Originally posted January 13 2013
Greetings Audio Professional,
Chances are that some nice person has just approached you with a crazy story about wanting lots of speakers, audio converters and amplifiers to make a virtual organ using Hauptwerk software.
You're probably thinking they are, at the very least... CRAZY! or, if you're feeling charitable, "mis-informed".
I'm not going to debate the whole "crazy" diagnosis (use your own judgement there). However, let me explain what they're trying to do on their behalf so that you can help them get the right equipment and make everyone deliriously happy. It's also going to make you a relative expert in this selling niche.
There are 3 key aspects to this project that are different than what you're used to:
I was providing a Hauptwerk setup for a large concert hall here in Toronto. The sound guy came tearing up on stage yelling "Turn it off. Turn it off! There's something wrong". Nothing was wrong. We were testing out the 32' Bombarde pipe sample. To him it sounded like a blown speaker (understandable actually since it's basically a piece of wood flapping at 16Hz...). To us it was perfectly normal. All of this just to say that this is a different kind of audio project.
This project is going to need equipment that goes from 16Hz up to 20KHz plus.
The largest pipe (typically) in a pipe organ is 32' long. To reproduce that, you need about 16Hz. Granted, it's more felt than heard but whatever sound emerges is going to merge in 3D space to enrich the other sounds that are being produced. More on this later.
Your challenge here is that most pro-audio subwoofers do not go as low as 16Hz. Many of them bottom out at 40Hz which isn't really useful in this context. This is one reason why we typically recommend home theater sub woofers instead of the pro-audio subs.
The second largest group of pipes start at 16' which need 32Hz to produce. Again, many studio subs don't go down that low.
Have a look through your own range of products to see what you have that can satisfy this product range for this customer. You may not have anything. However, maybe you can work out a referral relationship with someone in town who does have these products.
If you need current product recommendations, I'm happy to give them to you if you drop me an email.
You know about intermodulation distortion. You know about nodes and dead spots and that more speakers doesn't usually make for better sound. I can't argue with you on that. Physics is physics.
However, let me show you how this is a bit different from what you're thinking right now.
Dead spots and phasing happens when you have the same audio signal coming from multiple speaker sources (at least in the context we're currently talking about).
What we are going to do is have multiple, unique audio streams each coming out of their own channel. We are doing this because, it allows multiple sound sources to mix in three dimensional space like they would in a real pipe organ.
So, your customer is going to need an audio interface with multiple, discrete analog outputs.
Typically, we use an audio converter with 8 discrete outputs. In principle, we use 6 of those for 6 identical speakers and then 2 channels for a stereo sub.
The individual outputs from the 6 speakers are summed and mixed down to a stereo output, in software, and sent to the stereo sub (or multiple subs). That same stereo sub mixdown is usually sent out on the channels that correspond to the headphone output on the audio interface in order to give them a headphone feed.
Then we use the crossover setting on the sub to filter out the high frequency portion of the signal. Where it's set is a matter of taste and the speakers you plan to use. Often it's between 50Hz and 90Hz.
This also means that we really don't care about how good the mic preamps are on the unit. We only care about the quality of the output audio converters.
For ease of use we also are looking for the number of discrete analog outputs where we can send a unique audio stream.
The problem is that the specs on the audio converters are often confusing. It may say it has 24 channels of output on the box but 16 of them are ADAT, 2 S/PDIF, 4 of them are for the 2 headphone jacks, 2 say "main" and just duplicate outputs 1 and 2 and it really results in 4 channels of usable 1/4" TRS output for this application.
This is where your help will be invaluable to this customer. If you take the time to educate them, they will be back for other things.
If you take the time to look into the Hauptwerk's audio routing so that you can help them with their multi channelling, they will be back and bring their friends.
In the studio environment, you want relatively narrow, focused sound in order to minimize having the sound bouncing all over and creating standing waves or causing weird reflections.
When recreating a virtual pipe organ, you want the opposite. You want the sound radiating from as many directions as possible because vibrating pipes throw sound in all directions.
The overall effect you're after is a "semi-directional, broad wall of sound".
Here are some other considerations to help you to help our mutual customers make the best decision for themselves.
Find out if this customer is an audiophile or if he/she just wants a great quality sound at a reasonable price.
This could mean the difference between sending them home with an 8-channel converter for $499 or one for $1600.
If they're on a budget and really prefer high end audio, it's better to send them home with an amazing set of headphones (like some AKG K702s - my current favorite) than a cheap set of speakers.
It's hard to deny the simplicity of using a powered studio monitor instead of separate amps and speakers.
This decision is going to be a matter of trade offs. Ideally, you have a powered speaker with a super wide range and great dispersion at a price that the customer can afford getting 4 or 6 of them.
If not, you may look at providing them with a good multi-channel amplifier. Something in the 120-220W per channel is good. You can do less but the efficiency of the speakers can start to become an issue. So, an easy way to ensure it's going to get them enough volume is to find something in that range.
If you can find a multi-channelled amplifier, look for one that's simple to use. User configuration menus typically means answering lots of support phone calls for you.
You can check out www.midiworks.ca to get a better idea of what's going on in this niche and you can email me at firstname.lastname@example.org if you have more questions.