Originally Posted by Blackdevil77
Just out of curiosity, what levels are you able to obtain in that size room with the M2's and amps you went with? Are you able to hit theatrical reference? Also, any particular reason you didn't go with the I-techs? Do you think the I-techs would of given you additional output/headroom? I know your amps put out 300 watts into 8 ohms, the I-tech 5000 HD's is over 4 times more at 8 ohms.
Sorry if this has been asked, but I wasn't able to find it.
Below, find Keith Yates' response... To preface his remarks, I'd like to add that I've never been that interested in the numbers my system could generate. It's hard to explain how the effect of a great soundtrack performs in my theater - It is extremely powerful, very rich, full and _balanced_ with virtually no listener fatigue and no harshness. It's so powerful that the sense of complete immersion is nothing like I've ever experienced. Even though it can get very very loud, you never feel assaulted after a film. On the contrary, you want to watch another movie! The construction of the room and the way it's tuned contribute mightily to this. There's simply no ringing in the theater at all, so the distortion is extremely low. And because the room is so quiet, the dynamic range is highly extended - the effect is delicate when called for, but also powerful, concentrated & extremely intense.
The UberSubs are essential & are key. They supply an enormous foundation such that you don't have to crank up the volume to access subsonic frequencies that would normally be lacking in most theater environments.
There are many criteria you can use when vetting speakers in a private theater/screening room. In Rob’s case, it came down to 3 main things:
The physical relationship between the screen channels and audience head locations (call it “playback geometry”);
How pristine we could make the perceived sound quality in the upper-midrange and lower treble, where Rob is especially sensitive; and
How much undistorted output we needed at the money seats (middle of rows 2 and 3).
The first factor is straightforward: You sort through test data to find speakers whose horizontal and vertical radiation patterns fit the 3D geometry in your room model and “light up” all seats in all rows equally. (You can’t equalize or otherwise fix a funky rad-pat.) The M2s fit the bill here beautifully (though not uniquely so).
The M2s were uniquely suited to Rob’s project because they don't have the shout, honk or blare that almost all pro type speakers have at least a little of, nor do they have the sand-like texture problems that blight most high-end consumer speakers when you try to get them to fill up an appropriately treated room of this size.
That leaves the last and probably most interesting factor in Rob’s case: max level. Here things got interesting. Normally when you’re watching a 19 foot wide picture, in a room of that size, there’s an urge to crank it way the heck up. My theory – and that’s all it is – is that when humans see an event – let’s say a heavy object crashing to the ground, a collision, a streetcar rumbling through an intersection a block away – the brain naturally expects a corresponding aural cue – a thud, rumble or whatever – including the infrasonic energy that accompanies those sounds in real life. Viewers with big sound systems naturally want to turn it up to the point where they can assuage the nagging sense that something (read the infrasonic range) is missing. What they’re doing is overdriving the system until they can feel a little something. If there’s no feeling, it’s gotta be fake. In Rob’s case we solved that problem directly (14 UberSubs and 8 JL subs), without needing to test the dB limits of the speakers.
We talked about iTech amps vs Levinsons early on, including the fact that 4 times as much power means exactly 6dB louder. (You need 10 times as much power to produce a 9-10 dB increase in SPL, which is perceived as a doubling of level.) For the M2s he chose to go with amplifiers whose design goals prioritized the things he’s most sensitive to. And he had all the brute force playback of the sub-20Hz range a guy could ask for(!), so it was an easy decision.
It was important to me that I deliver on what Rob said was his number one goal, right from our first meeting: “Keith, I want to be able to play 3 or 4 movies back to back, have dinner, and feel like I can’t wait to go back to the Theater and play 2 more before calling it a day. I want the sound to be very powerful but not in a way that will make my ears bleed.” I think Rob would agree that the combination of M2s, Levinsons and UberSubs helped make it happen, no need to turn it up even louder to make up for a missing low end, because we've got that covered in spades.
What anyone who's experienced Rob's room can say is, "The room and system produce a more ohmigawd, grippingly real, you-are-there, PHYSICALLY involving effect than any movie theater, IMAX included, they've ever been in, no matter how loud it was being played."