Superlow frequency subwoofer

[soiset]

I'd like to build an extremely low frequency sub-subwoofer, to cover the range from 10 to 28 Hz. I'll have availble 15 cubic feet of enclosure, and plenty o' wattage. What I lack is a driver that will respond way down there.

The "cabinet," if you will, will be a 4' x 8' platform, on top of which will sit the second tier of HT seating. The amp will be a Crown professional model, probably the Macrotech 1200, running mono-bridged.

I see that Velodyne makes subs that can reach down to the 12 Hz range, but an extensive search on "subwoofer drivers" has turned up little, and that little doesn't seem to feel the need to mention anything below 20 Hz. I'm sure that it will take an 18" driver, and the fs will be below 30 Hz.

Any ideas?

[janmike]

Sid would be your man for this one. I am sure he will chime in at some point.

[hoosier21]

want 10hz here you go get building

http://www.royaldevice.com/custom.htm

[hoosier21]

want 5hz got 25k?
http://www.rotarywoofer.com/

[ben62670]

I'm not a pro at subs, but you would have to brace the piss out of a cab that big. I am assuming that you are thinking or using part of your structure for the enclosure? Maybe 2 or 4 sensitive 15's series/parallel? Here is a pair of 8 ohm 15's that go deep without huge power needs.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-130

[GV#27]

One of these bad boys in a big sonotube might get you what you what you want http://www.hometheatershack.com/forums/soundsplinter/3810-new-premium-series-18-driver-soundsplinter-unleashes-beast.html

Also check out TC Sounds for some excellent woofers.http://www.tcsounds.com/

[RuSsMaN]

http://www.mccauleysound.com/component_overview.cfm?ID=126

Horn loaded will play over 121db all day long at 19hz. Also, see if you can find a Bag-End sub driver. Parts express has a 'Bully' 15" that's a monster also. Properly loaded, you'll get all the response any media you have is capable of producing.

Cheers,
Russ

[GV#27]

[url]
Also, see if you can find a Bag-End sub driver.

Cheers,
RussBag End's sound fantastic but it is their dual integrator EQ circuit that gives them the potential to go very low. With a very good long throw 12" or 15' woofer and this circuit
http://sound.westhost.com/project48.htm you can duplicate their performance.

[unc2701]

Yep, get a bigass long throw driver, like an Aurasound 18" via www.madisound.com, put it in a sealed box, then add a Linkowitz compensation circuit (as in GV#27's post) to control the low end roll off (this will limit your max DB's, but keep it flat), then get a BFD or Velodyne SMS-1 to control the room modes and you're done. You should be able to pull >100 db's at 10 hz, but if you bring your goal up to more like 15-20hz, you're looking at 110+ db's easy.

[soiset]

want 10hz here you go get building

http://www.royaldevice.com/custom.htm

I should specify that I don't want to build a sub that would require a building permit, or more than a dozen drivers. But that shaping they did is interesting

[soiset]

want 5hz got 25k?
http://www.rotarywoofer.com/

I have not found this one. $12,700 seems like a lot for a really nice fan (maybe I could find one on ebay:D ). I had thought that it would be nice to run really low freqs from an electric motor somehow, but getting the req'd response times would be the hard part. I guess they've figured that out. I could also bolt down a briggs and stratton to a piece of plywood and attach the handle end of a hammer to the crankshaft. Then I'd let my pre throttle it up and down.

More seriously, could, in theory, a tactile transducer be mounted to a rigid diaphragm, to do the low freq job? Clark models respond at 5 Hz, but the response is really ugly down there.

[soiset]

I'm not a pro at subs, but you would have to brace the piss out of a cab that big. I am assuming that you are thinking or using part of your structure for the enclosure? Maybe 2 or 4 sensitive 15's series/parallel? Here is a pair of 8 ohm 15's that go deep without huge power needs.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-130

I looked at the Dayton drivers. The stated response is 19-1K Hz. Not low enough, and a lot higher than I want. As far as the cab goes, yes, the structure of the platform will be the cabinet. I figure 2 4x8 sheets of 1" MDF, with 6-8" clear between them, with 2x2 bracing in a 1' grid ought to do it.

