Old Production Takes From an Old Guy

Month: February 2011 (Page 2 of 2)

CTA Classroom: Using a High Pass Filter in Video Production

Let’s admit it: It happens a lot. Even when you pay careful attention to the audio you record for a video, and you used a good mic (you did use a good mic, right? if not read this…), you can still end up with a bunch of background rumble and noise in your recording. It happened some time ago at the video production company I work for.

They were shooting in a grocery store, capturing some interviews. They used a good shotgun mic, with good directivity to cut down on the ambient noise. However, there were dreaded refrigerator cases all over the store, and if you listen carefully (and you have to because our brain normally tunes them out), you’ll hear the refrigeration compressors running. Back in the studio, it sounds like a truck going by the whole time.

Because it’s a complex noise source, trying to run a noise reduction program on it probably won’t work well (and even when the noise goes away, it is often replaced by unwanted digital artifacts of the FFT process used to perform the noise reduction—but that’s another post). However, we do have one tool in our utility belt that can help (actually two, I’ll get to the second, which should actually be the first, in a minute): Enter the high pass filter.

A high pass filter is just what it sounds like—it lets high frequencies pass, while blocking low frequencies. Super-basic HPFs are a simple on and off switch with a pivot frequency (the frequency at which it “passes” signal) and slope (how quickly it drops off the signal below the “pass” frequency) set at the factory. Better HPFs that come with higher level editors like Premier Pro and Final Cut allow you to select the pivot or threshold frequency.

Here is an example of an HPF with a threshold frequency of 120 Hz, and a slope of 12 dB per octave (that is, at the frequency 1 octave below the threshold—60 Hz—the level will have been reduced by 12 dB).

High Pass Filter Example Graph


You can see how the frequencies above the threshold pass by unaffected, while the ones below get rolled off pretty quickly.This is when it actually gets useful. For the male voice, the fundamental frequency of the lowest notes one speaks is between 85-155 Hz. For a female, it’s a little higher, perhaps 165-225 Hz. This means that there is no real information that we need below 85 Hz for males and 165 Hz for females. And in reality, because of the way we hear and the way the voice is produced, there are plenty of harmonic frequencies that our brain will interpret clearly to make up for missing fundamentals.

So let’s say we have a refrigerator running in the background of a female interview. We can safely dial up a HPF with a threshold of 165 and not loose any of her voice. We can take it up even higher to eliminate more of the noise, and the clarity will improve markedly. In fact, the voice will “sound” louder once the low frequency stuff is removed because we can hear it better.

So this is exactly what we did for grocery store woman. We dialed up an HPF with a threshold at around 150 Hz, and it totally transformed the audio. There was still some higher frequency noise, and it was obvious she was standing in the store and not a studio, but the clarity of here voice was improved substantially.

Earlier I mentioned we actually have 2 tools in our tool belt. The other one may be on the mic itself. Many professional shotgun mics (and some interview mics, and the occasional lapel mic) have a HPF built in. For example, my beloved Audio Technica 835B has a switchable roll off at 180 Hz at 12 dB per octave. That means at the lowest fundamental of a male voice the mic will be 12 dB down, which is generally not a big deal unless you’re interviewing James Earle Jones. Normally, I like to leave this switched on because it eliminates a lot of room rumble, AC noise and other nasties right at the source. It’s just a good idea. If you use this when you shoot, you will require less processing in the edit suite.

Of course, you’ll want to listen to it through some good headphones first to make sure you’re happy with the sound. You do have good headphones, right?

Today’s post is brought to you by DPA Microphones. DPA’s range of microphones have earned their reputation  for exceptional clarity,  high resolution, above all, pure, uncolored accurate sound. Whether recording or sound reinforcement, theatrical or broadcast, DPA’s miking solutions have become the choice of professionals with uncompromising demands for sonic excellence.

