Church Tech Arts

It’s been a week since the FCC voted on the issue of White Spaces. The cynic in me believes that they chose Nov. 4 as their day to vote figuring the rest of the country would be earnestly following the other election, and they could escape any real critique. That may be, but the techies among us were just as concerned about what will happen to our wireless mic spectrum. 

Details are still coming out, but overall, it looks like generally good news for those of us who use wireless mics. I talked a bit with Chris Lyons of Shure and Kirk Longhoffer at WFX, and got a few more details. The short story is that the unlicensed white space devices will be limited to a few unused TV channels in each market, the will use spectrum sensing and geo-location to avoid other signals (which means churches can register their frequencies) and they are not allowed to use channels 14-20.

So overall, it’s good news. Kirk Longhoffer has a more detailed assessment that you can read at his site, TechnoPraxis. I just met Kirk and learned of his site at WFX, and I have to say, it’s a site to check out. Stay tuned for more details, particularly regarding the ruling on the 700 Mhz relocation plans. In the meantime, check out Kirk’s article.

While most Americans are busy watching the results of the presidential elections, those of us who regularly use wireless microphones have been anxiously awaiting the results of another vote. The FCC voted today to open up the “White Spaces” to other unlicensed devices from Google, Microsoft, Motorola and others. While this will be a boon to internet access, it is likely to be a nightmare for users of wireless mics.

So far, the white space devices have not been able to successfully detect and avoid wireless mics (and at times even TV stations) more than about 50% of the time. So over the next few years, expect to start having issues with wireless mics, even if you are properly frequency coordinated and under the 698 Mhz range. It’s a jungle out there, and it’s going to get more crowded. Don’t say I didn’t warn you…

As for the proposed 700 Mhz band relocation…well, I don’t know how that turned out yet. The final rules are not yet available. But as soon as I hear something, I’ll let you know. As we’ve been saying all along, start making a plan to move out of the 700 Mhz band, whether sooner or later. 

More to come…stay tuned!

Picking up where we left off, we’ll get back to soldering XLR cables today. This is an incredibly useful skill, as we probably use more mic cables (and break more mic cables) than any other. Today, I needed to make up a few 6-foot XLRs for our Worship Director, Jon. Jon needed to hook up his little mixer to the speakers in his office. It’s a simple job, here’s what to do.

First, assemble the tools you’ll need for the job. If you missed out on my first and second posts about soldering, you may want to go back and review. Here’s what you need. Left to right, you’ll need a soldering iron. You can find them at Radio Shack (one of the few things I buy there), or other electronics stores and of course online. You don’t need a super-fancy one with electronic temperature regulation. Just a simple 15-30 watt pencil tipped iron will do. My iron is switchable between 15 and 30 watts, though I leave it at 30 almost all the time. Next, a pair of diagonal cutters. These are the smaller ones, and spring loaded. Very handy. You’ll need solder of course, electrical grade–no plumber’s solder. The rosin inside the core is different between the two, so get the right kind. It comes in different thicknesses, and as I write this I don’t recall which I have, other than it’s the thicker kind they stock at Rac-Shack. The super-fine stuff is nice for mini-jacks, but XLRs take so much solder, the thicker variety is faster.

Also in the picture are some wire strippers. I like the kind I can adjust to strip all the way to 24 gauge wire, then count on the fact that I’ve stripped so much (wire that is) that I can tell when I’m through the insulation of thicker wire without nicking the copper. You may wish to get a wire stripper that is calibrated for different gauges of wire while you’re learning. A knife is very useful for cutting through the outer jacket of the mic cable. I use a box cutter I got when I worked at a grocery store in high school. But any sharp blade will do. Finally, there’s my vice, which is some 30 years old. It looks terrible, but is just the ticket for holding on to the connectors without burning my fingers. 

Let’s get stripping! Not so fast! Before you do anything, you want to slip the housing of the XLR connector down the end of the cable. There’s nothing worse than making a perfect solder joint on your connector, then realizing you forgot to do this step and having to de-solder the end off to put the housing on. Not that I’ve ever done that…

The first step is to carefully cut through the outer jacket of the cable. Make your slice about 1/2-5/8″ from the end. I normally try to not cut all the way through, then bend the cable at the cut and just touch the blade to the jacket at the cut line. This will split the jacket without nicking a bunch of the copper shield. Separate the copper shield from the 2 conductors, taking care to round up all the bare copper strands. Wrap them tightly together. Now if you’re using Mogami 2792 (and why wouldn’t you?) you’ll notice that both the 2 conductors are wrapped in black plastic. This black stuff is actually conductive, and it’s one of the reasons this cable is so immune to interference. Any junk that makes it past the copper shield is then shunted to ground via this conductive plastic. As great as it is, it has to go at the ends of the conductors. If you don’t take it off, you may find the cable buzzes slightly as the plastic forms a high-impedance ground to the positive and negative solder cups. So make sure you talk it off. Here, I’ve removed the coating from the red lead.

Next thing to do (after you get the black stuff off both leads) is to strip the ends of the white and red conductors. You don’t need much, just about 3/16″ should do it. Twist the copper strands together tightly, like you did for the shield. Next, we’ll tin the leads. Just like last time, put some heat on the wire, and touch the solder to the other side. Just a little bit here, you don’t need much.

You’ll notice that when you heat the wire, the insulation will melt back a little bit. That’s why you don’t need to strip too much off. Next, take your connector end, in this case a Switchcraft AAA series–my favorite, and chuck it into the vice. You need to make sure it’s not going to be moving around on you. You’ll want to fill the solder cups with solder. It should look something like this:

That’s kind of a lousy picture, but hopefully you can see the solder is coming just up to the top of the cup. Almost done now. Array the wires in the correct order for the pins. You want to make sure you follow the proper standards when building cables. With 2792, red would be hot or +, so it goes to pin 2. White is cold or -, so it goes to pin 3. The shield always goes to in 1. Switchcraft and Neutrik mold little numbers onto the ends so you know which is which. I like to start with the shield, since it’s the biggest. Heat up the solder in the cup, then drop the wire in, making sure to heat up the wire too. You want to get it all nice and hot so the solder flows together. Then remove the heat and wait. The solder will go from shiny and molten to a bit dull and solid. Then you can let go (and cool off your fingers). Do the same for the other two.

