Learning the ins and outs of live sound reinforcement
This past couple months, I was tasked by my church to identify the needs of our outdated auditorium PA system and bring us into this century in audio/video technology . . . without breaking the bank. Well, I’m not a professional sound stage engineer by any means. So what have I got going for myself? I’ve got experience as a car audio enthusiast, having done my own share of custom installs. I guess you can say that I am technically inclined. And finally and most importantly, I’ve got Google at my fingertips.
With those tools in hands, I set forth on a quest to design and install the most fitting sound and video system that our church needed. I’ve gotten some really uplifting comments from congregation members on what we’ve been able to do so far, but it’s by far still a work in progress. If I was a neurotic planner like other people, I would have had the presence of mind to take some photos to use in this for visual reinforcement, but that wouldn’t have been very characteristic of me. Instead, true to my form, I’ll try and get some shots of the finished setup posted later to help you get an idea of what I’m talking about.
Here were the needs in a nutshell.
1. Install a digital projector for displaying computer, powerpoint, and DVD output.
2. Relocate the mixer/sound/recording equipment from the weird stage left location to the back of the church house so whoever is on sound duty can better manage the sound.
3. Figure out how to fix the bad sounding praise and worship band. (Seriously, it’s a sound staging issue. The band is actually really good.)
4. Upgrade the recording equipment so we could offer sermon recordings in CD format. (Right now, we only offer cassette format.)
It’s been quite a learning experience for me. The existing PA equipment, although several years old, are reasonably good equipment that are professional grade. The core of the system is a Mackie 1402-VLZ Pro mixer that in my opinion sends a very clean signal to the loudspeakers. The loudspeakers being a pair of JBL Eon15 self-powered speakers. They’re the first generation of this model and are starting to show signs of age, but still provide good quality sound reinforcement.
In order of priority, my first obstacle was to figure out how to wire the equipment that would be relocated to the back of the church. Through God’s grace, I was able to network with Doug Gregson through Jeff at Faith Presbyterian Church in Mangilao. I believe Doug works with Trans World Radio and he helped Faith Presbyterian Church set up the A/V system in their church. He was able to direct me to a great site for digital wiring and equipment. I purchased a VGA extender that allowed me to run a computer source VGA signal over Cat5 cable. For the video signal from the DVD player, I ran a simple RG11 cable with adapters on each end to RCA plugs. Wiring the digital projector . . . check!! The projector itself, an EIKI LC-XB42, was ceiling mounted by a universal mount purchased by Pastor Andrew at www.kingdom.com.
The next task was to get the mic and instrument signals from the stage to the mixer and the mixer output back to the on-stage loudspeakers. To do this, I purchased a ProCo audio snake from http://www.sweetwater.com. The guys at Sweetwater are really helpful and their prices are some of the lowest you can find. The audio snake made the install really easy, clean and professional. Unfortunately, I might have made the mistake of ordering too small of a snake. I should have allowed for system growth, but the snake has enough channels to handle the 14 channel mixer, so I figured that if we out grow the mixer, then we could just upgrade the cabling as well. To be frank, with the size if the church, adding anymore sound sources might be overkill.
Now that everything was installed, I had to get all the equipment connected to the mixer so I could have complete control of the sound stage. Here’s where I learned the hard lesson of audio signal impedance. This is where the guys at American Music here in Guam come in. I wish I had gotten the name of the young guy behind the counter that introduced me to the Radial ProDI Passive Direct box. His explanation of the importance of matching audio signal impedance between instruments and equipment led me to understand what I was faced with when I couldn’t seem to get the guitar, bass and keyboard to jack in to the mixer just right.
With his help, I finally understood that the XLR mic inputs on our mixer expects a very low impedance “mic” signal such as that which comes out of a microphone. The signal that comes out of a guitar’s jack or a computer’s headphone jack is a high impedance “line out” signal. Just rigging an adapter in line won’t do the trick for you there. The DI boxes were expensive, but they are of good quality and really provide the best signal to the mixer at just the right impedance that the mixer wants.
With that knowledge, I was also able to understand that some of the channels of the mixer do allow for a high impedance (or High-Z) signal. So those channels ended up being where I plugged in the Electronic Keyboard, PC, DVD, and Tape Deck. Once I had those equipment all connected, I had everything wired up to the mixer and theoretically, full control of the sound stage for the church.
Now, with a properly wired mixer at my disposal, I now set forth in tackling my next obstacle – make everyone sound better. This step is where I’m at right now and is really a work in progress. First off, I’m not a sound manager by profession in the least, so I am learning all about acoustics and sound physics as I go along. Second, I am not a musician either, so I am also learning what each musician/singer’s needs are as I go along as well.
My first attempt to balance everything out, I forced all the players to lower their on-stage amps and keyboard speakers to help balance out the sound coming out to the audience. Suddenly, the music started to sound really out of synch and all the musicians and singers kept getting lost and off tempo. The band members started explaining to me that they can’t hear themselves play and are getting lost. Normally, they would be able to follow each other because they each set the volume of their amp or instrument at the level that was comfortable for them to hear themselves over the other instruments. As for the singers, they can’t even hear themselves, so with the band getting lost, they just don’t know what to do. Thus started my lesson in the importance of stage monitoring. I never realized that this aspect of live sound can get so complicated. A little research showed that even in some large venues, there’s even a dedicated stage monitor mixing board with a dedicated sound technician managing each performer’s monitor mix. Of course, this is nowhere near the level that my application is, but it gives you a perspective as to the importance of a good balanced stage monitor mix.
Now I’m faced with trying to get a good balanced signal to all the players and singers on the stage without overwhelming the first two rows of church members with the stage sound bleeding off to mix with the loudspeakers. This is especially a problem for our church because the pulpit is quite small and the front row is very close to it. As much time and effort as I have put into this so far, I think this is the biggest challenge. I need to find the right balance of all the needs because each requirement seems to be contraindicative to every other need.
There are so many questions now without obvious answers. Do I get stage monitors and set them up? If I do, where will I put them because the stage is so small? How loud will the stage now be with stage monitors, guitar amps and the keyboard with its own speakers. How do I create a separate mix for the stage monitors? Do I need to get another mixer?
I’ll do a follow up post when I’ve gotten closer to getting that right balance that satisfies all the needs of our church’s sound staging.
I leave you with a final thanks and praise to God for providing for the needs of the church as He has. He has provided me with this great opportunity to do what I really enjoy doing all while allowing me to serve Him through the gifts He has provided me. And another plus for me . . . being able to spend time in fellowship with all the praise and worship band members. I’ve been learning alot of cool stuff from all the praise team and their input into the setup of the sound system has been invaluable.
