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2

I’m Not An Idiot

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OK, I feel like I can finally get into this now so let’s talk about that distortion I was having on my RF mics. When I left off on the issue last month, we didn’t have a clue what was going on. We had borrowed some ULX-D mics from our Students, and they seemed to be getting us by while we tried to track down the problem. However, a couple Sundays later the distortion re-emerged in the afternoon while using the borrowed ULX-D rig. The distortion also reemerged on our keyboard lines.

Yeah, I didn’t mention the keyboards in the first post about this because when the distortion appeared on the keys on that Monday night, I initially thought they were two isolated incidents. Apparently they were not.

So while I was on my way back to our campus on that Sunday afternoon after getting the call the problem was back, I started thinking through what changed recently. Every time we would think the problem was fixed, it would suddenly pop back up so I started to think we were looking in the wrong places. Running through possibilities, the thing that stood out in my mind was our new studio console.

The studio console creating the problem didn’t make sense to me. The studio gets its power from our super-duper UPS that will keep our entire video world running in the event of a blackout. The console connects via fiber to its SD racks in our equipment room, and they are connected to one of the isolated splits off our 3-way analog split. So, basically, everything should be isolated from everything…right?

It was a far-out idea, but after two weeks without a clue what was causing the problem, far-out wouldn’t surprise me.

When I arrived back at North Point, I asked our team if they had checked to see if the issue was happening in the studio. They said they hadn’t had time, yet, so I headed into the studio to check the issue only to find everything powered down. I started powering everything up and got it all working just in time for the start of our 4:30pm service.

Everything sounded clean and clear when I solo’ed inputs in the studio. I then walked out to FOH where everything also sounded great. So I started looking for my Production Director to chat about my latest harebrained theory: when we power off the studio, everything falls apart.

It was the one changing common denominator I could think of. When we hosted Catalyst, the studio was running all day while they recorded the music in the studio. Then the studio powered off at the end of the day around 5pm when the issue appeared. Just when I thought the issue had disappeared, we had distortion on a Wednesday night rehearsal while the studio wasn’t in use because we had rehearsed that auditorium earlier in the week. The weekend before, everything had been fine all day, but the studio was also powered all day and didn’t get powered down until after the last PM service. Then on that Sunday afternoon when I arrived, I found the studio powered down.

In between services, I powered the studio all the way down. We checked the mics and keyboard lines, and they were all distorting. Next I started powering up the studio gear. I started with the SD racks which didn’t completely fix the issue. When I powered up the actual console in the studio, and it took control of the SD Racks, I immediately got a call on the radio that the distortion had stopped.

So what’s going on exactly?

I’ve traded a lot of emails with Digico who were very helpful in figuring out what’s going on, and this is not a bug. This is actually a feature. As I understand it, the preamps in the Digico use a bit of active circuitry to protect the preamps from excessive voltage. When the SD rack is powered down, it essentially goes into protection mode which changes the impedance on our entire system resulting in audible distortion on our other consoles.

Now, I’m still not exactly clear on why this happens because the electrical side of audio isn’t my strong suit. I’ve spent the last couple of weeks trying to understand this better, so maybe someone smarter than me can shed some light on this in the comments.

At the same time, in some ways it doesn’t really matter, though, because the good news is we found the source of the problem. The solution is also pretty simple because we just keep the SD Racks powered. As long as they don’t go down, everything is happy.

I’ve had some weird issues pop up in my career, but I feel like this has been the most perplexing and definitely the least fun issue I’ve ever had to troubleshoot. So I just want to give a big shout out to my friends at Shure, Avid, Digico, Clark, and Moyers along with many of my other engineer friends for all their help and support in trying to figure out what’s going on. It’s comforting to know that when something mysterious like this happens, there are a lot of folks interested in helping. I was going out of my mind on this, and I don’t think I ever would have figured it out without all the help and support we received.

0

Aiming for a Target

So, as some of you know I made a conscious decision to stop handing out SPL numbers a couple of years ago. You can go back and read the original post if you missed it, but the gist of it is that loudness is a perception and a lot more complicated than a single number. SPL measurements don’t offer any information on frequency balance which is a critical component of our perceived loudness. It’s not bad to keep an eye on SPL, but I think if there’s something you should really be monitoring, it’s frequency balance and level.

A couple years ago I took a mix that I considered to have a frequency balance that could serve as a benchmark for me to do this. I typically run Smaart’s RTA Averaging at either 5 or 10 seconds. I played back the mix at show level until I had a decent averaged measurement displayed and stored a trace. The beauty of this kind of measurement is not only does it show frequency balance, it shows the preferred level of that balance because I have the RTA set to plot a calibrated level.

I’ve used that trace on a regular basis since then to check my mixes for weekly consistency. The only challenge with this, though, is that since it’s a measurement trace it’s not the prettiest thing to look at. You can see the measurement below displayed at 1/24th octave banding.