[tryrrthg]

do you have an adjoining room, attic, crawlspace that you could use to run an infinite baffle?

http://home.comcast.net/~infinitelybaffled/

if not, get yourself the soundsplinter 18" driver (or two) and brace the heck out of the enclosure. if you can build a sonosub then you won't have to worry about bracing just two big ass silos in your room like below

http://www.polkaudio.com/forums/showthread.php?t=50296

[soiset]

One of these bad boys in a big sonotube might get you what you what you want http://www.hometheatershack.com/forums/soundsplinter/3810-new-premium-series-18-driver-soundsplinter-unleashes-beast.html

Also check out TC Sounds for some excellent woofers.http://www.tcsounds.com/

Assuming they aren't lying, BINGO.
Need to feel it deeper in the gut? Think size matters? For those who seek the cleanest, lowest of lows,
where your brain won't hear it all but your bones will sure feel it.. snap up those single Hertz signals by
strappin' this bulldog into an IB and brace yourself for something fierce!

single hertz...
Now we're talking.

[soiset]

http://www.mccauleysound.com/component_overview.cfm?ID=126

Horn loaded will play over 121db all day long at 19hz. Also, see if you can find a Bag-End sub driver. Parts express has a 'Bully' 15" that's a monster also. Properly loaded, you'll get all the response any media you have is capable of producing.

Cheers,
Russ

Thanks, Russ. I found the Mccauley driver. It runs about $890, and has a stated response of 15 Hz. No doubt this is an awesome driver, but it's talents and price have been geared toward stadium sound. It has something like an 800 Hz upper limit, which is a lot more than I need. I think that SoundSplinter 18" might be the thing to have, and maybe I'll bump up the enclosure volume to 20 cubes. That price, $702 for a pair of them, with promised responses in the single digits, is sounding mighty sweet to me.

Now to find out if putting swoopy channels in the cabinet a la "waveguides" does anything.

[soiset]

Bag End's sound fantastic but it is their dual integrator EQ circuit that gives them the potential to go very low. With a very good long throw 12" or 15' woofer and this circuit
http://sound.westhost.com/project48.htm you can duplicate their performance.

I may be wrong, but aren't there physical limits in woofers that determine their low end limit? I mean, if a motor will simply not move when presented with a 12 Hz signal, then no amount of circuitry would overcome that. Is that not exactly true?

[madmax]

A subwoofer in a sealed box will respond down to 0 hz. The problem is they become less and less efficient because of the box size and the electrical efficiency. Add to that what is lost in the recording process and the rolloff of your hearing abilities and you end up with nothing. It can be pulled off with the right frequency slope, cutoff point and lots of amplifier gain.
madmax

[appadv]

Sid would be your man for this one. I am sure he will chime in at some point.

Yes, Trey seems like the expert on this stuff...

[soiset]

Yes, Trey seems like the expert on this stuff...

It's like waiting for Jesus or something...

[soiset]

A subwoofer in a sealed box will respond down to 0 hz. The problem is they become less and less efficient because of the box size and the electrical efficiency. Add to that what is lost in the recording process and the rolloff of your hearing abilities and you end up with nothing. It can be pulled off with the right frequency slope, cutoff point and lots of amplifier gain.
madmax

Are you implying that in a ported box, the response limit is higher than DC? As far as box size, I may extend the rear seating platform all the way to the sides and rear of the room, to push it to maybe 40-50 cubic feet, depending on the return in investment (this is a dedicated HT room in ACAD 3d for now, but it will happen in about 1.5 years).

[soiset]

It looks like this "Ascendant Audio" is quite a popular brand right now. I guess they make the Avalanche 18" driver that is referred to earlier here in a sonotube design. The Ascendant website is under construction, and it looks like the whole company is getting an overhaul.

Perhaps the market for super-low capacity drivers is heating up? Maybe in a year I'll have some really great choices. Can anyone offer a comparison between the Avalanche 18 and the SoundSplinter 18? What does the Avalanche cost?

[madmax]

A ported box wont give you much output below the resonance freq of the cabinent.

