Cardioid Sub Workshop | Inverted Gradient

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LET'S GO
00:00 - Intro
00:59 - What we will cover
BASICS
02:39 - Why and what is a gradient inline cardioid array?
04:03 - Pros and cons of gradient inline
HOW TO PULL THIS OFF
07:54 - 5 steps to deploy this array
NERDY STUFF
10:55 - How does the gradient inline cardioid sub array work?
19:03 - Reviewing the data I got in the field
WRAP IT UP
22:30 - Outro

[@peterkadelbach7010]

Excellent info Michael. Thanks.

[@billhendrix4125]

So much info in your videos. We are trying to redo our sound system in our church, but on a tight budget. The main area is like 75ft wide and like 25ft deep. Have a suggestion on a video of yours to approach this? We’re pretty sure one of the first things we need to do is sound dampening. None currently exist. Whoever did the sound before just dropped a huge powered dual 18 JBL powered sub on one side corner of the stage.

[@atech9020]

You can do a similar deployment with only two subs and increase the rearward reduction of SPL. If you have to have your subs on the sides of the stage, and you only have two subs per side, you can lay them side by side and get a 45* angle of cancellation in relation to the plane of the subs. A picture is worth a thousand words, but that doesn't work here, so perhaps one day I will present it on my channel, but for now, you just have to imagine. There are also two different ways you can delay the subs for rearward cancellation. One will provide better forward coherence, the other will increase rearward cancellation at the cost of reduced forward coherence.

[@MichaelCurtisAudio]

Great insight here! Yes, I'm familiar with the sub array setup you described. I found about it from a webinar Mauricio at Meyer Sound did. Tell me more about the two different delay settings for forward vs rearward coherence?

[@mallkrawlerz620]

First off thank you for these videos. Second what is the best set up for 3 subs non cardioid and without all of the fancy delay and Dsp stuff? Basically quick on the go dj stuff

[@michaelhodges3841]

You're rocking the Opie look

[@MichaelCurtisAudio]

My current self wishes my past self would have got a haircut sooner and ditched the hat : )

[@MarcelGavalier]

What array you recommend when stage is solid concrete and subwoofers in in front of the stage front? Thank you

[@hezekiahcharles6754]

What would you recommend to be the crossover frequency, when using this Subs and kw12s?

[@OftheSeven]

Great information! So using this setup with electronic delay and polarity inverted, there is no need to physically move the center sub towards the stage (quarter wave-length behind the other subs)?

[@alinposmag86]

Great info, thanks so much! I have a couple of questions: can I do the same cardioid arrangement with just 2 subs? I am also confused as why the sub facing the rear would get the delay. Shouldn’t the one facing the front get the delay? Many thanks

[@edwardwhite_al]

Brilliant video and very clear, I was at a festival recently and noticed the subs stacked with one facing back, wanted to know what this effect was and why it happens. It was at a festival so I am assuming that they are trying to minimse the noise and vibration to the surrounding area. Totally a beginer comment and not sure if you ever work with music festivals, but would be really interested to learn more like stage positioning etc. Keep up the amazing videos and your craft shows.

[@MichaelCurtisAudio]

Thanks a ton, Edward! Can you clarify a bit more by what you mean by stage positioning? Meaning how to set up bands on stage? Or the PA vs the stage?

[@edwardwhite_al]

@@MichaelCurtisAudio So I have no knowledge around sound design but I noticed the subwoofers stacked that way and curiosity made me wonder why they would do that. Not the best shot but this shows a bit of the setup: www.dropbox.com/sh/7ij4kubf5bylcnr/AAAJKugyfz5EYpTwl6lMh33Ea/23-07-22_LIQUICITYFESTIVAL_TIFFANYKONINGS_597_LR.jpg?dl=0 I mean more the PA and how they would mininise noise from an outdoor festival or direct it in certain directions etc. I know that different countries have differnt laws and restrictions regarding this. Sorry for the long winded comment complete newbie here!

[@robendj]

Just checking Michael but would this also work with an array of 4 subs (2 ouside facing forwar and 2 inside facing back?), or 6 even (4 forward 2 back in similar arrangement to the video)?

[@yosukeDVJ]

I’m working with a bit of a Frankenstein passive set up - 3 srx718’s but two different amps to power them. How precisely do the speakers need to match in output before you start getting funky results?

