Nathan Lively's Blog, page 15

How to use a custom weighting curve in Smaart and why I don’t recommend it

At first, using a custom weighting curve in Smaart seems like a brilliant time saver, but it turns a guide into a rule and could make your optimization procedure too rigid.

A custom weighting curve is like a filter for your data, similar to a microphone correction curve. Its intention was to add A and C weighting to Magnitude and RTA graphs, but Smaart makes it really easy to turn your target trace into a weighting curve as well. Then, instead of matching your measurements to a target trace, you can simply match them to the 0dB line.

Here’s an image of me comparing a measurement to a target trace.

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And here’s the same measurement with the custom weighting curve.

[image error]

At first, this saved me time. My normal procedure of capturing multiple measurements at once means that I’m also hiding multiple measurements at once. It usually goes like this:

(G) Start generator(shift+space) Capture all(G) Stop generator(command+shift+H) Hide all tracesScroll down to find target trace. Unhide it.Repeat

Using the the custom weighting curve allows me to skip step 4 and work with a cleaner graph. I tried it on a show and it worked great.

Here’s how to create your own custom weighting curve:Load the appropriate target curve. (you can download mine here)Right-click on the name and choose Export as Weighting Curve(option-G) Open Measurement Config and choose one of your measurements.Under Global Settings, choose your weighting curve.

If you want to test this out on saved trace: right click > Info > Weighting

Pretty cool, right?

Here’s the problem.

Your target curve should be used as a guideline and not a rule. The guideline can trigger your intuition when comparing two traces.

Eg. The high shelf at 10kHz reminds you that measurements at different distances will show different amounts of air absorption. The low shelf at 50Hz reminds you that you should expect to see more room gain in the low end when you are inside rather than outside.

Here’s an annotated target curve to give you an idea.

[image error]

Unfortunately, when you use the custom weighting curve, you don’t have those cues and you can forget that you are looking at filtered data. Plus, if you ever want to review past measurements, you have the added complexity of trying to remember which ones were made with the weighting curve on or not.

I recommend that you try it out because it’s easy and quick, but I don’t recommend that you use it in your normal tuning processes.

Have you used custom weighting curves in Smaart? What were your results?

This article How to use a custom weighting curve in Smaart and why I don’t recommend it appeared first on Sound Design Live. Sign up for free updates here.

Loved this post? Try these:What do all of those squiggly lines mean? (a short intro to the graphs in Smaart) What is the best sounding target EQ curve to use in Smaart on every show? Smaart is just a tool. You are the analyzer.

Phase Alignment Science Academy Handbook: Introduction

The phase relationship is the wild variable: The one we must tame to make the summation junction function.

6o6

Year: C019

History of Mainland and Subterra

Throughout recorded history, the peoples of Mainland and Subterra have lived in harmony with one another. Though located on opposite poles of the planet Boh, each nation boasts ample quantities of Magnitude, the most valuable element found on Boh.

Though distant from each other, the two nations are connected by a thin but continuous land bridge that crosses the Sea of Spektral Xovr between them. This bridge has held solid for centuries. Forged from a perfect match of Magnitude and Phase, the bridge is a lifeline between the nations, allowing for commerce, diplomacy, and free passage between the two. The bridge is the key to Boh’s long-term success, and stability is particularly vital in the crossover region.

Vital Element: Magnitude

Infinite varieties of Magnitude exist. Mainland produces those varieties with high-frequency (HF) vibrations and Subterra produces those with low-frequency (LF) vibrations. Both develop into stable forms of Magnitude with specific qualities of coherence and phase. Scientists on Mainland and Subterra use delay and polarity (among other tools) to further refine the stable form of Magnitude into the structures of their productive societies. Without both HF and LF, life as we know it would not exist on Boh.

Conflict

In B992, a team of Dissonance from the planet Ekoeko arrived secretly on Boh. Faced with the environmental destruction of their own planet and seeking to colonize a new planet rich in Magnitude, the government of Ekoeko determined that the best way to overpower Boh would be to destroy the bridge connecting Mainland and Subterra. With advanced weapons of Displacement and Asymmetry their fighters began an unprovoked attack on the bridge that is still ongoing.

