How to verify main+sub alignment in Smaart® [GSwSST34]
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- Опубліковано 5 жов 2024
- 1. Match main and sub to target level
2. Identify crossover region
3. Are phase traces within 60º?
Credit to Merlijn Van Veen for his Absolute/Relative method.
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I love to geek out about the physics of sound. This channel focuses on the growing opportunity for live sound engineers to improve their confidence and consistency through the understanding of the principles of sound system design and optimization. My goal is to make this channel upfront and honest about my success and failure, so you can learn from both.
I am always open to suggestions and feedback so please comment on this video or contact me through my site.
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![How to phase align main+sub in Smaart® [GSwSST34.1]](http://i.ytimg.com/vi/5leb1k4LUA0/mqdefault.jpg)
![How to phase align main+sub in Smaart® [GSwSST34.1]](/img/tr.png)
![5 ideas to improve Main+Sub phase alignment with Smaart® [GSwSST35]](/img/n.gif)
I repeat 100x play this video,and now i undestand.thankyou you great lesson video.
I don't have Smaart, or any other measuring equipment. I literally have to guess what's going on and try my best at my venue. We currently do a lot of local bands, but we are moving up to booking bigger acts, and I told my boss that we are gonna have to get more serious about phase alignment and equipment, because bigger artists are much more meticulous about their sound and setups than we have normally dealt with at this point.
I watch these series of videos, so that when we do make the move, I'll have an understanding of what needs to be done, and how to do it. Thanks a lot for passing your knowledge on, Nathan!
Hey Acid, I get that. I guess the good news is that you work on a permanently installed system. So, worst case scenario, you don't need to spend $$ and time on Smaart. You can hire someone else to come help you much less $ and time and just get it done once. :)
I could get a RTA mic and use our X32 console pink noise generator to get a decent alignment. I know it's probably not as good Smaart, but it would be something at least.
Acid001 download the Smaart demo for free.
@Hank Weaverston Cool, I'll have to check that out when I get an RTA mic.
Acid001 X32 and RTA won't cut it. You need 2-channel measurement technique. And that's where Smaart is useful. Without it you won't be able to see a phase trace and impulse response. You can't measure transfer function with a simple RTA.
Thanks Nathan..
Always good videos...
Keep it up..
Thanks!
Amazing! You are the best, Nathan!
Hi Nathan, I thought you already had 2.6ms delay on output 1 from the previous video. But then you started this video with zero delay on output 1. Can you explain? Thanks
Hey DJ, it's been a minute since I made this video, but on rewatching it, it looks like the delay is still there. When I open the output processing at 4:28 there is still 2.8ms of delay. Maybe that's not what you meant?
Great knowledge but that loud clicking of the mouse is truly nerve-racking!
Hello. Thank you for your videos. I have a question. Some subwoofers can reproduce frequencies up to several hundred hertz. How to find the upper boundary of the crossover region in this case?
Hey Vyacheslav, this is personal preference, but I like to define the crossover as anywhere where the main and sub are within 10dB of eachother. They will continue to interact until they are 30dB apart, but 10dB is the really critical area.
Hey Nathan, could that phase issue actually be from the reflection from the floor? I wonder if those speakers were on the edge of a stage if that would still happen. Thanks for the smaart tutorial.
Hey Jason, the sub is on the floor so it's more likely to be a wall reflection or even ceiling. I'll have to take a look again to see the frequency.
Hi Nathan, Why did u do the calculation @ 100Hz. The Crossover point is on around 108Hz. Still you got 6 db summation :-)
8° off isn’t huge. I probably just rounded down.
@@nathanlively Thanks
Hi Nathan. I see a lot of people in Smaart videos delaying the mains to align phase. While this makes sense with a ground stacked system, when it comes to a system with flown tops does it not make more sense to delay the subs given that they are physically closer to the point of reference, in the same way you would delay a delay speaker to the mains and not the other way around? Is it possible to determine which matrix to delay to achieve the best results by looking at the phase traces?
Hey Ashley, you are correct. The biggest challenge to alignment between two sources is displacement. Many times the delay you need to restore alignment is equal to the distance offset.
>Is it possible to determine which matrix to delay to achieve the best results by looking at the phase traces?
Yes. Since we only add delay, not take it away, the source with a less steep phase trace will need delay to match the other.