It should look like the above. Notice the solder is just up to the top of the cup, and everything is nice and neat. You don’t want solder dripping all over the place, and you especially don’t want any stray copper or solder connecting any two pins. 

Finally slide the housing up (you may have a few other parts if you’re using Neutrik NC3 series). But this is why I love the Switchcraft AAA series. There are two parts to the connector, and when you’re done soldering, slide it up, screw it together and you’re done.

That’s it! You’ve just successfully soldered an XLR connector on the end of some mic cable. Just make sure if you put a male on one end, you put the female on the other. Not that I’ve ever made that mistake…

If you missed the earlier posts on where to get supplies, or how to do unbalanced speaker connections, you can find them here and here. 

I made this cable for $6.80. It’s all top quality material, and it took less than 5 minutes (including picture taking). Buying one of comparable quality would set me (actually, the church) back at least $15-20. And it’s just plain fun. So go make some cables, huh?

In the previous post, we got started talking about groups. Most church sound boards have groups. Some have VCAs. As a church sound volunteer, it’s important to know what they do and how to use them. To recap, Groups are additional mix busses on your board that allow you to collect inputs and make them controllable by a single fader. That’s the vast over-simplified version anyway. A more elegant way to accomplish that task is with a VCA.

So now, picking up where we left off…

The VCA Masters from a Yamaha PM5000 (click to enlarge)

VCAs
VCA stands for Voltage Controlled Amplifier. The clears it all up, no? Well, how about this: According to Wikipedia, “A voltage-controlled amplifier is an electronic amplifier that varies its gain depending on a control voltage.” In other words, rather than controlling the level of a signal through a resistance network, the way a typical fader control does, a VCA uses changes in control voltage (which is adjusted by fader movement up and down) to control an amplifier that alters the level of the signal. In a non-VCA fader, the audio signal actually runs through the resistance network of the fader and the level is altered based on how much resistance to signal flow there is. Lowering the fader raises the resistance, lowering the level of the signal.

In a VCA desk, when you raise and lower the fader, you’re actually raising and lowering the control voltage that tells the amplifier to raise or lower the level of the signal. It’s kind of like the difference between a switch and a relay. A switch has the signal (say 110 volts of AC to power your light) flowing right through it. When you turn off the switch, you directly break the connection. A relay however is controlled by another switch. Flip the switch, and the control voltage tells the relay to close and let signal through. Hopefully, this is making sense.

VCAs have several advantages over regular faders. First, they last longer and are less prone to get “scratchy” because of wear and dust. Second, because the fader is not processing the signal, VCAs can be more accurate and precise. Finally, because a VCA is sort of like a remote control, they can be remote-remote controlled. Enter what is known as the VCA (really, they’re VCA Groups).

For the purposes of illustration, let’s assume that we’re using a 1K tone as our signal source, and that we have adjusted the head amp (or trim, or preamp, or gain, or whatever your board calls it) so that the channel, when in PFL (or solo) mode reads 0 dBu.

Let’s say you turn up channel 1 to 0 dBu, or unity. That tells the amplifier in channel 1 to let the signal flow with no gain or cut applied to the signal. When you lower the fader to -10, that tells the amplifier to apply 10 dB of cut to the signal.

Now, let’s say we assign channel 1 to VCA Group 1 (more commonly known as VCA 1). And let’s turn channel 1 back to 0. If we were to now lower VCA 1 to -10, that would tell the amplifier in channel 1 to apply 10 dB of cut to channel 1 [above left]. And if we now dial the fader of channel 1 back to -10, that tells the amplifier in channel 1 to apply another 10 dB of cut to the signal [above right]. “Madness!” You might say, “Lowering the signal twice!” That’s true, but it’s also highly useful. 

Consider this; we can accomplish the same thing, level-wise, with a group. However, we’re sending the signal through 2 amplification stages. And once the signal leaves the group, it goes through a third amplification stage at the main faders. With a VCA, there is a single amp stage on each channel. The channel faders and the VCA faders simply tell that amp what to do. At no point does the signal pass through the VCA group, because there is no “group.” I said it gets interesting, so here’s how it could play out.

At Upper Room, we have our VCAs (well, technically they’re DCAs, but they act essentially the same) set up like this: 1–Kick & Bass; 2–The rest of the drum kit; 3–Guitars; 4–Keys; 5–All Band; 6–Vocals; 7–FX; 8 Speech mics. VCAs 1-4 act like groups for us, in that we can quickly adjust the entire drum kit up and down, add or subtract keys, whatever. However, we also have the whole band on another VCA. So that means that every channel that is assigned to VCA’s 1-4 is also assigned to VCA 5. That allows us to take the level of the entire band up and down on one fader, without altering the relative levels between each of those channels. If during the set the band gets crankin’ and starts to overpower the vocals, we turn down the band VCA. That’s it, the whole band comes down.

Where this is very elegant is that the signal is processed strictly in the channel amp; it’s not going through multiple amp stages of gain/cut to get there. So let’s play this out.

Take the kick, channel 1 in our setup. Let’s say on the fader, it’s set to -5 dBu. So at the channel level, we’ve knocked 5 dB off the level (relative to 0, or unity, which is determined by the head-amp control). Now, as part of the drum kit, it’s assigned to VCA 1. And we might run that at -2. That knocks another 2 dB off the level for a total cut of 7 dB. As part of the band, it’s also assigned to VCA 5, which we might run at -5 also. That’s 5 more off, for a final level of -12 dB. And again, all of this level changing is done on the channel strip itself, in a single amp stage; it’s not going through multiple stages at each VCA. The VCA groups simply alter the control voltage of that channel’s amp.

