www.Goingto11.com

Harsh Reality: Part 4 – Bridging the Loudness Gap

Dave — Tue, 07 Sep 2010 01:39:43 +0000

So I’m going to try and wrap this series up once and for all. I’m not going to say I have all the answers in this, but I will get into some stuff that has been working for me.

First a little recap. The topic at hand is really mix translation. It’s my feeling that as technology continues to advance, there is a growing need for our mixes to translate beyond the rooms where they originate; FOH engineers are more and more becoming simultaneous FOH and studio engineers. The latest thing these days is the webcast, but it is almost a guarantee that there will be something else in the future.

Mix translation creates a couple of challenges for us, though. For starters we have a dynamics issue because the nature of our programming can be spread across anywhere from 20 to 40 dB. Let’s just look at some hypothetical SPL levels. We have spoken word preaching averaging in the 60’s up to the low/mid 70’s. Then there’s our video content which we run a little louder around movie theater levels averaging from the mid-70’s into the 80’s. And then there’s music which will vary depending on the church, but for us it could be anywhere from the upper 80’s to even tagging 100 depending on style or the event.

The way I see it, there are typically three ranges of loudness to contend with on a Sunday that somehow feel very natural in the room, but at the end of the day we’re talking about a potential 40 dB range of volume. Now, I might be a little old school in that I like dynamics in audio when I listen to things at home, but 40 dB is pretty severe. If you want to see for yourself, put something on at home at a comfortable level, and then turn it down 40 dB. It’s probably not so comfortable anymore. Try it the other direction if you dare….

So part 1 of our translation issue is dealing with this loudness gap to simply bring the levels of our programming closer together–preferably WITHOUT the use of heavy or extreme compression–for the mixes to translate outside our rooms. Of course, leveling things up brings another challenge thanks to our friend, Equal Loudness, which will affect our tonal hearing perception when we listen back to programming at a different volume than it was mixed at.

Let’s start with Part 1 of this: moving the mix from the BIG room to a smaller room. This is something that started at FOH as a work around to bypass some internal latency issues on the console and turned into something I ended up implementing in the studio as well.

A few years ago I basically separated all of our programming into four categories: live music, spoken word, playback, and audience/ambience. I figured every feed we output from the console is going to need some combination of these categories. For example, the PA needs everything but the audience. The video control room needs all 4. Our message CD recorders really only need spoken word and maybe a bit of audience. Another way to look at this is each category is basically a stem mix that gets assigned to its own bus in the console. In my FOH world I use the LR bus for live music and then a group for playback and a group spoken word; at FOH the audience mics are on their own since there aren’t many, but in the studio they get a bus.

This can be done on other consoles utilizing sub-groups and/or aux sends. In some settings aux sends might be the way to go for some of this since the room size might dictate that your music mix won’t be properly balanced outside the room. If you’re in a little room with live drums and guitar amps, you might not have a lot of those elements in your room mix due to the spill coming from the stage. Using a couple aux sends for music could give you the ability to do a custom mix for outside the room.

When it comes to leveling the programming material together I use the PQ section on the VENUE which are basically stereo matrices. Custom feeds/mixes are created by adding the needed busses to a PQ, and then the levels are adjusted so that the average level of the overall mix is balanced. A little bit of compression is sometimes used on the PQ to help glue it all together and help with week-to-week variations in level. Pretty simple.

Outside of the VENUE a console with a matrix section is going to be a big help in making this work, but there are also some ways to do things without it. If you’re bussing with aux sends, you can feed those aux sends out and bring them back in on open channels if you don’t have a matrix section. Then you can level those individual channels and send them to a group or another aux send to get them out of the console. You can also send your stems to a smaller mixer for leveling things out if you are running out of resources on your primary console. It might not be a painless procedure because you might have to sack some of your auxes and inputs, but you can do this without a high end console if you think creatively with your busses.

Of course we still have another issue to deal with: our friend Equal Loudness. So one question that maybe is still hanging out there is how big of a deal is this whole Equal Loudness phenomenon when it comes to mix translation? I think the best way to examine this is to actually listen to what happens. I’m embedding a couple of samples below to demonstrate(RSS readers will probably need to visit this post on the web to listen).

