http://www.ultraaudio.com/twbas/twbas_20050915.htm

http://www.ultraaudio.com/twbas/twbas_20051215.htm

http://www.ultraaudio.com/twbas/twbas_20060215.htm

I do not know if they are relevant as they look like made a room to control problems with their relatively tedious (in my prediction) acoustic system.

http://www.ultraaudio.com/twbas/twbas_20090401.htm

You could bond (either completely or strategically) "hook-end" velcro to the horn and then have some custom sandbags made with "loop-end" velcro on one side.  http://www.uline.com/Product/ProductDetail.aspx?model=S-14556&ref=6426

If I were to have such horns (and in the future it is quite possible) I would be tempted to make them with two walls separated with sand or at least at the full weight.  For mobility/positioning I would mount them on robust castors for floor use.  I would be most tempted to fly them over the other channels, in which case I would love to use a jib crane.  https://www.gorbel.com/Products/Jibcranes/Ibeamjibcranes/wallcantileverjibcrane.aspx  They look quite reasonably priced...so much so that I would probably go for these even if floor positioning was the objective.

Did I ever mention that I am not married?  I guess it's obvious enough.
LBJ

decoud wrote:

I thought of filling with sand braided multifilament nylon cable sleeving (http://cableorganizer.com/nylon-multifilament/) which comes in 2 inch diameter and does not expand enough to allow coarse sand to come out. It can be wrapped around as densely or sparsely as required. The problem is that it offers little structural support, though the tension of the fabric may convert some of the weight into compression. So the underlying structure has to be very rigid, it seems to me.

Once again, there is nothing specific in this post just some further thinking on the subject, as I keep discovering new idea.

A couple weeks back I was looking at a house that gave in inspiration to think about it. The house was 3 bedrooms California Ranch with very nice for my purposes layout of the rooms. The Living Room was around 15x20, so called Family Room was about the same and the dining aria of kitchen was around the same. The have no caring walls between then, at least at my own first inspection, and were positioned in a way the turning de a few not solid walls it would be possible to convert it into a wade open plane and to have my 900 sq feet (preserving the bedrooms). I am not going to proceed with THAT house (because a multitude of reasons) but I just give a conceptual view – you will understand why. The house had marginally acceptable high of ceilings and as most of the Ranches it had a basement.   It was a full basement with a typical appliances room, and a large 35-40x25 empty-space room with low 8 feet-tall ceiling. The floor between Living Room and basement was horrible. I mean it was wonderful from a perspective of normal people but from the perspective of my objectives the floor was crap. I would rather much prefer do not have any basement at all and have a house sitting on a concrete slab (good luck to find it). This suspended, very not-solidly made, almost breathing flooring is the subject of my attention.

Let look at this farther. Installing the playback at the first floor of a ranch with a basement and cheap floor (all of them are cheap – I never seen then to be solid enough) I think I would never have proper bass. (BTW, in my current room I do have a concrete slab as my floor me and the bass I get is very nice in my view). The lower bass will be just passing through the floor like a hot knife through the butter.  However, then I begin to think about the content of bass in my playback.

It will be presumably 40Hz horns but it will not be the lowest bass. The folks who read my site know that I advocate the open-bottom lowest bass channels and in my case it will be 30-40Hz crossed truly LF channels, let call it ULF channel. So, for the ULF channel the light-suspended floor like I described would virtually not existed. If so, then I wonder if it is possible to put the ULF channel… in the basement, letting it from there to supplement sound in the room above. I never thought about this option before I wonder of anyone experimented with it.

Well, in context of a full-range speaker, like largest Wilsons or the similar, the answer would be unquestionably no.  Even if we biamp those speakers then the LF still is too wide bandwidth and too geographically bind to the MF section.  The worst case in this example is the people who use closed-bottom LF sections, all those “bass horns”. 

