Crossover vs EQ: Help me understand.

J

John Neil

Freshman
Mar 8, 2011
39
0
0
Virginia
Tonight, 800 cap club, historic theater. Sold out show. Me, house tech. System alignment done by me. Needs some refinement but is a good middle ground for the shows we do. Real PA. Watts, boxes, processing, two balconies, zones, delays, etc.

Band carrying everything, me just racks and stacks today. Venue desk and snake stay out for support. I'll do five mixes from FOH so that the venue mon desk can be struck and save space on stage. BE hands me left, right, subs and front fills. We have inputs duplicated in processing so getting between the two desks is a snap. Done.

Band is a B national with an upcoming Letterman slot. Typically they tour with a pretty serious A national arena show, so they are used to this game where appropriate PA is deployed and ready for them. This is a BE that regularly rubs shoulders with system guys from the big C touring provider.

No sooner than I have turned the rig on, I'm asked about the crossover of the system between L/R and subs. I reply with some reflection regarding electrical and acoustical reality of the setup. Next I notice, BE is using output graphics on the Profle desk as "death above" and "death below" filters for his four outputs to me. BE goes on to EQ the rig using inserted parametric on L/R, nothing on subs, nothing on front fills. No time alignment, no listening, all via pretty traces on SMAART.

Long story, but the phase shift at crossover imparted by the death above/below application was never accounted for. Non-trivial in this application given my insight into the crossover slopes and traces I used to get things where they are. Does it matter, yes, but no. Show was fine. I'm trying to reconcile my knee-jerk negative reaction to a band guy messing with my system, especially without listening first. Yes I'm personally attached. I'd say 15% of band guys in this role seem to want to crossover via EQ in some form. He had a fine show, really. Had he listened to the system (or measured) and had a request, I was standing by to make requested processing changes via laptop.

What I seek is some insight into the EQ as crossover mentality, especially death by convention. At this point I figure I must be missing something...something that happens in the big leagues with bands you've heard of. Anybody. "Stop caring" is also a valid suggestion. I recognize my inability to get over it is a part of the issue. Please, help me appreciate the rationale.
 
Re: Crossover vs EQ: Help me understand.

"Death by" crossovers, ignore the behavior in the transition region, when both frequency bands are generally active and need to play nice together.

With steep enough filters either/or could work for very low bass, but adjacent bands of GEQ are not really optimal brick wall filters.

JR
 
Re: Crossover vs EQ: Help me understand.

John -

I hear your frustration. Not much to understand, though, it is wrong. You would be surprised at how many people do this, including some very otherwise smart people who make great mixes.

Maybe you need to print a screen shot of your sub crossover, tape it to the console screen, and just show them, that no, actually, there isn't much 2k in the subs and you don't really need to cut it on the EQ.

I am starting to think that it is more so the engineer can have a easy VISUAL clue that he is on the correct EQ channel. Front fills are death below 100 and subs are death above 100... no need to read.

Although, we both happen to know some otherwise fairly decent subs that do require a bunch of out-of-band EQ even with a steep crossover :)

Jason





John Neil said:
Tonight, 800 cap club, historic theater. Sold out show. Me, house tech. System alignment done by me. Needs some refinement but is a good middle ground for the shows we do. Real PA. Watts, boxes, processing, two balconies, zones, delays, etc.

Band carrying everything, me just racks and stacks today. Venue desk and snake stay out for support. I'll do five mixes from FOH so that the venue mon desk can be struck and save space on stage. BE hands me left, right, subs and front fills. We have inputs duplicated in processing so getting between the two desks is a snap. Done.

Band is a B national with an upcoming Letterman slot. Typically they tour with a pretty serious A national arena show, so they are used to this game where appropriate PA is deployed and ready for them. This is a BE that regularly rubs shoulders with system guys from the big C touring provider.

No sooner than I have turned the rig on, I'm asked about the crossover of the system between L/R and subs. I reply with some reflection regarding electrical and acoustical reality of the setup. Next I notice, BE is using output graphics on the Profle desk as "death above" and "death below" filters for his four outputs to me. BE goes on to EQ the rig using inserted parametric on L/R, nothing on subs, nothing on front fills. No time alignment, no listening, all via pretty traces on SMAART.

Long story, but the phase shift at crossover imparted by the death above/below application was never accounted for. Non-trivial in this application given my insight into the crossover slopes and traces I used to get things where they are. Does it matter, yes, but no. Show was fine. I'm trying to reconcile my knee-jerk negative reaction to a band guy messing with my system, especially without listening first. Yes I'm personally attached. I'd say 15% of band guys in this role seem to want to crossover via EQ in some form. He had a fine show, really. Had he listened to the system (or measured) and had a request, I was standing by to make requested processing changes via laptop.

