EQ down low you'll need drivers with lots of displacement capability.
If you went for a QB3 alignment with my drivers, you'd end up with 8 cubic feet tuned to 28 Hz. This would give you an F3 of 35 Hz. My enclosure is 8.5 cubic feet tuned to 24 Hz. Without EQ, this gives pretty close to a 12 dB/octave rolloff from 40 Hz down to 20, with a 24 dB/octave drop below. If the room gain matched theory, no EQ would be required for flat in room response to 20 Hz.
My room has a set of French doors, windows and a large opening to the rest of the house, so I don't get full theoretical room gain. I use an adjustable Q second order 20 Hz high pass filter to compensate for the missing room gain. For Flat anechoic response I'd need 10 db of gain, and would have an F3 of 19 Hz. I ended up with about 5 dB of gain to get flat in room response.
If you look at the response modeled in WinISD you might think I really don't have a subwoofer if you forget about room gain. That is exactly the point - you probably don't need flat anechoic response to meet your goals. Just remember that to apply a lot of EQ down low you'll need drivers with lots of displacement capability.
How low exactly are you looking to go? If you want high output flat to 10hz (possibly a bit lower) in room, you don't need a 30" woofer, a capable 18" in a large and low tuned ported enclosure will do. Take mine for instance:
And that's without any EQ.
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An externally hosted image should be here but it was not working when we last tested it.
And that's without any EQ.
My suggestion...
Two 18" adire tumult drivers with anything that fully powers them(without a subsonic filter). Two huge enclosures tuned to the lowest frequency you desire and there you go....
My sub(adire tumult 15" tuned to 16hz via two 18" PRs) produces quite adequate infrasound for my liking... I've played around a fair bit with infrasound and I find that below 18hz its impossible to tell pitch. Different frequencys might make different things rattle, but essentially it's the same feeling you will get in your body.
Anyhow....If you find a pipe organ recording with <15hz content at greater than -10db from reference you'd suprise me
Two 18" adire tumult drivers with anything that fully powers them(without a subsonic filter). Two huge enclosures tuned to the lowest frequency you desire and there you go....
My sub(adire tumult 15" tuned to 16hz via two 18" PRs) produces quite adequate infrasound for my liking... I've played around a fair bit with infrasound and I find that below 18hz its impossible to tell pitch. Different frequencys might make different things rattle, but essentially it's the same feeling you will get in your body.
Anyhow....If you find a pipe organ recording with <15hz content at greater than -10db from reference you'd suprise me
BenVos,
Might you tell us more about your 32" Clarion?
Is 17hz the published fs?
How did you get it from Clarion, they don't list it.
Rumor has it that such is made by Misubishi. True?
Is the driver's frame rigid enough, won't warp and cause voice coil binding?
May I ask, how much did it cost?
What kind of enclosure do you have it in, sealed, ported, transmission line, other?
Is your enclosure built-in or movable? How big is it? How heavy is it?
How much amp power do you have for it?
tc_60quy,
The conventional wisdom is that while more drivers and an enclosure can go louder, you still can't go below fs.
Most large church organs go to 16hz. Two go to 8hz.
I'm interested in experimenting electronically with this range.
Generally it has been assumed that you can't go under fs. Now, I'm seeing some people call that into question. Do you have any experience with specifically trying to go under fs?
phase_accurate,
Thank for that European patent. I am fascinated with it and still studying it. I knew that by feedback methods you could go under fs. But that is fairly exotic and requires a special driver.
It looks like this Bag End does not use feedback. I still need to look at this further.
Bag End says they can go down to 8hz. Do they explain why they want to do this? I want to understand more about how they are pitching their product.
Might you tell us more about your 32" Clarion?
Is 17hz the published fs?
How did you get it from Clarion, they don't list it.
Rumor has it that such is made by Misubishi. True?
Is the driver's frame rigid enough, won't warp and cause voice coil binding?
May I ask, how much did it cost?
What kind of enclosure do you have it in, sealed, ported, transmission line, other?
Is your enclosure built-in or movable? How big is it? How heavy is it?
How much amp power do you have for it?
tc_60quy,
The conventional wisdom is that while more drivers and an enclosure can go louder, you still can't go below fs.