By definition, and unlike a group, a VCA group can never overload. This is because it’s simply a “master remote control” for a bunch of inputs. Even if you push your VCA group fader to +10, you’re merely telling all the channels assigned to that VCA group to add 10 dB of level to their respective signals. At that point an individual channel might clip, but the “group” never will because it’s really more of a virtual group.

We should also note that by lowering VCA 1 (kick & bass) to -2, it also tells channel 9 (bass) to turn down by 2 dB as well. And by setting the VCA 5 at -5, it tells all of the band channels (basically 1-14) to lower by 5 dB. But each individual channel can be adjusted relative to each other, so the mix is preserved.

You do have to be careful with VCAs, however. Because you are remotely controlling a channel (for lack of a better term), you could be tempted to over-drive your input channels with too much signal. This could happen in the above example very easily. Let’s say someone wasn’t paying attention and set VCA 1 (kick & bass) to -20, and VCA 5 (the whole band) to -30. That would lower the signal of the drum mics by 50 dB. That would be pretty low in most systems. You would probably want to hear more drums than that, and even if your channel fader is already at +10, the total output of the channel is -40 (+10 plus -20 plus -30). So you might be tempted to turn up the head amp control to get more level. However, you would quickly drive the head amp into distortion. When using VCAs, getting good gain structure is more important than ever.

Still, that shouldn’t dissuade you from using them. Their much cleaner than groups, and the level of control is far greater. You also have more options for control, as shown above. Moreover, when you mute a VCA group, you also mute the channels. On most boards, this will have the effect of shutting off the Aux sends as well, which keeps you’re monitors quiet when you want them quite. Another benefit of VCAs. 

DCAs
DCA stands for Digital Controlled Amplifier. Essentially, they are the same thing as a VCA, but on a digital board. Every digital board I’ve seen has DCAs, which makes sense because the signal is already in the digital domain, and it’s just a simple matter of programming to make a DCA group behave the same as a VCA group. So there’s not really any more to see here. Move along.

You do have to pay attention to your DCAs on a digital board, however, because most of the time they’re on a separate layer. So it’s really easy to have the scenario I illustrated above play out (40 dB of cut applied without you knowing where it came from). As always, proper gain structure is important.

I hope this has shed some light on the concept of Groups versus VCAs/DCAs. While they can all have the same ultimate effect on the signal, they go about it differently. And when you use one versus the other depends mainly on your board. If you have both, use VCAs for your channel “grouping” and groups for sending mixes somewhere else besides the main speakers. They are great for “submixes” for an Aviom system for example. If all you have are groups, break your band up into logical “groups” and control them as described. Most of all, I want to encourage you to explore what your mixer can do. It probably has more power than you thought. To paraphrase my favorite foodie, Alton Brown, “Get out there and play with your mixer” (preferably during non-service times…)

Picking up where we left off, today we’ll talk a little bit about how digital consoles are changing the way we think about a matrix mix. Perviously, we discussed what a matrix is, and how to use it. Rather than try to give a completely illustrated guide to every digital console and how it works (which I can’t because I’ve not used them all), I’m going to pick out a few desks that represent, at least in broad strokes, how a matrix functions in the digital realm. 

Yamaha PM5D
While the PM5D is a digital desk, it handles the matrix pretty much the same way an analog desk does. The PM5D has 24 mix busses, plus LCR. It really doesn’t do groups, you simply assign your channels to the mix busses. Any of the mix busses can feed into a matrix mix, as can the LCR mixes. Once you’re at this level of a board, the set up gets complicated fairly quickly. As I’ve not spent much time at all behind a 5D, I won’t attempt to suggest a variety of options. Suffice it to say if you have a 5D at your church, you should have someone on staff who knows how to use it.

Yamaha LS9
This board is becoming increasingly popular in the church arena. It’s small, has a high feature set and is very affordable. The LS9 has 16 mix busses (plus L, R & Mono and Monitor L,C & R), and 8 matrix mixes. Like the 5D, the matrix is fed from the other mix busses. In a church setting, the matrix mixes are going to be primarily used for recording sends, cry rooms & lobby feeds and things like that. With only 16 mix busses at your disposal, you will probably be feeding the main mix into your matrix most of the time. The matrix mixes then become a level control for your various outputs. 

If you are not running stereo IEMs (which consume mix busses pretty quickly), you might be able to do some quasi grouping with a few leftover mix busses and use them to feed into a matrix for various mixes as we discussed on Tuesday. If you even separated the band into 2 mix busses, and used a third for vocals, you could come up with a combination of “external” feeds for recording, cry rooms, etc. using those mix busses and matrix mixes. Though the LS9 only has 16 Omni outs, you can add additional outputs using the MY-Card slots. Those outputs can be fed from the matrix to give you some more output capability.

RSS M-400V Mixer
Roland’s entry into the digital mixer game is an interesting one. While I’ve not mixed on it yet, I’ve played around with the software, and I’m impressed. The M-400 is very well integrated with the REAC digital snake, which provides plenty of configuration and I/O options. I’m not entirely sure I have a full grasp on what it can do, but it seems quite powerful. Like the LS9, the M-400 has 16 mix busses, L, R & Mono. It also has 8 matrix mixes. And while the matrix mixes are fed primarily by the mix busses and L&R, you can also pick any two other input channels and put them into any of the matrix mixes.

This starts to get really interesting. For example, for a recording feed, to make up for the fact that the music is always going to be a lot louder than the pastor speaking, you could send L&R to a matrix, then also add in the pastor’s channel. That would bring the level up to a more comparable level with the music.

How useful this is depends a lot on how you set up your mix busses. But certainly, the ability to directly add a channel (or two) into a matrix mix could come in handy. This is a board I want to spend some more time with at WFX in November. It has some great functionality that and a price point that would work well for many churches under 1000.

