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Author Topic: Smaart subwoofer alignment  (Read 3786 times)

Michael Storey

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Smaart subwoofer alignment
« on: January 08, 2017, 08:38:42 pm »

I'm currently researching the process of time aligning subwoofers to mains using Smaart, and came across the video linked bellow. I'm curious what those of you well versed in the subject think about his method, particularly his choice to not "delay locate". I assume he is referring to the process of delaying the reference signal to the mic signal? Please correct me if I'm wrong.

https://www.youtube.com/watch?v=j6Z_sIDrs8A&t=11s
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Ivan Beaver

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Re: Smaart subwoofer alignment
« Reply #1 on: January 08, 2017, 09:15:17 pm »

I'm currently researching the process of time aligning subwoofers to mains using Smaart, and came across the video linked bellow. I'm curious what those of you well versed in the subject think about his method, particularly his choice to not "delay locate". I assume he is referring to the process of delaying the reference signal to the mic signal? Please correct me if I'm wrong.

https://www.youtube.com/watch?v=j6Z_sIDrs8A&t=11s
I did not watch in detail the whole video, but he is NOT delaying the reference to the mic.

He is playing with the delay between the full range signal and sub.

HOWEVER I find it REALLY strange that he is not "taking the time of flight" into account.

It will make the phase response MUCH MUCH easier to look at.

It will remove all the phase wraps he is seeing and be MUCH flatter-at least in the area of interest.

There are much easier ways to see this alignment.

His basic idea appears to be correct (again I didn't watch the whole thing), regarding get the phase traces to overlap. 

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Ivan Beaver
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Mark Wilkinson

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Re: Smaart subwoofer alignment
« Reply #2 on: January 09, 2017, 10:21:45 am »

Echoing what Ivan said, and just adding as to why delay locating makes it much easier to get more accurate results....

There is a lot more phase difference in slight misalignment between steep traces, than there is in flatter traces. 
IOW, his method looks easier because it is easier.....it requires less precise alignment than using flatter traces.


Also, we want to make sure we align to the fewest wraps possible...I don't know if his method makes this possible.
Kinda doubt it, but need to think it through..

It all really begs, why NOT use delay finder? 
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Mac Kerr

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Re: Smaart subwoofer alignment
« Reply #3 on: January 09, 2017, 01:07:46 pm »

It all really begs, why NOT use delay finder?

Because delay finder uses the peak of the highest frequency it can read, which may be well above the frequency of interest. Using the phase slope to set the time offset can be done at whatever frequency you want to use. The "phase wrap" can be eliminated by selecting phase unwrap in the menu.

The fallacy of all methods of sub to mains alignment is that unless the 2 systems are located very near each other the alignment only applies to a limited area.

Mac
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Mark Wilkinson

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Re: Smaart subwoofer alignment
« Reply #4 on: January 09, 2017, 02:39:04 pm »

Because delay finder uses the peak of the highest frequency it can read, which may be well above the frequency of interest. Using the phase slope to set the time offset can be done at whatever frequency you want to use. The "phase wrap" can be eliminated by selecting phase unwrap in the menu.

The fallacy of all methods of sub to mains alignment is that unless the 2 systems are located very near each other the alignment only applies to a limited area.

Mac

Yes, familiar with those points.  I just find it easiest to work with as clean a phase screen as possible and getting to traces as flat as possible, for aligning overlay. IMHO, starting with delay finder's time/distance on the main(s) helps that.....gives me a intuitive base for ballpark sub timing with just a few back of envelope calculations. And most importantly, let's me know if measurements are passing the smell test  ;D

I've been meaning to ask you...in a previous thread somewhere, I had wished Smaart had the ability to target a user select frequency for determining delay. 
IIRC, you suggested to put a single freq sine wave in the pink for smaart to lock on.
I tried it and found if the sine wave had greater or even competing magnitude, smaart wouldn't find delay at all.
If I lowered the sine magnitude down below the pink, smaart would find delay, but at exactly the same time as if no sine... still using highest peak.

So I hit the manual, and read that smaart can't use repeating waveforms for transfers....?

Maybe I misunderstood your suggestion or remembering it wrong...
Any redirection ?   

Thx.  mark
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Ivan Beaver

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Re: Smaart subwoofer alignment
« Reply #5 on: January 09, 2017, 07:05:55 pm »


The fallacy of all methods of sub to mains alignment is that unless the 2 systems are located very near each other the alignment only applies to a limited area.

Mac
Yeah.

I have done some designs/installs that violate EVERY rule in regards to top/sub alignment.

But that does not keep them from sounding great and everybody loving it.

It all depends on freq capabilities of the mains (how low do they go) and overall positioning.

There are a lot of "it depends" when it comes to alignments.

It is VERY GOOD to understand the "proper ways" and know how to do it, so you can better understand the tradeoffs you have to make and whether they are worth it or not.

Just "willie nillie" ignoring the "rules" is NOT an excuse and often leads to poor results.
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Ivan Beaver
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Tim McCulloch

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Re: Smaart subwoofer alignment
« Reply #6 on: January 10, 2017, 04:29:19 pm »

Yeah.

I have done some designs/installs that violate EVERY rule in regards to top/sub alignment.

But that does not keep them from sounding great and everybody loving it.

It all depends on freq capabilities of the mains (how low do they go) and overall positioning.

There are a lot of "it depends" when it comes to alignments.

It is VERY GOOD to understand the "proper ways" and know how to do it, so you can better understand the tradeoffs you have to make and whether they are worth it or not.

