Fun, although I would suggest bumping that limit to at least 120dB. I recall Tom Danley reminding me that the extrapolated audibility of 3Hz is somewhere around 130dB. For reference, playing Titan A.E. with a 110dB limit might easily overdrive it. Having played in a few rooms where coupling and/or EQ have allowed extension to 8-10Hz, my gut-feeling/experience is that about 100dB is the minimum capability worth playing with, and about 110dB is where you get really useful. 120dB plus allows us to be much more creative and is already possible with large quantities of conventional subwoofers. Having visited tzucc's theater once, I would be surprised if there were any structural concerns with this sort of level. Personally, I would love to have the headroom of near 130dB with a generally rising response of say 3dB/octave below 20-30Hz. Of course I've also been told I'm nuts for such talk. :cool:
I believe the ability to compare this capability with a device that won't otherwise affect the >30Hz performance is of great value. I still suspect a targeted and optimized 2-way subwoofer implementation to be the preferred method for delivering this sort of performance in a moderate to large room, although the most benefit would be had from properly optimized designs for both the upper and lower subwoofer sections (i.e. not common subwoofer offerings).
My preferred units at the moment are the SymNet (10Hz low limit) and Lake (12Hz low limit I think) processors, both having somewhat noisy fans. My pick for a non-fan, 2ch option is the inexpensive DSP-30 or DSP-4 from QSC (20Hz low limit). The low limits I note are the lowest frequency setting that is possible for the Fc of a filter. So long as you can measure and confirm the final transfer curve, there are a few easy means to get effective crossovers at lower frequencies. The catch is you have to watch for clipping along the signal path.
Hopefully I can justify($) and fit the trip in. It looks very likely right now, but nothing is confirmed yet. It should be interesting to say the least.
Originally Posted by brucet
The SPL goal for the demo is 110dB 0Hz to 20Hz in tzuccs room. This is a self imposed limit and is defined by the torque of the motor. The pressure limit for the woofer is somewhere above 130dB in a room, which depends on a number of factors which I will be glad to explain.
|The woofers we designed for this event are good from 0Hz to about 15-20Hz. The intent was to use the watchdogs to their low frequency limit and then be able to switch the rotary woofer on and off and demonstrate if there is any value in having content reproduced well below 20Hz.|
|If someone knows of a good crossover solution please let us know.|
|I will try and provide more information about the woofer and answer questions in the next couple weeks. Mark, thanks very much for commenting on this thread. It will be a pleasure to meet everyone.|