First a couple notes. The photo at left is a transfer function of the PA on the day this was mixed. As you can see it’s pretty linear above 200 Hz which means the PA isn’t coloring our room mix much. You should also note that the SPL level was in the mid- to upper-90’s dBA. Remember, the effect of Equal Loudness on mix translation is going to vary depending on the difference in volume between the mix environment and the outside listening environment.

The first sample below is the clean LR mix. This is what was going to the PA.

The second sample is what feeds our CD burners for rehearsal CD’s our musicians and production crew use for reference. This sample features my work-in-progress equal loudness compensation EQ. The compensation curve was based on examining the difference in the Fletcher Munson curves at our live mix volume and my studio mix volume which is in the 79-82 dB ballpark at unity. I’m basically attempting to compensate for a perception difference about 15-20 dB below the original mix level.

I’ve listened to these clips on a variety of what I would consider average “home” setups, and each experience was different. On some playback systems the difference was subtle and seemed somewhat insignificant. On other systems the first sample made me a little uncomfortable mainly because it just didn’t feel like a good representation of what was happening in the room. Now, I’m not going for a perfect translation because I think it will always be a challenge to pull a mix out of the vibe and energy of being in the room, but the first sample just feels flatter to me than what I remember the room experience to be. There is almost a cloudiness to it. I watched a little bit of the John Mayer at Red Rocks webcast on UStream last week, and my guess is it was a pretty straight board mix because it had some of that same quality.

The second sample, however, always played clearer to me. The first thing that stuck out to me was the snare sounds much closer to my memory of it in the room. The second sample, in some ways, feels more intentional to me, but here’s another way I look at it. When I hear the first sample, I don’t really want to play it for anybody. The second sample, on the other hand, is something I wouldn’t mind playing for friends, family, and neighbors who don’t go to church. If I was inviting folks to visit us on the web during a service, I’d rather they get the second sample than the first.

Here are two more samples. Again, the first one is the PA feed and the second one is the CD burner feed w/ EQ compensation.

Again, the second sample seems clearer to me and sounds much closer to the original feel of the house. Whether or not you feel like the compensation is truly necessary, I hope you can at least hear how Equal Loudness can affect mix translation when you mix at one volume and listen back at another.

On the practical application side of this, setting up an EQ to make this compensation isn’t necessarily a simple thing. This is because I only want my EQ compensation on the live music and don’t want it on any of our other programming; in my world the loudness gap on our other programing isn’t big enough to necessitate doing compensation. The trick I’ve landed on right now is to return my music mix to a stereo channel on the console. In VENUE world I have an EQ plugin that takes the LR Bus for an input and simply returns to a stereo channel. This could also be done by hardwiring a bus output to an input channel on just about any console.

Is the setup a little clunky? Perhaps. But it works and once it’s set up I don’t have to think about it. Plus I think future consoles are going to be better equipped to do this kind of processing. Another advantage to doing it this way in VENUE world is with my music bus sitting on an input channel, I can easily delay it back to my audience mics–thanks goes to Robert Scovill for that trick….

Now, if you’re with me on the Equal Loudness stuff, how much of it is actually necessary for mix translation is going to vary from church to church due to the wide variety of volumes Sunday services can range. But at any rate I hope this might give you some ideas and things to think about if you’re looking at moving into broadcasting or webcasting or even just improving your existing feeds. And remember, even if you don’t need to export your mix, there can still be advantages to figuring out how to create mixes that translate. Just think about the benefits of being able to evaluate things outside your room. Think about what kind of a confidence booster it can be for musicians to get a rehearsal CD that sounds good in their car. Creating mixes that translate can open up a new realm of possibilities.

The song above is called Bless Your Name and featured on North Point’s latest release:

Permalink | No comment
Categories: Audio, Mix Magic & Sorcery, System Optimization, Year of the System - 2010

Harsh Reality: Part 3 – The Wrong Tree

Dave — Mon, 30 Aug 2010 01:22:42 +0000

Now that my vacation is over, I’m going to try and catch up on some posts starting with this series.

First, let’s go back to a post in early July when I mentioned all the tuning and re-tuning we were doing to our rig. I mentioned I was having a love/hate relationship with the PA. Today I’m looking at some of those specific challenges we spent a few months working through.

