This topic is one that comes up a lot. It's something that certainly can be done. It looks like it should be a pretty logical thing to do. However, it needs to be done for the right reasons and with accurate expectations.
The Big Questions
Before you start, you have to ask yourself (or your committee) why you are planning to put your Hauptwerk instrument through the existing sound system. If it's strictly for budget reasons, you should stop right there and have a rethink. Hopefully, you haven't purchased the console or other parts at that point because you really need to start with a different premise. You need to start with "what our goal for this instrument and what effect does it need to have?".
These questions are big. You really should start with those. However, they really require a couple of blog posts on their own.
For now, lets just talk about the technical issues of implementing Hauptwerk through the house system of your venue. It assumes that you want an organ that sounds and acts like a genuine pipe organ as much as is possible.
Have you ever heard someone, or been the one, comparing seeing your favourite artist in a large venue versus seeing them in the intimacy of a small venue? The overwhelming majority of the time, people will favour the intimacy and connectedness of the smaller venue. Why is that?
We've all walked past people on the street with crazy-loud PA systems pounding out music. They've got lots of volume. Even if you like the music, you still might feel kind of assaulted by the sound rather than satisfied by it. Why is that?
We can talk about proximity issues, volume, equipment models and such but I think the bottom line measure of quality is really "how immersive was the experience?". In other words "were you enveloped by the sound in a luxuriant way?".
Creating an immersive experience using your Hauptwerk console is the goal of this exercise. Doing this with 2 channels is more of a challenge than doing this with the proper multi-channeled system.
A Great Recording
One main problem with using the house system is that the instrument will tend to sound like a recording of an organ coming though the system instead of sounding like an instrument live in the room.
There are some scenarios where this is does work:
You have a super large venue that would be too large for even a large pipe organ to fill (think stadium mega churches)
You have a room where the shape is so odd that regular room ambience wouldn't work anyway (i.e reverse sloped ceilings, odd seating areas, strange balconies etc)
Organ music in your service is seen as a nod to the past (read: to keep the people who have money giving money) but not really valued by the majority
Running the organ through the house system is a documented step in the evolution of the instrument where there are concrete plans to add the dedicated sound system later (e.g. the room is under construction)
You're in a temporary space and don't want to (or can't) invest in a full system for that space because it's not your space.
You're perfectly happy with it sounding like an organ recording coming through some speakers
What's the matter with a great recording sound? Nothing if that's what you're after. If that is what you are after, stay tuned for more issues you'll need to think about as well. In the meantime, I'll explain why it sounds like a recording.
What Am I Missing?
Why does the instrument sound so different when multi-channeled (properly proportioned to the room) versus a stereo channel approach?
Part of the answer is the position of the speakers in the room. However, main answer lies in the number of interactions between the different audio sources.
Just for clarity: When we talk about "speakers" or "channels", in reference to a Hauptwerk instrument, we are always assuming that you have set each speaker or channel to be sending different sounds than all of the other speakers.
A pipe organ has many pipes. Each pipe is an independent source of sound. If you have 1000 pipes, you have 1000 potential sound sources. Those pipes act together in real space. In this scenario, you will be reducing the interaction of 1000 pipes down to 2 speakers.
Here is why multi-channeling on even a small scale makes a difference. (and by multi-channeling, we mean different sounds coming out from each sound source)
When you have 2 speakers, you have 2 sound sources interacting with each other. Anyone used to listening to the real thing will immediately notice that something is different.
If you increase the number of speakers and channels even from 2 to 8, you have 4X the sounds bouncing around the room. You have also cut the number of destructive wave cancellations that happen when you combine audio signals internally to 1/4 of what they were in a 2 channel system. That is the good mayhem that you miss out on when you try to put a Hauptwerk instrument through a stereo mixer in a large room.
If you can picture it, picture standing in the middle of a squash court. Pretend there are 2 balls continually bouncing off walls at all angles. Each of the "balls" represent a unique sound wave coming from one speaker. They're flying around. Occasionally, you have to duck because one comes right at you. Now picture the same scenario only with 8 balls at once. Now you're surrounded. You're immersed. Using 8 balls is an very different proposition from only 2.
This is not a perfect illustration by any means. There are lots of other cool things that 8 channels bring to the table that we haven't even talked about and don't fit into that analogy (like the whole semi-directional wall of sound effect of a real organ). However, the squash court should illustrate how the sound surrounds you better with more channels. Increasing the speaker count from 8 to 24, 48 or even more just improves things further.
Remember that we're primarily talking about this in a large venue setting. In a smaller room, say at home, things are a little different. The closer you are to the speakers, the more your ears are fooled. However multi-channeling at home still makes a big difference for the same reasons.
