Approved!

Coming soon to Kensington Troy:  a new PA!  For the background on what’s been going on the past few weeks, make sure you check out this post from 2 weeks ago if you missed it.

I was recently involved in a process to actively prepare for a new PA that lasted almost a year.  However, due to the complete tanking of the economy in Detroit after the church finished pledging for our Trans4mation campaign, the project was put on hold.  A few weeks ago, I brought in a few different, smaller PAs then what we have currently or were planning to purchase, just to see how they would translate in our room.  Along the way, I think our whole team realized that a bit smaller rig (the leading candidate previously was d&b Q-series) turned out to have plenty of horsepower for what we do artistically and where our congregation is at regarding desired SPL.  Both the Kiva/Kilo & ARC’s rigs sounded fabulous in our space and had plenty of get up and go to make everyone satisfied.  It just so happens that there are some really great system options that fit in this category that also save us some pretty significant money which can then be invested into lighting and video, giving us an overall better product as well.  It really is a win/win for everyone.

So, we’re approved to proceed…evaluate, discern, and install!

The goals from a new rig are:

1. Even coverage with as few of boxes as possible so as to avoid all of the phase and comb filtering issues we have currently

2. Crisp, pleasing high end while maintaining rich, buttery, pleasing mids and thick, tight, feel-in-your-chest type lows.  The Kiva did exceptional with the highs and lows but the mids were lacking that pleasing quality.  The ARCs had wonderful mids and lows but were a bit smeary on the high end…especially with imaging and directionality.

3. Through our experimenting with these other rigs, we learned that a system that can get us into the mid-high 90′s without giving up is plenty for our weekend and midweek services.  Since we EXTREMELY rarely, if ever, bring in outside artists where we need to be concerned with rider acceptance or true concert levels, that goal isn’t the most critical for this system.

4. It is also a really good thing for the Troy main campus to have a similar level rig to what our portable campuses own since we’re all working in pretty similar size rooms.  If money were no object, it would be awesome to have a concert level J series or VDOSC in the space, but the reality is those boxes are TOO big for the room, throw too far, and are not the right choice.

D&B released a new PA a few months back that is an interesting solution for our room called the T series.  The system is comprised of T10 main cabinets, the T-Sub which is a single 15″ box that extends the response of the flown array down to 47 hz, and B2 subs for the ultra low-end.  The T10′s biggest claim to fame is that it is extremely flexible, used both as a line array and as a high directivity point source loudspeaker.  The HF driver is fitted to a unique waveguide horn producing horizontal dispersion to 105°, but by rotating the horn by 90°, the T10 is  transformed into a vertically oriented standalone full range loudspeaker with 90° horizontal and 35° vertical dispersion.

In our application this is incredibly unique and helpful because our rig will be comprised of two 6 or 7 box arrays at the front of the room covering 90% of the main floor, but we also need some front fill and balcony delays.  Due to the flexibility of the T10, we can use the same box for every application in the room, ensuring consistent voicing and performance throughout the entire space.  The dispersion of the T’s is also a better fit than the Qs (105 degree vs 75 degree) which will mean less fills to make up for dead spots in the dispersion of the main arrays.

I’ll write more about this as we start down the path of evaluating this rig in a few weeks. I’ve always been a really big d&b fan and this system carries on the same legacy of the larger J & Q series.  Can’t wait!

(For those of you who are more familiar with Kensington’s rigs, this is the same system we are planning for the Lake Orion campus which will be going live this fall.)

The great PA experiment

Ever since we purchased our last rig at Kensington a few years ago for the opening of our West campus, our vendor has suggested we should bring it in to the Troy main campus and see how it would perform in a larger space.  This past week I finally made that happen.

If you’ve been following me for a while, you know the current PA rig at the main campus is tired at best.  We went through an exhaustive design process last year to plan for an expansion and upgrade to the campus but due to the current economic realities of our area, those dreams have been on hold indefinitely since late last year.  On top of this, we’ve been especially struggling lately with questions of volume and volume quality as it relates to everything we do in the room.  This test provided a unique opportunity to evaluate how a more ideal speaker solution would effect the audio experience.