[@leemurray3487]

Watched this and other videos of yours a few times and this weekend, I'm going to try a 2 sub cardioid deployment. Unfortunately it'll be at one side of our "stage" as we have no room below or in front of us (function band ). I'm wondering if it'll be helpful to run the opposite side top full range and the sub side through the crossover?

[@MichaelCurtisAudio]

That's a good thought. I would just make sure if you're running the show pretty hot that you're not pushing that opposite main into limit before the other main since it's handling more of the frequency spectrum.

[@andrewgibbons2241]

Thank so much Michael. You reference stacking the array vertically. Do you have any more information on this? Does it change the coverage pattern?

[@MichaelCurtisAudio]

You got it. When stacking the subs vertically it will narrow the coverage pattern vertically somewhat, taking into account the floor bounce (unless you fly the array).

[@escalator9734]

Hi, thanks for the videos making it pretty clear how all this cardoid stuff works, 1 question : why 3 subs ? wouldn't it work with just 2 like the inline gradient ?

[@MichaelCurtisAudio]

Yes, it would work with just two, but the directionality of the array would actually shift 45° in the direction of the front facing woofer.

[@escalator9734]

@@MichaelCurtisAudio That makes sense, thank you

[@watchman316ly]

Very in-depth but this is making my head hurt-LOL! Show me how you do it by either using the your mixer or DSP on the sub box and letting us hear the difference!

[@MichaelCurtisAudio]

Keep spending time with the material. You'll get it! I personally do all the process at the mixer, not the sub, just so I can have all processing in one place.

[@fame4049]

@@MichaelCurtisAudio Mybe you can show us how you actually do it even even explaining. we will just follow you how you do it with physical speakers and consule. Thank you

[@MichaelCurtisAudio]

@@fame4049 You got it.

[@jamiechappa8538]

Is it possible to do 5 singles 18's. Just adding two more to what you have in the video. Inverting sub 2 and 4 in the line

[@MichaelCurtisAudio]

Absolutely! The total coverage pattern will be a bit narrower than a three element setup, but this is totally doable. Just make sure and put fist sized gaps between the subs.

[@Galaedael]

Michael, you may have covered this but in the 3 speaker cardioid array is the volume the same for all speakers.

[@MichaelCurtisAudio]

Yup! They're all the same.

[@drummerdude4696]

Hello Michael. I am currently using 2 powered subs, and 1 passive with a bridged amp. The subs, amp, nor the Mackie DL32S console I use, have a reverse polarization setting. Can I still set up my subs in a cardioid pattern?

[@MichaelCurtisAudio]

I would first take a measurement and see if the two power subs vs the passive sub are phase coherence. You'll also need to match their levels. As far as a polarity inversion goes, you can reverse the wiring going to your rear facing passive sub to get the polarity inversion (positive terminal in negative terminal and vice versa).

[@drummerdude4696]

@@MichaelCurtisAudio Thank you for your response. I will definitely try that. Man I wish I could shadow you as an A2 for some gigs. I have so much to learn!!!

[@jamesmckenzie9559]

What is the best external DSP to use to add the delay?

[@MichaelCurtisAudio]

If I just had to pick one external DSP that's reasonably price I'd go with the Allen & Heath AHM series. You can add the output delay on most digital desks if you don't have an external DSP.

[@pasekamosoetsa1559]

Can i apply this setup on dual subs?

[@rthgtrgaehgq4502]

I Michael, I am a Noob to sound, I was wondering, is it possible to do a the same thing with two subs of the same brand monomenbrane and a sub with 2x18" membrane. thanks in advance and thank you for your high quality/value content that you produce.

[@MichaelCurtisAudio]

It's possible if they have matching phase responses, and you'd have two turn down the dual 18" enclosure by -6dB or so.

[@rthgtrgaehgq4502]

@@MichaelCurtisAudio Thank you very much !

[@viktorzacik8988]

Hi, maybe just i didnt get the info right but how do you get physical displacment time? It is the physical dimension of the box? Why it is important to me?

[@MichaelCurtisAudio]

The full "recipe" for this setup is four things working together - the 1/4 wavelength displacement of front and rear sub, the 1/4 wavelength equivalent time delay to rear sub, the level offset due to displacement of front and rear subs, and the polarity reversal to provide the cancellation at the rear. If any of these four elements are changed, you don't get the full result.

