5 Unexpected PA Tuning Tips

[@christiaanbezuidenhout6984]

Hi Andrew. I've read this book a few times now. The next step up from there is Bob McCarthy's "Sound Systems: Design and Optimization". It's a difficult read, but it explains some various concepts in further details, such as the Cardioid Subs etc. Also, Merlijn van Veen as an excel calculator called "Sub-align".. where you enter you enter you audience plane, array height and sub position. It then calculates the front to back phase difference you will experience between mains and subs, and gives you the "perfect" compromise position to make your alignment. So that, the phase drift in front of that position and the phase drift behind that position is the same. It basically gives you the best place to align your mains and subs. For me, one of the biggest take-aways from Michael Lawrence's book, is that phase cancellation does not happen whenever two signals are 180deg out of phase, but when they're 180deg out of phase AND EQUAL IN AMPLITUDE. ONLY THEN, they will cancel out. We need to align sources where they are equal in amplitude. Last thing, I agree, we don't need expensive or calibrated RTA mics BUT, whenever we are using multiple mics, they MUST be calibrated to each other. Meaning, same phase and magnitude response. Otherwise we'll get false info as we spread those mics across the venue. Thanks for the content! Love your videos!

[@Mooonsterman]

Subs on aux allows you to be selective about what microphones that goes into the sub mix, and most importantly which ones that stay’s out of it. That, is way more important.

[@victorblakey4260]

Or You could just use HPF on anything you don’t want in the subs …

[@VictorCM]

@@victorblakey4260dave rat posted a video experimenting with this… I recommend watching.

[@joshuathelegendary6185]

@@victorblakey4260 I prefer having a aux to get that greater control

[@Fizzilord]

And if you're not careful you will probably move the acoustic crossover by turning your Subs up or down. Also applying EQ on the AUX will interact with your alignment / phase. Also on a lot of consoles the AUX is not coherent to the Main L/R. You can do it. But it comes with a lot of variables.

[@LaminarSound]

i would argue you have LESS control. If you want to toss a multiband compressor on your LR, it will not affect anything on that sub aux. This is a problem for anyone who uses a multiband comp to get *their sound. Like me. Vocals are all high passed to 100 or higher. Guitars at 100. Keys i actually might WANT a bit of info below 100 depending on the situation. Especially a killer analog synth thats covering a lot of low end here and there. Aux fed subs complicate things imho. Also, you should use them if thats what you like and get results with. To each his own.

[@ianwoodaudio]

A very old school sub technique I find quick to use: Play a tone, for example 80 Hz, out of your tops and subs. Flip one PA element out of phase, then add delay until it gets quietest, then flip it back in phase.

[@Mtaalas]

I never use spaced pair of subs if I can help it, I ALWAYS build at least end fire cardioid if I have 2 point source (normal) subs because that'll focus the energy towards the audience, off the stage and surrounding walls AND it creates more even response in the audience. You prevent the "power alley" effect. You can even turn the subs facing each other (turn the front one around) thus you minimize the distance between the elements and get better sound when bass notes changes from one to the other. If I have 3 subs, I create an array as well by putting them next to each other int he middle of the front of the stage and turn middle one around ,then some delay and phase magic and it'll create very good cardioid again. People shouldn't be scared of basic cardioid arrays because these days you have huge set of delays, filters and phase adjustments available in very basic x/m32 mixing consoled that you used to need a separate pa-processor for... so you can create arrays with very little investment.

[@ladjkaoz]

100% agreed... I tryied to explaing this to an Eng... in one of my gigs but not sure if I didnt explain my self well or he was a jerk... he give me a whole ran on cancelation Hz. etc.. Great video...

[@T1TAN-92]

Great video! Can you explain power distribution for line arrays (both passive and active). I’m struggling to understand how much power is needed.

[@geofgibson]

How much power is needed? MORE!

[@nickevansaudio]

Great video as always. Love Michael’s book. Read it 4 times now and it cements more in my brain each time!! Currently half way through Bob’s green book and whilst it is the bible, it can be quite an overwhelming read!!