Your role

Boh has but one hope for all the peoples of Mainland and Subterra–to repair the bridge and restore harmony. To accomplish this, your primary objective is to rehabilitate coupling through the acoustic crossover region. If coupling cannot be maintained Magnitude relationships must reach isolation as quickly as possible before causing instability. Combing and Transition, having the greatest potential for cancellation are to be minimized throughout the region.*

Both nations send their best and brightest here, to the Phase Alignment Science Academy (PASA), to learn to manipulate and control our most powerful elements so that we may build a bridge that is strong enough to withstand any assault. During your time at the Academy, your job will be to master the properties of our precious elements and fight back against the Dissonance.

Rankings

During your training, you will advance through the ranks of PASA before earning the rank of Master of Alignment. You will prove yourself at each level by earning experience points for every successful alignment you perform that leads to the restoration of a section of our bridge. The Academy’s Simulator will provide you with test missions in which to increase and demonstrate your skills before you are deployed into the field. Should you advance far enough, you may also choose to train as a Scout, using your skills to identify and anticipate potential threats and destroy them before they can do us harm.

Intern: we welcome you to the Academy. Together we will defeat the Dissonance of Ekoeko and enjoy harmony in Boh once more.

*Consult your handbook’s Definition of Terms.

Definition of termsAcoustic crossover region: The location where two separate sound sources combine together at equal level.Asymmetry: Lack of equal response characteristics.Coherence: Signal to noise ratio.Combing: Magnitude relationship of 0-4dB with maximum risk of cancellation.Coupling: Phase offset Displacement: Distance between two sound sources.Frequency: Cycles per second in Hertz (Hz).Isolation: Magnitude relationship >10dB with low risk of cancellation.Magnitude: Level component of the audio waveform expressed in dB. Also a vital element in the nations of Mainland and Subterra.Mainland: A nation on Boh located across the Sea of Spektral Xovr from Subterra producing high-frequency varieties of Magnitude.Phase: The relationship in time between cycles of a wave. The radial component of the audio waveform expressed in degrees.Subterra: A nation on Boh located across the Sea of Spektral Xovr from Mainland producing low-frequency varieties of Magnitude.Transition: Magnitude relationship of 4-10dB with medium risk of cancellation.

This article Phase Alignment Science Academy Handbook: Introduction appeared first on Sound Design Live. Sign up for free updates here.

Loved this post? Try these:How to flatten the phase for easier main+sub alignment How to practice reading phase traces when you don’t have a PA 3 Phase Alignment Hacks to Make Your Sound System Tuning Easier

What is the best sounding target EQ curve to use in Smaart on every show?

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In this episode of Sound Design Live I talk with touring FOH mixer and system tech Chase Benedict about the challenges of touring, the benefits of starting out at a sound company, the dangers of relying on a single target EQ curve, and that time a lighting fixture fell on his head from 10ft in the air and he had to mix the show with electrical tape holding his face together.

I ask:

In the book Get On Tour in a section called What I hate about touring you write, “There are many things that we take for granted in life and touring can shed a unique light upon them. In that sense, the lessons learned can make one especially grateful for what they have. One might find themselves giving up the most basic of life’s necessities, like showers or decent toilet paper. There was one tour in particular where, over the course of three months I spent more days off on a bus in a Walmart parking lot than I spent at home. I can think of another time when the entire crew had to go four days without showering and then hop on a plane. Our only saving grace was the baby wipes we had on the bus.” What’s it like touring on a bus?You have made it it clear in the book that an important step into touring is to work with a sound company that has touring accounts. But we’ve all heard stories about people getting hired straight out of concert venues or Laundromats. Is that still a thing? Why did you choose sound companies?Let’s talk about the danger of relying 100% target curves. You write, “One major problem for me was thinking that an FFT could provide qualitative data. For the longest time I had several target curves I would try to achieve when calibrating the PA. While I’ve heard of this technique working well for tours that carry their own system, it doesn’t really hold up when dealing with different makes and models of boxes. Different PAs have different sonic characteristics. For example, let’s say the first leg of the tour was spent with a Meyer Leo system and the second half was spent with a combination of L’Acoustic and VTX. All three are great systems, and while the magnitude traces in Smaart might look the same, they most likely will sound very different. I dug myself into so many holes because of this. It especially becomes a problem with some of the lesser quality rigs out there. Over time I started to paying more attention to he differences in transfer function measurements and began storing individual traces for each make and model of PA. Vertec has a specific magnitude trace, as does Leo, K1, and even some of the smaller trap boxes. Then the next time I encountered one of these boxes, I would listen and EQ, observing how similar the EQ decisions I made resembled my target traces. It’s usually pretty close. This strategy has been working well for me.” First of all, what is a target curve?So what’s wrong with using a target curve? If I take a measurement with one system in one room and then take another measurement with another system in another room and make them match, won’t they sound exactly the same?If a single target curve solution doesn’t work, what can I do instead?There is a lot of confusion about where to place the microphone for level setting and time aligning FFs. Could you talk about how you approach this? How do you find the right mic position?What’s in your work bag?What is one book that has been helpful to you?[image error]