Hard To Handle
You need to make sure that your existing house system can actually handle the frequency range that your Hauptwerk instrument outputs.
Many P.A. systems used by Churches are only set up to handle voice frequencies. Many of those systems are also mono systems; they're not even stereo. Many Church sound systems that are used by praise teams may be stereo but also are not designed to handle the frequency range needed to accurately reproduce organ pipes.
It's not uncommon for sound systems (even with subwoofers) to stop at 40 Hz on the low end. To reproduce the sound of a 16' pipe, the system needs to be able to handle down to 32 Hz. In order to reproduce a 32' pipe, the system needs to handle 16 Hz.
Usually, the upper frequencies are not so much a problem for the sound systems. Chances are that they technically handle up to 20 kHz. Whether or not they nicely produce and/or project those frequencies is entirely another matter and highly subjective.
Loss of Control
Arguments of sound quality aside, there are some practical things that you need to address when your Hauptwerk instrument is using the house sound system.
When you are the organist on a pipe organ, you are in charge of the overall volume of the instrument. When you're going through the house system, the "sound guy" is in charge of your instrument.
As the organist, you are used to being in control of your own volume. You judiciously pick a few, soft stops when you want to play softly. You pull a lot of stops when you want to play loudly.
Now picture this:
You are have chosen your favourite quiet stops to start off this hymn. Your plan is to build to a monumental crescendo for the last verse but you're holding back for now.
The congregation has heard you do this before on your old instrument. So they know what's coming. They are enthusiastic and start robustly.
At the back of the room, your sound guy says "Hmmm. That organ isn't very loud. I'd better turn it up". He does so. He feels helpful in a liturgical kind of way.
You have built things up. You are in the penultimate verse heading for the glory land of the final verse. You jab your preset and all the stops come out. You pounce on the keyboard with the confidence that righteous musical professionalism dictates and... it sounds like the veil of the temple being torn in two. The organ has just become a giant car radio between stations.
The sound of static is like a call from the Holy Ghost and so Mr. Helpful, at the back of the church, yanks the volume faders down from where they are down to 10 percent. Now, you can't hear, the congregation stumbles on from muscle memory and you've become Moses stuck on a mountain glimpsing but shut out of the promised land.
I'd like to tell you that I made that story up but I didn't.
The Way Forward
Running Hauptwerk through the house system is going to require a lot of team work and dialogue between you and the sound personnel. If you are a classical musician, chances are that you do not understand live audio equipment. Chances are that your sound personnel do not understand your Hauptwerk system or how organs typically work.
So, here's a blueprint of how to work together even when you don't understand each other's lingo.
Explain to sound people that, in Baroque music, if you wanted to get louder, you added more instruments. In Classical music, if you want to get louder you play harder. Playing the organ is like Baroque music. If the organist wants to get louder, the organist will pull some more stops. If there is no singing, this will allow you to get an idea how loud the organ is to the audience.
What you, as an organist need, is to have a monitor system near your console that represents about the same volume as what the average audience member is hearing. From there, you'll be able to hear the congregation and pick stops that will adequately support the singing.
Establish a sound check routine with your sound person. The overall goal will be to find input gain settings, your channel settings and the main volume settings on the sound board that they set and do not change as long as you are playing.
To do this effectively, you may also need to standardize the Trim dB and Volume settings for each sample set within Hauptwerk. See these settings by going to View > Large floating control panels > Audio MIDI performance
You may also need to tweak the output levels of your Hauptwerk instrument's audio card.
Record a MIDI file that will serve as your sound check for each organ sample set that you use. Make it one that incorporates a typical soft passage and works it's way up to a loud piece. If you are using a sample set that uses expression pedals, make sure you include a part that opens the virtual shutters at the loudest part of the recording. This will ensure that the sample set will not overload the sound system. If it does overload the system, you will need to work through step 2 again together.
If you make these steps a part of your startup routine, this will minimize any potential sound problems that might affect your realtime performance.
You Can't Always Get What You Want
Let me just note that the intention here is not to be snobby. The intention here, as always, is to give you best practices and accurately represent the outcomes one can expect from doing something a particular way.
We do not recommend implementing 2-channel Hauptwerk systems in Churches. Bad installations do not do the instrument, the music, the industry or Hauptwerk any favours. We know they happen though. Sometimes, they're the best answer out of a bunch of undesirable choices but we want them to sound as good as possible under the circumstances and for there to be an acknowledgement that the situation was not ideal.
If, in the end, you decide to implement a 2 channel system, we want you to do what you're doing because you're doing it on purpose in order to get an expected result. That way, you'll be able to justify your reasons down the road when you need to.