I believe it : ) You want to hear 50Hz in your IEM's, not always in your chest! Bob McCarthy has a CRAZY cardioid video in this rig: kzfaq.info/get/bejne/f7l2msZlzNS6nKs.html

Thank you so much! I'm very glad this was helpful for you. I've got a podcast coming up as well, so stay tuned.

@@MichaelCurtisAudio I wonder, may you do a video on " best Professional Audio Subwoofers and satellites/line arrays/tops etc money can buy"

@@josealfredfernandes I can share the equipment I like to work with within a given budget, for sure. I personally haven't worked with a huge variety of brands, but happy to share what I like.

@@MichaelCurtisAudio cool. I'll be waiting for your upload. Take your own time. 😛 Because, I really need to make new investment. Well, what you think.. shall I become a authorised distributor of Danley Sound Labs & McCauley? I have no experience and I'm just a teen.

Thanks a ton, Steve!

Yup! An effective and quick way to verify the setup, for sure.

The "recipe" relies on the delay time and spacing to be equal to work. I can get more technical and explain it in a future video, but that's the short of it!

Cardioid sub configurations require one of two things... 1) Subs on AUX (or matrix) driven independently of your top boxes, AND delay processing, AND polarity inversion.... *** OR *** 2) Subs that have built in DSP processors with a cardioid configuration option... two examples that come to mind are EV ETX series, and QSC KS series (but NOT KW series)... in each case one sub is set to normal operation, and the other is set to a cardioid configuration, and one is faced in the opposite direction. It is VITALLY important that you refer to the specific sub documentation before using this technique, because different companies have different menu options, and placement location requirements. Personally, I'd put big stickers on my subs to avoid setup errors. Option 2 can be used EXACTLY like you currently do it (pig tail XLR from the top box to the subs), because the subs DSPs are doing all the work. You can also get the QSC KS212c witch is cardioid in a single box (2x 12" drivers), but a little weak if you only have one box. Option 1) can be done with any 2 identical subs, and a reasonably competent digital console, ***PLUS*** Open Sound Meter on a laptop, a measurement mic (if it's not a USB mic, then you'll also need a basic 2 channel USB interface), and an understanding of what you are doing. Please keep in mind that this particular video discusses a GRADIENT cardioid setup, and if I'm not mistaken, you may be referring to a stacked cardioid setup, which requires different calculations.

Even if you place a cardioid setup flush with the stage front, your cardioid pattern will still fall apart. You will get mostly the same response out front, but no rejection on stage. Your best bet is to fly them (if you're able in your specific case).

The DriveRack PA2 should also be able to reverse polarity as well, so I'd do the delay and polarity reversal at the processor output. If for some reason you can't, then yes you can use a cable that reverses pins 2 and 3.

@@MichaelCurtisAudio after talking with dbx tech support, the DriveRack PA2 cant control the left and right outputs on the low end separately. Their driverack 260 and driverack venue products can do that. So what I will to do is use the low and mid outputs for the two subs and use some summing connectors to join the left/right outputs on each. Then I can phase reverse and delay the output on the low outputs and leave the mid outputs (for the 2nd sub) alone. I will of course have to set the low and high pass filters the same on both the low outputs and the mid outputs.

Thank you for your kind words, Ben! I started in music production world, but have moved over more to live. So I get the bedroom producer life : ) And you hit the nail on the head! Being able to TRANSFER universal concepts from one domain to another is a huge deal. I've got way better at recording now that I understand speakers a lot better, since mics are just the reverse of speakers.

In short SPL means loudness. Sound Pressure Levels = SPL

@@barrettm.9918 appreciate that 🙌🏾

This works with any sub topology.

Great question, Ján If you're running a left/right setup with your subs, have left channel from your console go to the left sub, right channel to right sub. If you're running a center sub setup (with both subs next to each other), I would send your LR mix to a mono matrix, then send that matrix output to the left input of one of your subs, then daisy chain to the left input of the other sub. I would also use a mono matrix of your LR mix to send to any center cardioid setups as well.

Hello Michael, thank you so much for your reply and feedback. Greetings from Slovakia.

Hey, Darth. Great question. I've actually been meaning to update and simplify this spreadsheet (and just have thanks to your question). The original formula was taking the crossover frequency intended for your subs, increasing by 8%, then figuring what frequency is 2/3 of an octave below that. The 8% increase was to help my formula match what I saw in MVV's spreadsheet, but I now know my approach was wrong there, for a few reasons I can explain later. All that being said, I've now reduced the formula to where the max summation frequency is calculated based on it being 2/3 of an octave below the crossover frequency. This is because in a cardioid setup like this we have 1/2 octave below our center frequency of usable bandwidth and 2/3 octave above our center frequency of usable bandwidth. This is due to us using the "inverse" of the comb filter we've intentionally created to make a bandpass filter around our sub range. This is due to the intentional timing offset that helps us get the cancellation in the rear. The built in processing/filtering on the subs you have may change some of this (one sub may have a very steep LPF, some very gentle), but this should get you in the ballpark!