The test PA in question was a L’Acoustics Kiva/Kilo/SB118 rig.  6 Kivas & 2 Kilos per side, 2 SB118s on the ground per side.

I hung the PA on Sunday afternoon as a part of the stage turn from the weekend to midweek.  On Tuesday morning we connected everything up and sent signal through for the first time.  One important part of this test was to keep our current rig completely intact so we could simply A/B between the two different systems.

The long and short of it, as to be expected, is that the Kiva/Kilo system was like listening to a set of nearfield monitors in the room, while the KF650s sounded like there were a couple mattresses stacked up in front of them keeping you from hearing any direct sound and instead deflecting all the energy everywhere but at your ears.  The clarity and musicality was something I’ve never heard in the room before.  The room became FAR less of a factor because it didn’t feel like you were listening to the room – you were truly hearing what was coming from the speakers.  Subtle EQ translated, TL Space verbs sounded amazing on vocals, and everything just sounded like it should BEFORE you touched channel EQ.  The low end was tight and defined.  Kick and bass each had a place in the mix and someone said you could actually hear the string noise on the bass rather than just hearing tones that you assume are coming from a guitar.

The tests on Tuesday afternoon confirmed everything I suspected about the importance of the correct PA solution for the room and we’d never see the kind of progress leadership is looking for with volume without it.

We decided to go with the system for the midweek service and the results were pretty solid.  The entire night averaged 5 dB less than normal (mid-80′s to low 90′s rather than topping out at 95-97 dBA) but it didn’t feel like we compromised anything artistically.  With our 650s, there is a point you have to run at in order to have some degree of clarity and get over all of the interaction with the room.  A line array in the room all but removes that variable.  At the end of the service, we had an extended response time with broken down acoustic/vocal and the teacher trading back and forth.  This moment was the most beautiful thing I’ve ever heard in this space.  I pulled everything WAY back so the music was in the high 60s-low 70s dBA and it felt perfect for the mood, but the vocal had every bit the same clarity, presence, and body that it had when we were 20-30 dB hotter earlier in the night.  Amazing!

Learnings from this test is that, in light of economic realities, we need to consider how a smaller and lower cost rig would fit into our room permanently.  The Kiva/Kilo combo wasn’t my favorite box, per se; I felt like it was a bit harsh and bright.  However, it was certainly enough box to get what we need from it on a week to week basis.  The 4 SB118s were a bit light on the low end, though, but that’s to be expected.  I also felt like I wished they extended down a bit lower then they did. We’ll have to experiment with the correct type of sub and quantity to get this right.

The next test is a set of L’Acoustics ARC’s that will be in the room for a few services.  Even though I know the pattern of these boxes is not a good fit long-term for our room, I’m interested to see what we think after living with something different for more than a single service.

The best part is that this test set some further ideas in motion.  A bit premature to discuss right now, but there will be more thoughts later…

Videoblog: Easter Console Setup

This blog falls in the category of things I wish other engineers that I looked up to would do. Hopefully some of you will find it interesting to see how things flow in my little space in the production world! On Monday I will post a video tour of Easter both on and off stage – drum kit, keys rigs, stage patching, IEM world, video control, and more (I can show behind the scenes once we’re into our service run without anyone getting mad at me for giving anything away too soon!).

I’m trying a different video format for this one to see if I can improve the quality.  Any thoughts or feedback compared to the previous uploads?  Uploading to Vimeo takes a bit more time than native hosting with flash video, but it should load faster and look better.

PA Processing Part 2

It’s time to share a major system revelation during Easter rehearsals last week so that hopefully you will not do likewise!

This service has an exposed ballad with just piano & vocal.  I struggled to find a vocal EQ that would work – there was a wierdness in the midrange (1k-3k) that some on our team described as distortion but I described as a frequency hot spot.  Regardless of the EQ filters I tried in this range, it was impossible to make the harshness and “pain” go away.  In fact, that “painful” feeling existed in almost every tune in the day.  The worst part was that it seemed to be a moving target based on the note being sung so I was feeling pretty helpless.  I spent literally hours trying to deal with this but by the second night of dress rehearsal, was no further ahead then the outset.