[soiset]

A ported box wont give you much output below the resonance freq of the cabinent.

Because I have so much volume available, and because of the technical difficulties of a ported box, I am pretty certain that I want to stay with a sealed enclosure. I can always build a stiff box (pretty easy job for a structural engineer with a ton of tools:D ).

[GV#27]

I may be wrong, but aren't there physical limits in woofers that determine their low end limit? I mean, if a motor will simply not move when presented with a 12 Hz signal, then no amount of circuitry would overcome that. Is that not exactly true?
What happens in a sealed box is the driver exhibits a 12db per octave rolloff below the resonant frequency of the driver and box combo.This rolloff can be compensated for with special EQ circuits like the Linkwitz transform,EAS,or shelving filters.
This means that there is a substanial amount of electrical boost so a good hi excursion driver or drivers are needed.You can extend the bass response atleast an octave lower this way.Here is a good link to read about this. http://www.linkwitzlab.com/thor-intro.htm .Im using the EAS circuit on my 2 12"sealed subs and it works marvelous.This circuit with the right drivers and a big amp can get you into the low teens.

A ported box uses the port to extend the bass instead of EQ and it will have the advantage of greater output.The ones I linked to in my first post are for real they are not lying.:)

[soiset]

Thanks for the info. My brain is pretty full, and I don't think I have the space in it to really learn circuits, so I need a black box solution for a low-freq crossover/equalizer, or, basically, a subwoofer processor. I'd like to cross at about 28 Hz, and then be able to equalize all the way down to, well, as far as I could. Ever seen such a thing?

Someone mentioned a Velodyne processor. Would that be the way to go?

[soiset]

Yep, get a bigass long throw driver, like an Aurasound 18" via www.madisound.com, put it in a sealed box, then add a Linkowitz compensation circuit (as in GV#27's post) to control the low end roll off (this will limit your max DB's, but keep it flat), then get a BFD or Velodyne SMS-1 to control the room modes and you're done. You should be able to pull >100 db's at 10 hz, but if you bring your goal up to more like 15-20hz, you're looking at 110+ db's easy.

The room will only be 19' on the long dimension, so the lowest mode I could have would be 27 Hz, which is about where I'd want to cross the super-sub, so I think the SMS-1 or BFD (what is that?) wouldn't be necessary, except for the regular subs, which would run from 28-80 Hz, inside of which I would have a few room modes.

But this "Linkwitz compensation circuit" sounds interesting.

ETA: Actually, that SMS-1 sounds wonderful. It has a low-pass xover that goes all the way to 15 Hz, and would manage all the room modes I would have from my regular subs. Now, where to find one for less that $749...
But it equalizes "only" down to 16 Hz. As I figure below that freq, the bass would just be rolling off, I would just need something to "lift" the bottom end single digits. Obviously accuracy wouldn't be a concern below 16 Hz, just output. So an SMS-1, plus some other black box to lift the real bottom end would do all the tricks. Almost there...

Oh, look: http://www.outlawaudio.com/products/sms1.html

[GV#27]

Thanks for the info. My brain is pretty full,

Ever seen such a thing?


Sorry for the info overload and yes there is such a device that is basically an adjustable Linkwitz circuit. If you intend to use a sealed box sub then this unit by Marchand is an excellent tool for maximizing it's potential.You can buy it as an assembled unit for $399or as a kit for $349.It does not contain a crossover however.
http://www.marchandelec.com/wm8.html

[soiset]

Sorry for the info overload and yes there is such a device that is basically an adjustable Linkwitz circuit. If you intend to use a sealed box sub then this unit by Marchand is an excellent tool for maximizing it's potential.You can buy it as an assembled unit for $399or as a kit for $349.It does not contain a crossover however.
http://www.marchandelec.com/wm8.html

It appears the graph in that link shows a 24 dB boost at 0 Hz (or, I assume, 2 Hz, as that is the listed freq response min.) The text says,"By adjusting the BASSIS, its own frequency response (curve B) may be made the inverse of the speakers curve, down to 15 Hz

So, it looks like it comes close to providing a flat response down to 15 Hz, and then does the best it can below that. Correct?
The specs say that it has a limit on the low end for a speaker resonance of 30 Hz. The giganto 18" models have Fs around 20 Hz. What would that mean in terms of performance of this unit on those kinds of drivers?