[@OffshoreAudio]

Thanks Nick! I must say I'm inpressed with your progress on Bob's book. I really struggle to read more than a page at a time. I've been at it for about 2 years haha

[@nickevansaudio]

Thanks @@OffshoreAudio . It helps that we are running a book club kind of system with one of our Discord groups where we have reading goals every two weeks to consume a couple of sections, then run through it on Zoom as a group. Super useful and helps keep momentum!!! ;-)

[@paulboregard4056]

@@OffshoreAudio I'm now at part 3 (optimization) of Bobs book but it also took me more than half a year. It reminds me of studying books about electrical engineering for university but at a slower pace which makes me think about it over a longer time. I think its not a bad thing to progress slowly. Michaels book lies in my shelf ready to be read next. Still have to get an internship in the live sound industry to put the theory to test and get in contact with more experienced people.

[@mistaowickkuh6249]

I was once having a weird low-mid feedback in a room where a meeting was going to be held. I wanted to tune a few mics for the possible Q&A sections before I even had the programme. As I walked around listening I kept hearing this short burst of low-mid feedback on certain spots and weirdly they didn't even last. After ripping my hair off for an hour I finally realized it was happening when I passed under these cursed hidden led sections on the ceiling, which were a little deep. After trying to tune it out I finally gave up since it was so short anyway and turned off the system until the event. When I returned I was having a chat with someone coincidently under these bloody hidden leds sections and heard the same cursed sound when one of us laughed! They sound system was off completely and I was still hearing it! I looked up and and said "HA! HA!" a couple of times and this cursed deep "voink! voink!" returned to me. It was so frustrating and funny. Environment is such a huge factor.

[@drennenanderson142]

Going through the same book! It’s a good read! Easy to digest

[@OffshoreAudio]

Yeah it's pretty accessible

[@josuastangl7140]

Fantastic video, really good info. Now I get why cardioid subs cancel out in only one direction, this always had me a little confused when we built one in a class at university. Thank you!

[@Boleskinebeatz]

Good video. The omni-directional aspect of the lo end/lo mid of a line array is an interesting point, as is the idea that if you are EQ-ing the array you can affect the HF individually but you'd have to accept that you can only affect the lo/lo mid of the whole array. Explains why to my ears the D&B SL series sounds so good every time I've heard it or used it. The cardioid design across the whole array and thus lack of spill from the Lo Mid not just the Sub as head at FOH is a real game changer. BTW.. fun fact/contentious statement, pretty sure me and the FOH engineer who did a series of shows for Trevor Horn's ZTT label including The Art of Noise and Propaganda in 1985 at The Ambassador's Theatre in London were the first people in the UK to run subs off an aux...! .. ( cue minor KZbin uproar) .

[@davidmiller3852]

You didn't hear my great grandmother ran subs off an aux for mMiles Davis back in the day?

[@ssoundspro]

I usually tell people that our ears should be the judge. Must people just spend time on smaart without actually listening to the PA. I also know that our ear response changing at different SPL , what SPL A weighted is right for tunning ?😂

[@TheHairbearCrue]

very interesting thoughts, might pick up a copy - thanks dude!

[@OffshoreAudio]

I'd recommend it. Michael was kind enough to offer a discount code so There's a link for a discount in the description.

[@MaybeDave]

Learned a lot, thank you! If I'm always in a single venue, is it worth learning how to tune the system, or should I just let the installers handle it?

[@niteshades_promise]

So I gotta transport, set-up, and operate the pa, but now I gotta tune it like a guitar also?🍻

[@RUGBYmusic]

Yes!

[@thoseonemusic]

If you don´t tune it don´t take the time to set it up

[@matthewcselby]

thanks for the reminder to actually read this book rather than continuing to let it collect dust on my shelf 😂💀 great summary and really enjoyed the editing on this!