[@censoredcitizen528]

Could you stack another 3 on top in the same fashion and processing for a total of 6 subs? What would be the difference in results vs duplicating the array in a horizontal fashion, with 6 subs?

[@MichaelCurtisAudio]

You absolutely could! Adding another stack of three on top would double your available SPL and keep the same horizontal coverage pattern. It would slightly narrow the vertical coverage pattern. If you made the array wider (put three more in a row next to those three), you would get close to doubling SPL, but not quite since all of the subs are not as close to the same acoustic center as the stacking method would be. It would also make your horizontal coverage pattern narrower since you've increased line length. So, I would use the stack method if I had a very wide audience and had enough vertical height to not block any sight lines. I would put them all in a line if I had a narrower audience and couldn't stack the subs because of sight lines.

[@censoredcitizen528]

Thanks so much for your reply. I’m enjoying the content you put up. I’m a new subscriber and will share you videos. You do an excellent job.

[@censoredcitizen528]

I know I need to learn how to use predictive software but was just hoping for some advice here. I am using 6 of the same subs (qsc kw181) in a medium - large sized outdoor setting that is somewhat as equally as wide as deep area in front of a large metal stage. The stage floor is about 4.5 feet tall. The stage is open underneath with the exception to some support framing and has a skirt in front of it. The back is open with a skirt and the roof is probably at least 12 feet tall. I have been setting the subs up in a L/R fashion stacked 3 high and I am wondering if there is a better way to do this in this case. I was thinking of setting up a cardioid array like the one you shown here and as we discussed either doubling and repeating it in the horizontal plane or more likely after your advise stacking it vertically. A new idea I also had was to treat 2 single boxes as a double inclosure and use the method from this video, not sure if this could work as i am thinking maybe you can respond to this. Also with the description of the stage if I have to still be a certain distance away from it. More or less, what would be the ideal way to deploy 6 of these subs in this circumstance in order to have decent coverage and not be drowning in bass on stage.

[@MichaelCurtisAudio]

@@censoredcitizen528 Great question and thanks for the detail. I would do the setup from this video, inverted gradient with a front-rear-front, then stack another three boxes with the same configuration on top. Then put the array about 3-4ft in front of the stage if you have the real estate. As long as the front surface of the stage isn't rigid, you'll still get a good bit of cancellation in the rear, even if you have to back array up to the stage front.

[@censoredcitizen528]

Thanks Michael. You are the man! I’m going to try it out and see how it goes on my own off site and get some practice. Digging more into more of your videos. So thankful for you to share your knowledge.

[@aaronduesterhoeft4866]

Any significance to using 6ft as the mic distance?

[@MichaelCurtisAudio]

Close enough to get accurate near-field data, far enough for the horizontal displacement between woofers to not matter too much.

[@andrewking6604]

great content thankyou. why would i use this as opposed to the inline gradient. this one takes up less space. why would i use the inline gradient instead of this?

[@MichaelCurtisAudio]

I'd do the inline gradient if I had a low stage and couldn't stack my subs, but had room in front of the stage.

[@andrewking6604]

@@MichaelCurtisAudio so basically changing the physical layout to suit circumstances with similar results? I have always used the L/R stack until viewing your stuff. I need to purchase something to process and invert the signal. What do you know about dbx driverack?

[@lostunflorin8120]

Hi Michael, we are meeting in a cinema so I have a concrete wall like 4 meters behind the scene and the first row of chairs like 2 meters in front of subs,nobody sitting in the first row. Will this set up working? Thanks a lot.

[@MichaelCurtisAudio]

I'd say it's not "optimal", but I still think worth a shot. Only way to know for sure is to give it a try and see. If the sub array was any closer to the wall I'd say it probably wouldn't work, but 4m is a good bit clearance.

[@lostunflorin8120]

@@MichaelCurtisAudio Thanks again

[@MatthewMcclatchie123]

Does it makes sense tuning your subwoofer with a graphic eq to get the perfect tone from the subs

[@MichaelCurtisAudio]

I wouldn't use a graphic EQ, but you sure can use a parametric EQ to be more precise and tailor the subs to your desired frequency response.

