[woodsyi]

Here a model of a subwoofer that is claimed as impossible to bottom out!
http://www.royaldevice.com/custom.htm#The%20compression%20chamber%20of%20the%20SUBHORN:%20Subwoofer%20connection
It would be something to listen to Telearc 1812 overture with that thing under my room!

[denverdoc]

Good god, now thats some HT. My only thought is he should have bought say 4 of the Parthenons from Adire instead.  Might have been able to get 175 dB as Adire claims equivalent Vd of up to 16x 18 inch drivers!
 

[Gordy]

Scott,   It's no wonder you felt ill!  Have you ever read anything of Vladimir Gavreau's research on weaponry?

http://www.borderlands.com/archives/arch/gavreaus.htm

I couldn't find the bass horn I was looking for, a fellow in Denmark built it for an outdoor festival I believe.  The photo I remember showed four guys sitting in the throat with room to spare!!!  These will have to do...

http://vincent.brient.free.fr/bass_horn.htm

http://www.diyaudio.com/forums/attachment.php?s=&postid=558303&stamp=1106477702

[Scott F.]

Scott,   It's no wonder you felt ill!  Have you ever read anything of Vladimir Gavreau's research on weaponry?

http://www.borderlands.com/archives/arch/gavreaus.htm

WOW!

I knew (a little bit) about infrasonic weapons but not to this extent. Excellent link!

The main resonant frequency of these pipes occurred in the "range of death", found to lie between three and seven cycles per second. These sounds could not be humanly heard, a distinct advantage for a defense system. The effects were felt however. The symptoms come on rapidly and unexpectedly, though the pipes were operating for a few seconds. Their pressure waves impacted against the entire body in a terrible and inescapable grip. The grip was a pressure which came in on one from all sides simultaneously, an envelope of death.

That about describes it.

Tolerances from 40 to 100 cycles per second have been recorded by military examiners. The results are sobering ones. As infrasonic pitches decrease, the deadly symptoms increase. Altered cardiac rhythms, with pulse rates rising to 40 percent of their rest values, are the precursors to other pre-lethal states. Mild nausea, giddiness, skin flushing, and body tingling occur at 100 cycles per second. Vertigo, anxiety, extreme fatigue, throat pressure, and respiratory dysfunction follow. Coughing, severe sternal pressure, choking, excessive salivation, extreme swallowing pains, inability to breathe, headache, and abdominal pain occur between 60 and 73 cycles per second. Post exposure fatigue is marked. Certain subjects continued to cough for half an hour, while many continued the skin-flush manifestation for up to four hours.

Been there, done that (some of it anyway but nowhere near those extremes though). It was completely disorienting though. I sure don't plan on revisiting that place anytime soon.

[walkern]

Dave Shahinian used to market a fairly compact horn based sub called (if memory serves) the Contra-bombard (or something like that).  He claimed that is was capable of very high output down to about 16hz (this was WAY before the home theater or car audio craze for deep bass at "hurt me" volumes) and allegedly sold them to churches to augment their organs.  I don't know where you'd find more info.

[rosconey]

looks like i'll be doing a ib for a friend sometime this year.i just set him up with my old yamy rxv1 and a few cheap speakers,he has a junk sub now so he can save for 2 ib drivers from pe.i tried to talk him into a small sub from av123 but he doesnt want anything in the room.
i'll power it with a caver pm350 i have-900watts mono

[Gordy]

You'll have to let us know how the installation works out rosconey!

Another source for several folded horn subs and or plans is the Decware site. There are several people over there that built quite a few, including a guy who goes by the name on Toxicbass, might be worthwhile doing a serach on his threads...

[gonefishin]

The most impressive description of a house breaker sub, that I've heard of, would be by Tom Danley.  He describes the sub as being able to produce high DB response down to DC (0Hz).  He also states that 3Hz becomes audible at levels 122db and higher.  Although, I'll admit...this wouldn't be your conventional home audio product

   click here for the link to see his description at AA.

click here to read the patent on the Servo valve loudspeaker.  Actually, if you want to...you can do a patent search on Danley.  You'll come up with some cool reading material.

