What kind of subwoofers do IMAX theaters have

The same kind used in any good movie theater. Just .... a lot more of them in a smaller space.

Many JBL 2245h 18" subs (two per each enclosure)....rated down to 30 hz.

vardo

An IMAX in Chicago has four Danley TH-50 Subwoofers.

“The TH-50 actually challenged the sample rate of the FFT analyzer being used in the final testing in that due to the combination of cabinets and room gain we are flat to 10Hz!"

Although completely without a storyline or plot, Avengers was a real rollercoaster ride of a movie, very exciting.

-10db @ 20hz to 500hz
plus or minus 3db @ 25hz to 250hz

not exactly sure on the low end

vardo

I just returned from seeing The Avengers at a nearby Imax theater. This was not one of the full-blown Imax theater like the ones usually asociated with science museums. It was one of the mall type Imax's. The sound was excellent. It was very clean and very powerful, but didn't seem to have all that much depth. I doubt there was much going on below 20-30hz. The mid-bass impact was some of the best I've experienced at a movie theater, however. The movie was a real blast and it sets the bar high for this summer's wave of superhero movies. I look forward to eventually seeing it again at home.

Unfortunately that's the Omnimax at the Museum of Science & Industry which shows features like Rocky Mountain Express and Tornado Alley, not the system at Navy Pier which shows normal features and has a reasonably impressive, but older sound system.

I don't know if you are into sci-fi like I am, but I suspect Prometheous will be a better movie than Avengers. The harding hitting bass and soundtrack I heard in the trailer along with what think seems to be a compelling storyline should make for a good summer movie.

I'm looking forward to that as well. It's an Alien prequel plus as an added bonus it stars Charlize Theron who I'm very fond of.

I 100% agree with you! For once!!

I snuck a peek behind the curtain one time and seen a bunch of eminence lab 12s or 15s, can't remember which.

I'm really looking forward to Prometheus also. I'm a huge sci-fi fan. This looks really interesting. I hope I'm not expecting too much....

Probably 2242s these days with eq down low with kilowatts of power.

I love Imax, but if it's in 3d / Imax i'll put the movie on a back burner and wait for non-3d version to come into my own Imax theater (I hate 3d!!).

You do but it will be masked by higher FR's. Many theaters features HP filters on the LFE going out, to protect the drivers that are not designed to reproduce bass below 30 or 25hz. THX mandated for years a roll off below 35hz, that might have changed, but if a theater use those typical JBL subs, it won't make a difference.

I have had one of those in my room at home before for a subwoofer meet. Incredible sound from Tue th50. Still amazed that a room that size can be driven effectively with only 4 15" drivers.

Bandwidth limited, I guess I can see it.

If they were relieved of any deep content, evidently they'd be ok. If I was spending the theater's money, I wouldn't have stopped at just four.

Looking at specs, each box is sensitivity rated @97dB(104dB@63), with 1kw continuous, 2kw program handling. That places each box around 130dB, four like powered cabs adds 12dB at all collocated frequencies,...give or take as acoustic summing indoor is tricky business. Approx. ~142dB,.... minus proximity losses, plus whatever boundary and whatever PVG gains may come into to play(wouldn't be that significant given the hi-pass and large room dimensions).

It'd be great to have someone from Danley comment, as I'm just pulling those numbers out of my

just came from seeing The Dark Knight Rises at an IMAX theater. My chest still hurts from the bass. Impressed to say the least. Definitely worth the thousands they charge at the box office to watch a movie.