Sound walls in Orchestra pit

[JLNorthGA]

We have an orchestra pit (of sorts). Currently our fill speakers and subwoofers reside in the pit.

We will be doing a musical. They would like to put the band down in the pit.

I will have to put in some walls between the band and the speakers.

My current thought is to build a wall using 2 x 4 studs with 1/2" Quietbrace sound deadening sheathing on both sides (NR 0.3) and also have insulation batting between the studs.

This is really just to "protect" the band from the noise from the speakers. After all, we wouldn't want a band to be deafened by the noise!

 

[MNicolai]

Front fills are ordinarily for subtle reinforcement in the first few rows where overhead clusters may not cover sufficiently. What are you using your front fills for that they're that loud to be a nuisance to your pit orchestra?

As for the subwoofers, I haven't seen the acoustical data on the QuietBrace product, but I expect you'll find that sheet goods are woefully inadequate for sound-isolating against low frequencies.

 

[BillConnerFASTC]

It would seem simpler and easier to relocate the sub's.

 

[JLNorthGA]

It would seem simpler and easier to relocate the sub's.

I would if I had another place to place them.

I could always place them in front of the stage and risk the ire of the director . I could also place them in the corner of the landing - which may be an alternative.

 

[AlexDonkle]

It sounds like you're system is main FOH speakers suspended overhead, the FOH subwoofers are on the floor in the pit, and you have separate front-fill speakers for the first few rows of people. Is that accurate, or are your fill speakers covering the entire audience?

Assuming the wall would extend from the pit floor to ~stage level, and neither the orchestra pit or the speakers would be covered with a ceiling, this is the same concept as a noise barrier wall. Quietbrace is a waste of money in this application, as most of the noise will be traveling over the top of the wall, not through it. I'd use 3/4" Plywood, but expect the most this wall could do is provide ~6-8 dB of attenuation which is noticeable but not likely enough to limit the typical noise level of FOH subwoofers to acceptable levels.

Re-locating the subwoofers as Bill suggested would certainly be the simplest / most effective solution. If there are no microphones in the pit, then you might also looking at having the band use in-ear monitors.

 

[JLNorthGA]

It sounds like you're system is main FOH speakers suspended overhead, the FOH subwoofers are on the floor in the pit, and you have separate front-fill speakers for the first few rows of people. Is that accurate, or are your fill speakers covering the entire audience?

Assuming the wall would extend from the pit floor to ~stage level, and neither the orchestra pit or the speakers would be covered with a ceiling, this is the same concept as a noise barrier wall. Quietbrace is a waste of money in this application, as most of the noise will be traveling over the top of the wall, not through it. I'd use 3/4" Plywood, but expect the most this wall could do is provide ~6-8 dB of attenuation which is noticeable but not likely enough to limit the typical noise level of FOH subwoofers to acceptable levels.

Re-locating the subwoofers as Bill suggested would certainly be the simplest / most effective solution. If there are no microphones in the pit, then you might also looking at having the band use in-ear monitors.

That is accurate for the speaker placement.

There would be a ceiling (more accurately the portions of the stage apron or floor that we didn't remove) for the wall though.

 

[BillConnerFASTC]

Top of lighting slots?

 

[derekleffew]

Top of lighting slots?

Speaking as a squint, not a squeak, Why top?

Cons:
1. Rigging a heavy sub(s) up high.
2. Top of lighting position is generally more desirable than bottom. Note on nearly every light plot I've ever seen: "Please hang box boom units as high as possible."
3. Wouldn't the low frequencies couple better with the floor?

Pros:
?

 

[FMEng]

Why would the subs even be needed for a musical? The mains are reproducing mostly voice for a musical with a live band. Turn off the subs off and lower the high-pass frequency to the mains as much as they will handle. Subs are not the necessity that we tend to think they are.

 

[BillConnerFASTC]

I suggested top because it looked like there was no pipe or way to mount lights near top. That could be fixed too and i could supportb your point about lighting but I don't think there is enough directionality to subs to matter.

FMEng is probably most correct - just turn them off.

 

[AlexDonkle]

Generally you want any speaker (subwoofer or not) to be high enough so that the difference between the closest and farthest listener is minimized. (e.g. the difference in sound level at 40' vs. 80' is minimum, but the difference between 2' vs. 80' is extreme). Rigging higher is typically better, so long as you can do it safely.

Personally I would build some sturdy shelves above or beneath your FOH wall-mounted speakers and set the subwoofers there.

 

[BillConnerFASTC]

Generally you want any speaker (subwoofer or not) to be high enough so that the difference between the closest and farthest listener is minimized. (e.g. the difference in sound level at 40' vs. 80' is minimum, but the difference between 2' vs. 80' is extreme). Rigging higher is typically better, so long as you can do it safely.

Personally I would build some sturdy shelves above or beneath your FOH wall-mounted speakers and set the subwoofers there.

Which is, I suppose, why you are a systems design consultant and not an interior designer. Personally, I'd try to conceal the wall mounted speakers.