5 Unexpected PA Tuning Tips 

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!

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.

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

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!

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

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

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

Amazing information

Good job. Thanks for the tips.

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!

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.

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.

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!!

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 RU-vid uproar) .

Thanks really great video

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

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!

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.

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.

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??

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 ?😂

Where can I get that calibration file?

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.

Yeah. This. All of it.

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

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.

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.

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.....

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

@Offshoreaudio Thanks