I will probably never be in the situation where i use a cardioid setup with multiple subs, but i'm always interested in the principles of sound and what's possible (little nerd) So it's always a pleasure to watch a new tutorial from mr. rat thx for the constant effort
I’m a shitty drummer that put microphones on my kit and have been watching your videos for a month or so. Seeing you do the equations, you are like the Einstein of sound. Amazing stuff Dave
Great video! super quick and easy calculations. Ive been playing with cardioid and end fire a little bit lately but never knew what distance/frequency to aim for so having this calculation makes it super easy next time I do it!
Years ago, around the late 90's, when I came out of school I went to a technical college and studied commercial music production. They had a full recording studio set up that was also being used by commercial clients and it all looked great. Unfortunately I'm pretty sure it was a fairly new program as the tutors didn't really seem to know what to teach us. They were kind of ex-rockers so seemed more interested in making rock stars than sound engineers. To be fair we did learn the basics of mixing and recording but it was all just too convoluted. Also to be fair, technical college courses are meant to be a springboard to further education at university so I shouldn't bag them too much (I was a clueless kid back then too). Basically what I'm trying to say is that your vids are at the university level of education Dave. I'm sure you know that already but just thought I'd point it out as a sign of appreciation. If a kid studied your vids they might not get a certificate but they sure as shit would have a solid foot in the door for becoming a professional sound engineer. Thanks mate and say hi to Anthony and Flea for me :p
Air times are a different beast than structural, ie concrete, dirt or sand. For instance, 1/2 mile down a beach you can measure a time delay offset of over 200ms under 80hz between air and ground, air will always lag because it is less dense. Outdoor delays, with the exact same spacial measurements, will always be off about 20-25% from indoor (at nose-bleed/parking lot distances). Most will miss this and start cutting frequencies that begin to stack in orders, ie sub 40hz and between 250-350hz. That point at which absorption and reflection equalize is ALWAYS a btch and it is way dependent upon what kind of mass is involved. Air is just 75-80% of it, like in a studio or a car - literally any space that is not anechoic. Glad to see you delving into the math on directional subs. At least get people thinking about it, aware of it, so that even if they don't do the perfect thing they do SOMETHING about it because, being totally real, walking in and out of a tuned space (that edge where everything just falls apart) is annoying to everybody.
For outdoor events, I've never had ground transmission be a significant factor. For the big festivals we do, getting delays close using a laser range finder is helpful. Then fine tuning with Smaart or by ear is common.
@@DaveRat I've had it be a factor a few times after it became a problem, ie after I noticed it. If it has never been a problem for you then that only means that it never MADE problems for you. I would never have believed that the ground was 20% of my muddiness, or even more of my power overhead, until I went several blocks into Copacabana and put a stethoscope on a structural column of a 10 story building and heard bass clearer and ~250ms faster there than I did over 1/2 mile away standing on the sand 200' from the stage. Side note: Brazilian federal police are some scary mofos in general but scary is JUST A WORD once they believe that you could make / already might have made them / their city liable for millions in property damages. ''Turning it down'' wasn't an option, only options were Off or On, On being contingent upon city seismologists' readings. Without knowing how to tune a cardioid array and some quick delay changes I'd probably still be there with 5 or 10 years left to serve. They don't care about overseas insurance plans or what nationality you are. I've since looked at Rio's ground surveys and that place is nuts. You think it's just sand and some hills poking through here and there but about 10'-20' down it is riddled with finger like rock structures. Start shaking one or two of those and you will turn several high rise buildings blocks away into tuning forks - but you won't know it.
Been to Brazil and mixed Rockin Rio and other shows there. And yes a level of lawlessness is bot beautiful and scary. I know sound speed is variable based on the sensitit of the medium. That said, I have always had enough PA to where ground sound was not audible in relation, in the coverage areas. Over sand, it should not be an issue as it is highly damped. In fact recording studios often seek out locations that are river beds so the sand below the foundation will not transmit low freq vibrations to the studio and recordings
@@DaveRat So you know the lay out. That beach is packed hard, millions of years of the Atlantic pounding it into place, plus, dig a 20' hole and it's like cement, unlike a river bed. Damped, in my mind, firstly, is a power loss, I'm throwing something away instead of paying a due if it can be avoided which is partly why we do delay lines instead of just cranking more current and facing diminishing returns per db/watt. In a studio, knowing what elements are interacting is the main game, bleeding off bass just makes sense if you don't want to retool up or down for efficiency's sake. If we forget about time alignment for a moment and just focus on efficient power that's when it becomes clear that not all of our potential problems are purely audible. Down where transmission is mostly absorptive is also where it transmits the quickest and that means that once you do have an issue it can begin to stack up fast in a way that you just can't account for in the air. Think of all the studios where the control room is awesome but there's a side room or hall that talks to your arthritic knees when the mains are cranked because corners were cut on the foundation's construction. Like I've said, most won't notice and who even meters power usage if the gig isn't run from mobiles? That said, once it dawns on you that you can easily reach a point at which your second (or third) line is fighting your first, literally bleeding 20% or more of your power, all those moments when you chose to cut anything 40-80hz and cranked others in that range to save face will come back to haunt you. I mention my Rio experience to point out the fact that I was 100% blind to such a loss even being possible, wait for it, because it slipped right past me (ie literally under me).
