Originally Posted by FOH
I'm not sure if you saw our discussion about all this. Bosso had a theory, and I explained it was tied to all the sources being up front.
This is what Bosso saw, and I explained as greater first length mode (1, 0, 0) excitation. You're driving the length mode maximally.
Modes exist, determined by the boundary distances. How much one couples to them, or how one avoids coupling with them, determines their significane. Similarly, you can experiment with this selective mode cancelation, across the width mode of your room, not strongly affecting the 12-26hz gains you like wrt length.
Here's Bosso inquiring about them;
Myself explaining what he's seeing;"It does exactly what one expects. Of the varying attributes to utilization of multiple subs, selective mode cancellation.
The physical characteristics establish a room's modal behavior wrt frequency. This doesn't change, regardless where one places the LF sources. However, the placement does affect the magnitude of the modal excitement."
"I see nothing inexplicable about Carp's measurements. Moving the LF source, changes the manner in which it couples too, and drives a particular mode. Just as one can minimize that excitation, one can similarly maximize it."
Again, not sure if you saw this.
That post is here
. It's not a long post.
Most importantly, I'm glad you're enjoying the results. Soon, I'm going to have precious few opportunities to post, so best of luck until I can.
OK, wow. You quote me asking a question and your answer is "It's doing what one expects...".
Yeah, just not THIS one.
Sorry for being dense, but that's not an answer.
I put Carp's data onto a REW graph because I'm old, a bit slow and resistant to change, so the OM graphs are sending me into a panic attack.
But, let's revisit my question, now that we have enough data:
I believe you (and Danley and Seaton and LTD, etc) said something like; "Small enough room, no more wave" and "... below which the room can no longer support a mode...". That would imply no more modes, eh? So, let's try to leave modes and boundaries out of this and focus on the reason for 10dB differences in this "no more wave" area by simply changing the # of subs and their placement.
Both the SubMersive and the single SI show zero modes or room gain effect. Add 3 SI and alter placement and wham, room gain. Add 4 more Sis and double wham, lots of room gain. The explanation is awaited.
I had just finished graphs of an 8dB L/T. Looks like yo beat me to it. In my version, I slid the Fo up higher than yours, but that the beauty of L/T on-the-fly, a la the Bassis I used for years, or the multi-L/T I use now, you can tailor the L/T to your actual situation.
When (if) you get over the output capability, how do you usually calibrate the sub vs mains? Looking forward to hearing SQ comments vs the SM more so than hi SPL ones, when you get around to it.