Gut wrenching power?

[johninCR]

Riddlah,

It sounds like this is to show off creative sound designs, and I believe you need to be creative in the equipment set up and what you do electronically with the recording as well what is on the recording itself.

Without a doubt bass horns are going to give you the most efficiency. What you need to know first is exactly what frequency range you need to cover. That will determine what design is best.

You mentioned that the room is "dead". Unless the room was specifically constructed to absorb low frequencies it won't be very dead as far as bass is concerned and the room itself has a huge effect on what goes in the bass region.

I realize that you mentioned not wanted dozens of cabs, however, I believe you really need an array configuration. This is because you don't want the people in the front getting good impact and those in the back getting little, and you don't what to cause ear damage to those in the front just for those in the back to receive good impact. The reason arrays are better (and why they are used in all large venues) is that the spl of line arrays decreases by 3db per doubling of distance vs 6db for normal speakers. This is a tremendous advantage SPL-wise and leads to a much more even distribution of sound throughout the room and effectively eliminates reflection problems in one of the 3 room dimensions.

In the bass region it doesn't take stacks of many speakers to accomplish array behavior but the arrays do have to be long. For frequencies under 100hz the cabs can be 2 to 3 meters appart. If you are running a mono signal you could line them up in front from side wall to side wall. If it's stereo then you need 2 floor to ceiling arrays.

Also keep in mind that each doubling of the number of cabs gives you 6db more max output. 3db for doubling the drivers and 3db for doubling the power handling. Also, stacking the mouths of horns together increases their overall low end extension.

If you want to go all out and can process the sound in the time domain you can build equal sets for the front and back of the room. You can use this to for cool location effects or just to eliminate front/rear wall reflections by firing off an out of phase signal from the rears on a delay, so they fire when the front wave reaches them (cancelling them out at the rear wall).

It's a creative sound course, so be creative. Don't just try to blast people out of their seats with noise and risk damaging their ears at the same time. I hate when theatres try to provide impact by turning the sound up far too loud instead of having a proper setup to cover the impact in the bass region.

[riddlah]

thanks alot for that write-up john, that was quite informative

i think i may have asked this before on another topic (cant remember)
but are there any issues with phasing of the bass if i have one stack af cabs on both sides of the room?
we have partly decided to go with using the tuba 36s and although Wayne parham 12pi bass horns looks very promising too it seems a little to complex to build.
now it just a matter of finding a serious driver to go with it.
As far as the tops and the crossovers etc that we are using, ill add that later.

[johninCR]

Originally posted by riddlah
.... are there any issues with phasing of the bass if i have one stack af cabs on both sides of the room?

If you are talking about left and right, possibly, that's where the creative part should come into play though. Are you going to use a stereo or mono LF signal. With mono, I'd probably array the cabs horizontally against the front wall.

If you are talking about front and back, definitely.

Also, with high impact bass you are going to need to test in room ahead of time to address room rattles. They could distract significantly from you presentation.

[m9k]

Originally posted by riddlah
but are there any issues with phasing of the bass if i have one stack af cabs on both sides of the room?

Here's an article about subwoofer cancellation for open-air applications - it also applies to indoor use.

http://www.prosoundweb.com/live/articles/jbrusi/pa.php

\Michael