The room dissipates LF, the lower the more dissipation and they try to pump more power LF into the room. However, the closed-bottom LF topology by nature can’t handle more LF gain then it can. So, the people pump unto LF driver more and more excursion but it does not produce more effective LF but only it magnify the amplitude of horn-chocking  and creating the mid-bass boom. Pros deal with is by multiplying the amount of LF sections and it works to a degree but the hi-fi Morons do not get. The worst illustration of the said I saw at the Oswald Mills playback. The guy use old-style stupid RCA very shallow horn with very large throat and twin 515G drivers. Those type of horns with proper drivers as more or less acceptable as upperbass horns, or midbass horns in a VERY small room. The Oswald Mill try to get from them the full lower bass (as it is an open-bottom topology!)  and the room in there is not just huge but beyond huge. The Mill is old 3-floor building with large holes in the floor between the floor sections. So, a combined room at sub 50Hz I would estimate is over 7.000 sq feet and to handle this space with closed-bottom LF topology is beyond laughable.  The actually of sound in there is exactly as it predicted. I think he used twin 845 in PP and they flood the sound with horrible gray gag of the overloaded closed-bottom horn. Thankfully the guy in there is so fucking stupid and so senseless that he does not able to understand or able to acknowledge it, good for him. I have seen a few other attempts of to do the same with absolutely identical results…

However, I presume that if to find out what lower frequency a room still can handle – let say 50Hz. Then to beef up a bit the suspended floor with sand to have let say “6dB suck out reserve” over the 50Hz. Then introduce the proper 50Hz horns, I mean the proper hors with no cheating. Then introduce an open-bottom LF section with 40Hz low-pass, the section that would topologically would able to care high gain and high power… I think in this case it would be possible to offset the suspended floor problems.  BTW, what do you think I decided to keen the direct-coupled B2 amp?

Sure, the open-bottom LF section with powerful amp (how about 300W SET) doe open a possibly but the biggest question is if the benefit of longer reverberation time at LF might be used in this configuration. I do not have an answer. I never people talk about the subject sensibly as well. So, it is more blind shooting with suspended floors.  I guess a right solution need to be found with respect to a given space and a given floor. I am sure it would be fun to have a room sitting right atop of concrete slob but it is hard to find and am not willing to build a room in basement but I want it to be in living space. This week I saw one ranch that had no basement and the description said that it was sitting on solid slob.  Upon visit the house I leas the it had a horribly -bouncing suspended floor raised a feet above ground. Sure, for the normal people it means: “sitting on solid slob with no basement”. For me it means:  ”a house with horrible suspended floor with stupid ultra-low height useless basement”. I guess it is not fan to be my real-estate broker…

The more-driver/more-power method has in fact been used to very good effect in rooms that +/- eat bass.  The set-up I remember had about 8 515s per side and LOTS of power that I suppose it did not actually use very often; but it did provide nice, fairly seamless LF.

And I might also say that IMO it is really no more difficult to create more LF with more drivers and more power than it is to deal with tons of LF in a super-solid room that "conserves" it.  When was the last time anyone heard good LF in a solid concrete room?  Some "give" might afford a chance to sort of sneak up on the LF, add it on as desired.

"Shores" would be a great way to tune a raised floor, as long as one had access to a slab or the ground under the floor in question.  In fact, it might be the best of all worlds if one were able to go back and forth between tuning the room and developing the LF speakers.  I am not at all sure I would try a LF horn, under any circumstances; too much risk.  But regardless of the topology one chose, the "tune-able" room would be a Godsend, IMO.

Best reagrds,
Paul S

Of cause it shall be mentioned in the context of thin there that there is always the ALE Acoustic solution. The Japanese ALE Acoustic make two midbass drivers: P1260 and P160.

http://ns.tachyon.co.jp/~sichoya2/ale/drivers.html

In US they are around $30K per solution:

http://www.aleacousticsusa.com/products.php?type=7

They do have own Aluminium casting horns that might go with them.

http://ns.tachyon.co.jp/~sichoya2/ale/horns.html

I personally do not have any curiosity in ALE horn but the drivers might be interesting. Like all of those “exotic Japanese” driver the midbass ALE drivers are with titanium cone, FRP suspension  and have a LOT magnetic flux in the gap – 2.3T.  The amount of flux for bass drivers I feel a bit alarming as in my experiments I never felt that higher flux was welcomed by bass. The P1260 driver has 3” and P160 has a 5” throat diameter, which is beyond perfect in my view. The 5” throat is what I would like to have for my 40Hz horn, but I do not think I will have balls for make a proper horn from such a small throat, but who knows. At this point my theoretical limit is 15” drivers that I plan to use not the length of the horn.