Superbowl Halftime Debacle: 2011 Edition

Ever since Sunday afternoon, when I was roused from my peaceful state of napping by my daughter chirping about how bad the sound was, I’ve been thinking about the halftime show. Based on the traffic on Twitter and various audio forums during and since, I’d say it’s a day that will live in infamy. Much hay has already been made about the event, and I won’t be pouring much gasoline on the fire (sorry…). Suffice it to say that mistakes were made and the result was less than optimal.

It’s pretty obvious things didn’t go well that night, and while I’m completely baffled at how that got on the air (let alone how the Peas were chosen to perform…), I think we better spend our time figuring out what we can learn from the event.

I actually have several reactions to what happened. First of all, I think it’s good to be reminded that what we do every weekend is incredibly difficult. Obviously, most churches don’t have several hundred people running around on stage with LED Tron outfits on, but from an audio perspective most of us handle more inputs on a regular weekend than they had for the Peas. And even with a production budget that exceeds most church’s annual budget (probably by a factor of 2-10), things still went horribly wrong.

Since it’s so easy for a single big mistake or failure to ruin the show (or for that matter, a series of cascading smaller disasters), it’s important to think through contingency planning. But that’s not what I want to talk about today.

Really, I want to put things in perspective. So for all you pastors and worship leaders out there who get your panties in a wad every time the mic isn’t on at exactly the right moment, chillax, OK? Just say, “Good morning!” again and go on with your life. Keep in mind that it happened at the Superbowl, and even though it sounded terrible, nobody died. And chances are you’re not preaching to an audience of 100 million on worldwide TV. So relax. Don’t publicly berate your tech team in front of the whole congregation.

And if you ever find yourself wondering, “How hard could it be? It’s just five faders!” I encourage you to remember the Superbowl. And, just for fun, why don’t you try it sometime? After all, how hard can it be? I think it’s also important to keep in mind that the production team for the halftime show had a year to plan and a month to rehearse. We do church every weekend, and often, we don’t know what’s going to happen until we get there (or maybe Thursday if your church is really on the ball).

Now, this is not to excuse perpetual poor performance. I think we should always strive for excellence and as sound techs, we need work hard to get the mics on when they should be and produce great mixes. But if you have a bad day, don’t head for the bridge. And like I said, pastors and worship leaders, don’t throw those hardworking techs under the bus.

You don’t get to mix anything at the Superbowl by being a flunky. Clearly whatever went wrong went wrong to someone who has been doing this professionally for a while. They’ve probably had some training.

Pastors, when was the last time you approved any training for your techs? Do you have a handful of well-meaning but poorly trained people behind the sound board? If so, stop complaining about it and pony up some funds to bring someone in to train them (I’m available on a limited basis…).

And while it may not have sounded like it, the crew at the Superbowl were working with some top-shelf gear. At your church, are your sound techs working on equipment that was manufactured when there was a Bush in the White House? The first time? Again, maybe it’s time to open the checkbook and get them the equipment they need. You’d never consider forcing your children’s department make do with broken and dangerous toys; why is it OK to put that on the tech team—and then let them have it from the pulpit when something goes wrong?

I’ve been doing this church tech thing for a long time, and I’ve made my share of mistakes. But I’ve tried to learn from them and have spent literally thousands, no tens of thousands of hours learning my craft. And the reason it’s taken so long (and why I continue to pursue my technological education) is because what we do is hard. At lot is on the line, and a lot can go wrong.

I want to wrap this up with two thoughts. First, if you’re a tech, especially a volunteer, I want to say I’m proud of you and appreciate what you do. If you make a mistake, don’t fret it; we all do. Regardless of what others may think, there is a lot to this, and it takes time, a long time, to get really, really good.

Second, I want to encourage the rest of you out there, pastors, worship leaders and congregants to thank your tech team this week. They work really hard so you can have a great worship experience every weekend. They don’t always get it right, but let’s be honest, neither do you. Pat them on the back, look them in the eye and tell them you’re thankful for them. I can almost guarantee that if you do that regularly, your results will improve—especially if you follow the rest of the advice in this post.

