Bill Fitzmaurice

On that subject fluid dynamics are often used to visually display sound wave behavior.

He fails to mention wall loading subs, which gives higher output. Not all venues can take advantage of that, but most can, and as sub output is omni-directional they can be placed to either side of the stage.

There are many branches of Physics, and some can be detrimental where understanding acoustics is concerned. The main obstacle for most, irrespective of their level of education, is realizing that sound waves and light or radio frequency waves are totally different in how they function. Light waves in particular are easy to comprehend, because you can see them. There is almost nothing intuitive about how sound waves work, and even at the post-graduate level there are few courses of study available. One very good source is here: https://blog.soton.ac.uk/soundwaves/

Ampeg V4 B.

You must consider them along with the rest, as the final result is the sum of all the parts. Another consideration is boundary cancellations, which occur when the distance from the speaker to a boundary is 1/4 wavelength, and/or when the difference in the distance from the speaker to a boundary to the listener totals 1/2 wavelength. These cancellations typically are manifested relatively close to the speaker, which is to say on the stage. They diminish as you get further away. It's why your on stage sound can seem bass weak while it's too much in the audience. It's the source of the myth of wave propagation, the notion that one must be a certain distance from the source for a low frequency wave for the dB level to reach its full potential. Accounting for it and the rest is why you need to do a sound check standing where it matters most, in the audience, or as close to it as possible, when setting your EQ. As often as not perfect tone on stage can be boomy out front.

You should aim them as the room demands, which is to cover the most listeners possible. That's listeners, not people. We've all played those rooms where far too many are more interested in their conversations than the music. When I played those rooms I aimed the PA where it would be most appreciated, at the dance floor.

Want to become an audiophile? First cut a small hole in one of your pants pockets, about a half inch across. Walk to the nearest toy store, buy a packet of marbles. Empty the packet into the pocket with the hole cut in it. Walk home. As you’re walking one by one the marbles will fall through the hole in your pocket. When you’ve lost all your marbles congratulations! You’re now an audiophile!

Bingo! I once had a guitar'd player who insisted on having his JBL loaded Fender Twin on the floor two feet in back of him. It sounded fine to him, but made the zone in the audience directly in front of him uninhabitable. I asked him why he didn't use the tilt back legs. He said it made the highs too loud. I then noted that placed flat it made the highs too loud in the audience. All that elicited was a blank stare. 🫢

Most cheap dB meters only have 'A' weighting. They don't measure bass. You need 'C' or 'Z' weighting. True, if it's lifted by a meter or more. Less than that and there's no loss of bottom end. If you don't tilt or lift it the highly directional mids critical for the perception of loudness are passing by your knees, which can't hear them, rather than by your ears, which can.

Mixed subs might not make a lot of difference to the sound, as it will end up being a blend of the sources. But due to the often wide differences in response between different subs it's a lot more difficult to get the best result when they're not matched. Looking at the SPL chart for the SWA1501, which is about as flat as the Matterhorn, I can see it being a challenge to get it to play nice with another sub. https://www.fullcompass.com/common/files/2965-SWA1501SpecSheet.pdf

Since the room affects everything in the PA you want to adjust the GEQ.

You wouldn't hear much, if any, difference if the tops aren't reproducing sufficient lows. However, they're still receiving the low frequency information, so the amps are producing low frequency power and the drivers are taking that power, which stresses both the amps and the drivers, while the THD of the tops will be higher than if high passed. You've got nothing to lose with high passing, and potentially much to gain with respect to amp and driver headroom and lower THD, so it should be done.

Knowledge is like good food and drink. It's best when shared. ☺️

One would be sufficient. ☺️

Steel is highly unlikely, tinned copper is common.