    For pure spl, he also made a siren for cleaning a baghouse that would produce a 300Hz signal at 150db.


     Oh, and I have my "little" 4'x4' 20 Hz horn sub that I bought from John Sheerin.  


  take care,
 dan

[Rob Babcock]

Wow, Scott F- neat subs, and a pretty cool looking room!  I did the lighting, but I don't think I could take the rocking chair!   If a properly tuned Shiva can play reasonably flat down to 12 hz, that would be plenty for me.  Not that I couldn't consider another driver, but the Shiva & Tempest are affordable and they're known quantities.

I actually do have a 2' X 2' opening in the floor for a cold air return for the furnace.  I'd bet a dollar the there's plenty of flow without that duct, so if I was braze I could probably disconnect it and stick a huge IB box there.  But I plan to move within 3-6 months anyway, so it's not worth dicking around with now.

BTW, where/how did you get the 1" thick plastic material you made the baffle out of?

Very cool to see what some of you guys have done.  It's certainly giving me some ideas for "the next step."

[Scott F.]

..... but I don't think I could take the rocking chair!

 

It's an old fart thing.

If a properly tuned Shiva can play reasonably flat down to 12 hz, that would be plenty for me.  Not that I couldn't consider another driver, but the Shiva & Tempest are affordable and they're known quantities.

Definately a known quantity. I haven't heard the Tempest or any of the other drivers. I can only imagine the 15" does a nice job plus it moves way more air.

When you do your cabinet (whatever form it may take), start with a simple aperiodic loading then work your way up in vent lengths, quantities and sizes. Measure along the way.

Don't trust the computor software (completely) because they give you kind of a 'Monet view' of what will actually happen once the subs are in room. Thats exactly what happend with mine. The computor said one thing (I think it was a 3" port 6" long or something) then I measured them and found they were pretty darned flat and left them aperiodic.

BTW, where/how did you get the 1" thick plastic material you made the baffle out of?

Believe it or not it's old toilet partitions. There are several companies out there that make plastic toilet partitions. Since I play an engineer by day, I specify these things in the buildings I renovate.

My partition supplier of choice is Global toilet partitions (they have a website somewhere). The supplier is also the installer and as it goes with all construction, sh*t happens. The guys measure wrong, install wrong, whatever, and they end up with a big pile of partitions that are unusable. I grabbed three or four slabs (for free) and drug them home knowing what I was going to use them for......speakers.

This stuff is heavy as all get out. At one inch thick, a 3x5 slab weighs somewhere near 100 pounds. The great part is the resonant frequency of the plastic is really low so you don't get much (if any) cabinet colorations.

If memory serves, new this stuff is about $16 a square foot. I'd bet if you found the Global rep in your area, he could turn you onto an installer or two. I'd bet a donut they've got a big pile of leftovers they'd let go for $10-$20 a slab. Oh, Global also does a high density laminate that is almost 1" thick too. That would be darned interesting to build something out of (if you could figure out how to cut it).

Something I found when I built these triangular shaped subs, that back wave breakup makes one heck of a difference. Unlike so many of the other subs I've built using the 'golden ratio', this one by far is the best (the least amount of weirdness).

[Rob Babcock]

Is that stuff easy to cut?  Do screws hold well in it?  That would be an interesting material to build with.

[Scott F.]

It cuts very easy. No worries about melting or anything. I used wood screws to attach the pieces. They hold fine but you have to set your torque a bit lower or it can strip out the threads.

[lonewolfny42]

Scott F. :

My partition supplier of choice is Global toilet partitions (they have a website somewhere)

[/list:u]

Global link...plastic laminate partitions....

http://www.globalpartitions.com/plastic_laminate.html[/list:u]