I never heard P1260 or P160 drivers, not to mention I never heard then in contest of proper installation. I know that Kevin Brooks from Utah uses ALE bass drivers and ALE bass horns

http://www.kbrooksaudio.net/photo.html

I never was in Utah. I heard a few people who visited Kevin reported very good bass. I invest absolutely no credibility to those feedbacks, partially because I heard absolutely the same positive feedback from the very same people about bass on other installation, the one that I heard, and that I consider was horrible. Well, when did you see me to invest any trustworthiness to what other audio-people say? There is an army of Morons out there who would swear that 5” Loather mounted into a typical toilet enclosure produce the best bass they ever possible, does it mean that I care what they think? I would not even mention that 99.5% of audio people have absolutely fucked up idea what proper midbass is  by audio means and not even familiar with the concept – where would they learn?

Anyhow, the ALE P1260 and P160 drivers with consequential horn to them might be an interesting alternative to my idea of use my Vitavox 15-inchers. They of course would be the horn of different topology: each of then would have own con and pros. What solution is able to produce the best theatrical results? Very hard to say.

From the perspective of pumping of atmospheric pressure the ALE bass drivers might be more capable transducers. It or might not be so as well. To get 40Hz at 110dB in 5” it would take some excursion.  I am sorry but you can’t bend the law of physics. Pressure is excursion by surface. In horn we as the horns EQ. Let presume that a horn would add even 10dB then we still have a lot of excursion necessary. The ALE drivers have titanium with plastic suspension diaphragms. The plastic suspension diaphragms are horrible for excursion, they good only for bending. So, I presume that ALE made a very large FRP skirt to let the metal cone to have lower own resonance and some freedom to move. To do it all within 2.3T guy I am sure was tricky. I would pay money to see HOW the P160 is made. What I know about the compression drivers idea I would guess that  a compression driver with too much flux and light soft cone would not make since as it would requires  very precise, almost surgical compensation of back chamber. Since ALE does not have the adjustable damping for the driver then the result is not optimum. Still, I might pres that ALE knows something that I do not know, so I will give to them a benefit of doubt.

From the perspective of pumping of tonal pressure I think that ALE bass drivers might be less capable transducers. They might be not and they might be able for great tone – who knows. No one talks or thinks about it and it looks like no one even knows what it is. People are accustomed that “tone” is a characteristic of a resistor or a tube, with compression driver is more complicated. With bass compression drivers that use metal diaphragms it is even MORE complicated. Who the hell knows where “tone” comes from in those drivers?

I think if I go for this project then it might make since to fry in Utah and learn what ALE bass drivers are able to do. I do have a point of reference of what my 15-incher is able off but it not necessary mean that if I render my project with 15-incher then I will hit the point of my reference. Still, the debate of to use 15-incher vs. the ALE-like solution is a legitimate debate. Unfortunately it is VERY difficult objectively and sensibly to reconcile positions in this topology comparing.

Paul S wrote:

The more-driver/more-power method has in fact been used to very good effect in rooms that +/- eat bass.  The set-up I remember had about 8 515s per side and LOTS of power that I suppose it did not actually use very often; but it did provide nice, fairly seamless LF. And I might also say that IMO it is really no more difficult to create more LF with more drivers and more power than it is to deal with tons of LF in a super-solid room that "conserves" it.  When was the last time anyone heard good LF in a solid concrete room?  Some "give" might afford a chance to sort of sneak up on the LF, add it on as desired. "Shores" would be a great way to tune a raised floor, as long as one had access to a slab or the ground under the floor in question.  In fact, it might be the best of all worlds if one were able to go back and forth between tuning the room and developing the LF speakers.  I am not at all sure I would try a LF horn, under any circumstances; too much risk.  But regardless of the topology one chose, the "tune-able" room would be a Godsend, IMO. Best reagrds, Paul S

The worst ever acoustical qualities ever encountered was in a unfinished cement basement and floor, and I am not exactly sure what the sound was doing in this room, but it was completely untameable in every way, for it to be a "sound of normal" and where a subfloor of 1 layer live Plywood covered by 1 layer heavier density waferboard, this 2 ply floor over 2x4 sleepers laid flat, and insulation/drywall, transformed this pityful cement soundhell into something completely different, my really excellent studio! A live floor is not a big deal, resonances are sometimes very "helpful", but "dead" thing are best left buried. This effect happens continuoiusly at the Community Arena here where concerts are held, reverbations create weird sonic behavior, and musicians and soundmen meet the "sound of doom and total wildness". So funny to hear the line arrays "hit the wall of reverb into their faces", and nobody knows who can win?  

As most things, too much of a good thing, is a problem. Opinion, not legally binding in any way.

j.