[GV#27]

The specs say that it has a limit on the low end for a speaker resonance of 30 Hz. The giganto 18" models have Fs around 20 Hz. What would that mean in terms of performance of this unit on those kinds of drivers?
That fs 20 hz spec is for the driver operating in free air.When it is put into a box the resonant frequency will always be higher.How much higher will depend on the internal volume of the box.Say you put that driver into a box that resulted in a resonant frequency of 30hz then adding 12db of boost with the BASSIS will give it flat response to 15hz.Then it will roll off below 15hz at 12db per octave.Hope that helps.

[soiset]

That fs 20 hz spec is for the driver operating in free air.When it is put into a box the resonant frequency will always be higher.How much higher will depend on the internal volume of the box.Say you put that driver into a box that resulted in a resonant frequency of 30hz then adding 12db of boost with the BASSIS will give it flat response to 15hz.Then it will roll off below 15hz at 12db per octave.Hope that helps.

Yes, this is all very helpful, thanks. How does this unit work? Is it some kind of negative feedback like the old Velodyne amps? Or do you take measurements and set the dials accordingly?

[GV#27]

Measurements would be helpful but not neccessary.You need to know the Qtc and Fc of the woofer/box combo you are using and adjust the dials accordingly.You can even experiment and see if you prefer some other settings as well but I would avoid applying any more than about 12-14db of boost.

[soiset]

You know, the Marchand unit is about as much as the SMS-1. The SMS-1 flattens the response to 15 Hz (it's listed freq response), and the subsonic filter can be set as low as 5 Hz with the new firmware update (low enough for me!). Since the SMS-1 is a digital unit, do you think that it would have a similar effect of providing boost below the 15 Hz limit, but obviously to a level less than flat?

I mean, if it takes a 10 dB boost at 15 Hz to bring the response to flat, then at an octave lower, which I think is 7.5 Hz, would the boost have disappeared (assuming 12 dB/octave falloff)? Or would the unit somehow fail to provide any boost at all under 15 Hz, brick wall style?

[GV#27]

You know, the Marchand unit is about as much as the SMS-1. The SMS-1 flattens the response to 15 Hz (it's listed freq response), and the subsonic filter can be set as low as 5 Hz with the new firmware update (low enough for me!). Since the SMS-1 is a digital unit, do you think that it would have a similar effect of providing boost below the 15 Hz limit, but obviously to a level less than flat?

I mean, if it takes a 10 dB boost at 15 Hz to bring the response to flat, then at an octave lower, which I think is 7.5 Hz, would the boost have disappeared (assuming 12 dB/octave falloff)? Or would the unit somehow fail to provide any boost at all under 15 Hz, brick wall style?I know very little about the SMS-1 but I will see if I can find some details on its operation.

[soiset]

Outlaw has a really good user's manual for it:
http://pdf.outlawaudio.com/outlaw/docs/sms1guide.pdf

[GV#27]

Cool i'll check that out.

[soiset]

I think I have the solution: Crank up the gain on the super-sub amp, use the SMS-1 to flatten the response down to 15 Hz, and whatever happens below 15 Hz just happens. I think a giant, well braced, sealed box for two of the 18" drivers, probably the Soundsplinter models that come in at $702 per pair, would be just fine. No fancy calculations or measurements for me to do, just build the super-sub cabinet well, and let the SMS-1 take care of the rest. I can use it to cross at 28 Hz. From 28 to, say, 100 Hz, I'll let the two PSW-1200's, which will be set just beside each of the two front mains, do their thing.

The SMS-1 has outputs for 3 subwoofers. I don't know if these subs can be managed as handling separate freq ranges, but if they can, oh, how sweet and easy it will be.

[GV#27]

The sms-1 certainly has a lot of useful features with built in crossover and phase adjustment etc but its EQ section is primarily meant to smooth out the in room response of a sub not boost the very low end.It will not do the same thing as a BASSIS but you may get satisfactory results with it ,and there is a lot of potential for tweaking.