[@OffshoreAudio]

Aw thanks! I guess I must finally be gettign better at editing haha. You should definitely read the book. It's really accessible, nice big font, short chapters. I find the Bob Mccarthy one a bit intense; every time I pick it up I sigh. But between the lines was very doable

[@pennsonvong3170]

nice one, thanks for the books and tips, love to watch more about PA tuning or any IEM and Monitors

[@OffshoreAudio]

Thanks, More to come! I just need a gig with IEMs where I have 15 minutes to spare to film a little haha

[@mixinglane]

This might stir a lot of controversy in some beliefs. The interesting take away is that (unless it's your listening room with a fixed setup and a one person sofa or you have a bilion dollar budget gig) 'it doesn't really matter much for all situations in between'. However, just knowing the physics of sound, sound systems and the tweaks possible will help generating a better sound. Shine on!

[@caleconrad2332]

my only question is, couldn't it be helpful with time aligning subs to move the HUGE energy build up right infront of the subs further into the room a little so at least the people up front aren't getting hammered with low end??

[@akusbass]

Great video! One more sub. Best regards from Spain!

[@OffshoreAudio]

Awesome, thank you!

[@elikamlian9164]

Amazing information

[@jensdroessler3575]

I agree with everything but the alignment and aux off subs. First of all, if you need it to make your system sound good then your system isn‘t properly tuned in the first place. Secondly, it‘s not only about the alignment between subs and tops, but about frequency response as well. How are the chances that the crossover point of your particular system is exact point where the bass guitar needs 5dB more below than above? Why boost all below your crossover point for the bassdrum instead of just what you actually need? Use the channel EQ, that‘s what it‘s for. If you want it just to keep non-bass instruments from the subwoofers you CAN do aux off subs this way: Set the aux to post-fader. Turn that aux on every channel you want on the subs to 0dB and leave all other off or at -infinity. Drive that aux master exactly like you drive the mains. That way the frequency response and alignment is kept intact, yet no unnecessary mud on the subwoofers. But then you can‘t use subgroups, at all. Good sub alignment is a compromise. Not doing it at all is a mistake. Some of us just stack their PA left and right, subs, sub, sub, top or something like that. Yes, power alley, but PERFECT alignment is possible. Just as an example.

[@geofgibson]

Keeping LF energy away from where you don't want it and directing it to the listening area will do far more for the audience than worrying about phase aligning the subs to the mains.

[@hotuser5783]

Good job. Thanks for the tips.

[@OffshoreAudio]

Glad it was helpful!

[@uncle_simy]

what if your subs have to be 6 or so feet infant of the array. Is it fine to delay the line array to get close with the subs?

[@geofgibson]

You can delay anything you want, but, and this is the important take away, your sub alignment is really only valid for a 1m or so circle where you chose to take the alignment reading. The key to getting a good sound is to get the sub energy where you want it and off of where you don't want it. So, a cardioid array or even an arc sub array (physical or delayed) will get you better sound over more of the listening area.

[@jorgerivera8238]

Where can I get that calibration file?

[@bugazavr]

Thanks really great video

[@OffshoreAudio]

Glad you liked it!

[@daveelliott7715]

As a 67 y/o pensioner with time to think, loosing top end hearing is disturbing when listening to flat screen TVs that bounce their sound off of the wall. YOU, my friend, could maybe get a lot of youtube interest explaining how this works. (or simply does not work) And what we can do to help.

[@TerenceKearns]

I jist finished watching Dave Rat explain why subs on aux is essential for music gigs because you only want to send mics where the low frequency information is musically purposeful. Well those were not his words but you get the idea. This probably doesnt apply to non music gigs.

[@Fizzilord]

The difference in position can be very big. But you should never make EQ decisions based on one measurement in a room. Do multiple locations and average them together. You're make decisions for the whole audience not only for one specific spot. So when you have a uncalibrated microphone, and you average multiple measurements together, the response of your mic will alter the average. This can lead to overdoing EQ.