I think we should take in consideration that there is a kind of delay that is caused by the distance between the speakers. One is forward, another is backward. The backward speaker will be delayed in relation to someone that is in front of it.
Another kind of delay, and I think this is the one Nathan was talking about, is when you have two speaker, say a main and a sub, that is in the same distance. Even so, delay could occur, because of the kind of processing that occur inside the electronics or even caused by the physical design of the system.
So internal processing causes one speaker to be delayed in relation to the other one. But how to know who is ahead and who is behind? The phase trace will tell you this. There are some seminars that explain this, including Nathan, I think.
Very thankful for this resource Nathan. One question. How do you set the reference delay when measuring the sub vs tops? Or do you simply take all the measurements without delay locating?
You're welcome Jake! Easiest is to set the reference with a full-range speaker, then not change it again.
Hi ! How do you know if you're not aligning with a whole wavelengh delay (or 2 and so on...) ? Thanks.
Hmmmmm, trying to figure out why the equation given towards the end is ∆Frequency? Didn't see you calculate that, rather just use the center frequency of your crossover region.
Hey Andrew, I didn't need to because I was only looking at one frequency. That formula is the complete formula for converting changes in phase to time, but I could have simplified it and gotten rid of the delta phase.
@@nathanlively I believe the formula you actually used was deltaPhase/360/frequency, not deltaFrequency. If the frequency is the same then deltaFreq would be 0 and then you would be dividing by zero...
Why you use crossover to check phase? I'm a beginner of SMAART.
Hey Carol, the crossover region gets my attention because is where we have two different speakers working together and I want to make sure that the transition is seamless.
Hi nathan , what about the delta phase if fro example my cross over point is 94 Hz and my sub phase is 100degrades and my tops phase is -89 degrades how i can calculate?
Hi Leonardo! At 5m58s I give the formula. Try it out.
Do you know: Can I do the delay measure in REW? (So : frequency response close together, then identify the crossing frequency, then see the delay degree value, and if not within 60 degree ?
Yes, REW is great! You can use the phase graph and the IR graph.
@@nathanlively ok perfect, I will try to find some guide for that, keep up the good work:-)
Hi Nathan, Can I do it with Smaart V8 demo? Can I verify phase with demo version? I really hope you can answer me, thanks
Hey Gigabyte, as far as I know, the demo version does everything the full version does. Please check with @RationalAcoustics
Thưa ngài tôi rất thích video cua ngài . Có điều tôi rất mong có câu trả lời . 140 - 47 = 93 vậy tôi có 120 là chính . Phụ của tôi là âm ( - 47 ) thì chúng ta nên cộng hay trừ
Hey Thanh, whichever source has the less steep phase slope is the one that gets delay. We can make the phase slope steeper by adding delay, but we can't make it less steep.
Does it make sense to use a burst or kick drum sample instead of pink noise that way the subs and mains are In time and not just phased??
No. The test is source independent. What's important about the test signal is that it is broadband or at least covers the entire frequency range of interest, and having high signal to noise ratio.
Nathan Lively so by using pink noise the algorithms are able to identify the random pieces of noise to be able to identify which wave length they are looking at? Like if this was done with a 100hz sine wave the mic and do signal could be years apart but “in phase” once they line up. Is using pink noise what avoids this? Lhasa is very small adjustments... what if the pa and tops are actually off by something insane like 40ms, how does smaart know which of the wavelengths to lock them together since you cannot delay locate the subs?
Mic and DI*** not “do”.. sorry, on gig on iPhone.
“Phase” not “lhasa” ... omg sorry man lol
Hey Nathan, great explanation! I have a question: when I check the two phase for the delta at the delta frequency, the first is at 150° and the second at -45°. Do i have to calculate 150-45 or 150-(-45)=150+45 ?
Hey greenshark, you're welcome! Try to picture both number on a number line. You want the distance between those number. That would be 150 to 0, then 0 to -45, which is 195, or 150 - (-45). The other possibility is the other way around the phase wheel, which is 360 - (150 - (-45)), or 165.
excellent explanation, the idea of the distance between the two values is very graphic, thank you very much! @@nathanlively
I am slightly confused about the centre of the crossover region, If the subs where I work are set to crossover at 80hz, how do I find a centre? Is this something done visually on smaart? Using Smaart di right now. great video btw.
I also got confused at 6:07 when you said" 4ms multiplied x 1000" I didn't see 4ms as part of the equation. Thanks again.