FFTs only provide you with quantitative data not qualitative. You’re seeing an analytical representation of what’s happening

Chase Benedict

NotesAll music in this podcast by Deborah Heltzer.Chase on InstagramTest tracks: Straighten Up and Fly Right, God Is My Friend, Doin’ It RightBooks: Get On Tour, Sound Systems: Design and Optimization, The Brothers Karamazov, The StrangerFoothills Brewery in Winston-Salem, Spotted Cow LagerChase’s workbag: hard hat, safety harness, high vis vest, Behringer Uphoria 404 interface, turn arounds, spare glasses, cold medicine, cable tester, multi meter, wireless CAT5 tester,Podcasts: Sound Design Live, Why Oh Why, Where’s my 40 acres?, Business WarsSpatial acoustic crossover point: The frequency and/or location where two separate sound sources combine together at equal level.Aligning front-fills to mains:Estimate spatial acoustic crossover point based on overlapping coverage patterns.Measure main solo.Measure front-fill solo.Use Smaart’s delay locate function to find the time offset (delta delay). Enter time offset into the delay DSP for front-fill.Download Chase’s target EQ curvesQuotesDon’t shit on the bus. That’s rule number 1.I was sick and tired of working with dodgy gear. I wanted to go work for a place where I knew there was a quality standard.I mixed FOH that day for this artist with electrical tape wrapped around my head.FFTs only provide you with quantitative data not qualitative. You’re seeing an analytical representation of what’s happening, but it’s not telling you anything about the actual tone or timbre of the sound system you are listening to.[image error][image error]All of Chase’s target curves with the average on top.

This article What is the best sounding target EQ curve to use in Smaart on every show? appeared first on Sound Design Live. Sign up for free updates here.

Loved this post? Try these:This Is How to Find the Perfect Show Volume Without an SPL Meter How Jamie Anderson Saves Time in System Tuning with Smaart Check Points Smaart is just a tool. You are the analyzer.

9 Smaart shortcuts that will make your life easier

#1 Spectrum sound check mode

One of the first steps in the Audio Analyzer Verification Checklist is to verify that Smaart is receiving all inputs. You can do this very quickly by pressing play on all inputs and then pressing the 0 (zero) key.

[image error]#2 Align all visible traces

Shift-click on any magnitude trace to align all visible traces at that frequency.

[image error]#3 Clear All dB Offsets

Now that you’ve made a mess by offsetting all your traces, Kondo your screen by clearing all offsets on visible traces with command+Y. If any hidden traces have offsets, they will be maintained.

#4 Hide all visible traces

When working with multiple microphones you can quickly fill the screen with saved traces. To clean it up, use command+shift+H to hide all visible traces.

#5 Quickly zoom in for detailed work

I recommend you edit your zoom presets to

30-400 Hz200-2000 Hz2-10 kHz10-18 kHzDefault

Now you can quickly navigate between them with option+1-5. Note that option+5 will return the currently selected graph to default view, but clicking on the perimeter of the Magnitude or Phase graph will return both Magnitude and Phase graphs to default view.

#6 Scroll

This is such a helpful one and a lot of people don’t know it. Most commonly I use it to scroll around the Y-axis of the Phase graph to make it easier to read. Combine this with my earlier post about flattening the phase and you’re in business.

