A Long Story With A Happy Ending

I came to Evangel Church somewhere in the middle of June of 2011 as the Creative Ministries lead.  It started out as a “worship leader” portfolio and quickly evolved into a bunch of other things, including pretty much all of the technical aspects of the church.

The thing I noticed right off the bat was that I didn’t like the sound in our sanctuary, and I wasn’t sure why.  The components were pretty much A-list stuff, and there was no reason for it to be as thin as it was.  But it worked — at the time — and I didn’t want to embark on a gigantic project in my first week on-staff so I let sleeping dogs lie, and just “worked around it” often applying outrageously extreme equalization at the sound board to compensate for the system’s shortcomings.

Oh… and buzz.  Let’s talk about buzz and ground lifts.  If there was a book on the number of different kinds of buzz we had, we had all of them.  Sixty cycle was obviously the main offender, but we would get other weirdness from time to time.  It was kind of like a “noise du jour” situation where it would change from week to week.

Suddenly, I would say about in late February of this year, something gave out.  And we didn’t know what it was.  And we didn’t have the budget to have a big shot sound engineer come in and diagnose it.  The worst part was that it was very intermittent in nature, so it was very hard to diagnose.  I would chase a suspect, apply a fix, it would be gone for a week or three and I’d think it would be cured when the problem would come back again.  It was very frustrating.

What was the problem?  I’m so glad you asked.  At a random point in our Sunday service the gain would go flying through the ceiling (resulting in feedback) and the EQ would do strange things.  I’m sorry, but “strange things” is the best I can do.  There are no words in the English language for the sounds that came out of the speakers when this phenomena presented itself.  Often I found if I shouted into the mic as loudly as I could it would “reset” and everything would be fine and dandy and happy again.

I’ll give you our signal path as best as I can, so those among you who think you are smart can try to guess what the culprit was.

We start with an Allen-Heath GL2400 mixer, which then routes to our amp room where the signal would go through a JBL compressor/limiter, a Yamaha digital graphic equalizer, a JBL crossover, and then into two Bryston 3B ST power amplifiers that are connected to a custom enclosure in our sanctuary of unknown lineage, as well as a number of small satellite “repeater” speakers that I would like to practice my handgun targeting skills with.  ‘Nuff said.

This is how it was “when I came here”, and up until recently we didn’t touch it.

We sent the Allen-Heath out to be checked.  We sent the Brystons out and had them completely refurbished.  The amount of money I spent on rentals while this was going on was bordering on obscene.  (By the way, I had no idea how difficult it is to rent a crossover these days… it’s virtually impossible.)

This whole process took about three to four months.

One day while doing some stress testing (the phenomena also seemed to be triggered by high volume levels) I happened to luck out and “the culprit” decided to misbehave for about twenty five minutes instead of the usual two to three minutes.  A sprint from the sound board to the amp room and some furious hot patching, and we found the culprit…. at long last…. it was the Yamaha digital graphic equalizer… whose programmed curve that displayed on the front panel had always looked suspect to me anyway.  It looked too “artificial”.  Too perfect.  I knew there was no way that the frequency response in our sanctuary could resemble a french curve so closely.

So I went and bought a cheap to mid-range graphic equalizer that probably cost $800 less than the Yamaha did.  Fifteen band stereo.  Nothing fancy.

Then I got looking at the crossover.  As knowledgeable as I am about audio, I have never really messed with crossovers that much.  And I didn’t know the specs of the speakers either, but it seemed very odd to me that the crossover frequency knob was panned as hard to the left as it would possibly go.  It was at this point that I realized that whoever had set this thing up, had directed 80% of the signal to the horns.  Things were starting to come into focus.

I went looking for an RTA to rent and couldn’t find one of those either.  So I did something that is going to make some of you sound purists cringe.  I downloaded an RTA app from the iTunes App Store, and we used the internal microphone of an iPad to RTA the system.  I figured even if it wasn’t totally accurate it would at least give us a starting point, and we could adjust the rest “by ear”.  After all, there were only fifteen bands.

Here’s the shocker:  We EQ’ed the room flat with the iPad and decided to see what it sounded like.  First some familiar music.  The hairs on my arms were going straight up.  It sounded delightful.  The sound was full-bodied and clear with not a hint of mud or over-exaggeration in any part of the EQ.  In short… it was accurate sounding!  I picked up our cordless “preaching mic” — a mic I have HATED since the day I came here — unmuted it, and did the usual “Test 1, 2….” and almost fell on the floor.  The midrange was present, it sounded warm (unlike it had previously) and I actually liked the sounds of it.

The thing I have forgotten to mention is that during all of these tests, we set the channel EQ FLAT, making only the very smallest adjustments in the very top or very bottom.

And after flicking the built-in ground lift on the new equalizer, we have not had a single incident of hum ever since.  The system is totally quiet at idle, other than a small hiss that is almost impossible to hear.  We have had almost a month of services now with zero sound problems.

Oh… and the best part is yet to come.  The first Sunday after the new equalizer was installed and we had redone the EQ in the room, I was cornered by one of my board members.  This fellow wears hearing aids in both ears.  With tears in his eyes he told me that he had been able to hear everything in church for the first time since he started attending here.  He went on to say that he didn’t like it (previously) when I would be playing softly when the pastor was saying something because it “would all come through like mud” in his hearing aids.  But since the changes, he was able to separate the two sounds and hear them both clearly.

So… what’s the next step.

I want to get rid of my mains and hang a couple of powered 12’s… maybe QSC K-series stuff.  Not for more volume, but for more headroom.  We’ll see.  For now I’m just happy to be able to have an uninterrupted worship service.

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Posted on July 5, 2012, in Uncategorized. Bookmark the permalink. Leave a comment.

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