As we’ve grown into the PA, a sort of running theme seemed to be that when we played back CD’s and listened to spoken word, everything sounded good if not great. I was actually pretty happy with spoken word from Day 1 because our far seats sounded so much better than anything I’d ever heard in the room, and we’ve improved it a bit at a time as we’ve worked on the rig. However, live music was a struggle pretty much from the start, and a very intense one at times. This wasn’t something I expected to happen when we installed our new world class rig especially when I’d already had success in other rooms on similar systems.

I just found myself having to do a lot of surgery especially on the mid’s and upward. Sibilance could be an outright nightmare. I started to feel like I understood why there are a lot of folks out there who tend to characterize Meyer boxes as being harsh; I honestly had always thought those gripes were more operator related, but now I was starting to wonder.

Now, don’t get me wrong. The PA still sounded good and mixes on it were improving as the weeks went on, but I think that’s to be expected on any rig; on a side note, it’s also why I don’t typically like going to opening night of a tour. Still, something didn’t seem right, and it didn’t seem like it should be so hard to get the mixes there. Having mixed in a variety of environments including the pristine confines of a studio, I was quite perplexed. In the midst of all this, I really started to question the whole linear PA thing for live music. After all, it seemed like the lower volume programming was good, but when we turned the rig up we were running into trouble.

It smelled like a perception issue to me, and I wondered if I should start shading the PA to deal with the challenges we were having. Part of my thinking was that this could also potentially help with mix translation. I theorized by shading the PA it would force us to make tonal decisions based on what we heard in the room that would work both in and out of our room. That line of thinking led me to study Equal Loudness a bit more and really look into some of the differences in our perception of sound at different volumes, and I have to say I actually walked away with a pretty good EQ compensation setting to counter the effects of Equal Loudness.

However, looking at it all now I’m pretty sure I was barking up the wrong tree. It happens to all of us.

The EQ compensation settings I came up with were definitely a win for me, but I’m convinced now that the system side of things was not the place for them. So what changed my mind?

Well, long-time readers probably know that my friend, Robert Scovill, has been a very large influence on my approach to tuning PA’s over the last few years. When he was in town a few weeks ago he was very gracious to give me some coaching while we looked at some stuff on the PA. In a very short amount of time he affirmed one of my fears; that we had been chasing our tails with EQ on the system. It’s an easy trap to fall into and looking back at the last four months it makes perfect sense to me how we ended up there.

It starts with a little tweak one week that seemed to work so you leave it on. Then the week after you need to tweak a bit more, but instead of first turning off what you did last week, you just add to it. Then you add some more and more and more and more. It’s misleading because the overall mixes seem to be better week to week, but the PA is slowly getting strangled.

So we peeled all the processing away to start with a clean slate, and after maybe 20 minutes of working on the main arrays everything sounded better. We had less EQ on the system than ever before, and the whole thing just seemed to open up. I hate the whole three dimensional description of sound that some folks like to use, but that might be another way to describe it. Most importantly for me, though, this was the first time the MICA’s were giving me the warm fuzzies I had previously only experienced from some other manufacturers’ rigs. And make no mistake, I live for line array warm fuzzies.

I mixed rehearsal that night, and that’s when the system really started to show its true colors. The MICA’s were really a breath of fresh air to mix on. It was just one of those mixing experiences that I didn’t want to end. I was really enjoying myself for the first time in a few months and remembering how I loved doing this mixing thing. My old vocal chains were finally working again, and if anything, I needed less processing than ever before. The rig still needed some little tweaks, but all-in-all it was meeting the expectations I had for it.

And of course the resultant transfer function we arrived at was essentially a linear transfer at the mix position (see accompanying photo). It might still get a little bit of tweaking in the 200 Hz range, but on a whole it plays so much nicer now. So, yeah, I just renewed my subscription to the Linear PA fanclub.

Now, I’ve still got at least one more chapter in this series of posts. Once the system is right, there’s still this whole translation issue. We still have a dynamics challenge to contend with; that didn’t magically go away when the rig got right. If anything, I think it may become more apparent.

Next up I’ll actually look at some of my own experiments–really, I will this time–along with some other little things I’ve set up to help with the dynamic and tonal challenges of getting an entire Sunday to translate outside the room. And I’ll also tease that most of these are things you probably don’t need a $50k+ console to do, either.