Another common use is scrolling left and right on the X-axis after entering a zoom preset. Maybe I have zoomed into the low end to look at a crossover alignment and I need to scroll a few Hz to the right for more information.

[image error]#7 Recapture

A good way to keep your data bar organized is to avoid unnecessary traces. If you realize you’ve made a mistake, instead of saving a new trace, recapture an old one. Select the old trace and press shift+command+space.

#8 Stop the generator

There’s no need to continue running the generator while you are capturing and naming a trace. Quickly hit the G key and then the space bar to stop the generator right before you capture the trace.

#9 Get rid of the clock

Why does every audio analyzer think you need a clock? I guess it’s nastalgia from SIM3.

Use option+k to get rid of it. Simply pressing k will switch back and forth between the clock and the SPL meter.

What’s your favorite Smaart shortcut? Let me know in the comments below.

This article 9 Smaart shortcuts that will make your life easier appeared first on Sound Design Live. Sign up for free updates here.

Loved this post? Try these:3 Phase Alignment Hacks to Make Your Sound System Tuning Easier Smaart: Tracking peak frequency without the mouse cursor What do all of those squiggly lines mean? (a short intro to the graphs in Smaart)

I made sure every sound engineer, tour manager, and production manager knew I wanted to tour

Subscribe on iTunes, SoundCloud, Google Play or Stitcher.Support Sound Design Live on Patreon.

In this episode of Sound Design Live I talk with FOH mixer for artists such as Spin Doctors, Indigo Girls, Styx, Melissa Etheridge, Gwen Stefani, Kesha, Jewel, Mr. Big, Goo Goo Dolls, Christina Aguilera, and Adam Lambert, Michelle Sabolchick Pettinato, about how she went from mixing local bands to international tours. I ask:

In the book Get On Tour you write, “For several years before I started touring I worked at a local sound company, in the A/V department at an entertainment complex, as a stagehand, at a nightclub, mixing local bands, and occasionally as an assistant at a recording studio.” How did that happen?The milestone in this story is that a friend of yours called to offer you the tour with The Spin Doctors and you credit that to simple word of mouth marketing. You say, “I made sure everyone knew that I wanted to be on tour. I talked constantly with friends and colleagues about touring, and when I worked with visiting bands and engineers I would pick their brain about how they got started. When the opportunity came, I seized it.” Could you talk in a bit more detail about what that looked like in practice? How did you make sure that everyone knew that you wanted to be on tour?Can you explain the hiring process to me? From the initial idea where a production company or artist says, “I want to go on tour,” what are the chain of events and people that then lead to you or someone else getting hired for a tour?Let’s talk about the Mr. Big tour. Could you give me an overview of the inputs you are mixing?What’s in your work bag?What is one book that has been helpful to you?[image error]

It’s always someone who knows someone.

Michelle Sabolchick Pettinato

NotesAll music in this podcast by Niklas Harju.Books: Get On Tour, Illusions by Richard BockHardware: Beyer M88, RE20, EV ND76, Telefunken M80, kettlebellMichelle’s workbag: headphones Sony MD7506, flashlight, sharpies, tuning CD, karaoke mic, iPod to XLR cable, cool towel, batteries, adapters, ear plugs Sensaphonics, Gerber multi tool, e-tape, PurellQuotesThat came from a classmate who I was friends with and remembered always saying that this is what I want to do and he gave me a shot.Meet the crew, production managers, tour managers, stage managers, and other crew members and build connections with them because they are the people who are going to refer you for a job.It’s always someone who knows someone.I love the kettlebell because it’s the only workout where I feel like, Wow, I just did something.

This article I made sure every sound engineer, tour manager, and production manager knew I wanted to tour appeared first on Sound Design Live. Sign up for free updates here.

Loved this post? Try these:Do you want a job as a touring FOH sound engineer? You need to hear this. Get On Tour – Download FREE for 1 week The good, the bad, and the ugly of being a Tour Managing FOH Engineer

How to place and aim your stage monitors for maximum rejection

To maximize gain before feedback on stage you must place and aim your stage monitors for maximum microphone rejection. The more precise your aim, the more gain before feedback you can get out of the system.

Aim the stage monitor at the null point of the microphone for up to 20dB of rejection for a fun show instead of a feedback nightmare.

