Compromise driver orientation?

[revboden]

I just modeled two of the sd315a-88s in a ppsl 2.877cf sealed box with a linkwitz transform (f0=56.962, Q0=.703, fp=20, Qp .707). =

[peace brainerd]

Don't want to get too off track here, but what is the state of the Linkwitz Transform today? Last I was looking into this stuff was about two years ago. Is the circuit available as an inexpensive plug/play compliment to an existing plate amp? Or at least simple to incorporate on the board? Two twelves for the price of my single eh? You want to poison any hope for settlement on this matter don't you?

pure music types... 'cough' BS 'cough',
some of us are mastering engineers for movie production. FOH squeeks, roadies, system designers, and Cal. what more could a person want?

I seem to have an unpopular take on the home theater experience. If I'm there in Florida witnessing a live launch of the space shuttle or viewing a blockbuster adventure film near front center of an IMAX theater, then visceral thunder is pretty much a natural accompaniment; an expectation that needs to be satisfied.

I've viewed films in a few home theaters on 90+ inch screens with pretty spectacular subwoofers and surround channels in operation and while satisfying in some sort of faster, more powerful, 0-60 thrill seeking regard, the whole experience just seemed fundamentally out of balance to me, like a housecat with a lion's roar (and I suck at simile). Maybe more like a moped with a harley engine. Ok, no better.... but you get my point.

I've got a 50in plasma television and I watch movies via the internal speakers and a diy 10in powered 1.5ft sealed subwoofer in a slim flat box tucked under the television stand out of sight. Even that sub is set as I described above in this thread; It just extends the internal speakers. 99 percent of home theater lovers would reject this with a shudder of contempt. But I think it's precisely right for the size of my screen and dimensions of my 12 x 20 x 8 living room. And I'm definitely a movie "lover" who logs a lot of hours watching. If I'm still around when wall sized 8'x12' LCD becomes an affordable installation for middle income types like myself, then I'll be talking subs to match the experience. As long as I'm viewing "reality" through a 50 inch rectangle the audio shouldn't jar too overwhelmingly with that "reality".

But again, I realize my tastes aren't anything like the norm.

[peace brainerd]

Honest to god I didn't go looking for this. Just after I posted the above I dropped by avsforum following a google search for applications using that Dayton 12in DVC and saw this in the same thread there.

This is a 4th order isobaric sub with 2 18" Peavey Black Widow drivers. 3/4" Particleboard veneered with Poplar veneer and a 1/2" Poplar surface with glass inlay. Port (not shown) is on the wall side.

Somehow... I just don't see why the toddler that belongs to that toy bucket needs to be evacuating his bowels in terror while watching Franklin the Turtle on a 24 inch set.

Joking aside, even though this television is well shy of the, I don't know... 90inch average ? of the more serious HT setups, it does illustrate the point. Watching Transformers, or Black Hawk Down, on the above might just test the limits of anyone's willing suspension of disbelief.

[abn1701]

Bottom view of Muse 18 subwoofer.
They used the 831727 peerless driver , not suited for downfiring, so the designer opted for an angled baffle. I also would like to build something like the Muse
but I only have one driver (831727).

[revboden]

actually, I'm all for subtle. my personal HT uses a single 12, the old 315-88 in a 4.25ft^3 box port tuned to ~18Hz it rolls off nicely ~4db per octave and is very musical and accurate at low levels. The bonus is I can watch movies at night without upsetting the neighbors and still get a visceral experience because of the clarity at low frequencies/spl.

But, It can keep up with my 7.1 system flat to 110db, 60hz to 90Hz... which is frightening. I've seen friends jump over the couch during LOTR 1 when the bad guys army starts marching.. from a sitting position (which is funny). Having something that can do both is nice to have.

[revboden]

I should add that the box has dual ports, one port open tunes the box to ~14Hz, both open tunes the box to ~18Hz.

For background music i choke it down to 14Hz, for movies or music with more oomph open both ports. For classical I plug both ports and have a sealed cab with a Qtc of .512

[Cal Weldon]

Originally Posted by peace brainerd

Cal, do you think it's worth my while to return this driver in exchange for the
Peerless XLS 12 inch?

Hi pb,

I don't know the driver so I can't comment. Anyone else know?

[peace brainerd]

actually, I'm all for subtle. my personal HT uses a single 12, the old 315-88 in a 4.25ft^3 box port tuned to ~18Hz it rolls off nicely ~4db per octave and is very musical and accurate at low levels. The bonus is I can watch movies at night without upsetting the neighbors and still get a visceral experience because of the clarity at low frequencies/spl.

But, It can keep up with my 7.1 system flat to 110db, 60hz to 90Hz... which is frightening. I've seen friends jump over the couch during LOTR 1 when the bad guys army starts marching.. from a sitting position (which is funny). Having something that can do both is nice to have.

If I'm reading the correct spec for the 315-88 it's 7mm xmax. Then you don't think the 9mm of the Vifa 12 will be pose any real limitation for the needs I've described? If I could get some consensus on this I'll stick with this driver.

[peace brainerd]

Depending on where in the world it was made and when, that might be Ash rather than Oak. Cheers if it is, great find.

I used a dead blow hammer and hardwood block to separate the cabinet today. All tongue in groove and dowel pinned. Fortunately all the glue was brittle enough to separate without taking any wood with it. There was a piano lesson book wedged in a bottom corner with the owner's name inside and dated June 1915. It's at least that old.

It is solid oak. Appears to have been a file for 12in 78s? There is a bar running along the back of the shelves that limits their depth to approx that of a record album. May be a bit of sacrilege to cut 4inches off of the height, but it doesn't have any markings describing its provenance or manufacture and I doubt that it's terribly valuable.

Maybe in another 100 years some dude will have it on the antiques roadshow and be told that it might have been worth big money if an obvious idiot around the turn of the century hadn't turned it into a loudspeaker. Oh well, I could get sentimental and change my mind.

[ßart West-VL.]

Originally Posted by revboden

I should add that the box has dual ports, one port open tunes the box to ~14Hz, both open tunes the box to ~18Hz.

For background music i choke it down to 14Hz, for movies or music with more oomph open both ports. For classical I plug both ports and have a sealed cab with a Qtc of .512

Sounds interesting! Is the design on the forum?