Permalink | 2 comments
Categories: Audio, System Optimization, Year of the System - 2010

August 2010 Webinar: Point Source vs. Line Arrays

Dave — Sat, 21 Aug 2010 18:05:24 +0000

I’m currently on vacation, but I wanted to give you a quick heads up that our August webinar will be this coming Tuesday, August 24th at 10pm EDT. This month Mike, Jason, and I will be talking about line arrays and point source approaches to loudspeaker systems. There’s no magic bullet when it comes to loudspeaker system designs, and we’re going to try and bring some of our actual experience with both approaches to bear on this topic so we can cut through things like fads, hype, and old dog resistance so you can be a little better informed when it comes to deciding the best approach for your own needs.

We’ll be back at our Livestream channel for this month’s festivities. See you Tuesday!

Permalink | No comment
Categories: Audio, Webinars

A Quick FFT Tip For the Weekend

Dave — Fri, 06 Aug 2010 21:24:14 +0000

I had the privilege to spend a lot of time with Robert Scovill this week while getting ready for the Avid webinar, and the downtime in between setup and the webinar was filled with a lot of audio geekery talk about almost everything audio we could think of–I apologize for not running a tape recorder the entire time. This quick tip comes out of those many conversations, and I’m sure there will be more in the coming weeks and months.

So this is a cool little thing you can do if you are a Smaart or other FFT user using our handy-dandy transfer function. While Robert and I were discussing system optimization, he mentioned that on the current Petty tour he likes to take a reference trace at Tom’s mic position. Why, you ask? It’s a lobe study. By looking at a reference trace of the PA from the lead singer’s position–or maybe senior pastor in our case–he can get an idea of what kinds of strangeness might be happening behind the PA. That little reference trace can give him some quick insight into where he might have gain before feedback issues during the night.

This week is our first week out on our new stage extension so gain before feedback is definitely something we’ll be watching a little more than we’ve had to. To get a leg up, I took a cue from Robert advice and took a measurement out on the new extension. My measurement trace quickly confirmed an area that was a problem during rehearsal earlier in the week while also revealing a couple other areas to watch. Problem areas appear as non-linearities in the trace; the areas of the trace that have more energy are the places to watch. I made a few notes for Sunday, and then shut the whole thing down. The whole thing only took a couple of minutes, and is something I could even pretty easily repeat on a Sunday morning.

And while I’m on the topic of Scovill, if you’re serious about this audio thing you really owe it to yourself to attend one of his classes like The Complete FOH Engineer course. Robert is a great teacher with a level of humility that is unfortunately rare for a professional with his level of experience and knowledge.

Permalink | One comment
Categories: Audio, System Optimization

One-Off Webinar – August 4th

Dave — Thu, 29 Jul 2010 03:36:27 +0000

Next Wednesday I have the privilege to take part in Avid’s monthly Live Sound Webinar. The topic for the month is achieving great mixes in houses of worship, and as it’s Avid’s webinar we’re definitely going to be talking about VENUE and its impact on how we do what we do. If you’ve been reading this blog long enough, I don’t think it’s a secret that the VENUE has been a big part of what I do for the last five years, and now I get to be shameless about it….

The webinar is Wednesday, August 4th at 1pm EDT, but they typically archive these things in case you can’t make it. Although, if you’re not there live, you can’t ask any questions. The webinar is free, but you do need to register in order to attend.

Permalink | No comment
Categories: Digidesign Venue, Webinars

Harsh Reality: Part 2 – A Dynamics Challenge

Dave — Tue, 27 Jul 2010 03:44:03 +0000

Inverted Fletcher Munson Contours

In my last post I started talking about Equal Loudness, and the comments seemed to skew more towards considering Equal Loudness for system optimization. While that might factor a bit into where I’m going with all this, that’s not quite what I’m really getting at right now. But for the record, I’m still in the linear PA camp using Smaart, SysTune, SIM, etc., to get there. I’m just not a believer that there is one right way to do things when it comes to the world of audio which is part of why I float Dave Rat’s approach to tuning his PA out there. But I digress…..