[image error]

For example, imagine that you are using a common supercardioid microphone like the Shure Beta87A. You eyeball the placement and aim and hope for the best. It’s more likely that you will be slightly off than dead on.

So what if you are slightly off?

If will be different with every microphone, but if we look at the polar pattern of the Beta87A, we can see that an error of 30º could cost you 5dB. At first, 5dB may not seem like much, but think back to every time a vocalist has begged you for a tiny bit more vocal in the monitor. Maybe you could have given it to them if you had aimed dead on.

[image error]

How do we aim more precisely?

Find the polar pattern of your mic.Buy a Polar Pointer from Rat Sound.Place the stage monitors at the laser dots and aim them at the laser origin.

Alternatively:

Print out my aiming triangles business card.Use your own laser to point out the optimum position. NOTE:Look up the polar pattern for your microphone.

The null point angles I found for supercardioid and hypercardioid were 125º and 110º from Dave Rat, which I assume is what he used in the polar pointer and is the reason for the updates I made to the aiming triangles business card. That being said, I could not find a manufacturer that actually followed that.

We already discussed the Shure Beta57A, which claims to be supercardioid with null points at 120º. I also found the Beyerdynamic M201, which claims to be hypercardioid with null points at 120º.

[image error][image error]

We can’t make assumptions. We have to know our microphones. Maybe someone should create big database we can reference with all of the null point angles for every microphone. Maybe I should do it? Maybe it exists already?

Here’s a chart from the Shure website. As you can see, it disagrees with the Rat Sound Polar Pointer.

[image error]Check the pattern all the way around

From Dave Rat’s blog:

If you point a cardioid mic parallel to the ground it is impossible to get a floor wedge in it’s rejection zone! Furthermore, to optimize wedges for the rejection zones of super and hyper cardioid mics you will find the wedges either need to be surprisingly far apart or your mic will need to be pointed at a fairly severe upward angle.

This 3D image of a supercardioid pickup pattern should help.

[image error]

This article How to place and aim your stage monitors for maximum rejection appeared first on Sound Design Live. Sign up for free updates here.

Loved this post? Try these:Single Miking Groups On Stage With Condenser Microphones Condenser Microphones For Live Sound Mixing Monitors from FOH: 17 lessons I learned from Grealy at Soulsound

What do I need to know about my speakers?

Do you know everything you should about your speakers?

Maybe you know the model number and power requirements, but do you know the coverage angle and forward aspect ratio?

How long will it take you to find this information in the field? How many people will wait while you look it up?

I spend a lot of time on every show getting to know all of the speakers I’ll be using. I want to be as informed as possible for quick decision making on site. It’s frustrating and embarrassing to take my phone and try to look up some facts that my colleagues on site may not even understand or think is important.

For a lot of people, the answer to this problem is an app like the PA Bible. My problem with this solution is that you are still spending precious time getting your phone out to go through a database. At least it’s faster than Googling around for the data sheet, but it still takes time.

What if every speaker came with all of the most important information printed on itself, like the tag in your shirt with care and washing instructions? Except this tag would include:

Angle, order, forward aspect ratio, and lateral aspect ratio for both vertical and horizontal coverage.Voltage, current, and resistance.Operating frequency range.Peak SPL and class.Spectral divider (crossover) specification.Impedance and power handling capability for each driver.

Now multiply that list by every speaker in your inventory and it’s a lot of information to try to memorize.

But do we really need to know all of this? Will it help us in the field? Let’s look at some example questions we might need to answer.

Where do I put my speakers?

For speaker placement decisions I rely heavily on forward aspect ratio (FAR) and lateral aspect ratio (LAR). FAR will tell me how well my current design matches the audience. LAR will help me space my front-fills for a solid unity line across the front row.

To calculate the FAR and LAR for your speakers use the following math, which you can find on my aiming triangles business card:

FAR = 1 / sin (coverage angle / 2)LAR = 2 / FARWhere do I cross over my speakers?

The speaker manufacturer will include information in their documentation about how to combine match pairs of speakers. If you are combining two un-matched speakers, their operating range is important to know so you can expect a big area of overlap or a gap.

How many speakers can I put on a circuit?

