Compression in the mains??

[Brad Weber]

Originally Posted by joshuacrispin

Acrossthe board, live-sound pro mixers like myself either use gentle compression on the subgroups, OR the Master Out for polish...IF needed.

Since the term has been used twice in this context, can someone describe what "polish" sounds like? Seriously, I think an important aspect here is that the compressor is being used for something other than general volume control and it might help some people if you could describe what the compressor is actually doing in your application and how it affects the sound.

The fact is that many of the more subtle nuances that might matter in a studio may not be relevant in most church sound situations. The speaker system, open mics, room, ambient noise, listener area and so on associated with your average church that impact what the listeners hear may be significantly different from what you might experience in a studio environment. That is not saying you don't want to use all the tools and techniques available to you to provide the best mix you can but rather that one has to consider the practical effect of some studio techniques and tools when being applied in a potentially significantly different application and environment.

[bbrunskill]

Why I use it live and in the studio is really hard to explain.
It's like it brings the mix elements together slightly more. It grabs level changes and very subtly controls them.
I've you haven't tried it, you should. Remember, it's needs to be subtle, and tweaked very carefully. Should only be actually compressing when the band is really pushing, or when there is a sudden volume change on stage.

If you are running digital desk with racks of virtual comp on everything, it' won't really do much. It's best in a fairly dynamic mix. It adds control without having to slam stuff. I'm not sure I would bother doing it with a digital comp (live) at all.

Sort of like mastering for a CD (without the volume boosting that seems to happen these days).

Anyway, I'm not a super experienced pro mixer, but it's something I've tried and liked. I don't have the desk at church setup in that way because I think it would cause havoc with all the volunteers who use the system.

ben

[Brad Weber]

Originally Posted by bbrunskill

Why I use it live and in the studio is really hard to explain.
It's like it brings the mix elements together slightly more. It grabs level changes and very subtly controls them.
I've you haven't tried it, you should. Remember, it's needs to be subtle, and tweaked very carefully. Should only be actually compressing when the band is really pushing, or when there is a sudden volume change on stage.

I'm one of those who often likes to understand not just that something works or not but also how and why it works or not, so please forgive my continuing on this.

A basic compressor does nothing unless the signal level increases above the compressor threshold, at which point it 'scales' the overall gain, actually applying a gain reduction, based on the compression ratio. This type of device would not affect even the most dramatic change in level in the main mix unless the change caused the signal level to exceed the compressor threshold. However, with a 2:1 ratio then for every every 1dB whatever component of the signal involved is above the threshold, there is a 0.5dB gain reduction applied. So if a vocal was 10dB over the threshold there is a 5dB gain reduction applied, thus the output signal experiences a 5dB increase due to the part of the signal generating the peak with a corresponding 5dB decrease in the level of all other signal components. In this way you maintain most of the relative levels between signal components while reducing the dynamics of the output signal. The vocalist or soloist can get above the rest of the band without having as large an increase in the peak overall level.

If you have an audio system that pushed to support the levels and dynamics desired then this may help significantly by reducing the headroom the sound system must support without having to reduce the levels of multiple sources. At the same time, it may have minimal impact in a church that has excessive stage levels as those stage levels would not be affected. Similarly, any compression of the overall signal, or any effects in general, may not translate to all listeners the same. In addition, the musicians being live in the room, the listeners being distributed over a large area, the effect of the room and so on that are part of a live church performance could impact how different listeners perceive such effects. For example, do listeners located near the stage who will likely hear at least some of the stage sound directly without any compression end up hearing something significantly different than those located in the back rows and relying much more on the sound system?

[bbrunskill]

Brad, I think you've explained it in detail far better than I ever could.

However, I think you've missed one detail.
When I've put a comp over the mains, I've always used something analog or tube. I've done it live at my home church with 2 channels of a DBX 1066, I've done it in the studio with Focusrite, Joe Meek, Buzz Audio comps.

I've never though about it that closely, but now it occurs to me that while the compression is part of it, a big portion of why it sounds good to me and my ears, is the tonality of these great units.

So does it need to be done? Nope. It could frustrate feedback issues.
It, like Brad mentions, might not translate well to many people in the room.

But still, I like it. I will always compress my main outs in the studio, and I've got good mixes live using mains compression.

Really, I think it's just another tool, that can be used badly or well.
Some people like to use Snap-On tools, some people like Stanley.

Ben

[FlamHappy]

I put a dbx 1066 across our mains bus, set it to over easy and shave of maybe 2db depending on how zealous the speaker is.

We have a new associate pastor who was amped up for Jesus last week.
I could hear the dbx clamp down on the shouts and keep is normal voice at the same powerful level.

It wasn't enough for your everyday congregational member to notice though.
The comp was not pumping in the least.

I hooked it up after a Christian Arab spoke at our church some years back.
They can get after it! I was fearing for our speakers!