Two small speakers, huge hall, what could possible go wrong

I took family and friends to see a show at Bass Performance Hall this afternoon. I had seen a show produced by the same company before which was one of the best shows I’ve ever seen so expectations were high. Sadly the production became more of a learning experience for how not to do sound.

The production included only (2) speakers. One on each side of the set. The speakers were both on tripod stands which tipped the speakers backward a bit. I didn’t think much about this at first but as soon as the show started it became obvious that the spectral balance of the sound system was not balanced at all.

I purposely bought seats in the center and as close to the stage as I could get so that we could see and hear well. What came out of the (2) speakers was excessively low end heavy. So much so that the prerecorded female dialogue was muddy sounding. The male dialogue was even worse and mostly unintelligible. Consequently, there were whole scenes that just didn’t work.

For me, this makes a few things very clear that need to be considered whenever designing a sound system.

1. air loss is inevitable and it tilts everything toward the low end over distance
2. inverse square law dictates that level will decrease by half with each doubling of the distance
3.To make matters worse, low frequencies are supported by room boundaries so the inverse square law only applies to direct sound that doesn’t get reflected back into the room.

So the voices were muddy sounding which made it near impossible to follow the story which made the show difficult to enjoy. Proof of this was that people left at intermission. People got up and left during the show, kids started crying, cell phones came out, etc… A missed opportunity for a show that has all the potential to be stellar.

I actually texted house crew at intermission about the situation hoping it would be resolved before Act 2 began but knowing that without a reference point, there was no way to easily resolve the situation.

Before the show started I texted with house staff whether or not the production tuned the system. The answer was no. 🙁 The logical question is “Why Not?” How is it even considered anything but mandatory to tune your system once it’s located in a acoustic environment? That is the equivalent to tuning your guitar at home and not tuning it when you get to a new location.

Let’s optimize the existing setup and also redesign the system as an exercise in who things might be made better.

OPTION 1 – AS IS and optimize as much as possible.

The existing (2) tripod mounted speakers should be aimed to cover the most seats evenly. I can’t know for sure but my gut says the speakers were aimed upward too much for the seating configuration. So aim the speakers and then equalize the system to compensate for the distance and air loss. There would have to be a balance between excessive high frequencies at the front rows and not enough at the rear seats but that would be a worthy pursuit. If in doubt, error toward less low end than more knowing that the room, air and distance is going to make things bass heavy anyway.

OPTION 2 – redesign and optimize

Anyone that been to a modern venue or concert in the last 20 years has likely noticed that the main speakers are up in the air. This design approach evens out the playing field so that those in the front seats aren’t bombarded by excess level so the sound system can reach the rear of the venue. With speakers on the stage, you can only get them so high off the deck.

So I would fly the main speakers until they provided acceptable coverage for all but the first few rows of seating. I would add front fills for those seats so the on axis point of the main speakers could be aimed further back in the venue without worry about leaving the front rows uncovered. This is a typical approach to coverage. At some point in a large venue, it’s just time to add delay speakers to make up for air loss and distance. Doing so adds intelligibility back to the rear seating areas. With the flown mains, front fills and delay speakers, it would be possible to provide even coverage to all the seats.

Interestingly, what I describe is exactly what the venue has for a house sound system. If the traveling production had used the house system, I dare say the audience would of had a much different and better experience. The moral of the story is that a system that works well for a smaller venue might be completely inadequate for a larger venue. This is probably a true statement in general. “If it works for a smaller venue, it won’t work for a larger venue.” Physic isn’t affected by budgets or shortsightedness.

So a recap.

With absolute certainty:

Your sound system WILL lose high frequencies due to air loss over distance (loss of intelligibility)

Your sound system WILL lose general level over distance (loss of intelligibility)

IF your sound system is near stage level and raised up high enough, those up close will experience excessive level in order to provide adequate level for the rear seats. The one tool for correcting this is axial loss (being off axis of the sound system) but that is not a good tool to use IF it causes excessive reflections in the room (loss of intelligibility)

At least indoors, the venue will enhance low frequencies due to boundaries but not mid and high frequencies which will tilt a sound system’s response toward the low frequency range (loss of intelligibility)

At the end of the day, intelligibility is king as far as I’m concerned. Especially when it comes to story telling. It may be acceptable to have a muffled vocal at a rock show but not for musical theater or theater. If we can’t understand the words, we can’t follow or even care about the story.