What I seek is some insight into the EQ as crossover mentality, especially death by convention. At this point I figure I must be missing something...something that happens in the big leagues with bands you've heard of. Anybody. "Stop caring" is also a valid suggestion. I recognize my inability to get over it is a part of the issue. Please, help me appreciate the rationale.
Click to expand...
 
Re: Crossover vs EQ: Help me understand.

Hmm, sounds more than faintly familar.

On the opposite side of the story, I was recently in a smaller (400 seat) community theater down your way where I went in and fired up the center cluster (all there was) and had no mids at all. I check the driverack and it is set to a custom three way crossover. However the amps look like it is wired as a two way with a passive crossover in the tops. The house tech could not confirm for me which way the system was wired. The manager has fallen back on the "thats how it always sounds" argument and is convinced their preset is correct, and I have doors coming up in 15 minutes with no further time for troubleshooting.

I end up with no amplification on the banjo and fiddle, and the lead vocalist triple bussed (L/R, Group 1/2 vocals assigned to L/R, and group 5/6 solo group assigned to L/R) just to keep up with the instruments acoustically.

Fortunately it was a quiet crowd.

I left convinced they were sending the HF band from the crossover to full range tops.

Now that I have gotten comfortable with measuring an installed system fairly quickly, I have to figure out a time alotment to allow me to respond to problems I find. Knowing there is a problem with the PA as people are filing into their seats is not a great feeling.
 
Re: Crossover vs EQ: Help me understand.

John,

Just repeat "serenity now, serenity now!". My frustration with how some BEs treat a PA I feel I've really done a good job on led to me create this video, I'm sure the humor will hit home with you:


At the end of the day, the BE is the creative one and you and I are the scientific ones, but all the audience cares about is whether it sounded good. If the BE feels that they have done themselves a service by dumping sliders on the EQ, they're the boss... Admit it, it didn't really sound bad, it just annoyed you because it wasn't "right". Even the +/- 15dB available on a graphic EQ can't fuck up your sub/top alignment that badly, and if they really want those frequencies gone... well, maybe you weren't using a steep enough XO. Maybe they didn't like your answer to their crossover question. Frankly, I always answer "80Hz". That makes most people happy, and the folks who "get it" aren't going to ask that question anyway.

At least you can rest easy knowing that because you've done your job well, anything they screw up will be screwed up throughout the house! :D

P.S. This is why I try and never give a BE a separate line for fills.
P.P.S. Were his pretty traces on Smaart correct? You were measuring, right? What do you mean by "needs a little refinement"?
 
Re: Crossover vs EQ: Help me understand.

Bennett, not seeing the video.

All house zones are derived from L/R and I intend to route front fills through processing...soon. BEs that usually play larger venues usually look at me like "why would I want to mix those independently" to which I reply "unity on channel sends is a pretty good start for vocals" or "I'll just route L/R to that matrix for you and you'll be set." Nine times of ten it seems better to derive from L/R, so we'll see how often I revert back to front fills via aux once I default the other way.

Steve Bush from Meyer made a pretty similar remark regarding art vs. science in his optimization seminar.

Jason, the room expresses some pretty nasty out of band issues on the subs based on the cinderblock wall behind them. Those are addressed in the DSP via crossover choice and EQ, and then timing adjusted accordingly. Previous to addressing those I saw plenty of nights where a BE would listen to Hey Nineteen through the subs (haystacked by 12 db nonetheless, but that's another thread) and want to steepen things up.

P.P.S. Aside from measuring only one point the BE achieved an accurate measurement and used it to EQ the mains to his liking while playing a very bad mp3 conversion of Death Cab as source material...at a volume very similar to his show levels. I took issue that he had the opportunity to account for his "death by" maneuver but never looked at a phase trace to approach the subject. Further, he never measured or listened to the system before making the death by move. I don't turn a knob unless it's a perceived positive result to do so. Somewhere along the line a significant population of BE types learned that using EQ as crossover serves to make their end product better. Right, wrong, or doesn't really matter, that's the mindset I seek to understand.

P.P.P.S. In the end I would forget about the whole deal if they would use Mark Knopfler to tune the rig.

P.P.P.P.S. I still got the guy a drink during sound check. That's my job, right?