Thank you so much!

That sounds like a good plan to me!

With a LR setup, even if it's cardioid, you would still get overlap and therefore power alleys and valleys. You can do a LR cardioid rig and angle the arrays out 45° for less overlap, which may work for some designs. A center setup has all energy coming from one place, so no power alleys and valleys.

ok the second one is the end fired and only works with one freq.

You figured it out : )

If your amplifier has two inputs for each of the two channels, you could send a separately processed signal that feeds the rear sub.

I'm honestly not familiar with those other brands besides Yamaha, so I'm sorry I'm not much help here! If you're on a budget it's best to stick with what you know will work, just so you're not having to replace anything AGAIN if you're unhappy with a new product.

If you're able to measure your subs with Open Sound Meter or SMAART you can compare the two different models and see if they're phase compatible. As long as you level match them and their phase traces are within 50° of each other and no single sub is pushed into limit, you should be able to use them. Check out this video at 12:10 - kzfaq.info/get/bejne/h5qerJphmNuRm6c.html

These formulas are still true even without my spreadsheet. I just simply aggregate them there. A good place to start for "most" subs is a 4.5ft (1.4m) separation and a 4ms delay on the rear sub for an inline gradient setup.

I'd say give it a shot and measure if it's effective. It won't be "ideal", but I think you'll get at least some benefit.

900-LFC for single 18" 1100-LFC for dual 18"

Great question! Without seeing the specific audience and venue layout it's hard to say for certain, but I think any cancellation in the rear on subs is better than none! So yes, I'd definitely gived an inverted gradient sub array a try there.

Unfortunately cardioid sub arrays don't work well under a stage. It doesn't hurt much out front, but there's little to no cancellation.

I'd have to get a hold of a unit, but sure thing.

@@MichaelCurtisAudio id be interested in this too. new to this subject and trying to be more educated approach to spesker placement. im converting from two stacks either side of stage! also why would i use inline gradient as opposed to inverted?

They're all fed from the same matrix, just different polarity and timing processing on the outputs. So the EQ changes will go for both subs.

I'm assuming it would interfere, but the only way to know is to test it! Get out a measurement rig and see you find.

Yeah I was kind of thinking the same thing, i’m having a hard time picturing any scenario where a PM or stage manager or whatever would ever allow you to put 2 (or more) subs right smack dab in the middle and 5ft+ of space in front of the stage unless it’s a huge festival/arena/stadium

@@BendyDH You're right, not always practical, but good to have it in your pocket as sub array building block nonetheless.

Unfortunately no. It's too large of a displacement for this type of setup to hold up.

Thank you, Nick! I'm so glad these videos have been helpful for you. What would you like to see me cover next? More sub array stuff or something else?

Great question! It kinda depends on how wide your stage is and your venue/audience shape, but shooting from the hip, I would point out each sub array 45° outward. Even though you'll have a cardioid pattern from each there still will be a substantial amount of overlap in the middle. Angling them out (in a 90° "V" shape) will make the subs have less overlap in the middle of your audience, therefore less power alleys and valleys. If you're able to put all four subs in the center, I would follow the design I do in this video: kzfaq.info/get/bejne/b7-Cf7Cfy9mlcaM.html

@@MichaelCurtisAudio thanks Michael, stack of single subs placed in the Center of the stage works but what if we use 3 stacks same like how you did in this video but left Center and right then the distance between each stack matters isn’t it, and also how much wide you want open the spread of the low frequency. There are number of softwares which do that with delays and presets loaded which makes it easy for user, but if we need to calculate manually and use is what I like most, coz not all Audio manufacturers make presets for cardioid or end fire presets for there model speakers. So building up these kind of sub configuration is really good if we understand the concept. Thanks for replying to my question thou, one more question where are you based out of ? Which country ?

Yes, you're totally right in saying that if you had three separate inline gradient arrays all in the center, but spaced X amount of distance apart would definitely affect the width of coverage. Having them as close together as possible (or stacked on top of each other) would get you the WIDEST pattern. You could spread out the far left and far right arrays up to 2/3 wavelength away from each other of the highest frequency you want the sub stack to reproduce. So, if your crossover was 100Hz, I'd put them no more than 7.5ft away from each other. I'm based out of Arkansas in The United States.

@@MichaelCurtisAudio thanks for the reply. I understand it

Nathan Lively just put out a great article on this: www.sounddesignlive.com/how-do-you-calculate-cardioid-subwoofer-spacing-gradient-array/?