Interesting. Yeah, we deploy 600 boxes for Coachella with loads of delay clusters. Ground is never an issue. 20% power loss is a fraction of a dB. 50% powerloss is 3db. Still not a big issue that can't be overcome with a slight gain tweak.
It should apply to any sound source. Energy adds when the timing, distance and polarity are aligned. And energy can be cancelled when the timing, distance, polarity and levels are aligned for a a null
I remember going to one of my first shows that had a phenomenal audio and seeing RAT speakers. This is so full circle now that you're posting on RU-vid?
Thank you and I try and share the info I wish people had shared with me. And also, now that I stopped touring, this helps me stay connected with my people, our people, sound people
Great stuff Dave! Can't go wrong with math. Can it be applied to a 3 subs setup as well? (Ex: frontfacing/backfacing/frontfacing) I usually use the EV ETX15SP with the cardioid setup included. thanks!
Is the measurement from outer edge of speaker cone outer edge of speaker cone? So end-fire is simplified as grille to grille, but cardioid would need to factor in the distance between grill and the outer edge of the speaker cone?
It's actually acoustic center to acoustic center with any added distances due to cabinet interference added in. But that said sound travels the shortest path it can find so from the grill to front a grill should get you extremely close for both cardioid and end fire
Dave, what's your thoughts on cabinet ratios / relative gain settings on front vs rear in the cardioid config? IIRC, I think you were using 3:1 cabinets in your "in the round" setup. A 2:1 ratio seems commonplace. What about gain settings for 1:1? (I realize that may vary on different setups, but ballpark starting point?).
In the round I was using 5 to 3. With supersubs I use 1 to 1. Many factors but the way to sort is do a prediction and do a measurement at the point or area where you want max rejection. Alter the ratio of cabs to match and fine tune with gain
Hi Dave… awesome video… i never thought that i would need a cardioid setup until i re designed my subs and the are real beasts … a couple days ago i played the drums behind those and i left dizzy with all the bass… I have 8 simple subs and 1 powersoft K20 for them… can i do any decent cardioid with that combo? Thanks in advance …
congratulations for the video. I wanted to ask you if possible: does the volume of the subs stay the same and is only the delay calculated? or do you have to turn down the volume of the sub closest to the microphone during the measurement?
The volumes of the subs typically stay at the same levels this is important because turning down subs means you're wasting energy or that they are not operating the same which can cause problems For subarrays that are highly tuned for accuracy of cancellation, slight adjustments to gain and EQ as well as differing the quantities of subs in the front and rear are all options that can be effective. To see one such a ray maybe give a watch to my Bassnectar 360 subwoofer video
@@DaveRat I'm sorry but I didn't understand. for the same level you mean for example in a cardioid measurement if the sub back gives me +5/6 db on smaart because it is closer to the microphone I have to lower it right?
Make sure the mic is not too close to the subs or pick a spot to cancel that's farther away if you have that much of a difference. Ideally you would use less subs behind rather than turns subs down
@@DaveRat thanks a lot for your replies. one last thing if you can. as for the frequency you choose for the distance is it correct to choose the strongest frequency of the sub? in my case my rcf8006 2x18 has the maximum point on smaart at 60/63hz
Since the freq chosen impacts the cancellation and not the coverage, select the frequency that you want cancelled most. If the sub gas a peak resonance , use that, if it's smooth and flat, choose the midpoint
Curious if there is a processor for delay that can alter amount of delay automatically based on a tempurature sensor. I.e. shift the delay when the venue warms up with people.
There are but it's not so simple. The temperature is not a single thing, it is the average over the distance travelled so measurement is complex and adding in the variable of stuff auto changing gets messy fast and takes loads of time to test and calibrate.
Actually, can we dig into this a little? Can a cardioid sub array be designed/calculated if the subs are placed apart, across the front of the stage and within about 1/2wavelength of the band pass’ centre frequency?
Yes it will work as long as the subs are all point at the same direction. With hornloaded subs the front sound is quite different than the sound coming off the back. With bass reflex subs you can point the rear subs backwards to save space, but with hornloaded subs they all need to point forward
@@DaveRat If using reflex subs and pointing the rear backwards, do you still apply a polarity inversion? PS As always, great and practical information.
Yes, subwoofers are the same polarity in front and behind and to the sides. Open back speaker cabs are polarity reversed behind. Looking at it another way, polarity reversed signals will cancel, so if you walk around a sub and and don't hear a huge cancellation where it's super quiet to the sides, then it is in polarity all around. Treat sealed back, ported, and horn loaded speakers designs as in-polarity.
No, the back energy does not exactly match the front energy. So pointing a sub backwards will never reach the highest level of cancellation, even if level and EQ compensated.
This is outstanding!! As I play with this info, if the mains are lined with the front subs, would they also delay the same? Or should they fire with the rear sub? 🤘🦻🤘
