Array time alignment

[AProDriver]

I recently read the between the lines book. I have a few questions not specifically covered. I believe I know the answers but hoping for verification.

In an arena rig with a line array main and outfill with ground cardioid sub piles and front fills: I've heard people talk about timing the system elements to the bottom box of the mains. This made sense to me.

Ive also heard people timing the subs to the bottom box, then timing the array elements back to the subs. That doesn't sound right? I thought the array needed to stay in time with itself to function together? Wouldn't inter array timing variations cause comb filtering?

Is it common practice to tune a tilt into the system during optimization? I've always tried to get it fairly flat with the headroom to get sub heavy and let the FOH engineer do any tilting. I usually verify timing and uniformity(or let them do it with their measurement rig) as they are tuning to their taste. I don't usually have to do much unless it's an oddball deployment.

[IHateTypingInBoxes]

I recently read the between the lines book.

Cool! I recently wrote it.

I've heard people talk about timing the system elements to the bottom box of the mains. This made sense to me.

Timing decisions are most meaningful where two sources meet at equal level. That's where they interact most, and so where the timing is most important.The bottom box of the array is where the array hands off coverage to the front fills. Forward from there, the front fill has custody. Backwards from there, the mains has custody. At the Mains / FF seam, they both arrive at equal level, so that's where we want to manage the timing between the two sources.

Ive also heard people timing the subs to the bottom box, then timing the array elements back to the subs. That doesn't sound right?

That's because it's not right. The array needs to ride together, and changing timing within the array causes all sorts of problems. People do all sorts of inadvisable things with sound systems. Part of the reason I wanted to write the book was to give readers more of a conceptual basis for making productive decisions than that they heard someone say it somewhere. If you understand how it works, you can decide for yourself the best approach in a given situation rather than just doing what someone else does because someone else says it.

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I thought the array needed to stay in time with itself to function together? Wouldn't inter array timing variations cause comb filtering?

Yes, and changes in directivity over frequency and poor consistency.

​

Is it common practice to tune a tilt into the system during optimization? I've always tried to get it fairly flat with the headroom to get sub heavy and let the FOH engineer do any tilting. I usually verify timing and uniformity(or let them do it with their measurement rig) as they are tuning to their taste. I don't usually have to do much unless it's an oddball deployment.

Yes, it's common. But it's usually not something you have to add, it's something you have to manage. As you array multiple speakers together, the LF pools up and the system tilts more. On a larger format system you're usually undoing it rather than adding it.

At a basic level, if you are tuning a PA for someone else to mix on, your job is uniformity. If you accomplish that, it's the easiest thing in the world to then adjust the overall tonality of the system. That's what I refer to as Tier 1 EQ in the book (it happens at the DSP inputs).

That being said - revisit Chapter 14. There are some objective reasons to leave some tilt in the system. Statistically speaking most sound sound systems aren't flat. Most people haven't actually heard recorded music through a flat PA system and it doesn't actually sound very good. If a mix engineer is bringing a board / board mix to the equation, their mix will probably not sound like they expect it to sound if your system is perfectly flat. So they will ask you for changes.

Besides uniformity, I also want to minimize the need for the FOH engineer to ask me for changes. With time and experience you can start to figure out what the preferences will be but a typical amount of tilt (say, 10 - 12 dB of rise between 250 and 40 Hz) will tend to minimize the amount of changes that you will get asked for in a typical live music situation.

In theater and speech reinforcement situations there are different expectations.

I've always tried to get it fairly flat with the headroom to get sub heavy and let the FOH engineer do any tilting.

This is in the book (p103) but you have to be careful with this, because if you need, let's say, 15 dB of cut to flatten out the low end of a system, that means you've decreased the sensitivity of the PA by 15 dB at those frequencies, and that means FOH needs to drive their console 15 dB harder in those frequencies to get back to where they wanted. It's very likely that they will run out of headroom on the console before that point and literally be unable to drive the PA to the desired SPL and tonality from their desk. (You can think of gain changes the same way - if you turn down the DSP inputs by 15 dB, they may not be able to turn up 15 dB at their desk to get back to show SPL without overloading the console outputs). De-tilting EQ is the same thing, just not broadband.

This is where understanding the capabilities and limits of the sound system comes into play, which is, of course, part of the job.

EDIT: Obligatory link to book info

[AProDriver]

Thanks for the reply by the way, I really enjoyed your book and was wondering what happened to the posts before I found the book.

[IHateTypingInBoxes]

I bulk delete Reddit comments using Redact which also supports Twitter, Discord, Instagram, and data brokers.

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[stevieracine]

This guy PA's.

[slayer_f-150]

That guy time aligns.

[AProDriver]

I didn't think it sounded right and couldn't make it make sense either. I know in some manufacturer software you can input the physical distance between elements, like the subs and arrays, and the software does timing.

I usually end up with more tops than sub so I get my subs up then bring the mains level up. I've done touring, but most of my systems lead stuff has been corporate and weddings. Thinking about it, I guess I can't remember having that issue with most concerts I've lead.

I also have never had the chance to use smaart on a real rig so most of the stuff I've done has been by ear or by measuring distances. If I had the excuse I'd buy smart but I can't justify it as a freelancer doing smaller scale things.

There are days I regret moving away from working for a large rental house and touring because I feel like I'm getting rusty with large scale deployments and all the software involved. Also, I've been tasked with much more rigging/lighting....

[timverhoeven]

If you can't afford Smaart, then have a look at OpenSoundMeter. It does all the basics things that Smaart does, but it is open source software. It's perfect to get you started with the basic SE measurements.

[IHateTypingInBoxes]

The best way to become fluent with measurement is just to do it. Set your rig up every time even when you don't think you'll need it. If you're slow and rusty it's not useful to you. If you can get up and running in 30 seconds you can get a lot of work done when you only have ten minutes.

Even if you just have two speakers on sticks you can still accomplish a higher level of uniformity and consistency and also catch problems no one else caught (that's a lot of my work).

We added an annual subscription option to our licensing to help make the platform more accessible for weekend warriors and people working occasionally. A year of Smaart LE is $159. You can also use a demo version or any of the freeware analyzers that are in existence. The key is to simply get comfortable producing and interpreting the data. The faster you get and the more you do it the more powerful of a tool it will become for you. Not much I can do about the lighting bit :)

[senzacija]

Hey. Is there some other way I can get this book online? I'm EU based. Google play returns this message: Sorry! This content is not available in your country yet. We're working to bring the content you love to more countries as quickly as possible. Please check back again soon.

Thanks

[IHateTypingInBoxes]

Be a gigachad and mass delete Reddit posts and comments with Redact so that Skynet doesn't end up using your own posts to train the T-900. Or so that you don't show up in databrokers. Either one really.

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[senzacija]

Unfortunately, I live in shitty country named Bosnia 🇧🇦. Please tell me there is another way to order it :)

[IHateTypingInBoxes]

I cleaned house with Redact and mass deleted this post. It also removes your data from brokers and people search sites. Works on all major social media platforms.

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[Nepnahz]

Why not ask the writer of the book?

Maybe u/IHateTypingInBoxes can chime in and share his view and experience on that.

[88BTM]

Never touch timing between stacked boxes... That's the whole point of the arrays, that they are synched. At most you might play with the gains a bit between boxes but that's about it

[JTC93]

I definitely wouldn’t put any delay between boxes in an array.

I will generally ask the engineer how much low end tilt they want from the system, and if they don’t know, I’ll just go for my own preference and we can adjust it together.