To answer this question you’ll need to know the rating of your circuit and each of the speakers you want to put on it. The circuit will be rated in amps so if your speaker only has information in watts, you’ll need to do some quick math. Another reason to get that information ahead of time.

Where do I set the limiter for these speakers?

The more separate components you combine in the chain, the more complicated the calculation. I have little experience in this area, but I know that you’ll need to know about the power handling and resistance of every driver in every box you plan to use.

How many speakers do I need in my delay towers?

If you are using unmatched speaker models between main and delay, you’ll need to know the power scaling relationship. Look up Peak SPL on the data sheet.

As you can see, there’s a lot of information we need to know about our speakers. With enough time in pre-production we can gather all the information and make a spreadsheet, but what about when you just show up in the field and are handed a pile of speakers?

Have you ever seen a sound engineer stop to look up the data sheet for every one? I haven’t. And you can’t expect anyone to know every spec of every loudspeaker.

Speaker Stickers [image error]

What about a label on every speaker with the most important details that will help us with quick decision making in the field?

It might look like this.

And I might make them.

So what do you think. Would this be useful to you?

Yes, I want them!

This article What do I need to know about my speakers? appeared first on Sound Design Live. Sign up for free updates here.

Loved this post? Try these:One Simple Tool to Find the Right Size Speaker for Any Space SIM3 is easy. The hard part is figuring out what to do with that data. How to set the limiter threshold on a DBX PA2 so you don’t blow up your speakers

How to flatten the phase for easier main+sub alignment

Which is easier to read?

This?

[image error]30-400Hz

Or this?

[image error]30-400Hz

Proper phase alignment in the field is hard. It’s one thing to measure in the near field when you can get a nice clean trace, but once you get into the far field and add reflections it gets a lot harder.

One thing you can do to make the whole alignment process easier on yourself is to flatten the phase trace around the area of interest. To do this, add more delay to the delay finder.

A standard main+sub phase alignment goes like this:

Measure Main solo. Auto set delay. Save trace.Measure Sub solo.Make the pictures match.

The easier it is to read the graph, the easier it will be to match the pictures. Let’s find out how.

Normally, using the procedure above, you’ll start out with a flat phase measurement in the high end (on time arrival relative to the reference) and it will slope up and wrap around as you move to the left in the low end (late arrival relative to the reference).

[image error]20Hz-20kHz

We want to move that flat portion to the left and we’ll do that by adding delay to the delay finder in Smaart.

But how much delay?

[image error]

Start by adding delay with the arrow keys so you can see the gradual change. How much delay do you need to move the flat portion of the phase graph to 100Hz?

If I click down incrementally, I find that it takes 10.5ms to move the flat portion of the graph to 100Hz. Let’s see if we can do it faster with a quick calculation.

number of wraparounds * 10ms = additional delay

current delay + additional delay = total delay for an on-time arrival at 100Hz

Let’s try it.

Here’s a measurement of a Meyer Sound UPJ-1P. I can see that the phase is flat starting at 2kHz, but we want it to be flat around 100Hz. It looks like there are about 1 wraparound starting at 100Hz and moving left.

[image error]

1 * 10ms = 10ms

90.52ms + 10ms = 100.52ms

Looks good. Much easier to read.

[image error]30-400Hz

Let’s try a real measurement from the field. This one is more difficult to read, but it looks about 1 wraparound.

[image error]20Hz-20kHz

Let’s add 10ms just like in the last example.

74ms + 10ms = 84ms

[image error]

What have you found that helps you read the phase graph? Comment below and let me know.

Credit to Timo Beckman for introducing me to this idea.

This article How to flatten the phase for easier main+sub alignment appeared first on Sound Design Live. Sign up for free updates here.

Loved this post? Try these:3 Phase Alignment Hacks to Make Your Sound System Tuning Easier 3 Simple Ways to Phase Align Main+Sub with SATlive How to practice reading phase traces when you don’t have a PA

How to set the limiter threshold on a DBX PA2 so you don’t blow up your speakers

A student blew up his speakers because he had the limiter on his DBX PA2 set incorrectly. Find out how we fixed it.

Download the calculatorsFill out the Poweramps calculator.Use the dB Relationships calculator to convert dBV to dBFS.

