7 hz to 20 hz how do I allow powered subwoofer to play at this range

[nonutin]

I want to have a powered subwoofer to play at mainly the 7 to 14 hz range. I will use a computer to input the signals. What will I need to change to allow this. Most subwoofers are rated above 20 hz. I am aware that I will be only pushing air and not sound that I can hear. thanks

 

[fuzz092888]

It's not about changing anything on or about your subwoofer. If you want infrasound, odds are you need to change your subwoofer.....and by change I mean add a lot of large (18"+) driver subs to your space and/or go IB and/or look into rotary subs.

In order to reproduce infrasound with meaningful oomph, you need a lot of cone area to move enough air. Furthermore, odds are you won't hear a darn thing at those frequencies. Also, infrasound isn't that thump, kick you in the chest type frequency range. Infrasound is more whisper you feel emanating through your entire body.

Infrasound can add an extra layer of visceral appeal to a system, but only if the content is there for it. There aren't a ton of tracks or movies that have sound down that low.

 

[nonutin]

Thank you. I apologize for being clueless although my handle may have given a hint. What is IB. I am only trying to create the infrasound in a 30 cubic foot area or less. What type of cabinetry would you suggest. I assume ported. Thanks again. I am looking up rotary subs.

 

[BoredSysAdmin]

only rotary sub will play in that range

 

[fuzz092888]

only rotary sub will play in that range

You can get other alignments to reach that deep, but only with an extreme amount of drivers. We're talking about 12+ 18" drivers or larger. It can be done, just not as effectively as the rotary sub.

Thank you. I apologize for being clueless although my handle may have given a hint. What is IB. I am only trying to create the infrasound in a 30 cubic foot area or less. What type of cabinetry would you suggest. I assume ported. Thanks again. I am looking up rotary subs.

IB is infinite baffle. I've seen different projects on different websites that have had good results reaching into the teens with that alignment. However, like a rotary sub, it requires an attic, basement, or side room and like a multi-driver alignment it requires a bunch of drivers

No, ported wouldn't be best for this. When trying to reach that low the port would just become too large. Sealed is the only way to do it, and then only with many many drivers and a ton of power.

 

[BoredSysAdmin]

True that Fuzz,
But I am curious to know - WHY? Why such need for extreme infrasonics?

 

[nonutin]

It may be impossible at reasonable cost but maybe I need to clarify what I am trying to do. I would build the cabinet and put a thick plastic sheet with holes like a pegboard over the woofers. I would then lie down on the "pegboard". I only need to feel the vibration at the speaker not for an entire room. I hope this situation allows a smaller footprint and less electronics. Thanks

 

[fuzz092888]

True that Fuzz,
But I am curious to know - WHY? Why such need for extreme infrasonics?

For all practical purposes, there is no need. None. At all.

However, (and I think you knew this was coming ) once you've felt them, they're pretty awesome. While there aren't a ton of movie soundtracks that make use of that frequency range, the one's that do are just different enough with the infrasonic, IMO, that I can at least see why guys would want to chase that. Plus there's always organ music. I'm not 100? sure what my subs are reaching in the room I have them in now, but they're reaching at least deep enough that I was able to get a little of that whisper from the organ in Interstellar. I can only imagine what a rotary sub can do. From what I've read about them, NASA uses a few of them to reproduce a rocket launch and an IMAX uses them to accurately reproduce Niagra Falls.

http://www.rotarywoofer.com/niagara fury index.html

In this link, there is actually a file of the rocket launch that you can play on your home system. Do so with care!

http://www.rotarywoofer.com/titan web page/evergreen aviation rotary woofer installation.html

 

[fuzz092888]

It may be impossible at reasonable cost but maybe I need to clarify what I am trying to do. I would build the cabinet and put a thick plastic sheet with holes like a pegboard over the woofers. I would then lie down on the "pegboard". I only need to feel the vibration at the speaker not for an entire room. I hope this situation allows a smaller footprint and less electronics. Thanks

I feel like this answer only raises more questions.

 

[BoredSysAdmin]

I feel like this answer only raises more questions.

Maybe he's looking for vibration actuators?

 

[nonutin]

I was excited when I read about rotary subwoofers until I found out about the cost.

 

[nonutin]

I need to find out about vibration actuators. I looking at google but if you have a better idea or a specific website, even better

 

[TheWarrior]

Do you, or someone you know, have difficulties hearing? I'm trying to stab at why you might be wanting something like this, and simply need the guidance to know that those frequencies are 1) beyond the audible range of humans, 2) not going to be reproduced by any man made instrument (short of a cathedral organ, meaning that those frequencies are seldom recorded) and 3) you would do quite well with even just *one* quality subwoofer.