Hey Jonathan, the logarithmic center of the xovr region is calculated like this: √(f1*f2). So if your xovr region starts at 60 and ends at 100 then just drop sqrt(60*100) into Google and you get 77.5Hz. The xovr setting on your subs at work does affect this, but will not tell you the answer. You have to measure the acoustic result.
>" 4ms multiplied x 1000
I'm actually saying "for milliseconds, multiply by 1,000". That is, to convert seconds to milliseconds.
@@nathanlively Excellent, thanks for your response.
Would this still work for my sub to mid top ? I run my subs from 30hz to 80hz & my mid tops that are already phase aligned with a nexo controller. I run them 80hz to 22khz ! Just I can hear my subs eat at the punchy kick section where it’s not phasealigned properly 🙁 knew to all this n wanna make it sound okay !
Hey Josh, this should work for any spectral alignment.
which speaker should i delay to make in phase between subwoofer and midhigh?
The one with less steep phase trace.
May contact you when i am in hometown🤗
Hi Nathan - I really appreciate all of your hard work! Really informative and easy to understand, however, I do have a quick question regarding this topic. I've seen this process done in various videos, however, it always appears that sub crossover alignment is verified against only one main. I happen to use a center sub configuration. Would you still just align with just one of the mains?
On another note - I saw in your video on mic placement for center sub alignment that you, more or less, suggest ONAX L mic placement at head-height. But In other videos, you suggest having the mic nearly touching the floor to avoid reflections. Can you shed any light on when you might choose to use head-height versus close to the floor for sub alignment?
I may have answered my first question through trial and error. Would you use one speaker as the "reference" (probably the speaker furthest away from FOH, and therefore, not delayed) and then align all other speakers to that reference individually?
Hi Alex!
>Would you still just align with just one of the mains?
Yes. Hopefully it's symmetrical?
>when you might choose to use head-height
Start with head-height. If you can't get actionable data because of the floor bounce AND you know the floor will mostly disappear when covered with humans, switch to ground plane.
>use one speaker as the "reference"
I'm not sure if there's any other way to do it. What alternatives are you considering?
Thanks so much for your response! So since both mains are symmetrical relative to the center sub, the polarity should be roughly identical plus or minus any room reflections. Also, makes sense about starting with head-height.
What about in the scenario of a sub that is off-center and also not directly under the mains? In my home theater setup, I have an LCR configuration with my sub to the left of the left speaker, so the symmetry isn't quite there like it is in the case of the of a center sub configuration(which I use for the system at my church). Is that just unideal? Any ideas?
My initial inclination is to use the sub, which is furthest away from the listening position, as the time reference, then align left/right (next furthest from and roughly equidistant to the listener), then lastly, align the center (closest to the listener) channel. Not sure if that makes sense.
What order do u use on your crossovers point
Hey Mayito, I'm not a filter expert, but I can tell you that I tend to use 24dB/oct filters, unless they are very close to the native filter already.
What's the raison 60° is good to be in ?
Hey Andrew, check out this image - www.prosoundweb.com/wp-content/uploads/2018/08/20180807summation5.jpg
Notice that at a phase offset of 60º you get almost 5dB of summation. So 60º is an arbitrary limit that I picked up from Merlijn van Veen, but it guarantees that we will get at least 5dB.
@@nathanlively Thanks for the answer. So it's some kind off "we all have to agree on some point that we can not get everything we desire" :-p
More or less. I don't know if we all agree. I got this idea from Merlijn van Veen, but I think it's a great guide, which is why I use it.
@@nathanlively Or as Bob says it "there's no such thing...." :-p
Hello sir, what's the software and components required for this process...can u pls let me know
Hi Deepa. Can you be more specific?
You might want to watch the entire series first - www.sounddesignlive.com/get-started-with-sound-system-tuning/
u need a audio inerface and a calibration microphone and a software like ARTA or Smaart live
Hi How can I contact you (prefer me your email) for some clarification regarding Smaart for sound system setups?
nathan@sounddesignlive.com or www.sounddesignlive.com/contact/
Just stumbled upon your channel. Love it! Was wondering what processor you are using to add delay, etc..
Hi Amar! In most of these videos I'm using an X32, but I just got my own BSS BLU 160, which I'm excited about.
4:36 how to calculate
It really helpful to understand TY😊
How to calculate what?