In some ways, using a matrix mix on a digital board is a little less useful than an analog board because you don’t really have groups to derive your matrix mixes from. Because every digital board I can think of uses DCAs (a topic for another post), you don’t need to group say, the drums, the keys, the guitars, etc.. You can do it all with DCAs and with better sonic purity. The cost is that the matrix becomes less useful. That is, unless you’re driving an M7…

Yamaha M7CL
In many ways, I saved the best for last. I’ve said before that I believe the M7 is just about the ideal all-around console for churches between “large enough to need digital” and several thousand. And once you cross that 3000-4000 attender threshold, you probably have someone on staff who can efficiently drive a Venue or a 5D–that is, if you really the need additional capabilities of those boards.

The M7 breaks new ground with it’s approach to the matrix. At first glance, it appears to be set up just like the LS9–16 mix busses plus L, R & Mono. It also has 8 matrix mixes. What makes the M7 unique (for just about every digital desk I could find) is that you can assign anything to the matrix mix, right down to the channel level. This effectively makes the M7 a 24 mix bus board, only better. It’s better because you can assign mix busses to the matrix; L, R & Mono to the matrix and individual channels to the matrix. 

Because you can stereo link matrix mix pairs, you could create an additional 4 stereo monitor mixes. Or stereo record mixes. You can use it to break out record sends to different places if you want. At Upper Room, I use Matrix 1 as my video record send, and use Studio Manager to mix it on the fly without affecting the FOH engineer. You can read more about that here. We also have another record send that goes to the cassette recorder & HD24 fed by Matrix 2. Because we don’t have the time to deal with that mix much, it’s fed mostly by the mono mix, with a little extra pastors mic for good measure. 

In a sense, the matrix becomes another “layer” of mix busses on the desk. For mixing the CPC contemporary service, we use a matrix to feed the ButtKicker for the bass player. We have matrix mixes set up for wedges when we need them. When thinking about how to use a matrix mix on the M7, just think, “What would I use a mix bus for,” and you can use a matrix for it as well. 

I originally thought the LS9 had this functionality, but it doesn’t. So far, it’s unique to the M7. I don’t know if it would be a simple software update to enable this on an LS9, or if it’s a matter of processing power. Either way, until the LS9 can do this, the M7 remains my favorite all-around church board.

Hopefully, these three posts give you a little more insight into the strange and wonderful world of the matrix. While not exhaustive, I tried to give an overview of what you can do with these useful tools we have at our disposal. Happy mixing. Next up, VCAs and DCAs…

Continuing our series on the Matrix, today we’ll talk about some uses for them. A matrix mix can be used for quite a number of things. Rather than try to give a definitive list, I’m going to put forth some suggestions, and some examples of how I’ve seen them used in various church sound settings. I’ll leave it to your imagination to come up with other ideas. But don’t forget to share them with the group!

Recording Feeds
This is probably one of the more common uses for a matrix mix. Of course, their usefulness is predicated on proper usage of groups. If you assign everything to the L&R mix, and then send that to a matrix for recording, you have a glorified level control. If on the other hand, you split your band into say, Drums, Guitars, Keys, Vocals, Lead Vocals, Speaking Mics and Computer/Video, you can actually create a separate mix that will sound good on a recording. Not as good as a full channel split, but better than the house mix. 

There are two ways to approach this. The easy way is to assign the L&R mix to the matrix you wish to record from. Then use individual groups to feed into that matrix to boost the lower level signals. This is sort of a “mix-plus.” Start with the house mix, and add more of what you need. This is what we were doing at Crosswinds when I started mixing there. It’s not elegant, but it works.

A better way is to leave the house mix (the main L&R) out of it, and build a new mix straight from the groups. This way, you’ll get a cleaner mix, and you’ll have more control over it. It does require that you check in on it once in a while, and it’s one more thing to manage. But if you have the bandwidth, you’ll get better recordings.

Lobby/Cry Room/Overflow Feeds
Another common usage for a matrix mix. What’s wrong with just sending a house mix? Excellent question. Unless your band is playing/singing in a sealed box, or in another room, they are contributing some energy to the house. In our current setting, the drums are hardly in the PA at all. They make enough sound all on their own. So if we sent a house mix to an overflow room, they would get almost no drums and the mix would sound dead and lifeless. Using a matrix would allow us to dial up the drums to a level where they actually sound good. 

If you have ceiling speakers in the lobby, you may find they don’t put out a lot of low end. In fact, they probably sound pretty bad when you try to put a lot of low end into them. By setting up your groups with this in mind, then building a matrix mix that dials the bass and kick back a bit, you’ll get cleaner sound in the lobby. And you won’t be replacing blown speakers as often.

Speaker Zones
When I was engineering at the church I referred to yesterday, we used the matrix to feed various zones of speakers in the house. To be sure, not every situation warrants this, nor is it always a good idea, but sometimes it’s handy. In that setting, we had a Turbosound speaker system that was zoned into 3 zones horizontally and 2 vertically. The zones across the rooms were handled by the processor, but we used the matrix to control the balance between the main clusters and the down fills. 

We probably could have done it using the L&R faders, sending the Left mix to the mains and the Right mix to the down fills, but that would have meant the L&R faders wouldn’t have been at the same level, and that just looks and feels wrong. Using a couple of matrix mixes that were fed by the L&R mix, we accomplished the goal.

Press Feeds
This probably doesn’t get used often in churches, but once in a while it comes in handy. Just before I was hired at Upper Room, there was a funeral held that received quite a bit of media coverage due to the situation. Often, news photographers will want to get decent audio for the story and you can give that to them via a matrix mix. I’m assuming that the proper channels have been consulted for permission. 

For happier events, such as a large Easter or Christmas production, local media may want to get some footage. On-camera audio is going to sound terrible, but a matrix mix will present everyone’s hard work in the best light (er, uh sound).