Most large church organs go to 16hz. Two go to 8hz.
I'm interested in experimenting electronically with this range.
Generally it has been assumed that you can't go under fs. Now, I'm seeing some people call that into question. Do you have any experience with specifically trying to go under fs?
phase_accurate,
Thank for that European patent. I am fascinated with it and still studying it. I knew that by feedback methods you could go under fs. But that is fairly exotic and requires a special driver.
It looks like this Bag End does not use feedback. I still need to look at this further.
Bag End says they can go down to 8hz. Do they explain why they want to do this? I want to understand more about how they are pitching their product.
Skramstad, I'm very interested in understanding what you are saying. Might you know of any text which describes what you are saying, being able to build an enclosure to go under fs?
The most theoretical loudspeaker book I know of is by Martin Coloumbs.
fs is the driver resonance in free space. If you enclose it in any way, the resonance goes higher.
If you try to slew you signal done into the resonance and below, the sound goes away.
The only way I can think of to have an enclosure that gives a lower resonance, would be to do something like Bose does with their real tiny subwoofers.
The design of such is covered in the Coloumbs book. We can copy a patented design if it is for personal research.
Bose uses real tiny drivers. Say I built the same type of thing with an 18" driver?
The Bose design, as I remember, has three chambers. One is on one side of the driver. The other two are on the other side of the driver. These second and third chambers are connected by a tube, and a tube connects the third chamber to the outside.
Such a box could have its own resonance, below the driver fs.
Maybe then you could go under fs. I'm not sure. I don't know what the practical limits of such a design are.
Personally I've never cared for Bose, because it seems like they mostly want to make it small. What they accomplish is impressive, but I don't share their objective.
But if their approach could also be used to go under fs, then I could be interested. I fear that their design is quite complex to realize, and probably does have some real limitations.
I know that in the 1970's the Allen electonic organ company developed some big coffin like speaker box to do the 16hz or 32 foot organ octave. Maybe it worked something like this?
The most theoretical loudspeaker book I know of is by Martin Coloumbs.
fs is the driver resonance in free space. If you enclose it in any way, the resonance goes higher.
If you try to slew you signal done into the resonance and below, the sound goes away.
The only way I can think of to have an enclosure that gives a lower resonance, would be to do something like Bose does with their real tiny subwoofers.
The design of such is covered in the Coloumbs book. We can copy a patented design if it is for personal research.
Bose uses real tiny drivers. Say I built the same type of thing with an 18" driver?
The Bose design, as I remember, has three chambers. One is on one side of the driver. The other two are on the other side of the driver. These second and third chambers are connected by a tube, and a tube connects the third chamber to the outside.
Such a box could have its own resonance, below the driver fs.
Maybe then you could go under fs. I'm not sure. I don't know what the practical limits of such a design are.
Personally I've never cared for Bose, because it seems like they mostly want to make it small. What they accomplish is impressive, but I don't share their objective.
But if their approach could also be used to go under fs, then I could be interested. I fear that their design is quite complex to realize, and probably does have some real limitations.
I know that in the 1970's the Allen electonic organ company developed some big coffin like speaker box to do the 16hz or 32 foot organ octave. Maybe it worked something like this?
Mashaffer,
Transmission line enclosures are favored by many because you can get very close to fs, but not below.
If you are saying you can go below, then I feel that it must be with massive amounts of power.
Of course the cone will move no matter how low you want to go, but the efficiency is real low.
Are you actually driving your system with a signal generator, and starting at like 200 hz, and then going down below its resonance?
I don't see how you could make this work in a musical application?
Tell me more. It does seem that BagEnd has something. I need to study it.
Transmission line enclosures are favored by many because you can get very close to fs, but not below.
If you are saying you can go below, then I feel that it must be with massive amounts of power.
Of course the cone will move no matter how low you want to go, but the efficiency is real low.
Are you actually driving your system with a signal generator, and starting at like 200 hz, and then going down below its resonance?
I don't see how you could make this work in a musical application?
Tell me more. It does seem that BagEnd has something. I need to study it.
phase_accurate, post #13, Thank you for that link to Elliot Sound Products. I am going to have to study it. They say it drops 12dB/Octave below resonance.