P.P.P.P.P.S. At the end of the day, bar sales far outweigh crossover integrity. I get that, but it doesn't make it right.
 
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Re: Crossover vs EQ: Help me understand.

Bennett Prescott said:
John,

Just repeat "serenity now, serenity now!". My frustration with how some BEs treat a PA I feel I've really done a good job on led to me create this video, I'm sure the humor will hit home with you:

Maybe they didn't like your answer to their crossover question. Frankly, I always answer "80Hz". That makes most people happy, and the folks who "get it" aren't going to ask that question anyway
Click to expand...
That reminds me of an actual gig I did years ago. No names will be used to protect those involved.

The gig was a 3-4000ish civic center. The gig wasa hardcore metal type show. The PA was up and running when the band arrived. The first words out of his mouth were (and I remember them clearly) "MAN, I bet this PA kicks ass--(pause)--in a small club-but it won't do shit in this room".

Nice to meet you to. It's gonna be a long night.

So when his band comes on, I am back at FOH, expecting him to try and kill the PA. After a couple of songs (and me knowing the system would do more), I checked on the amps and they were just fine.

I went to FOH and told him he could come up a good bit if he wanted. He said he was fine with the level.

Now that PISSED me off. You insult my rig like that and then don't try to blow it up?????? He is supposed to try and blow it up, and it is my job to stop him. That's the way of the sound world.

Nice video BTW-and very true. Ignorance does not make people better than you.

You mean you ask them whether they mean the electrical or acoustical crossover point is 80Hz? yeah-that is a bit over most "engineers" heads. They think the crossover "stops" the sound at the freq it is set at. Oh well----------------
 
Re: Crossover vs EQ: Help me understand.

Kemper Watson said:
Too funny Bennett.. You should make more of these..LOL
Click to expand...

Maybe some day, this one was the perfect storm... right mood, right time, late at night, enough bourbon...

John, here's a hard link: http://www.youtube.com/watch?v=PD0xOSv7cQM

I thought everyone had seen this one! It's got a totally unreasonable number of views.
 
All you need to know is that guy is the audio industry version of an idiot. Happens all the time. Thank you for trying. Keep up the hard work. Keep fighting. We will educate all of them collectively a little at a time.
 
Re: Crossover vs EQ: Help me understand.

Tonight at venue...I give up. Perhaps during the next re-tune I take this into account.

subs.jpg
 

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Re: Crossover vs EQ: Help me understand.

Perhaps you need a couple of presets in the dsp like "sane" and "insane".I have several bands that I could bring in there that we would be plenty happy with "sane".
 
Re: Crossover vs EQ: Help me understand.

Bennett Prescott said:
John,

If the BE feels that they have done themselves a service by dumping sliders on the EQ, they're the boss... Admit it, it didn't really sound bad, it just annoyed you because it wasn't "right". Even the +/- 15dB available on a graphic EQ can't fuck up your sub/top alignment that badly, and if they really want those frequencies gone... well, maybe you weren't using a steep enough XO.
Click to expand...

Bennett,

Not to beat a dead horse, but I assumed you menat that I was getting fussy over nothing. Took a few weeks but finally had chance to do some acoustic housekeeping. Took a quick shot in the interest of investigating your point. Two traces of subs measured from FOH position. One with death above 100 on a PM5d graphic inserted on subs.

deathsubs.jpg

Turns out "death above 100" shows up as a difference of right about 180 degrees across my crossover region.

Fortunately, a quick polarity reversal undoes most of the damage even if not ideal.

I was able to get the mains/subs aligned for the better part of an octave each side of crossover over 2/3 of the audience. That'll be nice for the club of BEs that prefer to move crossover around in order to get steely dan sounding right.

On a related note, anybody know if BSS has made all-pass filters available in London units? Six different types of speaker across eight zones...
 
Re: Crossover vs EQ: Help me understand.

John Neil said:
Not to beat a dead horse, but I assumed you menat that I was getting fussy over nothing. Took a few weeks but finally had chance to do some acoustic housekeeping. Took a quick shot in the interest of investigating your point. Two traces of subs measured from FOH position. One with death above 100 on a PM5d graphic inserted on subs.
Click to expand...

I meant more that just because you're RIGHT doesn't mean you're "right". The point of the gig is often to make the BE happy and get paid by the promoter... educating someone who has a method that works is not always a recipe for new friends.
 
Re: Crossover vs EQ: Help me understand.

Thanks for clarifying Bennett. I think we were on the same page regarding that component from the start.
 
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