So what does Equal Loudness have to do with what we’re doing in church audio? Let’s start with a quote from Bob McCarthy’s book Sound Systems: Design and Optimization as he takes a brief look at the Equal Loudness Contours:

This does, however, put us on notice that in order for listeners at different locations to perceive the same frequency response we will need to match both frequency response and level. If the level is not matched, the listeners will perceive a matched frequency response differently due to their ear’s non-linearity over level.

Bob McCarthy – Sound Systems: Design and Optimization

So we have a challenge, and that challenge relates to a debatable concept: live mix translation outside our room. In this day and age of webcasting, podcasting, and who-knows-what-casting still to come, I believe mix translation is becoming more and more important to what we do with church audio on a weekly basis. This is especially true as budgets and resources become more and more limited, and it really becomes the job of the lone FOH mixer to provide a mix that can literally go around the world. And while the concept of a mix that translates may be true to an extent for just about any mixer in a live environment, I do believe we have a unique challenge that can be difficult for those outside our little church audio niche to understand.

The way I see it, we have a dynamics challenge. The dynamic range of a modern church service can run anywhere from 20-40 dB, and I’m talking RMS levels–not peak to average. However, the range we are probably used to listening to at home or in our car might be closer to 10 dB, and maybe less than that at times. So let’s look a little closer at this.

It seems there are generally two main components to just about every church service these days: talking and music–I’m skipping video for now, but I’ll probably touch on it a bit in another post. I don’t know what other churches are doing, but the volume of talking in our services is usually pretty close to the volume I would listen to talking in my car or at home. It’s almost conversational in level. So going back to system tuning, a linear PA can be great in the case of talking because if it sounds good in the room, in theory, it’s probably going to sound good if I play a recording back somewhere else. We’re mixing near the same level our content will playback in other rooms/environments.

But then there’s that whole music thing. When I talk with other church sound guys, it seems the trend with music these days seems to be moving towards louder music especially with more modern music styles. The result is the level we listen and mix music at for services in our rooms is moving farther away from the level we listen to in smaller environments like our car or home or on an iPod. In fact, the level we’ll listen to music at outside of our rooms is actually probably closer to that same level we’d listen to talking at.

Look back at that Bob McCarthy quote above. Knowing what we know about Equal Loudness, if we are making tonal and mix decisions based on our perception of sound at a given volume that is different from some of the places we’ll listen to it, what happens when we listen to the same mix at that different volume? Think about what will happen if we webcast/broadcast that mix for people to listen to on their laptop speakers or through their TV? When we start to understand equal loudness contours, we can start to see that we are going to perceive things a bit differently at home than how we perceived things in our louder live mix location.

Looking back at Dave Rat’s approach to tuning a system, we know from his video that he gets his tones and balance through headphones. In a way, he’s simulating a studio-esque, controlled environment for his mix. He builds the mix on the console and then modifies the PA so that the mix translates from night to night in different rooms at a volume that is probably quite higher than what he pumps into his ears through a pair of headphones. If those headphones are linear in nature, do you really think his PA’s get tuned to be linear? I haven’t heard Dave’s mixes, but knowing what I know about Equal Loudness, I would guess if he played his headphone mixes back through a linear PA they might lean towards being somewhat bright and harsh.

But back to our audio niche and the big question: Is it really that big of a deal if at most our music is 20 dB or so louder than that studio environment? In fact, how many churches out there even have a 20 dB difference to contend with? I’ll even admit that on paper, the curves might look a little different at a glance. Some might characterize them as subtly different. However, I would contend that the mixing business is all about the manipulation of subtleties.

Up next I’ll start to look at some of my own experiments related to the equal loudness phenomenon and some of the challenges that got me looking more in its direction.

Permalink | 6 comments
Categories: Audio, Mix Magic & Sorcery, System Optimization, Year of the System - 2010

Harsh Reality: Part 1 – All Things Not So Equal

Dave — Wed, 21 Jul 2010 12:26:21 +0000

Fletcher-Munson Contours

I’ve been wanting to thrown down some thoughts on something for a while now, and Dave Rat’s latest video on EQ’ing a sound reinforcement system has provided actual motivation. Today I’m going to be talking about one of my favorite audio subjects. If you are streaming your services online using your FOH mix, I think this is important stuff to understand because it can bite you and is what I think might be one of the major challenges facing audio in church world right now.