Certainly there are other uses for a matrix mix, but all that I can think of are derivations of those listed above. Hopefully, this gives you an idea of what you could use all those extra knobs for. And if you have a creative use of a matrix mix, please share it with us. If there’s one thing I’ve learned in the last 20 years of doing sound in churches it’s that there’s always something new to learn. In our next installment, we’ll touch on how the matrix differs in some of the newer digital boards.

With apologies to Neo…

I remember it like it was yesterday. It was one of the more momentous days of my life, in fact. Two milestones, occurring on the same day. I graduated from an MI (Music & Instrument Store) board–a Mackie SR-24–and I was getting paid to mix at church. The new board was a beauty. To this day it’s one of my favorites; the Yamaha PM3500-56. It was a beast of a board, one I’m glad I never had to move. It was the kind of board where congregants would linger on the way in, peer over the edge of the sound booth and say, snickering, “That’s a lot of knobs. Do you know what they all do?” My reply was always the same, “Well, yeah…” with just the right amount of “what do I look like, an idiot?” facial expression. And in fact, I did. But it wasn’t always thus. 

My first day on the job was interesting. Not only was I getting used to being paid to be a sound guy, I was learning a new board. The great thing about sound boards is that once you learn one, you more or less know them all. The more part is easy. It’s the less part that can be tricky. All boards have gain (or trim or head amp) controls, aux sends, pan and faders. Many boards have groups and matrixes. Some have VCAs. I was familiar with groups, and I quickly grasped VCAs, but the matrix had me confused for a while. As the outgoing sound guy was explaining the setup to me, I remember when he got to the matrix. In that setup, we used matrix 1 to feed the main speakers, and matrix 2 to feed the downfills. OK, I’ve got that, but my question was, “How does the sound get there?” He looked at me as if I was from Mars and said, “These knobs!” That really didn’t help.

So I did what any self-respecting sound guy would do. I went home, downloaded the manual and studied the schematics until I figured it out. What’s that? You don’t enjoy reading schematics? Well, that’s OK, because today we’re going to clear up the mystery that seems to surround The Matrix. 

First, know that there is a difference in the way a matrix behaves on an analog desk versus a digital desk. We’ll deal with analog today, and digital tomorrow (or the next day…). But before we get to understanding how a matrix works, we need to learn more about the thing that drives our sound boards, the bus. 

Much like urban transportation, a bus in sound parlance is a place where we can stick audio signals and send them someplace. If you are in downtown Minneapolis, and want to get to say, Fort Snelling, you could take the 52 bus. (I’m making this up, I’ve never actually taken the bus in Minneapolis). But you know how it works; wait at the bus stop at the right time, get on the bus when it arrives and get off at your destination. 

On a soundboard, a bus is very similar. Once the sound comes in to a channel, we send it out on a bus. That bus could be a group, it could be an aux send, it could be the main L&R bus (or all three). Sometimes, putting a signal on a bus means turning up a rotary fader (aka a “pot”) as is the case for an aux send. Sometimes it means pushing a switch as is the case for a group.

Once we put that signal on a bus, it heads off to it’s destination. That could means an output jack on the back of the board. More often, we have the signal do the equivalent of a mass-transit transfer. For example, we’ll often send all of our drum mics to a group 1 bus, but instead of sending that mixed signal (of the drums) out the dedicated group 1 output on the back of the board, we’ll send it instead to the L&R bus where it gets mixed in with everything else. 

We do this so we can easily raise and lower the level of the entire drum kit with one fader, while still keeping the relative mix of each drum mic in tact. So all the drum signals get on the group bus, then are transferred to the main bus for output. Just picture passengers coming from all over the city and ending up at the same place and you’ll get the idea.

Now that we have that clear (it is clear, right?), it’s time to answer the question, “So how does the sound get to the matrix?” Let’s take a look at the matrix sections of a few popular analog boards, and we’ll see what they have in common.

This is the matrix section of a Soundcraft MH2. This desk has what is known as an 11×4 matrix. That is, there are 11 inputs and 4 outputs. Let’s keep looking.

This is an Allen & Heath ML4000 (which is a pretty sweet board if you ever get the chance to mix on one). This goes the Soundcraft 1 better and is a 12×4 matrix (it adds an additional “aux” input that you can mix into your matrices. click the picture to enlarge

Here is an A&H GL4800. I’m ending with this one because it is the most unconventional, yet makes the most sense. click on the picture to enlarge

I chose each of these boards for a specific purpose. The Soundcraft gives us a great clue about what goes to the matrix by thoughtfully labeling the controls G1, G2, etc., as well as L, C & R. Any takers as to what that might stand for? You in the back…That’s right! Groups! As I’m sure you all know, the MH2 is an 8 group, LCR board. Do the math and you come up with 11 mix busses (8 groups + L, C & R = 11). Look at the caption under the photo and you’ll see that the MH2 has an 11×4 matrix. Lightbulbs are going on all across the country now.

The A&H ML4000 follows the same convention, only they add the additional input for good measure. Both the MH2 and the ML4000 follow the industry standard convention of lining the matrix up like, well, a matrix. All the controls are kept together, and they are read top to bottom, left to right. Columns represent the individual matrix buses, while rows represent the groups (or the L, C & R buses). Turn up the G1 knob of matrix 1 and whatever is happening in group 1 gets sent to matrix 1. It’s just like an aux send, only for groups instead of channels.

Conceptually, the GL4800 illustrates this the best. The GL4800 is an 8 group, LCR board as well, but rather than cluster all the matrix knobs off in their own little world, they stacked the 4 matrix sends right above the group and master faders (just like aux sends on a channel). And this is how they work. 

The matrix gives you 4 (or on larger boards 8 or even 12) more places (outputs) to send a mix of your groups. It’s like having 4 more discreet “main” outputs–only you can also send the actual main outputs to the matrixes. Each matrix mix can be different, which means you can create mix-minus feeds, lobby feeds with lower drum levels so you don’t blow up ceiling speakers, record feeds with better balance and all kinds of things.