Lots of subwoofer drivers have fs from 30hz to 25hz. I wish there were more that were lower. So to get to 8hz will be real tough.
I had wanted info about giant low fs drivers. But it seems there is more interest in ways to go under fs. I'm finding this fascinating.
Along with eq schemes to go under fs, there can also be eq for finite room size considerations. The room becomes the front part of the speaker enclosure when you go that low.
Thanks to all of your I'm still trying to read and understand your posts and fascinating links.
Lots of subwoofer drivers have fs from 30hz to 25hz. I wish there were more that were lower. So to get to 8hz will be real tough.
I had wanted info about giant low fs drivers. But it seems there is more interest in ways to go under fs. I'm finding this fascinating.
Along with eq schemes to go under fs, there can also be eq for finite room size considerations. The room becomes the front part of the speaker enclosure when you go that low.
Thanks to all of your I'm still trying to read and understand your posts and fascinating links.
Steve Callas #23, What is that you've got a picture of there? Did you make that? Who makes that? Please tell us more about its design.
You say it works to 10hz. Have you actually driven it with a sign wave generator, and slewed down from say 200hz, down to 10?
And are you sure you are hearing the fundamental, and not overtones or some kind of rattles?
Rob Wells #17, I would ask you the same kind of question. And what exactly are tempests, do you have a web link, or give me a specific post number.
badman #18, What kind of subwoofers are you referring to exactly?
You say it works to 10hz. Have you actually driven it with a sign wave generator, and slewed down from say 200hz, down to 10?
And are you sure you are hearing the fundamental, and not overtones or some kind of rattles?
Rob Wells #17, I would ask you the same kind of question. And what exactly are tempests, do you have a web link, or give me a specific post number.
badman #18, What kind of subwoofers are you referring to exactly?
BassAwdio,
Tell us more about the 18" drivers and enclosures to go that low. It still sounds like you are talking about going under fs. I'm skeptical.
As far as organs. A nice church organ has a 32' stop, so the lowest note is C, at just above 16hz. You can hear it. You can certainly distinquish pitch because there will be overtones. So it works very nicely with the music.
Radio City Music Hall and Wannamakers have organs with the 64' stop. You can distinquish pitch the same way. Some might not consider this serious music, but rather a sound effect. I want to experiment electronically.
Tell us more about the 18" drivers and enclosures to go that low. It still sounds like you are talking about going under fs. I'm skeptical.
As far as organs. A nice church organ has a 32' stop, so the lowest note is C, at just above 16hz. You can hear it. You can certainly distinquish pitch because there will be overtones. So it works very nicely with the music.
Radio City Music Hall and Wannamakers have organs with the 64' stop. You can distinquish pitch the same way. Some might not consider this serious music, but rather a sound effect. I want to experiment electronically.
Low frequencies are about displacement (Vd =Sd x Xmax). Below Fs the efficiency of the driver (at those low frequencies) drops, to make up for that you need more excursion as Sd is fixed. This at a higher rate then above Fs.
Bag end doesn't use or have drivers with an Fs of 8 Hz. You can use an efficient large Sd driver with reasonable Xmax and high efficiency or a small Sd driver with more excursion.
The lower you want to go the more you trade overall efficiency for the low end extension.
It is a border that can be crossed with consequences not an border that can't be crossed.
With horns you can do more because the drivers efficiency is largely dominated by the horn parameters.
With BR I got reasonable output 7 Hz under Fs without electronically enhancements. 350 ltr BR tuned at 18 Hz, 18" driver, 9 mm Xmax. A Helmholz resonator can counteract excursion at a small frequency band of desire, increasing overall mechanical powerhandling.
with kind regards Johan
Bag end doesn't use or have drivers with an Fs of 8 Hz. You can use an efficient large Sd driver with reasonable Xmax and high efficiency or a small Sd driver with more excursion.
The lower you want to go the more you trade overall efficiency for the low end extension.
It is a border that can be crossed with consequences not an border that can't be crossed.
With horns you can do more because the drivers efficiency is largely dominated by the horn parameters.