Also I remembered another unit that can be made to work like the BASSIS and has some features similar to the SMS-1.Not sure of the US pricing but check it out.http://www.behringer.com/DEQ2496/index.cfm?lang=ENG

[anonymouse]

Im using the EAS circuit on my 2 12"sealed subs and it works marvelous.This circuit with the right drivers and a big amp can get you into the low teens.

A ported box uses the port to extend the bass instead of EQ and it will have the advantage of greater output.The ones I linked to in my first post are for real they are not lying.:)

I have two AA Atlas 12 subs I want to do the exact same thing with. I want to design sealed subs which would double up as stands for the LSi9's. Which subs are you using and can you give me some pointers on how to model the subs and the circuit out? The subs will be driven by a NAD2200PE and I need something to take the preamp and crossover to the subs. This is a strictly 2 channel rig.

[GV#27]

Sure amouse,Do you have info on those drivers namely the TS parameters ?What is the maximum size the enclosure can be.I assume you want to keep the enclosures fairly compact.Also can you build simple opamp circuits?

[anonymouse]

Sure amouse,Do you have info on those drivers namely the TS parameters ?What is the maximum size the enclosure can be.I assume you want to keep the enclosures fairly compact.Also can you build simple opamp circuits?


Atlas 12 specs are here: http://forum.carstereos.org/atlas-12-specs-t59973.html?t=59973&highlight=atlas+12
There was some debate about whether Ascendant Audio misrepresented some of the specs, specifically how they change with the use of the second coil, but I have no idea what to believe as it was surrounded in controversy.
I'm decent with electronics, so building an op-amp circuit is not a huge challenge. Did you order the PCB's or make it on protoboard?

[GV#27]

Ok with those drivers the NAD amp and an EAS circuit you can have yourself a very nice pair of subs that can reach into the <20hz range in compact sealed boxes.
Designs built using the EAS controller have excellent transient response and tight controlled bass which is what you want for music reproduction.
The circuit is very simple,I built mine up on a small protoboard.Here is a link describing the controller, click on project 48. http://sound.westhost.com/projects-3.htm

[GV#27]

Here is a pic of my controller.I'm using two relatively inexpensive but good performing 12"car woofers because they suited the design.

[GV#27]

oops here is the pic of the controller.

[anonymouse]

Nice workmanship there.

Did you implement project 48 or 71? How would I go about choosing the values for the components? I'm planning on an 85L box or so, which I base on a design found for a Shive sub, which is rumored to be pretty close to the Atlas.

[GV#27]

I meant #48 thats what I used and it is much simpler to implement and the enclosure can be more compact.For it you would just use the values stated in the article.#71 is an option as well and there is a spread sheet that will calculate the component values but you need to know the Fc and Qtc of the driver box combo.This info is easy to obtain from a modeling program.

[Sherardp]

tcsounds or soundsplinter subs look insane, check those out

[Sherardp]

tcsounds or soundsplinter subs look insane, check those out

[GV#27]

tcsounds or soundsplinter subs look insane, check those out
check the links in post #6 of this thread..

[soiset]

Gott in himmel:

http://www.tcsounds.com/lms5400.htm

Which do you think would deliver better super-subsonic response, one tcsounds lms5400, or two of the soundsplinter rl-p18's : http://www.hometheatershack.com/forums/soundsplinter/3810-new-premium-series-18-driver-soundsplinter-unleashes-beast.html

in a huge, minimum 8 cubic feet, but possible 40-50 cubic feet box? Most likely driven by this: http://www.gbaudio.co.uk/data/ma1200.htm

[GV#27]

Which do you think would deliver better super-subsonic response, one tcsounds lms5400, or two of the soundsplinter rl-p18's :

Both will give you very deep bass but the dual SS's will have more maximum output capability.
Here is another player in the big woofer game. the Fi Q18:) https://ssl.perfora.net/www.ficaraudio.com/sess/utn;jsessionid=1545f87a8c4b377/shopdata/0020_Q/product_overview.shopscript

If you have that much space to use I would consider building large ported box.It would not need any electrical assistance(EQ) to reach into the low teens.