In fact, I changed my mind. Tomorrow we’ll talk in more detail about how you can use matrix sends on an analog board. Then we’ll get to how matrixes work on digital boards, and if I’m looking for one more post for the week, what you can do with them on digital boards. This is great–a week’s worth of material on one topic! Stay tuned…

When I joined Upper Room, our tech booth was in need of, how to say, a little rennovation. There was a lot equipment packed into a small space. Some of it was hooked up, some not. Wires were coming in from all over the church; some labeled, some not. And there was some equipment that could best be described as “temporary.”

This is what I walked into when I started. (click on any of the photos to enlarge)

This is the view looking in from the doorway. Welcome to Minnesota!

The video control desk. I’m not even kidding, this is what it looked like.

I have nothing to say about this.

How about that lightboard. Yup–it says Behringer. And yes, those are cinder blocks.

The reason for the cramped table space was this huge rack,
with hardly anything in it. Part of the original deisgn-build.

Clearly I had some work to do. What you don’t see is some really bad wiring (BNC ends not crimped, but put on with heat shrink; DMX cable running next to fixtures with melted insulation; a DMX network with no splitter or DA; a single audio feed from FOH that had 9-count ‘em 9- Y-cords in it; etc.). For the first month, my main task every Sunday was just trying to make things work. I don’t like having to function in such a situation, so I decided to start tearing things apart, and making it better. I wanted to be like Ty and just blow it up. But they wouldn’t let me. So a rennovation was in order.

As the first step, we pulled all of the DMX cables and ran new ones. We had been having issues with lights turning on and off randomly, or not responding at all. Rather than mess with it, we ran new. I also installed a DMX DA to properly split the DMX signal to the 4 dimmer racks and color scroller. Contrary to popular wisdom, you’re not supposed to split a DMX signal without a splitter. Causes all kinds of relections and other bad stuff.

Next, we tackled the audio feed. I pulled all the Y-cords and used a proper DA (which, oddly enough was lying on the floor in a pile of cables…go figure). I also cleaned up the video table with a proper rack, and replaced the monitor. We moved the rack to a better part of the room, and added another table. In the process, we dumped the el-cheapo DJ style Behringer light board for an ETC Express 3 (which, also oddly enough, was sitting in a closet, unused–I wish I had good explanations for this…) Just doing this was a huge improvement.

You feel better already, don’t you?

It’s starting to look like a real tech booth now.

The video desk still has a big clump of wires on the floor, but at least you can put your feet under the desk now and not worry about turning the cameras off (that was a real issue before. I wish I was joking).

The extra table gives everyone room to spread out, and easily accommodates the new light board. I can now stand between the presentation tech and the light tech and see what’s going on in the room. There’s now an iMac on the left side as well, but I forgot to take a picture of that.

I call this phase, part 1. Clearly it’s an improvement, but I knew there was more work to do. It got us through the last half of the ministry year, however, and everyone just felt better coming in to do their thing. It’s amazing the difference the physical space has on how one performs their job. In the old space, which was clearly in chaos and not thought highly enough by anyone at the church to clean up and improve, the volunteers felt unappreciated and didn’t take their jobs too seriously. It was fun watching the looks on their faces when they came in the first time after phase 1. Not surprisingly, everyone’s game improved.

As I said, there was still work to do. Though Cat-5 cable was pulled all over the church, and video over Cat-5 baluns purchased, the system to route the video was a bit convoluted. This made for some challenging times at Easter and a later large funeral. Though we had a tie line between the stage and the booth, using it to send video (or SGA signals) down there was difficult. And we could not easily address the projectors and any other video destination separately.

Audio was also an ongoing challenge. Though I’ve taken to mixing our own mix remotely using Studio Manager (read about it here…), controlling the volume was a challenge. And I found we were sending too hot a signal to the DVD burner, which meant most of our recordings were distorted. While I had sorted out the big problems during phase 1, what we needed was a plan. A holistic plan to accomplish what we needed to, and make it easy. Here’s what I came up with. You can click to enlarge, or view a PDF of the file here.

This plan gives us a lot of options. We can send video to anywhere, in full RGBHV resolution, without effecting any other destination. I can address our sanctuary projectors independently, and can send sanctuary cameras, or computer, or DVD, to the multi-purpose room, fireside room or fellowship hall for overflow–all with the push of a button. Audio can now be controlled properly, and the booth volume no longer effects the record volume. Best of all, I’ve posted this diagram in the booth, so anyone can take a minute and figure out how to get video and audio where they need it.

I also went through and labeled all the cables. I’m a big proponent of labeled cable. It takes no time to do, and saves so much time down the road. One of the interesting things about this plan is that it required very little new gear. Most of the equipment on the diagram was already there, it just wasn’t utilized. Or it was in another room not being used. I did buy a new scan converter, a scaler, a BNC patcbay (so I can turn around our tie line to the stage and use it as an input or output), and I’ll be picking up a DBX 266 compressor to manage levels on the booth feed. Otherwise, my predesessors bought everything else.

After two really long days, this is how the booth turned out.

Finally, it looks like it should. It’s almost Zen-like now, wouldn’t you agree?

Oh, I forgot, I also bought the Alesis M1 powered speakers. And the hardware to wall-hang them. I’m very happy with those. There’s still a lot of wire running down the wall…I may wiremold that some time in the future.

What was once an unruly mess is now a comfortable workspace. I even left some desk space open to put my laptop on Sundays. There’s an 8 port network switch tucked back there, so I can go wired.

This rack used to be half-empty, and what was there was not all that effective. I’ve moved all of our RGBHV routing, switching and distribution here. This keeps the runs short, and makes it easy to wire. The Cat-5 video also leaves from this rack now. Future updates will include moving the Clear-Com base station up here (from FOH), and additional Cat-5 video baluns, as well as the aforementioned BNC patchbay.