This post is brought to you by Horizon Battery, suppliers of  award-winning Ansmann rechargeable systems that are used worldwide by Cirque du Soleil and over 25,000 schools, churches, theaters, broadcast companies, & businesses. Learn more about their pro-grade batteries and chargers by visiting their web site. Tested and recommended by leading wireless mic manufacturers and tech directors.

Church Tech Weekly Episode 33: Chain Smoking Grand Poopbah

It’s like the band is back together! Mike & Van are joined by Colin Burch and John David Boreing to talk about getting the sermon online. We talk about the recording process as well as post-processing. Stick with it to the end and the title actually makes sense!

Van Metschke
Colin Burch
John David Boreing

Picks of the Week:

Remote Access Apple-Style

After quite a few @replies on Twitter this weekend, I figured I should write up a quick post on how we’re doing remote access at Coast Hills. But first, a quick rundown on what we access remotely. We have five computers at FOH all but one of which is a Mac Mini. Two of them are BootCamped to Windows 7, the other two run 10.6. Here’s what we’ve got; the SD8 remote (Win7), the Roland remote (Win7), iTunes playback and LAMA. We also have a 17″ MacBook Pro running Reaper for virtual soundcheck. We routinely access the SD8 and Roland remotes from down on the floor (FOH is in the balcony) to adjust the mix or the M-48s for the band. It’s also nice to have a look at LAMA once in a while from down there.

Network Diagram Here’s a simplified view of our Sound network.Now, for remotely accessing one Mac from another, it’s super-easy; just use the Mac’s built-in Screen Sharing. The Screen Sharing app is really just a VNC app, that accesses the VNC server that is configured in the Sharing preferences panel. Open a new finder window, select the Mac you want to screen share (assuming you have File Sharing turned 0n), and click on “Share Screen…”

Mac Screen Sharing This is how easy it is to take over the family computer…The Screen Sharing app will launch, ask for login credentials and you’re good to go. You can now completely control the other Mac as if you were sitting right there. What a lot of people don’t know (in fact, I didn’t know it until recently) is that you can use the Mac’s built-in Screen Sharing app to access Windows computers. Now, it’s important to note that you’ll need to install and run a VNC server on the Windows box. Unlike Macs, Windows doesn’t have a built-in VNC server (I know, lame…). We use RealVNC, which is a decent and free server. My ATD Isaiah set it up so it launches automatically at launch.

Now to get to the Windows box, go to Finder, select “Connect to Server…” (Cmd-K) and enter the IP address of the computer you wish to access preceded by vnc://.

Connect to Server Using the IP address to get from Mac to WindowsScreen Sharing will launch, you’ll be asked for the password and in just a second you’re controlling the Windows machine. Personally, I much prefer Screen Sharing to other VNC apps like Chicken of the VNC (even though that is perhaps the most cleverly named app ever…Chicken of the vnC, Chicken of the Sea…get it?), mainly because Screen Sharing just seems to be a smoother, more seamless experience.

Now all that’s cool, but we decided to kick it up a notch last week. See, we have all of those aforementioned computers connected to a dedicated sub-network called “Sound.” It has it’s own IP range (a 10.0.xxx.xxx vs. our regular church’s 192.168.xxx.xxx), and is only connected to the regular church network through the Airport Extreme. So what we normally do is connect to the Sound Airport, then remote in to the computers. That works OK, except our laptops and iPad normally default to connecting to the regular wi-fi network, and we have to keep changing it. So last week, Isaiah decided to configure Port Forwarding.

We have the Airport connected to the church network through the WAN port, so it’s easy to get from the Sound network to Internet. But getting in doesn’t work as well. At least it didn’t. To make it work, we launch the Airport Utility and configure a few settings on the Airport.

AirPort Extreme Advanced Tab Step one in configuring port forwardingSelect “Advanced,” then the “Port Mapping” tab. Click the little “+” at the bottom of the list to add a new rule. That opens this dialog.

