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Author Topic: Sub alignment questions with Smaart  (Read 4207 times)

Frank Koenig

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Re: Sub alignment questions with Smaart
« Reply #20 on: July 16, 2023, 11:39:34 AM »

Exactly. Would it be easier to use wrap phase trace reading or delay locate so the phase trace is flat at the crossover point? I pretty sure with the latter will be easier since if I need a polarity inversion due to crossover slopes configurations, it would be easier to read.

I imagine everyone has their own favorite way of doing this. Here’s mine using Smaart:

--After doing a full-range health check set the frequency range of the display to, say, 40 to 200 Hz to get a clearer view of the sub crossover. Mute the sub and let the “delay finder” do its thing.

--Bump the measurement delay up or down to get the phase trace around the crossover away from the edges of the graph and not too steeply sloped. It really doesn’t matter except to make it easier to see. Capture the trace. From here on out do not touch the measurement delay or the mic position.

--Mute the main and unmute the sub. If it’s just a simple field delay setting, not designing a crossover, read the phase difference at the crossover off the graph. If putting the delay into the DSP (Armonia in my case), calculate the required delay and type it in (delay = deltaPhase / 360 / freq). If introducing the delay on the sub output of the mixer, twiddle the dial until it looks good. The main and sub can be done in either order depending on where you expect to change the delay. If, in the above example, it turns out the main needs to be delayed, capture the sub trace and go back and adjust the main.

--When satisfied, unmute everything, do a final sanity check and play “Chameleon” by Herbie Hancock 😊 This may cause bass players to play along.

--Frank
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John Schalk

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Re: Sub alignment questions with Smaart
« Reply #21 on: July 16, 2023, 11:50:03 AM »

Exactly. Would it be easier to use wrap phase trace reading or delay locate so the phase trace is flat at the crossover point? I pretty sure with the latter will be easier since if I need a polarity inversion due to crossover slopes configurations, it would be easier to read.
If your system needs a polarity inversion to make the mains and subs play nicely together you should be able to see that issue using any spectrum analyzer although it's very apparent using Smaart's live magnitude trace.  Here I am referring to there being a distinct dip in the crossover region of the mag trace that fills in our flattens significantly when you invert the polarity on the subs (or mains).

I just got my Smaart license last December.  I watched the online video series and passed the Smaart basic user certification test.  My recommendation to you is to take Art's advice; pull up Merlijn's subwoofer alignment process and start working your way through it.  When you get stuck, send your trace files to the good people at [email protected].  As a newbie, the key point in Merlijn's process for me is that I'm doing the testing in my driveway under ideal conditions.  I have time to think about what Smaart is showing me and, if I still can't figure it out, I save my traces and ask the experts for help.  As Frank pointed out, if you get your system in alignment in your driveway or parking lot, then it's going to sound good at the show even if you don't apply more system delay. 

I've tried to do an alignment for a friend at a gig, but my unfamiliarity with his system and time pressures combined to make me very uncertain of my results.  I'm much happier playing with systems in "the lab" at this point and I think you will be too.
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Jose Peralta

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Re: Sub alignment questions with Smaart
« Reply #22 on: July 31, 2023, 06:55:42 PM »

If your system needs a polarity inversion to make the mains and subs play nicely together you should be able to see that issue using any spectrum analyzer although it's very apparent using Smaart's live magnitude trace.  Here I am referring to there being a distinct dip in the crossover region of the mag trace that fills in our flattens significantly when you invert the polarity on the subs (or mains).

I just got my Smaart license last December.  I watched the online video series and passed the Smaart basic user certification test.  My recommendation to you is to take Art's advice; pull up Merlijn's subwoofer alignment process and start working your way through it.  When you get stuck, send your trace files to the good people at [email protected].  As a newbie, the key point in Merlijn's process for me is that I'm doing the testing in my driveway under ideal conditions.  I have time to think about what Smaart is showing me and, if I still can't figure it out, I save my traces and ask the experts for help.  As Frank pointed out, if you get your system in alignment in your driveway or parking lot, then it's going to sound good at the show even if you don't apply more system delay. 

I've tried to do an alignment for a friend at a gig, but my unfamiliarity with his system and time pressures combined to make me very uncertain of my results.  I'm much happier playing with systems in "the lab" at this point and I think you will be too.

John, thanks for the detail information.
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Tim McCulloch

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Re: Sub alignment questions with Smaart
« Reply #23 on: August 01, 2023, 12:04:55 AM »

If your system needs a polarity inversion to make the mains and subs play nicely together you should be able to see that issue using any spectrum analyzer although it's very apparent using Smaart's live magnitude trace.  Here I am referring to there being a distinct dip in the crossover region of the mag trace that fills in our flattens significantly when you invert the polarity on the subs (or mains).

I just got my Smaart license last December.  I watched the online video series and passed the Smaart basic user certification test.  My recommendation to you is to take Art's advice; pull up Merlijn's subwoofer alignment process and start working your way through it.  When you get stuck, send your trace files to the good people at [email protected].  As a newbie, the key point in Merlijn's process for me is that I'm doing the testing in my driveway under ideal conditions.  I have time to think about what Smaart is showing me and, if I still can't figure it out, I save my traces and ask the experts for help.  As Frank pointed out, if you get your system in alignment in your driveway or parking lot, then it's going to sound good at the show even if you don't apply more system delay. 

I've tried to do an alignment for a friend at a gig, but my unfamiliarity with his system and time pressures combined to make me very uncertain of my results.  I'm much happier playing with systems in "the lab" at this point and I think you will be too.

I took my first Smaart class in 2004 with Jamie teaching, back in the EAW days.  I came home and proceeded to make hundreds of invalid measurements, or measurements without specific test criteria/reasons for measurement *at that point in space*.  It was a learning experience, for sure.  The moral of the story is to practice, practice, practice.  Ask yourself *why* you are placing a measurement mic in a particular spot; what is this measurement supposed to tell us?

EX:  on a system I've already voiced (mains and fills sound the "same" given respective coverage areas), what I'm mostly interested in is where various sub-systems present overlapping coverage, and if there are listeners (esp paid/VIP/entourage d'Artistes) in those areas.  How I pick where the mic goes is part of that "learning experience" from 20 years ago. ;)

A little Scovi story:  in 2007 or 2008 I attended one of Robert Scovils "Complete FOH Engineer" seminars, meeting Doug Fowler (RIP) and Chip Self (Logic Systems St Louis) for the first time.  Scovi spends a lot of the first day talking about having An Honest System and how time alignment of the various sub-systems is a big part of it.  The end conclusion is that for the main PA there is only one spot that be be optimized for, so where should that be?   The class had several answers but the winner that day was "eight feet to my right and six feet forward, that's where managment and influential band spouses watch the show."

Have fun, and practice, practice, practice!
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Riley Casey

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Re: Sub alignment questions with Smaart
« Reply #24 on: August 01, 2023, 06:56:22 PM »

If ever there was a post on the forum to bookmark this is it.

... The end conclusion is that for the main PA there is only one spot that be be optimized for, so where should that be?   The class had several answers but the winner that day was "eight feet to my right and six feet forward, that's where managment and influential band spouses watch the show."

ProSoundWeb Community

Re: Sub alignment questions with Smaart
« Reply #24 on: August 01, 2023, 06:56:22 PM »


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