TargetHouse trace
Reference Mix Measurement

Over the years I’ve gotten more accustomed to looking at measurements in Smaart with less and less averaging across the frequency spectrum. These days I typically opt for 1/24th or even 1/48th of an octave banding. It makes for a messier display, but I’ve kind of gotten used to averaging out what I’m looking at in my head so that I can see trends in the measurement. The advantage to less averaging is that when there are narrow errant frequency peaks or dips, you can actually see them in the measurement. With a lot of averaging, those peaks and dips simply get averaged across the banding of the octave.

While I prefer less averaging across the spectrum on live measurements, when I’m using something as a target, I have always wanted to have something that was a little cleaner to look at because once you start overlaying a lot of messy measurements and traces, it gets harder for me to see what I’m really measuring against each other.

I guess I’m not the only one who desired a way to have cleaner targets to look at because Rational Acoustics released an update to Smaart this week that makes this a whole lot easier. RA calls them Target Curves. Now we can overlay a Target Curve in the foreground on Smaart’s RTA. I’ve always wanted to draw a straight line through my target measurement from 2 years ago, and with Target Curves now I can do just that.

Here’s my new Target Curve(purple) displayed against my original measurement(red). Note how it pretty much cuts right through the middle of my original measurement.

TargetHouse curve
Target Curve with Reference Mix

So how’d I do this?

First, I took my original measurement and set Smaart’s banding to 1/3 octave so I could get a baseline decibel level and figure out the trend for my mix. What I found is that my personal preference is for a frequency balance that drops about 4 dB per octave across the listening spectrum. I originally thought 3 dB per octave was the magic number, but that ended up too shallow. Go figure.

The next step was to place the data into a curve file Smaart can read. You can find out more info on Smaart’s curve files and how to format them in Smaart’s Help section within the software. They’re basically text files with tab deliminated data, but I just downloaded some curves from the RA site and modified one with my data. I picked a frequency like 500 Hz, looked at the dB level in my original measurement, and then just added or subtracted 4 dB from that level for the other octaves. The photo below shows my original measurement with 1/3 octave banding along with my new target curve overlaid to display the result. Based on this averaging I might end up tweaking my target so that it’s up a dB or so, but in the meantime I’m going to go with what I’ve got.

1 3octave
Mix Reference @ 1/3 Octave Banding

If you’re using Smaart’s RTA on a regular basis, I’d recommend you check out this new feature. I’ll even make it easy for you to try this out. You can download my personal target mix curve right here. For the best results, make sure you set your RTA averaging for 5 or 10 seconds if you’re going to try and use it.

NOTE: that this is NOT for use in tuning the PA.

FOHDave Target Mix Curve

As you can see from the screen shots above, this target was based on an actual mix and is basically where I put the louder music portions on a Sunday morning these days. In other words, this target is how loud I currently mix on a Sunday. Of course, your mileage with this particular target curve may vary depending on your own tastes and the tastes of the people you mix for, music style, etc. For example, I would guess that in a smaller room, this might be perceptually much louder than in our spaces.

If you’re going to use a target, though, you should probably make your own target curve based on your own personal needs for where you’re mixing. However, after years of looking at measurements of both live and studio mixes, the one thing I can say that you’ll probably want with this is some sort of straight or straight-ish line because a great mix typically features a great balance across the entire frequency spectrum. That doesn’t mean there aren’t times when you stray from that, but this is just what I’ve found seems to make most people happy.

Now, let me leave you with a tip to consider when using targets while mixing.

Targets are great, in my opinion, and far better than a simple SPL reading, but they’re just targets. You shouldn’t be nickel and dime’ing a mix with these. Targets are simply a visual reference you can check when you are hearing something that seems off.

Did you get that?

You LISTEN first, and then you can look if you need/want to. Ears always come first. If you do end up looking, you should be looking for a trend. Here’s my measurement photo along with the target one last time:

TargetHouse curve

Note how the squiggly measurements go above and below the target. That is completely natural. You’re not going to get a perfect line like the target, and you should’t be trying for one. It’s just a target and not the real world. However, if sections of the measurement skewed way above or below, that could be confirmation to me that what I’m hearing is truly off; remember, listen first.

One last thing to keep in mind when using these is that hitting your target still doesn’t mean your mix is any good. All a target show us is the overall relative frequency balance. A target says nothing about the musicality of the actual mix. Only an ear is going to tell you if it sounds like music. You still have to put all the instruments in the right place within that spectrum.

If you’re a Smaart user and interested in this sort of thing, be sure and check out the new Target Curve feature in v7.5. If you’re using a different RTA I’d highly suggest checking to see if there’s a similar feature available to you. References can be a powerful tool for mixing.

5

State of the Mix 2014: Going Under

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I still don’t have anything definitive to say about the distortion issues so here’s something that has been working for me lately.