This article How to set the limiter threshold on a DBX PA2 so you don’t blow up your speakers appeared first on Sound Design Live. Sign up for free updates here.

Loved this post? Try these:Download the DiGiCo Session Setup Checklist How To Find Speaker Coverage In One Step

How to practice reading phase traces when you don’t have a PA

The hardest thing about learning to read the phase graph on an audio analyzer like Smaart is finding a PA to practice with. In the world of my dreams I would have a giant warehouse with every speaker model on earth and endless time to practice tuning different configurations. In the field, we have the opposite. We have one or two speaker models to work with and little to no time to complete our tuning.

[image error]

So how can we practice learning to read phase traces when we don’t have the time and resources?

Solution: MAPP XT

MAPP XT, even with all of its problems and limitations, is still the best sandbox to play in for sound system engineers. Sure, it only offers Meyer Sound speakers and 2D drawing and predictions, but those predictions have highly precise 1/24th octave frequency resolution and you can place a measurement microphone anywhere in the sound field to investigate the amplitude and phase response.

What does that mean? You can use MAPP XT to practice reading phase traces, even when you don’t have a real PA.

Of course, measuring real speakers in the wild is always preferable, but unless you are on tour or working shows every day, you may not have access to them.

Let’s get started.[image error][image error]Register for MAPP XTRegister for the Meyer Sound website (yes, they make you do this twice)Download MAPP XTInstall MAPP XT (If you’re on a mac you’ll need to install Java first.)Wait for an email from Meyer Sound with a login name and password.Open MAPP XT and log in under the Settings menu. At the bottom of the Sound Field window it should say Server Login Status: Online Mode. If you have any trouble, contact tech support.

You’re ready to start your practicing. You may want to watch some of the support videos, but it’s simple to get started. Here’s what I recommend:

[image error]Right-click anywhere in the sound field and insert a full-range loudspeaker from the popup window. Tip: Do not switch away from MAPP XT while choosing a speaker. For me, this causes it to crash.Right-click anywhere in the sound field and insert a microphone.Open the Measurement Viewer under the Tools menu.Switch to the frequency response tab and the results view.Hit predict.[image error]

You should see an amplitude measurement on the top and phase on the bottom, just like an audio analyzer. In fact, the Measurement Viewer used to be called Virtual SIM in previous versions.

WARNING: Keep calm and resist the urge to send me an angry email that says, “What do all of the squiggly lines mean?!” You are looking at a lot of information at once and it is mostly useless unless you have a question to answer and/or something else to compare it to.

Let’s start by making the graph a little easier to look at. Press Auto-Set Delay.

Ah, that’s better.

[image error]

Now press the up and down buttons on the delay field. Without worrying about what the specific number is, just observe what happens to the phase trace.

I’m going to save any comments about what you are looking at for another article. For now, practice moving your speaker and microphone around the sound field and observing the changes in phase. For easier comparison, save traces by clicking Store and then recalling them into one of the four available memory groups.

[image error]Practice

What trends can you notice about the orientation of the speaker relative to the microphone and the result in the phase graph? Once you’ve identified a trend, can you predict it accurately?

Next, try enabling a single wall under Settings > Prediction Plane. What happens to the phase measurement as the path lengths change between the direct signal and reflection? How are they connected to the amplitude graph?

As you can see, it is easy to make the design more and more complex. You might want to turn off the walls and insert a subwoofer so that you can practice a main+sub phase alignment. Notice that you can solo a speaker by clicking on it in the Sound Field before you press predict in the Measurement Viewer.

After you practice reading phase traces in MAPP XT for a couple of hours, you may wonder how this will transfer to your audio analyzer.

How to import MAPP XT measurements into SmaartFile > Export Measurement Data. Save.Open the spreadsheet. Save as CSV.In Smaart, open the transfer function module.File > Import > Import ASCII (FFT: MTW, Sample Rate: 48000, Interpolation Type: B-Spline). Import.Right-click the trace name in the Data Bar. Click Info.Set dB offset to -85. Ok.Drag the magnitude trace to adjust the offset.

Have you discovered any other good ways to practice reading phase traces when you don’t have a PA? Let me know in the comments below.

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