Or I am totally off base and you are just in to some sort of kinky sense deprivation therapy.... ;-)

 

[BoredSysAdmin]

I need to find out about vibration actuators. I looking at google but if you have a better idea or a specific website, even better

http://www.thebuttkicker.com/lfe-kit
much cheaper than rotary subs

 

[TLS Guy]

I need to find out about vibration actuators. I looking at google but if you have a better idea or a specific website, even better

For what you want that is probably your best bet. However it will not be the same as infrasonic reproduction, as it will be direct rather than air transmission.

To produce infrasonic frequencies with a loudspeaker is very difficult.

With respect to Fuzz, I doubt it is realistic with a sealed driver. I think the power required and cone excursion preclude it.

I don't think IB will do the trick for much the same reason.

In a ported enclosure, you really have to use the correct alignment. Extended bass and low tuning is fools gold and not satisfactory. In addition they roll off too fast below F3. They are often excellent to 20 Hz and a little below sometimes.

That leaves the transmission line and horns as the best option.

The standard exponential and tractrix horns are too big and need far too big a horn mouth for domestic situations.

The tapped horn is a potential solution, but I have never designed one, but I'm familiar with the theory.

I know my TLs produce infrasonic frequencies and without being driven hard.

TLs with F3 around 20 Hz are practical if you are so inclined. The taper at 12 db per octave instead of 24 db per octave. In addition they don't demand excessive power or cone excursions, so can produce low frequencies without distress.

My TLs have a measured F3 of 20 Hz in room, which would put them 15 db down at 10 Hz. I can not measure below 20 Hz.

However I do hear vibrations though out my body, with organs using the 32 ft ranks, which go down around 16 Hz.

I get this in the Interstellar movie. I had the same sensation when hearing the organ used for Interstellar at a recent wedding.

I also had the sensation on a recent BBC broadcast of Choral Evensong from Temple Church.

I also get it on a number of good recordings and on other Choral Evensong broadcasts form the great cathedrals and churches of the British Isles. I don't have to turn the rig up loud to get the effect either.

So I have I high degree of certainty my speakers are producing useful output below 20 Hz.

It remains though a difficult undertaking and requires a significant real estate be devoted to your speakers.

 

[fuzz092888]

To produce infrasonic frequencies with a loudspeaker is very difficult.

With respect to Fuzz, I doubt it is realistic with a sealed driver. I think the power required and cone excursion preclude it.

To be fair, I didn't say a sealed driver, singular. I said it would take at least 12, probably more of 18" drivers or larger with a large amount of power. With all that going on I thought the very difficult was implied .

 

[TLS Guy]

To be fair, I didn't say a sealed driver, singular. I said it would take at least 12, probably more of 18" drivers or larger with a large amount of power. With all that going on I thought the very difficult was implied .

I agree, but I was trying to imply practicality. To do it elegantly does requires some type of acoustic transformer. 12 18" drivers gets you into the exponential horn practicality issue.

My solution is borderline practical. I have never experienced the actual physical effect of a 32 ft stop from any other speaker system. To me it indistinguishable from the live effect.

I should add that this was never a design goal, and frankly came as a surprise to me. I had assumed the Fs of the drivers would be pretty much a brick wall, but it appears not to be this case.

The other surprise was the lack of any requirement for a high pass filter. The pipes seem, at least from inspection, to still control cone motion well below the Fs of the drivers, quite unlike what happens in a standard ported box. I'm not sure exactly what is happening here. There is not much world experience with TLs covering the whole last octave.

 

[KEW]

I am only trying to create the infrasound in a 30 cubic foot area or less.

30 cu. ft.? Is that really what you meant to say?
A cube 3 ft. on each side is 27 cu. ft.

 

[fuzz092888]

I guess it really depends. Given the size and build complexity of your TL speakers, they could be viewed as just as impractical as any of the other options. Although, cost wise, they're easily the most obtainable.

I agree, but I was trying to imply practicality. To do it elegantly does requires some type of acoustic transformer. 12 18" drivers gets you into the exponential horn practicality issue.

My solution is borderline practical. I have never experienced the actual physical effect of a 32 ft stop from any other speaker system. To me it indistinguishable from the live effect.

I should add that this was never a design goal, and frankly came as a surprise to me. I had assumed the Fs of the drivers would be pretty much a brick wall, but it appears not to be this case.

The other surprise was the lack of any requirement for a high pass filter. The pipes seem, at least from inspection, to still control cone motion well below the Fs of the drivers, quite unlike what happens in a standard ported box. I'm not sure exactly what is happening here. There is not much world experience with TLs covering the whole last octave.

 

[KEW]

30 cu. ft.? Is that really what you meant to say?
A cube 3 ft. on each side is 27 cu. ft.

Are you trying to see if you can make Gunea Pigs Sh!t themselves, or what?