[soiset]

Both will give you very deep bass but the dual SS's will have more maximum output capability.
Here is another player in the big woofer game. the Fi Q18:) https://ssl.perfora.net/www.ficaraudio.com/sess/utn;jsessionid=1545f87a8c4b377/shopdata/0020_Q/product_overview.shopscript

If you have that much space to use I would consider building large ported box.It would not need any electrical assistance and will reach into the low teens.

The Q18 has an Fs of 24.5 Hz, and the others I listed are at 18 and 20. Wouldn't that indicate that the Q18 would deliver less pressure in the sub-20 Hz region at the same wattage? Well, that and the sensitivity. If I were to use a spreadsheet to determine the optimum configuration, which parameters would be entered? I assume, for starters, given a sealed box, I would enter volume, wattage, sensitivity, and Fs. What else?

For a ported box, I think I'd need to farm out that design, bc I understand that is a bit more advanced. Is that advisable?

[GV#27]

Better yet why not try a box modeling program like Win ISD.It will allow you desgn sealed and ported boxes.You can download a free version here.https://ssl.perfora.net/www.ficaraudio.com/sess/utn;jsessionid=1545f87a8c4b377/shopdata/0020_Q/product_overview.shopscript
Their are many examples of a large ported designs around you could duplicate one of them.for example check out this one. http://www.hometheatershack.com/forums/soundsplinter/3519-dual-rl-p15-d2-llt-sub-project.html

[soiset]

sweet, thanks

[soiset]

Guess what is being sold within 5 miles (that's as close as ebay will tell me):
http://cgi.ebay.com/Velodyne-SMS1-SMS-1-Subwoofer-Control-Unit_W0QQitemZ180096559714QQcategoryZ3275QQrdZ1QQc mdZViewItem

If anyone wants to bid on one, let me know, and we can collectively bid on more than one, maybe saving some dough. I have sent a question regarding shipping, and maybe they will let me pick up.

[soiset]

Better yet why not try a box modeling program like Win ISD.It will allow you desgn sealed and ported boxes.You can download a free version here.https://ssl.perfora.net/www.ficaraudio.com/sess/utn;jsessionid=1545f87a8c4b377/shopdata/0020_Q/product_overview.shopscript
Their are many examples of a large ported designs around you could duplicate one of them.for example check out this one. http://www.hometheatershack.com/forums/soundsplinter/3519-dual-rl-p15-d2-llt-sub-project.html

That forum is great. There are folks there doing almost exactly what I want to do, and getting the results I'm after. I really appreciate the tip.

[GV#27]

Your welcome.
Yes there are some interesting designs over there for sure.I really like that monster that I provided the link for.It was very well done.

[Vr3MxStyler2k3]

I dont have any real advice. Ive never even thought about making a subwoofer that hits to 10hz. Haha.

What I will say is this...

Making a subwoofer isnt rocket science.

You need a massive enclosure, a low tuning point, multiple drivers capable of handling alot of power, low frequencies.

Things to remember though, the drivers ability to move does not nessicarilly mean low frequency response. You could take 16, 18" Pro Audio drivers with the -3db of 30hz and tune them to 10hz in an enclosure and you will get effortless 10hz. Just based on the fact its in a MASSIVE enclosure, you have 16 drivers - so you are moving TONS of air and you will have a massive amp.

The hardest job a sub does is below 30hz. If you crossover it over at 30hz and let it dedicate its job to that point.... your bounds are endless to what you can do. You are not looking for fidelity at this point. You can use whatever you want because it does not matter.

Its all about moving air, as long as its done one way or another - it dosnt really matter.

Im hardly the guru on this though. Just what I have gathered from reading and such.

Really though, if you could put these subs in the ceiling and work from there - itd be better :)

[soiset]

Well, I was thinking more like two 18's, not sixteen! When you say "tuned," do you refer only to ported enclosures, where the port diameter and length are coordinated with the box volume and speaker parameters? That is, are only ported enclosures "tuned?"