I'm not positive if the subs being that close to each other would be a big deal, but I'd give it a shot and test the amount of cancellation you get. If it's a problem, try a farther spacing. If it's still an issue, I would stack your subs then reverse the bottom one to get the distance offset. I would steer away from having differing sub models in the same cardioid configuration. You need matched level and phase across the whole range to get good cancellation. Not all sub models will behave linearly at all SPL levels.

@@MichaelCurtisAudio thanks for your opinion on that👍

Yes it will. You could do End Fire and inverted gradient stack. Not to mention more SPL (if you have bigger shows that require it).

@@MichaelCurtisAudio Thank you so much for all your help.

@@iglesiasion You got it!

Inline gradient (the setup in this video) will have a wider pattern and you have more flexibility with the front to back spacing of the subs to account for different crossovers and center frequencies. If you do FBF, you're stuck with the enclosure depth and having a line source three cabinets wide will narrow the coverage, which isn't always a bad thing depending on your audience size and shape.

Unfortunately, no : / Any major boundary near a cardioid array will cause the rejection pattern to break up.

Thanks, Niklas! I can't go into great detail here, but long story short your proposed solution would not get the same results as the 1/4 wavelength spacing + 1/4 wavelength delay recipe. Those two unique attributes together make it all work.

@@MichaelCurtisAudio aha, ok i see some do "center frekvency" of the sub bandwidth -10dB, and have this as a reference for decision of the distance and delay. What are your opinion about this? As I understand you take the xover frekvency from sub to mains , in this video

@@niklaskarlsson236 Both approaches work! Using crossover maximizes the amount of total summation. Using the center frequency you can set up even if you don't know where your crossover will be, but it may not necessarily be where you're able to get the most amount of summation throughout the sub range.

No worries at all! This setup isn't necessarily better, but just another way to get a cardioid pattern out of your subs. It all depends on the number of subs you have, processing outputs, number of subs. Knowing multiple ways to get a cardioid pattern out of your subs is handy. To your second question, I choose the sub spacing based on 1/4 wavelength of the center frequency of the subwoofer. OR, I can do 2/3 octave below the crossover frequency between mains and subs. If you're not sure with RCF8006 subs, 63Hz is a safe bet.

@@MichaelCurtisAudio thanks Micheal. I have the impression that in the gradient mode there is more pressure, perhaps because the subwoofers are both on the ground? Also, sorry if I ask a lot of questions, in the inverted stack frontback, what is the frequency doubling in the audience? can't choose right?

@@tony8236 Having both subs on the ground will get you more equal behavior between the subs, since the floor bounce is the same, but it doesn't necessarily mean there is more SPL. It's just SPL in a different place than if one is stacked on top of the other. Yes, you're correct on not being able to "choose" the summation that happens in the front if you do the inverted stack with one sub on top of the other, with one of them facing backward. It's up to the cabinet depth and how long it takes for sound to propagate from the front facing subwoofer to the rear that will determine their timing offsets. That one's a little harder to predict ahead of time since you have to factor in the extra "wraparound" time.

@@MichaelCurtisAudio i try to find the rcf8006 center frequency. would you suggest with 4 subwoofers to have a horizontal distance? within the 1,70m limits? or does this technique work if they are attached?

@@tony8236 It depends on your audience area. If what you're trying to cover is long and skinny, push your subs further apart to make the coverage narrower. If you have your subs close together that will make your sub coverage wider.

Yes, you're totally right! I was mixing that up with how the signal from the rear sub arriving at the front. Thanks for the fact check.

@@MichaelCurtisAudio thanks for coming back on this. I hope I didn't come across like an internet smarty pants. I was just in the middle of fully understanding the principles myself and this was a curve ball. Its so easy to get muddled in this complex set-up. You do a great job....for the most part! 😉

@@videyo098 Not at all! I want my teaching to be clear as possible and I obviously dropped the ball there : )

I don't know of any : ). The reflection from the rear ends up ruining the rejection in the rear. BUT, you can get a passive cardioid subwoofer (Fulcrum Acoustic has one) and they claim their box can still keep a cardioid pattern.

@@MichaelCurtisAudio could you suggest somewhere I can look up info on making a larger center sub array or lining the front of the stage best practice

@@stevenbanquer8552 Hey, Steven. I can't point you to a specific video at the moment, but in the meantime I would check out Merlijn Van Veen's subwoofer array calculator and try out a delay arc. That's how you're able to get a ton of subs in the center, but widen out the pattern.

If you're stuck with a hard front AND cannot fly your subs over the center, it's unfortunately a no-go on a cardioid setup : (. What you CAN do is still place your subwoofers downstage center all right next to each other, packed in tight. Depending on how many subs you have and how high your stage front is, I'd run three sub cabs wide, then stack three more on top if needed. Run the same signal to all three, no delay processing or funny things with polarity.