I’ve been having some mixed feelings about cymbals lately. Well, maybe not lately. I’ve had a love/hate thing with cymbals for a long long time. I’ve often felt like I’ve either got too much or too little in the mix. I’ve experimented with overhead mics, placement, varying amounts of compression, and working on monitor mixes; parenthetically, you do understand that what a musician hears of himself affects the way he plays, right?

Regardless of what I’ve tried, I’ve just never had things where I really wanted them. I work with about a half a dozen different drummers on a regular basis. One technique might work with one guy, but not so well with another. Maybe I’m lazy for trying to settle on one approach, but the reality is when you do this every week it’s not so appealing to have to reinvent that wheel every time especially when it could be reinventing it on a nearly daily basis in some seasons. So lately I’ve been trying a new approach…again…that I’ve tried before: under-mic’ing the cymbals.

Historically I’ve never liked under-mic’ing cymbals. It either sounded weird or unnatural or just lacked something to me. But at the same time I know there are engineers like Big Mick Hughes(Metallica), John Cooper(Bruce Springsteen), and my friend Andrew Stone(Church on the Move) who have been making this work for quite a while. There’s always been something appealing to me about the approach because it really cleans up the look of the drum kit on stage, and with our kit going on and off I can’t say that my overhead(s) always wind up in the same place when the riser comes back out on stage. That’s not a big deal when you’ve got a break between services to get it back in place, but when there’s a song happening right after the move the results can be mixed

I’ve been listening to some of the official live bootlegs Bruce Springsteen started to put out this year, and they got me thinking about this approach again. Since I’d read the boots are basically a version of the FOH mix, I asked John Cooper directly about his approach, and Coop gave me some ideas to try. After adapting them a bit for my own use and playing around a bit, I’ve actually been growing to like this a lot.

The key for me was all in the mic placement. If the mics are too close to the cymbal they sound weird, and if they’re too close to the center they get really weird. So it took me a couple tries to get them where they sounded like cymbals. Mic selection was also important, and I seem to prefer pencil condensers. I’ve tried larger diaphragm condenser and dynamic mics, but they never did it for me.

So I’ve got pencil condensers about 5-6″ below the crash cymbals and ride. I kind of rough in the starting position by putting them about a fist and a half to two fists below the cymbal. Then I put them halfway-ish between the bell and edge of the cymbal. Whenever possible, I tried to mount them so they’ll move with the cymbal if the drummer wants to raise or lower it.

I started with some Shure SM-81′s and recently swapped them for some Shure KSM-137′s. The 81′s worked great, but the 137′s have a different clarity and top that I’m liking a little more. This makes sense because when I look at the frequency response of the 137′s, they essentially have a lift right in the area I was boosting on the 81′s, and I think mics typically sound better when they handle the EQ’ing instead of the desk. Per Cooper’s instructions, I filter the mics really high and compress them a good bit with Waves Renaissance Axe.

In terms of the benefits, I feel like I’m getting a lot more control of the cymbals in the mix. I’ve got the crashes folded into a stereo channel with the ride on a separate input which works great for the current style of music we’ve been doing. For example, if we’re doing a song where it’s crash-ride city, I can pull the ride down a bit while leaving the crashes present. Then if we follow that up with a quieter song, I can push the ride back up. It just feels a little more flexible for me. Plus I feel like I can get a lot more of the detail out of the lighter playing now.

I also think these close-mics sound a little better with the drums behind a shield. With the overhead mic, I not only get the sound of the drums in the mic, but also the drums reflecting off the plexiglass. The underhead mics are much closer to the cymbals, though, so the reflections from the glass are reduced in the mics.

The downside is that this takes a little more work to get the kit balanced right. With the XY stereo overhead stuff I do, I can really just push the overhead fader up and augment a bit with close mics. But now I’ve basically swapped that for a close-mic approach on all the drums. I know close-mic’ing drums doesn’t seem like an unusual approach, but I’ve heard so many guys screw it up that maybe it should be. Close-mic’ing a drum kit is basically slicing up ONE instrument into its individual notes and then reconstructing it. It’s like giving every note of a piano or guitar its own input. If I didn’t have a good grasp on what a real drum kit sounds like, I think this would be a challenge. The kit-mic overhead approach, after all, can provide a natural sound of what the overall kit sounds like. But if you’re doing this method, I think you at least have to acknowledge that this is not a natural approach which means it will take more work to make it sound natural.

For the time being, I’m still leaving my overhead mic in place. I know there are songs that we’ve done in the past where the overhead mic just worked better stylistically for the song, and I’m sure there will be more of those in the future. Plus, I also think the overhead kit mic might be better for monitors, but I’m working on that a bit to see if I can make these work for the band as well. There’s a small possibility that we’re going to make some changes on our stage in the coming months that might limit our ability to use overheads at all so I want to at least be prepared if that happens. But for the time being it’s underhead mics in the FOH mix and the overheads at monitors….Of course, I’ll probably change this all up again in 6-18 months and talk about how the last approach I tried didn’t cut it….

On Mixing...
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