I've recently gotten involved with an HoW (House of Worship) system and the question has come up: what is a realistic SPL. I'm so involved that for the first time, I'm working the board. And there's a difference of opinion. And it's a black church. Let's just get it out there: that can be a factor.

A new director of music is pushing for music SPL in the range of 95 dB. The system is very clean and would probably start clipping around 105 dB. Exact components don't matter because I'm asking about best practices regarding, basically, ears and their ability to keep working.

Right now there's a recently borrowed Hammond B3/Leslie combo, there's always been a bass player and drummer, and none of those are miked. Thus I have no control over those volumes and to get a correct house balance I turn up the singers. Oddly, until this week it was easy to be at 85 dB; today it had to be 95 dB to be balanced, and we had complaints from the attendants.

So what's a reasonable SPL for worship, especially considering they're trying to get younger people to attend... and I'd like those younger people to be able to hear forty years from now!

As I'm sure you already looked it up and know, 95dBA is permitted for 4 hours under OSHA guidelines. So how long is the service?
Also, where are you measuring the 95dB at? And is it dBA or dBc?

You mentioned the bass player and Drummer are un-miked. But you recently had to adjust volume on the miked channels +10dB to keep up now. That's a HUGE change. What has happened in the system to cause this?
Were the bass player and drummer always over powering the rest of the performance? And you are just now compensating?

Usually drum sets in small venues, have an isolation kit around them. To help reduce the volume so they aren't over powering. Does the drum kit have such a barrier around it? Was it recently removed?

Brad, start off thinking zero budget. Now... The drum kit is on the stage and has never had anything around it. It spent some time on the floor in front of the stage... aha, I just realized something: the drummer can't hear the house audio now as well as he could when down on the main floor, and he's probably playing louder now, thinking he's mixing in nicely. I'll have to ask him about it.

And yes, today's audio was about 10 dB hotter than previous services. That's measured on a Radio Shack-type SPL meter with a needle-type meter movement. I don't remember an important fact, though, which is whether it's set to dBA or dBC. It might have gotten switched from taking it in and out of the bag. So my report on level might be my bad. However, someone did complain about the level, and hasn't for weeks.

As to the level, I've wandered around the sanctuary with the meter while playing music and the SPL is remarkably uniform in most places with the obvious exception of the front five or so rows of seating. I set the meter on top of the board, which is open to a 24" h x 36" w opening in the wall to the booth. It's close enough to have an idea what the SPL is out there.

It took me six months and an actual change of musical director to get someone to get through to the bass player that a bass with no overtones ( = no character) that obliterates the rest of the sound is NOT a good idea. He's been well balanced for about two months now. I didn't want to tell him what to do since I was just the volunteer audio guy but the improvements I've made have given me some cred. That, and when the music director did something dumb I was able to tell him where on the keyboard, from there up, the problem manifested. I think he was a bit intimidated by me knowing so much what he was doing.

FYI the area has a main floor of about sixteen rows of pews. There's a balcony over the last five rows. To the left and right of this area, there are risers on each side, with five rows of pews, and a similar upstairs area of risers with the same pew layout. I got started with the audio here when I was tired of looking at silent obviously 70volt speakers in all of the ceilings not over the main area: under and above the balcony, under and above the side sections, in the narthex, in offices and bathrooms, even a feed going to a separate building. And all of it is zoned as left and right and such, something I can't work with to add the kind of delay that would really smooth out the audio delivery.

Since the congregation complained, let them complain to the Music Director and they need to be specific about their complaints. If it's SPL, he needs to accept defeat- 95dB is loud, when the music is full-range.

Use a DI for the bass and organ- it will make your life a lot easier. Might want to use a DI for the guitars, too. Less stage volume makes for a much better-controlled system and better sound quality.

Tell the drummer to buy thinner/lighter stick, or tell the Music Director that people will always complain as long as the drummer and bass player have free reign on their output. The drummer should be using Simmons, or something like that, or clear panels to block the sound. They (drummers) don't usually effing understand, so I'm not sure I would bother to talk to him/her and the bass player is just trying to hear over the drums. For that matter PA systems really serve one purpose- to make everything heard with the drums. Make the drums more quiet and you can make everything more quiet.

I worked for an A/V contractor that did primarily LDS facilities, based on the design by the EE for the church. IIRC, the systems were set up to perform at 85dB, but I could be wrong. I do know that Salt Lake City made the decisions for damn near everything, but the engineer was able to achieve great system response with Atlas in-ceiling speakers that were mounted in plywood boxes. We did all retro work, so the speakers replaced whatever was there already.

The EE definitely knows his shyte, too- he designed the system for Texas Stadium.

Here ya go-
[Link: ehpub.com]

[Link: sweetwater.com]

[Link: wfxweb.com]

[Link: waves.com]