[@GuillaumeLortie]

I never used Sub on Aux. I don’t find that to be relevant for the audience and it just a lazy way to not clean up your inputs. Specifically when you run IEM form FOH, you need those clean sources

[@gregorykusiak5424]

Yeah. This. All of it.

[@gregorykusiak5424]

But also check out Merlijn Van Veen’s article/tutorial on the subject of time alignment of subs.

[@Richard1977]

As I like my life simple I will just stick to 2 speakers on a pole or 2 speakers on a pole on a sub. Just the right amount of work.

[@LaminarSound]

I HATE aux fed subs. I know Dave Rat talks about not sending frequencies you dont want to subs needlessly blah blah blah.... come on man mix engineers dont have aux fed subs in the studio... you ultimately have an LR!!!! And albums mixed well sound incredible, without the need for a completely separate channel for low end (Atmos be damned...). If youre wielding your mics/EQ/hi pass filter correctly this is a non-issue and have proven true in my own real world experience. Aux fed subs cause many more problems than they fix. If you need more low end, roll the bass and kick up. If you still need more low end, your system isnt tuned well. In a well tuned system, you know exactly how much low end you have at concert volume and can control things extremely well with ONE master LR fader and you mix as normal. Im speaking mostly of houses of worship and other venues with permanently installed systems. Obviously this can vary more for touring rigs. Still... i dont get the hype behind aux fed subs.....

[@christiaanbezuidenhout6984]

Back in the day when analog consoles where still mainly used, the HPFs were only 12dB/Oct. Most were locked at 80Hz etc, with only some consoles allowing selectable hpf frequency. Now imagine you're doing a larger show with about 60+ stage inputs, and a PA with excess bass for rock content for an audience of 40 000+. There was a lot of unnecessary rumble on the subs due to those factors. That's when engineer's came about the idea to run their subs on an aux. As Michael Lawrence says "not sending an input to the subs, is the best kind of HPF". With modern consoles you can sweep the HPF as far as you need, with the advantages of even changing the slope per channel. Not even to mention the tools we have when we start using plug-ins etc. So yes, with modern tools, its perfectly fine to run Subs from the main mix. But, some engineers still like having "clean" subs with nothing in them but Kick & bass, and I think they have all the right do to as they please. Not going to hurt anyone.

[@brandonschulte160]

I totally agree, anytime I show up to mix at a festival where I have to work off a techs file and it’s aux fed, I automatically look for other flaws in their workflow. Aux fed subs create really really bad habits

[@teganburgess]

@@brandonschulte160 funny thing is I would say the the same thing about a room on LR only. A studio monitor is not a live PA. Comparing a dainty 200w studio monitor to 5Kw just for one sub yea I don’t want 5000 watts of “grumble”. I don’t think the audience will wanna feel every pop and puff of a vocal mic nor am I gonna waste watts on that. To each their own 😊

[@tgsmusic4481]

Look at it this way, its definitely only applicable in live sound and its faster. But you can really do without it. I would always prefer to do it this way though

[@ciskokidd1313]

Some like steak sauce and some don’t!

[@alanakafang6143]

oh the art of doing this with pure skill and actual knowledge of speakers, components, amps, processing, time alignment and phase is gone .. you would all be lost without your computer .. it's really sad how reliant you are all becoming on software when you don't understand the raw basics.

[@GotWeez]

Let the computer waste time on the raw basics. Leaves me more time to do things the computer isn't yet good at.

[@Kitzy]

You still need to understand all of those things to do it right. The computer just helps you process the data faster and easier.

[@alanakafang6143]

@@Kitzy and keeps you brain-dead, you don't actually need to understand the basic principles to get an answer.

[@UrMusicConceptz1]

@Offshoreaudio Thanks

[@OffshoreAudio]

You're very welcome!

[@tonygardner4077]

Nice one... Thanks ... liked and subscribed from NZ ... chur

[@OffshoreAudio]

Thanks and welcome! NZ is about as far away from me as I can think of so that's cool! I hope to visit some day.