Port Forwarding VNC protocol uses Port 5900 by default.What we’re doing here is telling the Airport, “If anyone out there (192.168.xxx.xxx comes knocking on door 5900, send them here (10.xxx.xxx.52).” In our case, “this address” is the IP of our SD8 remote computer. You’ll notice in the “Connect to Server” dialog above, the address is a 192.168.xxx.xxx address. That’s the address of the AirPort Extreme on the regular church network. If we were connected to the church network and tried to put in the SD8 remote address directly, it wouldn’t work (two different IP ranges). So instead, we hit the Airport and the Airport forwards that traffic on to the appropriate address on that network. Here’s the result:

iPad Remote Access The iPad is connected to the regular church network, but controlling the SD8 remote on the Sound network.Our iPad, on the church network, is controlling the SD8 remote on the Sound net. Cool, huh? We suspected there might be some slowdown, but in using it all weekend, it’s no slower than connecting directly.

So that’s good, except we have two Windows boxes up there that we need to access. But since we already forwarded VNC traffic to the SD8 computer, how to we get to Roland? Simple: Configure another port.

Port forward configuration Instead of 5900, we’ll use 5901Compare the Private IP Addresses: the SD8 remote is 52, the Roland remote is 55. So what we’ve done is tell the Airport, “If anyone comes knocking on this other door (5901) send them here (10.xxx.xxx.55). If we want to connect to Roland from the church network, we specify the port after the IP address (remember, by default the VNC protocol uses 5900).

Connect to Server Note the :5901 after the IP address; that specifies the port.The base address is the same, our AirPort Extreme; only this time we specify port 5901. Here we go.

Roland Screen Sharing And now we’re connected to the Roland remote.On the iPad, we use an app called Desktop Connect, and it’s easy to specify a VNC port to direct the traffic like this. So now we can either switch networks and connect directly, or stay on the regular church network and control whatever we need to. And it’s easy to save both configurations of those machines so once we set it up, we select the appropriate configuration depending on which network we’re connected to.

I should point out that we don’t need to configure port forwarding for our Macs, because we have them dual-homed. The Ethernet connection goes to the Sound network, while the Airport connects to the church network. One more reason to run Mac whenever you can…

Other important safety tip: I’m not an IT expert, so if you start asking me questions, I may not be able to answer them. Just trying to manage expectations. Now that I’ve told you how we access the computers remotely, I’ll start working on another post that will give you the practical implications of doing so.

CTA Classroom: Understanding VCAs and DCAs

Today I’m going to try to make sense of some of the most useful and perhaps misunderstood faders on a mixing board, the VCA (or on a digital board, the DCA). Right off the bat, I should acknowledge that not all mixers have VCAs. They are typically found on larger-framed analog consoles, and most digital boards have some implementation of them. VCAs are known as VCAs on every analog desk I can think of; however digital manufacturers call them by various names: Yamaha has DCAs, DiGiCo refers to them as Control Groups and most everyone else just calls them VCAs. Regardless, they all act pretty much the same. It’s important to note a VCA is not the same as a group, though they are often used similarly.

A group is an actual mix bus; that is, a set of channels are sent to the group post-fader and are thus “mixed” to that bus or group. For example, if I was using Group 1 for my drums, all of my drums would be mixed to Group 1, and the output of Group 1 would then go to the main L&R mix (after the Group 1 fader, of course). That can be very useful for a lot of reasons, but it does add an additional gain stage.

VCAs on the other hand are sort of like a remote control for the set of channels assigned to that VCA. VCA stands for Voltage Controlled Amplifier. Basically what the VCA control does is affect the signal coming off the faders for every channel in the VCA group. So, if you lower the VCA control by 10 dB, it is like lowering each individual channel fader in the VCA group by 10 dB as well, only the faders don’t actually move.

The difference is that typically (but not always) the channels controlled by the VCA are sent straight to the main L&R mix, without going through a Group mix. Sometimes VCAs and Groups are used together, and there are very valid reasons for doing that, but for the purposes of this discussion, we’ll assume that all the input channels are going straight to the L&R mix.