@@MichaelCurtisAudio thanks so much. Very insightful. So, a cardioid array always needs room in the back. I will explore with the other options.

@@fgrondon You're very welcome! Yes, a cardioid setup always needs room in the back. If it didn't, the immediate reflection off the back wall would counteract all the hard work we're doing to get cancellation. I don't ALWAYS defer to a center sub arrangement, but it's pretty common for me to do, cardioid configuration or not.

@@MichaelCurtisAudio What about JBL SRX828SP, it has cardioid formation preset too.. but.. 3x units worth it?

@@josealfredfernandes If I'm understanding you correctly, is it worth using the JBL dual 18" enclosures to pull off an inline gradient setup? I'd say yes, if you have the real estate to do so. Even if there is an enclosure that can do cardioid within itself (three drivers, one facing backward), it still needs to be away from a wall. It looks like the SRX828SP have a cardioid DSP preset, but that's only in relation to other boxes, not something it's pulling off with a single enclosure.

You’re very welcome!

@@MichaelCurtisAudio can you help me to improve my sound knowledge?

@@ruwenonmix8210 Feel free to watch my other videos and dig into the audio toolkit. I've got some courses in the works, too!

Great question, Ivan! Yes, when comparing a speaker to a snare drum it would seem wrong for the wave to be positive on both "sides" of the woofer. The answer is that sound from a subwoofer radiates as a point source - the wavefront moving in a spherical shape outward from a single point. That being said, in every direction the wavefront has the same polarity from the point it emanated.

​@@MichaelCurtisAudio Yes I "know" this but I would like to know physics behind it. If something is pushing air in front and pull it on the back that means it makes positive pressure at front and negative pressure at the back right? why this apply to a drum head (membrane) but not on speaker membrane and why wavefront is not moving like this on a drum head when hit? Actually it feels like snare drum would be the one that make positive pressure on both sides because you have physical hit point from which waves start as positive pressure and radiates omnidirectional if not stopped by some material like damping or cabinet (that's why we can control higher frequency direction while subs are omnidirectional). I'm still confused :)

Now my question is, can wave start as negative pressure (omnidirectional) at all when something is phisicly hit like snare drum with drum stick? That would explain speaker cone as one wave is made from both positive and negative preasure at one point, but than, it would mean that theory of inverting phase on a bottom snare drum is false or misunderstood as wave is radiating omnidirectional in same phase, starting as negative or positive in all directions and why this actually working in real life is because physical distance of bottom microphones from the source. If this is true it means almost everyone explaining why you should invert polarity of the bottom mic are wrong, but hey, it works :)

@@IVL3 The snare drum is also radiating in (mostly) a sphere. The reason why you invert the polarity on the bottom mic is that it is facing the opposite direction of the other microphone. At least that's my understanding!

Sound Pressure Level. The acoustic equivalent of voltage in electronics.

This could technically also be classified as a two-element end fire. But end-fire is only effective with at least three, optimally four or five elements. If you only have two elements there's only one key frequency being attenuated in the back.

@@MichaelCurtisAudio the same could be said about cardioid... 3 elements are better...

I take my earlier comment back, it's not a two-element end fire. End fire syncs from REAR to FRONT. We ask the front sub to wait for every sub behind it to get sync to the front, then propel forward. In inline gradient, we're syncing from FRONT as it travels to the REAR (to get cancellation in the rear due to the polarity inversion, delay line, and physical displacement). But then through that synchronization we're able to gain some summation in the front with the rear sub being a half-wavelength offset from the front, but polarity inverted so we line up for a limited bandwidth. As far as you saying 3 elements are better for cardioid, for what specific sub array? Are you talking about inverted gradient? Even with this video's approach with only having two elements, there's still full frequency bandwidth cancellation in the back. End fire is the only array in which you need at least three elements to get near-full bandwidth cancellation in the back.

@@MichaelCurtisAudio well in my case, when I stack my 3 meyer 700hp subs, the middle is inverted, creating a cardioid setup. I’m not sure what “terms” you are putting to that (“gradient”). I know HOW to deploy, align and delay various sub configurations - I’ll leave the wordsmith and classifications to you.

Totally with you. The three subs with the middle inverted is an inverted gradient stack. I go over that in this video: kzfaq.info/get/bejne/m8l_f9x71dvVk3k.html Like you said, you can stack them one on top of the other, or horizontally. I promise I'm not trying to attack your knowledge or setup, but since there are multiple sub array types that can achieve a cardioid pattern, I think being able to classify each configuration so we can have a common language to refer to them is important. I understand that the inline gradient configuration in this video LOOKS like a two-element end-fire, but is functioning much different.