A great pipe organ in a great room and the money to keep it in tip-top shape is the ultimate sonic situation!
However, the reality is that having those three elements in one church is hard to come by these days. If you have them, get the pipe organ!
I do get a lot of emails and calls from individuals and churches who lack one or more of the three criteria above. I get very concerned about the end result when I hear people's plans. So, I thought I'd write a general article addressing some common issues on the subject of "audio systems for churches" and follow it up with further articles on exceptions and special cases.
The number one motivation I hear for implementing Hauptwerk-based instruments in churches is cost. This is fair enough. Implemented properly, Hauptwerk instruments tend to be about 10%-20% the cost of an actual pipe organ appropriate to the worship space. That's quite a bit of savings and there are lots of caveats to that. However, it's a lot more than many people envision when they call me.
It's not unusual for people to call me looking to implement Hauptwerk in a church of 400 people, from scratch, for $5000.
It's often the audio portion of the instrument that people underestimate. Having an audio system with optimum channelling and that can be relied upon to work when you need it to, can be pricey.
Similar issues arise with the computer gear. There are products that are great for home users and others that are made for a commercial environment where it must work when it's called upon.
Be prepared to get the proper equipment for the job.
Function of the audio system:
What is the instrument going to be used for? Is the instrument intended to be a recital quality instrument? Will it be accompanying other instruments or a choir? Is it exclusively for congregational singing in a church that just wants something vaguely organ-ish to sing along with?
A Recital Instrument
When recreating a pipe organ in a worship space, multi-channelling is key. Recreating pipe organ is different than just putting a stereo sound system on the instrument. Both have their uses, advantages and disadvantages.
Ideally, you want as many unique sound sources as possible when recreating how a pipe organ acts in a room. So, if you can do it, you want to have a lot (8 - 32) of low wattage (120W-220W) channels instead of, say 2 channels of 1000W each.
This technique allows the room to work as it would with a real pipe organ. The many pipe sounds, from different sources, bounce around the room and react with each other in 3D space. It allows the sound waves to combine in wonderful ways and diffuses the sound so that it becomes semi-directional as well. You'll need to use this in a situation where the congregation wants the organ to be a performance instrument and they care that the effect is that of a real pipe organ.
Note that you will need a sound system capable of handling from 16Hz (for a 32' pipe) up to 20KHz or higher.
Baseline Functional Instrument
The other way to go is to use a stereo output from a pro audio system. For example, 2 channels at 1000 watts each plus a sub woofer. You will still need a sound system capable of handling 16Hz up to 20KHz. This is rare in a typical church sound system unless it is specifically requested.
The advantage to this technique is that it's easy and less expensive. Only use this for congregations that just want an organ sound and don't care about how real it sounds. Since you only have 2 speakers, it will sound like a nice recording of an instrument rather than an actual instrument. The sound will be very directional. However, don't fool yourself into thinking that this setup will pass for a pipe organ.
This is not a setup that we tend to recommend ever except in a very few cases.
Sometimes, this is the only solution in a space which has acoustic or architectural (strange balconies or other architectural oddities) challenges to overcome, is a 2 channel system with many repeaters throughout the space. However, this is definitely an exception to the rule.
The other exceptions can be in a temporary installation (for a concert with other instruments or a choir) or in a venue which is just too large for the multi-channelling to be effective (like when we put the Metz organ on the Plains of Abraham for 50,000 people).
We have had a degree of success with this method. However, in all cases, the sound systems we used were well over $100K. So the reasoning for using them had nothing to do with budget.
Somewhere In Between
I realize that people can, and have, been worshiping in all sorts of environments for thousands of years. Rarely do they have the best of the best in instrumentation. I also realize that sometimes "good enough" is just that. God looks at the heart and isn't necessarily concerned about how wonderful things actually sound.
I suspect that your requirements will be somewhere in between a basic organ "sound" and a recital instrument. What equipment to use, how to implement, and the budget can all change based on the answers to a few questions. I recommend that you discuss these with the decision makers, and have some firm answers to the following questions, prior to calling anyone to get quotes or "ballpark figures".
What role does organ music play in the life of your congregation or venue? How valued is the sound of your instrument by your constituents?
If there is no particular love for organ music or no commercial value (renting the place for recitals or weddings where an organ is featured), find the simplest, cheapest solution out there. You're probably looking for a used toaster.
However, if you value what the instrument adds to your community, let's find a way to make it happen. People will get inspired and you'll be able to find the resources to do it. If there's no overall will though, no matter how hard you try, there will always be insurmountable opposition.
Do you have access to craftsmen and computer-music minded people in your organization who can help you to create, acquire and maintain this equipment? For example, sometimes you have a cabinet maker who will build your console shell for you or a computer person who is willing to donate a capable computer to the cause.
How large is your worship space? How much ambient reverb is native to the worship space? Do you have access to existing pipe chambers, speaker chambers or cabinetry? Have dimensions and pictures ready to send.
Do you have existing pipes that you want integrated into your virtual instrument? We'll need to talk about the number, types sizes of chests. We'll need to know how the magnets are wired (if there are any), the resistance of the magnets and what is driving them now.
It's also useful to discuss which organ sample set(s) you are planning to use.
What resources do you have available currently? A console or pedalboard to re-use? Bench? Someone familiar with Hauptwerk who attends? Computers? Audio equipment?
Have a discussion on what the right solution would be worth to you (the collective you). Then find out how much you have and see what will there is to come up with the rest if you're short.
Even if you don't think you have answers that will satisfy someone like me, contact me anyway. The fact that you have done the diligence to attempt to answer those questions is going to be very helpful. And, if there is a will, there's usually a way that you may not have thought of. We probably have thought of it and would be happy to share that possibility with you.