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

Videoblog: Drum Shield

3/16″ Clear Plexiglas

90 degree brackets:  http://www.abctarget.com/product1~P~P174.htm

Total Cost:  $240

Easter 09

Today is day 8 of my 17 day Easter setup/rehearsal/service marathon at Kensington. This year we’re doing 22 identical services at 5 locations. Last night the Troy team premiered the service for the cast & crews of all of the other campuses at the end of our dress rehearsal process. Next week the campuses will go through their rehearsals in their spaces.

I’m really excited about this service but it has been a unique challenge from an audio perspective. There are a couple of really cool original tunes in the day, a “stomp”-esq percussion opener, video screen blending, drum & keys decks that move, 62 physical inputs plus effects returns, 20 channels of RF (ears, instruments, vocals, drama, & speakers). I’ll write more about the process for the service and learnings once there’s free time on the other side of next weekend.

In the meantime, I shot a “teaser” time lapse of rehearsal on Wednesday night. Check it out! If you’re in the Detroit area, come check out the service Easter weekend!