Just "willie nillie" ignoring the "rules" is NOT an excuse and often leads to poor results.

Herein lies The Truth.

Not everything we did in The Days Before Measurement was wrong but it was almost always the result of a blind compromise.  We could hear things working (or not) but we weren't really sure *why*.

Today we can over-measure something and turn a situation with no clear best outcome into paralysis by analysis.  Having some experiential basis for making the adult-in-the-room decision about what alignment & optimization compromises to make is much more important than making yet another measurement and hoping to find The Solution.
« Last Edit: January 10, 2017, 04:35:24 pm by Tim McCulloch »
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Ivan Beaver

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Re: Smaart subwoofer alignment
« Reply #7 on: January 10, 2017, 08:41:52 pm »



Not everything we did in The Days Before Measurement was wrong but it was almost always the result of a blind compromise.  We could hear things working (or not) but we weren't really sure *why*.


When I started actually LEARNING about "how audio things worked", it was like a whole bunch of light bulbs getting turned on.

I started learning WHY all of the "things I had experienced" actually happened.

NOW I could start to put some actual science/math etc to my sonic experiences.

This now makes it MUCH EASIER to "guess" about a lot of things-by understanding the basics behind it.

I was EXHAUSTED after the first day of my first Synaudcon class.  It was like "explosions" all day with experiences and reason coming together.

But one without the other leaves a bit of a "hole" in the whole "understanding experience".

Many people often talk about things as if they understand, but have never experienced, so they don't know the "topic at hand" and tend to "blow up" what is actually going on.
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Ivan Beaver
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Mark Wilkinson

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Re: Smaart subwoofer alignment
« Reply #8 on: January 11, 2017, 01:30:21 pm »

Yep to all said...  ears, experienced from so many situations, rule.
I think we do have to admit though, that making measurements, along with DSP control, are impacting nearly every area of audio setup and SQ, from the largest arrays all the way down to home theater.
IMHO, making good measurements is mattering more and more...

I like to think of good measurements as needing two wings to fly. 
One wing being practical application; as in why measure to begin with, exactly what to measure, and what can really be done with the measurements.
Second wing being technical proficiency; how to make the measurement, how to isolate and know what's actually being measured,.. and how to achieve as much accuracy and repeat-ability as possible.

I really think it takes both for measurements to make better sound. There's of course many additional points to each of the "wings", but I'm sure you get the drift...experience and practicality on one side, technical ability and consistency on the other.......

I do enjoy measurements and know I can be a bit of a measurement junkie sometimes... I do apologize if this comes off overbearing...

Please realize I recognize my experience level is at best a few % of each of you who has posted in this thread.... ( what I'd give to apprentice to any of you....=)

Also please realize,  IMO measurements are often very valuable for learning audio fundamentals,..... having no immediate goal to set up a system or make better sound. 
And I do believe in trying to routinely achieve the best accuracy and repeat-ability we can....you know, whether it 'matters' or not...
Thx for listening....Mark
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Tim McCulloch

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Re: Smaart subwoofer alignment
« Reply #9 on: January 12, 2017, 02:56:31 am »

Yep to all said...  ears, experienced from so many situations, rule.
I think we do have to admit though, that making measurements, along with DSP control, are impacting nearly every area of audio setup and SQ, from the largest arrays all the way down to home theater.
IMHO, making good measurements is mattering more and more...

I like to think of good measurements as needing two wings to fly. 
One wing being practical application; as in why measure to begin with, exactly what to measure, and what can really be done with the measurements.
Second wing being technical proficiency; how to make the measurement, how to isolate and know what's actually being measured,.. and how to achieve as much accuracy and repeat-ability as possible.

I really think it takes both for measurements to make better sound. There's of course many additional points to each of the "wings", but I'm sure you get the drift...experience and practicality on one side, technical ability and consistency on the other.......

I do enjoy measurements and know I can be a bit of a measurement junkie sometimes... I do apologize if this comes off overbearing...

Please realize I recognize my experience level is at best a few % of each of you who has posted in this thread.... ( what I'd give to apprentice to any of you....=)

Also please realize,  IMO measurements are often very valuable for learning audio fundamentals,..... having no immediate goal to set up a system or make better sound. 
And I do believe in trying to routinely achieve the best accuracy and repeat-ability we can....you know, whether it 'matters' or not...
Thx for listening....Mark

Don't get me wrong, Mark.  I'm not denigrating measurement, I'm actually heavily invested in it.

Rational Acoustics and AFMG do a great job providing training to use Smaart and Systune (respectively).  What they can't do in 20 hours is give the operator the experience of:  making bad measurements, measuring for the wrong thing, or making measurements without a clear idea of why a particular measurement is being made.

Measurement does not exist for its own sake - it's there as a visual aid to system alignment and optimization.  Effectively using measurement requires the operator to have some foundational knowledge of those things or the operator is just making pretty pictures on the laptop screen.

Finally that gets us to *where* in the venue do we align the major parts?  You can pick any seat (or sometimes a small block of seats), put the measurement mic in that spot and align away.  There is good reason to do this:  at least a few people can experience a fully aligned listening position and if you align for where the artist's manager, spouse or band VIP guests congregate you'll be more likely to keep your FOH mixerperson gig.

Aligning to one spot is just that, one spot.  You can't align for 3 or 7 or 28 places, what you can try to do is minimize the differences.  In the end, there is still one physical place in the venue where things come together in time.  Over thinking the impossible distracts from applying our principles of alignment and optimization to the things that *are* possible.
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut
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