With BR I got reasonable output 7 Hz under Fs without electronically enhancements. 350 ltr BR tuned at 18 Hz, 18" driver, 9 mm Xmax. A Helmholz resonator can counteract excursion at a small frequency band of desire, increasing overall mechanical powerhandling.
with kind regards Johan
Rademakers, Ok. I'm starting to see this the way you all are, that fs can be crossed. I'd still like to know more.
350ltrs bass reflex is quite a big box.
Going to a helmholtz resonator certainly does define a definite bottom end , no?
Do you get 7hz in a musical situation? What? How does it work?
Clearly there has to be good electronic eq to make this all work.
How about more info on giant low fs drivers. Why aren't more made? It seems like the simplest solution.
350ltrs bass reflex is quite a big box.
Going to a helmholtz resonator certainly does define a definite bottom end , no?
Do you get 7hz in a musical situation? What? How does it work?
Clearly there has to be good electronic eq to make this all work.
How about more info on giant low fs drivers. Why aren't more made? It seems like the simplest solution.
zenmasterbrian said:
Interesting. 64' pipe should be 16Hz, so the 8Hz organs have 128' pipes? I mean, 64' is (roughly) the wavelength of 16.4Hz, which I thought was the lowest note used in composing music for the organ (eg Saint-Saens 3rd).
I know a fellow who built his own - in his practice room - and tunes the pipes for quarter wave resonance (not sure if this is how you're supposed to say it - but his bass pipes are the same length as you'd expect for tuning a TL). But to have a 64' pipe producing 8Hz would be 'half-wave tuning' - which I've never heard of in musical production (then again I've not heard a lot of things).
Brian;
I have not yet built it. See My TL thread for a complete discussion of the evolving design. The Woofer Fs is about 45 Hz. Our designs simulate output down to around 30Hz before significant rolloff. Of course room gain will add some more. Even your basic BR or EBS results in a system response significantly below Fs as shown below. Also bass horns regularly result in systems with output well below the driver's Fs.
mike
I have not yet built it. See My TL thread for a complete discussion of the evolving design. The Woofer Fs is about 45 Hz. Our designs simulate output down to around 30Hz before significant rolloff. Of course room gain will add some more. Even your basic BR or EBS results in a system response significantly below Fs as shown below. Also bass horns regularly result in systems with output well below the driver's Fs.
mike
Attachments
ZMBrian - people have been going below fs since the beginning of moving coil speakers.
In 1952 Jensen released plans for the Transflex, a tl tuned to 18 hz. It used an old 1952 driver with an fs of about 37.
Actually most designs will work very well below fs. The cost is sensitivity.
That's why you don't see any 8 hz drivers. They are not necessary and they cost too much to make.
You need to do some research on Linkwitz Transforms in sealed boxes, EBS ported/vented, even bandpass and transmission lines are very capable of getting to 8 hz, but the boxes will be large and sensitivity goes down with tuning frequency. Horns won't do you any good unless you want one the size of your house.
In 1952 Jensen released plans for the Transflex, a tl tuned to 18 hz. It used an old 1952 driver with an fs of about 37.
Actually most designs will work very well below fs. The cost is sensitivity.
That's why you don't see any 8 hz drivers. They are not necessary and they cost too much to make.
You need to do some research on Linkwitz Transforms in sealed boxes, EBS ported/vented, even bandpass and transmission lines are very capable of getting to 8 hz, but the boxes will be large and sensitivity goes down with tuning frequency. Horns won't do you any good unless you want one the size of your house.
I gotta disagree. My feet on the floor and my butt in the seat can definitely feel the difference between an 18hz sine wave and a 10hz sine wave.
It's my subwoofer - I designed and built it. 700 liters, Avalanche 18 driver, tuned to 13.5hz with an 8" diameter port, fed with 600 watts. 7' tall, ~150lbs.
Umm, right under the picture of the sub I posted a FR measurement. I'm pretty flat with a very subtle house curve.
I'm not hearing anything at 10hz, it's all tactile. Definitely no rattles or anything like that, this sub was designed from the get go to be a true bottom feeder. In addition, a large and low tuned ported subwoofer has MANY advantages. In the musical range, which I consider 30hz+, the output is almost entirely created from the driver, so it behaves like sealed in the muscial range and ported below that, meaning you get free clean output where it is needed the most. All "negative" side effects of using a ported design are pushed down so low with the 13.5hz tune that it's like having your cake and eating it too. For a single driver subwoofer, as far as I know of, it's about the best design there is. I've got two more Avalanche 18 drivers, so when I move into a larger space, I'll have three of these subs.