By now, this is starting to get confusing, so let’s look at some visuals. In this example, I’m using three input channels, Kick, Snare and Hat, and a single Drums VCA control. These images come from the DiGiCo SD8 software because they include a handy gain indicator which makes it easy to see what’s going on. However, the concept is the same regardless of what desk you’re mixing on, analog or digital. The same thing is going on behind the scenes, it’s just that DiGiCo makes it easy to peek behind the curtain.

VCAs at unity

So here we are in our example. Notice the yellow-highlighted box; all three channels are currently at 0 dB, or unity (the faders are not adding nor subtracting gain from the signal). You also see that the blue strip labeled “Drums” is also at unity, which means it’s not acting on any of the channels assigned to it. To make it clear what’s going to happen, let’s move some faders around.

Now you can see we’ve boosted the kick by 5 dB, cut the snare by 5 dB and boosted the hat by 2 dB. The VCA is still at unity, so it’s not acting on the channels yet. This is where the fun begins. One of the great things about VCAs is that they affect the individual channels by the same relative amount. So you can raise or lower the VCA and while the individual channels will go up or down, they will do so maintaining the relative balance between them. Not clear? Check this out.

Now we can see that the VCA fader has moved down by 10 dB, and it’s also lowered each channel by 10 dB. The kick was at +5, it’s now at -5. The snare was at -5, it’s now at -15. And the hat was once at +2, it’s now at -8 (this display rounds to the nearest whole dB; I didn’t notice it until I had the graphics finished and didn’t feel like going back and fixing them all…). In reality, it goes down by 10 dB, I must have had it slightly lower than +2.

Anyway, you get the idea. VCAs also work the other way.

Here I raised the VCA by 5 dB, and you can see it adds 5 dB to each channel. VCAs are wonderfully useful for controlling a large group of inputs with a single fader, perhaps the best example is the drum kit. You might have 8-10 mics on a good-sized kit and trying to raise or lower the overall level of the drums all at once is very tricky, especially if you’ve turned some faders up and some down. With a VCA, it’s a simple matter of moving the single VCA fader to make them louder or softer.

I also use VCAs for turning the band on and off. I have 4-5 VCAs set up for the band and vocals and by grabbing all them, I can quickly dispatch all 20 or so channels of the band.

Here you can see that the VCA fader is off and the channels are showing significant amounts of attenuation. While not completely off, they are effectively off, and that’s good enough for my purposes.

Different boards use various methods for assigning channels to a VCA, but it’s not hard. Sometimes there are VCA assign buttons on each fader, other times, it’s a matter of selecting the VCA, then selecting the channels you want to include in that VCA’s control.

It’s important to note that it is possible to have multiple VCAs controlling the same channel, and in that case their effects are cumulative. It’s easy to assign a channel to a VCA, then turn that VCA off and not be able to get signal out of the channel, even though the fader is at unity. I used to get caught by this on the M7 all the time. When you start working with VCAs, start slowly until you get comfortable with them. They’re not hard to use, and are immensely useful. Once you master them, they can make your mixing a lot easier.

What’s Your Definition of Success?

The other night my good friend Van Metscke was over at my house recording Church Tech Weekly. It’s fun when we get to do that in person because we usually get to talking afterwards. As often happens, we talked about a wide variety of subjects. One thing that we talked about was people who work for us. We both agreed that a lot of people tend to get threatened when their subordinate starts to surpass them in knowledge or “success.” Van and I both feel that if we’re doing our jobs right, the people who work for us should surpass us. It’s a simple principle of multiplication; if we pour into them everything that we know, that gets multiplied by what they know and what they learn while working for us. Hopefully they’ll go on to bigger and better things, and we can take a small amount of pride knowing that we helped them on their journey.