Also, what does it mean to the performance of a system over a range of frequencies to say that it is "tuned" to a specific freq? Does that mean it will peak at that point, or that it will fall off below that point? Or does it mean something else?

Thanks for your help.

[Vr3MxStyler2k3]

In a ported enclosure - you tune it to a specific point.

Below that point the ported enclosure loses ALOT of output.

Port = Fall drastically
Sealed = Fall gradually

But, you will most likely need a port - and a massive one at that.

[TennesseeOutlaw]

Even though the box we be quite a bit larger, why not consider a 4th order ( or possibly 5th or 6th order) bandpass enclosure that can be tuned to a specific point, and puts out substantially higher output than your conviental sealed or ported enclosers. If you have a cetain frequency range that youre trying to achieve with this sub with the highest SPL possible, go with bandpass.. You will just have to be very careful to not blow the speaker.. Distortion is a bit harder to hear in a bandpass enclosure, as you only hear/feel the air coming out of the ports/vents and not the movement of the speaker itself.

Josh

[Vr3MxStyler2k3]

Yeah but who wants a one note 10hz woofer...

Your goal would be 10-30hz Id think.

[soiset]

I think I'm sold on the LLT idea. Two 18's, giant box, giant port, big amp, bone-crunching fun.

[madmax]

Most bass is 50 to 90 hz anyway. What is below 50 (which is almost nothing) is pretty much lost through the recording process anyway. Speaking of the recording process the AudioControl Epicenter (car version) or the home version utilizes a cool idea to synthesize what should be there. The way it works is through some sonic traits of the notes lost. Lets say there was a real low bass note present but it was very low and pretty much lost in the recording process. Even though it is not there the multiples of it (higher frequencies) are still there. Sometimes listening to the multiples allows your brain to know it was there even though the actual frequency was lost, like listening to a song on AM radio. Anyway the Epicenter looks for the multiples, synthesizes what it thinks should have been there and adds it to the output. Might be something worth looking into for your sub-subwoofer. If you get to the point of wanting to try one let me know.
madmax

[GV#27]

Madmax is correct you would not need deep bass response for music (other than pipe organ)but there are some movie soundtracks like War of the Worlds that contain <20hz material.If your subwoofers are capable of cleanly reproducing it it will add some serious impact to the those scenes.

[soiset]

There can be quite a bit of extremely low freq info on dvd, and I can only imagine that with hd-dvd, and the improvements in movie sound, their will be more such effects in the future.

[soiset]

Madmax is right you would not need deep bass response for music (other than pipe organ)but some movie soundtracks like War of the Worlds that contain <20hz material that if your woofers can cleanly reproduce will add some serious impact to the those scenes.

Yeah, for music, only pipe organ and maybe cannon fire require the capacity for low freqs; for that I have my two-channel rig, which is supplemented with a Velodyne ULD-15. This mega-sub is just for HT.

[dave shepard]

That forum is great. There are folks there doing almost exactly what I want to do, and getting the results I'm after. I really appreciate the tip.


When visiting the Home Theater Shack call on Ed Mullen "Dr. Spec" he can answer all and any questions you have with facts that will leave most scratching their heads, also tell him I said hi..

Dave

[Deadof_knight]

Ok soiset what is the point of going that low ? your pushing air really below roughly 18 hertz. Im just asking not trying to rib you or anything, The human ear doesnt hear that low correct ?

[goingganzo]

i would go with the sound sploter my curent setup of 4 avalanch 18 will hit 120db@10 hz with 1000 wats aplyed

[jdhdiggs]

Watch out on your amp. Most drop their output like a rock below about 18Hz so getting to 10, you'll need to check the amps profiles. Also, I think you are looking at the Fs for reading how low a driver will go. That's not true, that's just the resonance frequency of the driver. It can play above and below that frequency, however it does get sloppy at and below this rating. You can kill it's efficiency and lower the number by adding mass to the driver.

The things I would look for most in your configuration is Qts and Displacement. Nothing else really matters in what you are looking to do.

Also, download WinISD and play around with it.

Gonzo: With your alignment @ 1000W aren't you bottoming out the drivers? I'd think you'd bottom those beasts at around 300W in the IB setup you have.