Cloth Ears, about organ notation.
If we activate the 16' stop on a standard organ, then the lowest note will be C of the 16' octave.
This means that the pipe is 16' long from the mouth to the end. There is extra lenght for the valve and air chest.
This 16' cooresponds to 1/2 wavelength. So, it works out to be just above 32hz.
For american tuning, A is 440hz. So middle C comes in at about 262.1 hz. If you imagine it was instead 256 hz, you can see how it goes down, 128, 64, 32, 16, 8
So, the middle C note on a piano corresponds to 2 ft C. Again, the 2 feet is 1/2 a wavelength.
Most theater organs only go down to 16' C. This is the lowest C note on an 88 key piano. But remember, such pianos go down to A of the 32' octave, which is at 27.5 hz.
Most big church organs have the 32' stop. It really does sound nicer in a large building.
The only pipe organs I'm aware of that go lower are at Radio City Music Hall, and at Wannamakers. They have the 64' octave, starting at just above 8hz.
Now, some organs us stopped pipes for the lowest octave. The end away from the air chest is closed. So the pipes are only a 1/4 wavelength long. These work, but they do not sound the same. Some churches have stopped pipes laid out sideways, for this lowest octave.
The Radio City Music Hall organ does have stopped pipes for the 64' octave.
I've never seen it, but I believe Wannamakers does not. I believe it is a 7 story building with an attrium. It sounds like it was built around the organ. The pipes might even be structural vertical elements.
If we activate the 16' stop on a standard organ, then the lowest note will be C of the 16' octave.
This means that the pipe is 16' long from the mouth to the end. There is extra lenght for the valve and air chest.
This 16' cooresponds to 1/2 wavelength. So, it works out to be just above 32hz.
For american tuning, A is 440hz. So middle C comes in at about 262.1 hz. If you imagine it was instead 256 hz, you can see how it goes down, 128, 64, 32, 16, 8
So, the middle C note on a piano corresponds to 2 ft C. Again, the 2 feet is 1/2 a wavelength.
Most theater organs only go down to 16' C. This is the lowest C note on an 88 key piano. But remember, such pianos go down to A of the 32' octave, which is at 27.5 hz.
Most big church organs have the 32' stop. It really does sound nicer in a large building.
The only pipe organs I'm aware of that go lower are at Radio City Music Hall, and at Wannamakers. They have the 64' octave, starting at just above 8hz.
Now, some organs us stopped pipes for the lowest octave. The end away from the air chest is closed. So the pipes are only a 1/4 wavelength long. These work, but they do not sound the same. Some churches have stopped pipes laid out sideways, for this lowest octave.
The Radio City Music Hall organ does have stopped pipes for the 64' octave.
I've never seen it, but I believe Wannamakers does not. I believe it is a 7 story building with an attrium. It sounds like it was built around the organ. The pipes might even be structural vertical elements.
mashaffer, just a guy, Steve Callas, Thank you all.
I'm going to have to carefully study your links and posts.
I am seeing the fs issue differently than I was before, and I am going to have to do some additional research.
I would still like to start with fs as low as possible.
So I'm still interested in knowing about low fs drivers. Also, an enclosure which can go real low, is going to be big. So why not a real big driver too.
I'm going to have to carefully study your links and posts.
I am seeing the fs issue differently than I was before, and I am going to have to do some additional research.
I would still like to start with fs as low as possible.
So I'm still interested in knowing about low fs drivers. Also, an enclosure which can go real low, is going to be big. So why not a real big driver too.
I looked this up after your post, and it looks like (according to Organstops) "There are exactly two true 64' stops in existence. One is the Diaphone Profundo at Atlantic City; the other is a Contra Trombone at the Sydney Town Hall."zenmasterbrian said:
Thanks for the info - I didn't know there were such large pipes really in existance. I thought all the really low note were done using harmonics. You really do learn something new every day!
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