Stan Sliver was the guy who got me thinking about this almost ten years ago. Ironically enough, Stan was the HVAC contractor I used when I was building a retail business (long story…). He was then in his 60’s and had been doing HVAC work longer than I had been alive. Not only did he do great work, but he also explained everything he was doing. If he thought I could do something, he’d loan me his tools, teach me how to do it and not charge me for anything. One day he said to me, “Mike, if you ever have any questions about what I’m doing or way, please ask. I’ve been doing this a long time, I can’t take any of this knowledge with me.”

I know a lot of people in our business who want to closely guard their “secrets.” They somehow feel that makes them indispensable or at least more valuable. That may work out for a short while, but here’s something you need to know. Taking that tack is not a good long-term plan. The next generation of techs will surpass us in knowledge whether we help them or not. I’ve got a few young guys working for me (as staff and volunteers) who are crazy-smart. The way I see it, I can either be part of their success story or get left behind anyway.

Anyone younger than 25 years old doesn’t know a life without computers. They don’t know how we ever existed without everything networked together. They can’t figure out why we can’t control everything with our smart phones yet. Figuring this stuff out comes as easy as breathing. If you’re an old guy like me, you can figure it out, too; it just takes a little more time and effort.

But hear this fellow old guy; while the young guys may know how to use technology, they may not always not know why. They may not know how to interact with a difficult worship leader or senior pastor. They may struggle with troubleshooting because they haven’t had as many things go wrong for them as we have. That’s where we come in. We can help them develop those skills. And if we’re really smart, we’ll be learning from them as well.

If you’re an old guy in this business, find someone younger than you to pour into. Don’t be afraid they’ll steal all your secrets and replace you. Sure they’ll surpass you, but look at it this way—when they land that big gig on a big show, they’ll get you backstage passes (at least that’s what I’m hoping for…).

And if you’re a young guy, find an old guy to work with. Ask questions, pay attention and learn from them. And share your knowledge with them, too. We’re not in competition with each other; we are all working together to advance the Kingdom here.

One more story: Many years ago, I was leading the youth group of a small church in Ohio. One of the junior high guys and I became fast friends because he was a techie geek who loved Macs. We ended up spending a lot of time together talking about technology, theology and life. I was there for most of his high school life. We stayed in touch when he went to college, after his graduation and after he started working for a national radio program. A few years ago, he got married to a wonderful woman. I was able to go to the wedding, and the impromptu “bachelor” party that happened the night before.

It was weird being there as everyone in the room was 15 years younger than me. All the guys shared something about Zach and what his friendship had meant to them. When it was my turn, I shared some things (I don’t even remember what now), and after I spoke, he stopped and told me what a huge influence I had been in his life. He told me that a big reason he was who he was because of all the time we spent together. And he said he was so honored that I would drive all the way to Nashville just for his wedding.

I’m not going to lie, it wrecked me. It also challenged me. It made me ask if I’m making a regular habit of pouring into others. Now I don’t share this to tell you how great I am, because the truth is I don’t this nearly enough. But if you’ve never had someone tell you that you’ve been a huge, positive influence in their life, you’re missing out. My young friend has already achieved more in his career than I had at that age, and I expect him to keep climbing. As for me, I’m just glad to have been part of his journey. And that’s my definition of success. What’s yours?

This post is brought to you by Horizon Battery, suppliers of  award-winning Ansmann rechargeable systems that are used worldwide by Cirque du Soleil and over 25,000 schools, churches, theaters, broadcast companies, & businesses. Learn more about their pro-grade batteries and chargers by visiting their web site. Tested and recommended by leading wireless mic manufacturers and tech directors.

Church Tech Arts Webinars: Analog vs. Digital Pt. 2

Following up on the first part of this great debate, the guys get back to it and talk about a few things that might appear deceiving about analog and digital desks, talk about various applications where one might be a better fit than the other and take a look at the future of audio mixing.

If you missed Part 1, we recommend you go back and listen to it first, as it will provide the baseline for this episode. If your church is in the market for a new audio console, we hope you’ll find this informative and useful as you debate formats.

Download this Episode (below) or Subscribe in iTunes

CTA Webinars: Analog vs. Digital Pt. 2

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