So there you have it. Already, people who have seen it feel really good about it. It’s much easier to work in, and it just feels better. There’s so much to be said for having a workspace that feels productive. And when you raise the bar in your physical plant, the people who work in it will step up as well.

We still have some gear that could be upgraded. Our camera package is essentially a security camera system. Our video mixer, the MX-20, is getting a bit long in the tooth. And some real broadcast monitors would be nice. But given what we actaully do with video right now (which is not much more than archive), the current gear is fine. And I want a new PA first.

Personally, I feel really good about it. Many were thrilled with Phase 1, but I knew it was only 1/2 complete. Now that it’s done, I’m ready to go on to our next project. I’ll be telling you about that in the coming weeks. For now, I’ll just say that this was good practice.

ProSound Web issued a story on Tuesday that detailed an FCC proposal to ban all wireless mics operating in the 700 MHz band. You can read the whole story here. For even more information, click here to read the actual FCC news release in pdf format, or here to read the Notice of Proposed Rulemaking Change order.

Having read through the article, the FCC news release and the NPRM (OK, I’m a geek…) a few times, here is my take. First, it’s still in the proposal stages. However, the writing is on the wall. I would guess it’s highly unlikely that this will get shot down. The dealine for comments is less than 30 days, and they have to reply in under 45. So my guess is that within a month or two, we’ll know for sure that all 700 MHz mics will need to be shut down on February 17, 2009.

But in my mind, that’s not the bad news. What worries me is the second half of the NPRM  which states the FCC will start investigating claims of false advertising against wireless mic manufacturers for leading the wireless mic buying public to believe that we could operate wireless mics without a license to do so. Huh?

Here’s the deal. The FCC requires all operators of RF transmitters (TV & radio stations, ham radios, wireless mics and IEMs) to have a license to operate on a given set of frequencies. I don’t know about you, but I know of no one who actually has a license to operate a wireless mic. This is because the transmitting power of a wireless mic is so much lower than a TV station that it’s laughable to think a wireless mic would cause interference. Since the only other devices operating in the same specturm as wireless mics were TV stations, and TV stations obviously have the power advantage, the FCC left us unlicensed (and technically illegal) wireless mic operators alone.

This could all change if the FCC decides to open up the “white spaces” (the open frequencies between TV stations in any given market) to other low-power RF devices (to deliver broadband internet, for example). Presumably these devices would be licensed by the manufacturer, and could be the victim of interference by a wireless mic.

Depending on the outcome of the investigation, and/or complaints filed against wireless mic operators by any new devices, we could be in a lot of trouble.

The uptake on all this is simple. If you have wireless mics operating in the 700 MHz band (that is from 698-806 MHz), you have about 173 days to get rid of them. And don’t wait until after the deadline to put them on ebay hoping people in South America will buy them because the rule prohibits the sale of 700 MHz equipment after the DTV transition date. Get the stuff listed now (thought it’s not likely to be worth much).

Also, be prepared to endure a possible licensing process or the restriction of your wireless spectrum. If you currently run a bunch of wirless channels every weekend, start thinking about how you can get back to some wired mics (they’ll sound better to boot!). We moved all our vocal mics to wired earlier this year, and I’m in the process of cutting our wireless mic inventory down from 16 channels to 8, and our IEMs from 9 to 4 (and adding 4 Aviom mixers to make up the gap).

I know the wireless manufacturers have been telling us it’s all going to be all right, just buy new gear and it will be fine. That’s good for them, as they’re selling tons of new wireless gear right now. But if the rules change again, which they might, we’ll be stuck with the tab (again).

Remember, a wired mic (with good cable anyway) is far less suseptable to RF interference and will almost always sound better than a wireless one. And you won’t (for the foreseeable future) need a license to operate it!

Alright, so yo have your computer happily talking away to your Yamaha digital board. You move a fader on screen and it moves in real life (that never gets old). Getting here was the subject of yesterday’s post, which you can read here if you missed it. Hopefully, you’re wireless so you can even to it from across the room. And that’s all well and good, but what are some real-life applications of this very cool technology? Well, here are a few that I can think of.

Digital Patching
One of the greatest things about digital boards is that you don’t have to physically patch anything anymore. You can route any input to any fader (or even two faders), and any mix to any output (or combination of outputs). And while it’s as handy as a bluetooth headset for talking in the car, it can be a bit of a pain to do right on the board itself. It’s not hard, mind you, it’s just not always 100% intuitive. Especially if you are a visual-type of person (guilty as charged). This is but one reason I never mix on the M7 without my laptop handy. Check out the patching editor:

Changing the input or output patching is as simple as point and click!
(click to enlarge)

I really like this interface. We’re looking at the Output Patch here, because that’s where I do most of my patching. The mix busses are listed on the left, and it’s easy to name them so you can keep them straight. The actual outputs are on the top. Want a mix bus to go to an output? Put an orange dot there. It’s that simple. If that doesn’t save time, I don’t know what will.

Metering
Perhaps the most common use for my laptop during a service is to act as a complete input meter. With the meter pane up, I can monitor all 48 channels in, plus stereo. Or I can quickly check my output levels (which is a bit redundant since we have the meter bridge–but if you don’t, it’s right here).

All of your inputs and outputs can be metered at a variety of points in the signal chain, with or without peak hold. (click to enlarge)

I don’t know if this ever happens to you or not, but every week, I do a sound check and get initial levels from each instrument. Then, during the service, everyone plays louder. Sometimes a lot louder. I’ve taken to setting my initial levels at -12 or less, knowing that when it all comes down, everyone will be up near 0. Because we’re digital, once we run out of bits, we’re done. So I try to avoid clipping at all costs. The meter section helps me keep an eye on who got way too loud so I can dial them back a tad. Turning on Peak Hold makes it even easier to spot. Sure I know the console has a full-screen monitor page, but this looks way cooler.