So, quick refresher for those tuning in. One of the big concepts I’ve beat a drum on is the concept of a linear PA and optimizing to achieve this. Basically the theory is that what we deliver to the PA is what we should hear; the loudspeakers should sound just like the outputs of our console. This is kind of a big system tuning approach that a lot of big names get behind like Meyer, Scovill, McCarthy, etc, etc. Of course like many things in audio world, there are other approaches.

For example, I feel confident in saying that Dave Rat(Red Hot Chili Peppers, Rage Against the Machine) does not tune his PA to exhibit linear performance. I haven’t talked to Dave or even watched him tune his rig, but I have a good sense of this simply from his philosophies on tuning that he outlines in his video. Now I don’t think there’s anything wrong with how he tunes his rigs, and in fact, I’m starting to wonder if in some circumstances it might be a better approach.

So what clued me in on Mr. Rat’s optimizing preferences? Something very simple: his board tapes sound like CD mixes. In the world of sound reinforcement this doesn’t always work if you tune the PA linearly, and it’s basically a consequence of our good friend Equal Loudness. Equal Loudness is a concept I first learned about in college, and it’s something that has always interested me. I touched on this a few months ago, but today I want to start to dive into the stuff I’ve been dwelling on lately.

So, brief school lesson on equal loudness. Equal Loudness is all about perception and the way we perceive loudness of frequencies. Equal Loudness is basically the reality that we humans don’t perceive all frequencies equally when we hear different frequencies at the same measurable sound pressure level. This is a backwards concept at first glance because the reality is we don’t hear things equally. Our ears are NOT linear. However, the concept is referred to as Equal Loudness based on studies that have been done to measure how loud frequencies need to be for us to hear them equally.

The Fletcher-Munson contours displayed here are one of the first/more-famous studies done on equal loudness, and as I just mentioned, the curves display how loud a given frequency needs to be for us to perceive it at the same volume as another frequency on each contour. When the studies were done, they would typically play two tones for a subject: a 1k tone followed by another frequency. The subjects would then confirm when the two tones were perceived to be the same loudness. There have been more studies done over the years, but the Fletcher Munson graphs are easier to find on the internet and aren’t that far off from the current standard, ISO 226:2003.

Of course, the plot thickens with equal loudness as our overall sound level changes. If you look at the different contours, you will notice that our perception changes as volume increases or decreases. Basically, if we turn the volume up or down on our stereo, our perception of the spectral content of what we’re listening to will change. So, it’s almost like there is an EQ in our brain that changes dynamically as we’re exposed to different volumes. It’s wild stuff.

To better understand this, I like to look at the curves after flipping them. This way I can see what that brain EQ is actually doing. What I can see is that when things get louder(the lower contours), our perception tends to get more even, although we tend to get more sensitive to the 4 kHz area. When things get turned down, we gain increased sensitivity to low-mids in the 400-500 Hz range while that 4 kHz bump comes down a bit.

When I start to look closer at Equal Loudness and how it affects our hearing perception, it makes me wonder if the concept of having a perfect mix that sounds great at any volume is really achievable. Next up I’ll start looking at how this applies to us more specifically in Church World.

Permalink | 8 comments
Categories: Audio, System Optimization, Year of the System - 2010

July Webinar: Take 2

Dave — Wed, 21 Jul 2010 04:51:19 +0000

Thanks to everyone for their patience with the webinar. Unfortunately technology derailed us in our first shot at the July webinar, but we’re going to try again this Thursday on Livestream.

Thursday July 22
10pm EDT
Church TechArts Livestream Channel

Permalink | No comment
Categories: Webinars

Mixing Webinar Tonight

Dave — Tue, 20 Jul 2010 22:16:49 +0000

We’re back at our Livestream channel tonight for the webinar. We’ll get rolling around 10pm EDT. See you tonight!

Permalink | No comment
Categories: Webinars

More Mixing for the July Webinar

Dave — Mon, 19 Jul 2010 03:37:46 +0000

Well, the July webinar has arrived, and this month we’re going to continue our discussion from last month about mixing. The webinar will be this Tuesday, July 20, at 10pm EDT. We might be trying a new provider this time out so I’ll have the link here before we go live on Tuesday night. See you then!

Permalink | 2 comments
Categories: Audio, Mix Magic & Sorcery, Webinars