On that second night, I had a revelation…the signal sounded normal on a board mix CD and in the headphones or monitors soloing the channel from the console.  That meant the problem must be part of the PA – perhaps worn drivers (its been several years since they have been replaced) or another malfunction.  Then it hit me to check the crossover points for the KF650s and lo and behold, the problem spot was occurring directly over the crossover point between the mid and hi drivers.  Now we’re on to something…

I called our local vendor who installed and performed the initial configuration of the London for advice and an outsiders perspective to see if he could give me any suggestions on the best path to follow for a remedy.  After listening to my description of what was happening and what I suspected to be the cause, he pulled up the EAW factory box settings while on the phone and suggested we double check the crossover numbers.  EAW has made two different models of the KF650s – the KF650E and the KF650Z (we own E’s).  As luck would have it, somehow when he first configured the BSS London BLU-80 a year and a half ago, he entered the crossover data for the Z’s rather than the E’s.  The result was the mid crossover point set too high, causing an aweful overlap between the mid driver and where it transitions into the highs.  This created all kinds of comb filtering and distortion as you swept through the 1k-2k range.  Each frequency caused a different horrible interaction between the two drivers.

Of course once I entered the correct settings, the difference was staggering.  Its like having a new PA.  Here’s a picture of the correct crossover settings:

As you can see, the large dips between the three different drivers is extremely important for correct box frequency response.  Rather than the mid low pass point being set to 1.12, it was set to 1.58.  That seemingly minor difference created HUGE problems!

MORAL OF THE STORY: Check and double check all of your crossover and factory specified settings. It never even occurred to me to check this stuff.  I’ve massaged all of the various parametrics since the box was installed, but have never opened the crossover and verified the correct settings.  Since finding this inconsistency, I’ve gone back and checked all of the settings for the driver parametrics and found a few other things that needed adjustment as well.  The result is literally night and day to the old settings.

Stop what you’re doing right now and verify your PA processing settings!  Everyone who listens to your PA will thank you.  Don’t take anything for granted…

PA Processing Part 1

I’ve meant to write about our PA processing for the past few months but an experience last week during Easter rehearsals has moved this up the topics list. We have a BSS Soundweb London BLU-80 that functions as our primary system controller. The London is tremendously powerful, allowing the user to create a completely customized signal chain that is only limited by the available processing power. In our configuration, it takes separate stereo music and speech L/R mixes from the Digidesign D-Show Profile and handles all system equalization, delay, crossover, and limiting to 12 output channels:

1. KF650 Left Hi
2. KF650 Left Mid
3. KF650 Left Low
4. KF650 Right Hi
5. KF650 Right Mid
6. KF650 Right Low
7. KF300 Left Outside
8. KF300 Left Inside
9. KF300 Right Inside
10. KF300 Right Outside
11. KF260 Downfills
12. Balcony Delay

Here is the routing design in London Architect for how the BLU-80 is configured. Each box on the diagram below represents a processing unit. From left to right, yellow boxes represent physical inputs or outputs from the box, orange represents delay, purple is equalization, gray is a high pass filter, green is a matrix mixer, blue is gain control, and green is limiting.

The signal flow through the box is as follows:

• Signal enters and is separated onto two paths – one for music and one for speech. Each goes through a delay that aligns the master mix to the subwoofers (12 ms) and then into a master “house” parametric EQ. This is the artistic curve that adjusts the frequency response of the entire system. There are different curves optimized for music & speech.
• After passing through the artistic parametric EQ, each of the two mixes are split into a full range version and a high passed version that then hits a matrix mixer which routes to the various individual speaker chains. With music, for example, a full range mix is sent to the main KF650s, but a high passed version is sent to the downfill speakers and center cluster in order to reduce 250 hz buildup in the room. The matrix mixer really acts more as a router – its all or nothing for each speaker channel, either full range or high passed.
• From there, the KF650s hit another parametric that allows for some sculpting of the 650s as a whole. The output from this parametric hits the three-way crossover for the boxes. These crossover points are factory specified. From there, each driver’s output hits a dedicated parametric with factory specified settings, driver gain controls, and then driver limiting.
• For the KF300s, KF260s, or Balcony feeds, the output from the matrix hits a dedicated parametric for box sculpting, then a parametric for factory specified box settings, gain and limiting, then channel delay to align with the KF650s.