Preservice Building
Since I can, I like to get as much of my show built before I arrive at church. I’ll plug in all my channel names, set some initial monitor levels, get my patching in line, that sort of thing. Studio Manager lets you do all this off-line, and gives you the ability to save your settings to a file that you load onto your USB key. Pop in the key, load the show, and you’re 80% there. Using the individual Channel Overview, you can dial a lot of things in quickly.

In this window, you can adjust nearly every parameter available for each channel. (click to enlarge)

Using this window, you can dial in monitor mixes, matrix sends, load EQs from the library, adjust initial settings for dynamics 1&2, set up DCA and Mute assigns, turn phantom power on and off, even patch in stuff from the Rack. And using the arrows in the top left, you can quickly go through all your channels. I’ve found this to be a huge timesaver.

In-Venue Remote Mixing
Now, I’ll make a distinction here. When I say in-venue, I’m referring to mixing by remote while being in the room the console is in. It’s the functional equivalent of picking the board up and dragging it around the room with you while you listen from various points (if that were even possible). Unless you have a room and speaker system that is really, really good, it’s likely that it sounds a little different depending on where you sit. If you have a room like ours, it can vary wildly depending on where you sit. Getting a good mix is all about finding a happy medium.

We used to walk the room, listen, make mental notes, then head back to the desk and implement changes. This process was fraught with problems. Not the least of which being that you can’t immediately hear the result of your changes in the area that you need to. Now, we just carry the laptop around and tweak from where we are. This has the added benefit of giving us the ability to respond to monitor requests from anywhere as well. It would never fail that we’d be all the way over on the other side of the balcony and someone would need a little more keys. Now, we just dial it up. Everyone’s happy.

Plus, it looks really cool. One day I was mixing for the contemporary service and one of the pastors saw me wandering around the main level with my laptop. He said, “What are you doing?” I answered, “Oh, just making a few mix tweaks here and there.” He took a look at the screen and said, “OK, now you’re just showing off.” We both had a good laugh, but the reality is this goes a long way to helping convince people you know what you’re doing.

Out-of-Venue Mixing
This is the mode I operate in every weekend when I’m TD’ing Upper Room. I normally sit in the tech booth, which is essentially sealed off from the main room. We have a matrix feed sending to the booth, which is what we use to record the services. I used to spend a lot of time calling down on the com, “Can you give me a little more lead vox in our mix,” and “a little less electric guitar.” It got to be a bit annoying, for both me and the FOH engineers.

A few months ago, I figured out that I can dial in my own levels in such a way that doesn’t impact the FOH engineer, and gives me a reasonable mix. It’s not “mixing” in the truest sense of the word since it’s a bit coarse, but it’s close enough and gives us decent results. The key is in setting up the workspace correctly.

My standard, weekly preset with all 48 channels plus stereo inputs and DCAs accounted for.
(click to enlarge)

By selecting to view only the first 4 mix busses (which I then toggle to the Matrix), I have enough height on my screen to almost get all 3 sets of 16 channels visible with minimal overlap. Now to really appreciate this, you need to enlarge the photo. Go ahead, we’ll wait. Circled in yellow is where we mix. As I mentioned earlier, it’s a bit coarse, but by dragging those little orange bars left or right, you can adjust the send for that channel. When I need a little more lead vocal, I go to that channel, and pull it up a little. It’s not an exact science, but it works. You can accomplish the same thing with more precision by hitting select, and going to Channel Overview, but that means you’re also hitting select on the board, and that can mess up the FOH engineer.

Now, from a setup standpoint, I highly recommend you go with mix busses for monitors and a matrix for a remote venue. The reason is simply this: If you have your mix busses in front of you, it’s way too easy to think you’re turning up your mix and accidentally turn up the lead guitar in the worship leader’s mix. Yeah, I did that. Once. But no more. I don’t even have the mix busses on my screen, so the worst I can do it turn it up too loud in the lobby. No real harm done there.

The beauty of this type of mixing is that you can be anywhere on your network. The tech booth up the stairs or in the gym on the other side of the building. Doesn’t matter. As long as you’re on the same subnet and can access the mixer, you can tweak the send to your heart’s content. And you don’t bug the main FOH guy. 

One More for the “Because We Can” Category
We have now crossed into a whole new realm. I’ll give the disclaimer that it’s not entirely practical, and because it’s a bit slow, you really can’t mix this way. But it’s really cool. With the advent of version 2.0 of the iPhone (and iPod Touch) software and the App Store we can now ascend to the 7th level of geekiness.

Using Mocha VNC, a Virtual Network Control application you can remote control your Mac. Technically, you could do it on a PC too, but I understand it’s tricky to set up. Download the App onto your iPhone, then drop into System Prefs on your Mac and enable VNC control (that’s a bit redundant, isn’t it?). How to do that is beyond the scope of this article, but it’s not hard. Poke around in the Sharing pane a bit, you’ll find it.

Next, launch Parallels, Fusion or Bootcamp and get Studio Manager running on your Mac. Now, connect to your Mac via Mocha VNC. Guess what? You can now control the M7 from your iPhone.

Now we’ve reached a whole new world of geekiness here…
(click to enlarge)

Now, before you go rushing out to buy a new iPhone just so you can mix from it, let me warn you that due to the limitations of bandwidth, the screen refresh rate is pretty slow. That means that your visual feedback loop is so slow that you can’t tell if you’re actually moving a fader until the screen updates. The fader moves in real-time, but you can’t tell if you’re actually on it or not. The most useful function of this is turning on and off DCAs at the moment. But it’s only version 2.0–we’ll get there. I keep wanting to do this in front of Brad, the aforementioned pastor who thought I was showing off when I was mixing from my laptop. Now I want to tell him, “Oh yeah, the laptop is just way to heavy to lug around. This is where it’s at…” Now that’s showing off!