While you read the signal chain in the London from left to right, the process of equalizing and aligning the system basically works from right to left. The first step is to enter all of the factory box settings, gain balance between low/mid/hi drivers, and align the delay times between the various boxes. From there, we use EASERA to start with the KF650s, scope them, and make adjustments until the response is as desired. Then add the KF300s one at a time, scoping them individually, then adding each one into the 650s and making the necessary adjustments. Continue the process until all of the boxes are active and frequency response is fairly flat. At this point the artistic master parametric EQ comes into play to sculpt the overall response to fit the mix and the room

SMPTE Part 1

Christmas 2008 was my first experience diving into SMPTE, MTC, and VTR decks so that we could sync our primary Beta deck with ProTools for audio track playback.  In order to start this discussion, I thought it would be a good idea to start out with SMPTE 101.  Brent Hoover wrote a great overview over at the study hall on ProSoundWeb.  Below is a summary of his thoughts…

What is Timecode? 
Timecode is simply a way of recording a “time” along with either a visual or audio event. This allows you to say, “The beginning of the song is at 0 and the cymbal crash happened at 2 minutes and 53 seconds.” The information is then stored along with the audio or video medium so that, as it is moved from device to device, the time information stays the same.

The most commonly used timecode format was developed by the Society of Motion Picture and Television Engineers. Referred to as SMPTE (pronounced Simp-Tee), it was originally developed to synchronize sound for film but has since been adapted for video as well as audio-only use.

The other commonly used timecode format is Midi Time Code (MTC), which was developed by Chris Meyer and Evan Brooks for Digidesign.

How does Synchronization work? 
Imagine that you and a friend have the only two watches in the world, so that you have no time reference other than your own watches. You need to meet at an exact time later that day. No watch is exactly accurate – maybe yours is a bit slow and your friend’s is a bit fast. Over the day the result is that there is a 10-second difference between your two watches. While it may be okay with your friend that you’re 10 seconds late because he likes you, it would be very bad for a cymbal crash. In audio, even delays of a fraction of a second with doubled vocals can be noticeable.

The next day, in order to circumvent the 10-second time difference, you and your friend work out a system. You pick one person as the Master and one person as the Slave (it’s that kind of friendship). The Master calls the Slave on his cell phone and tells him what time it is every few seconds, and the Slave resets his watch to match the Master’s. While this system may be an annoying prospect for human beings, it works quite well for machines. Similarly, in every timecode set-up you must determine which machine is the master (there can be only one) and which are the slaves. Usually the constraints of the machine will define who is master and who is slave. 

How would I use Timecode? 
Sync-to-Video - The simplest video sync scenario works much like this: a VHS tape has LTC on one of its audio tracks (it is the Master). The device to be synced (the Slave) reads that timecode and chases it. The tricky part is determining which type of SMPTE frame rate to use.

When using SMPTE at 30 frames-per-second (fps), one second equals one second. Unfortunately, NTSC color video does not run at 30fps — it runs at 29.97fps. Why in blazes does it do that, you ask? Well, let’s just say that video, like life, was simpler when it was in black-and-white. But when color was introduced, they decided to cram that little bit of color information in the space left by .03 frames.

At 29.97fps, a second of material is no longer a second, but just a hair longer. While a few hairs may not matter to you and me, they matter a lot to people in television who make their living selling seconds, so these people came up with a solution called “drop-frame”. This means a few frames are dropped so that SMPTE time matches with real time.

So we have SMPTE at rates of 30fps, 29.97 “drop” and 29.97 “non-drop”. All that really matters on a basic level is that you need a tool that can handle all these different frame rates, and you must know exactly what frame rate the video you are syncing with is using.

In the next post on SMPTE, I’ll go over our setup and implementation, along with some learnings from an intense production process.