[@MatthewMcclatchie123]

@@MichaelCurtisAudio 🤔👍

[@tony8236]

Hi Micheal. Can it work in this way with 4 subs? _ _ _ _ I ask you this because with 2 subs behind I have to lower the level even by 7/8 db. if I only put one in the back I'll still have to lower it but not that much and you get more sound pressure in the front?

[@MichaelCurtisAudio]

With four subs I'd probably roll with setups 6 or 7 in this video - kzbin.info/www/bejne/h2XRqmpmaNpgodU

[@tony8236]

@@MichaelCurtisAudio number 7 is my favorite, a bit complicated number 6 with 4 (2x18) too long face to face. using number 7 I thought about the solution I proposed. of course it's just theory but when I analyze the level of the subs behind the stage they are much higher and I thought that just one behind can be enough without lowering or lowering 2/3 db

[@MrMotoden]

I've messed around with end fire, but not this. (time is NOT on my side) Here's what I can't wrap my head around with this set up. You take 3 boxes, flip one around, which puts it out of phase relative to the other 2, (minus the difference in driver alignment) then polarity flip it, which puts it back in phase with the other 2, then add your delay. Subs, being relatively non-d, are going to radiate relatively omni whether they're front, back, side or standing on their head, right? So, why bother flipping and phase inverting? What am I missing?

[@MichaelCurtisAudio]

I had this misunderstanding as well for a bit, but turning the speaker 180° around does not actually change its phase relationship (except its new timing offset due to physical displacement). It's not the same as your top and bottom snare mics now facing each other and needing to do a polarity inversion on one. Sound waves still emanate spherically from the original source, so absolute phase stays the same, not matter the sub orientation. That make sense?

[@MrMotoden]

@@MichaelCurtisAudio Thank you for replying! You're right and I see what you are saying about the spherical radiation being the same regardless of the orientation. (minus that pesky driver displacement) But this still begs the question, why bother flipping the center cabinet around? Wouldn't the physics remain the same with them all facing forward? I don't know, maybe I'm just dense.

[@MichaelCurtisAudio]

@@MrMotoden Another great question. It's for a few reasons. The spatial relationship of the drivers helps create the directivity. The driver displacement also helps create the level offset between both sides of the cabinet, which further increases the rejection in the rear. And some physical offset is required period for the whole formula to work.

[@MrMotoden]

@@MichaelCurtisAudio Well, I'm intrigued enough about this setup that I will mess around with it when the weather around here cooperates. Don't have a big enough garage. Really appreciate your videos and sharing your knowledge. Peace to all.

[@davechin-sang2618]

I tried this cardioid set up with (3) of my QSC KW181 (2) facing out on the floor (facing away from stage 3’ from stage )and (1) sitting facing to stage on top of the (2). My results were exactly what you explained, I used (2) SM57 (1) set on stage 6’ from the reverse sub and the other 15’ away from the (2) facing crowd area. I used my Midas M32live to generate a 60hz signal to subs. With only front facing subs on I adjusted the volume to read 0 db on the equalizer screen with RTA on for both mics , the stage mic read -1 db , Then I reversed the phase switch on the stage facing sub and did 3.8 ms (tried every delay settings b4 choosing 3.8) on reverse sub with the exact volume and gain setting on all 3 subs (2 o’clock) my results were awesome FOH reading went from 0db to + 6db and the stage reading went from -1db to -11 db on stage. The big question is, is FOH hearing the same volume as if all (3) subs we’re facing forward? Or is the reverse sub just removing db’s from stage. IMO it’s probably same as if all 3 subs we’re facing forward because of the 5db gain but want to know the facts. Thanks again for your awesome videos.

[@fame4049]

DO YOU HAVE ANY VIDEO WHERE YOU ACTUALLY CONNECT ALL THESE SPEAKERS AND DIAL IT WITH M32 CONSULE?

[@MichaelCurtisAudio]

I do that at the end of this video : )

[@josealfredfernandes]

I have noticed it doesn't increase SPL much in the front, compared to using 3 subs together in normal stacked formation.

[@MichaelCurtisAudio]

You're right, three stacked subs all summing together will definitely have more SPL. The tradeoff is you'll have just as much SPL in the rear, which may or may not be desirable for your gig.

[@josealfredfernandes]

@@MichaelCurtisAudio Indeed, a sacrifice I'd be willing to make.. only if.. it's necessary.. if those on backstage or on stage.. can't tolerate the bass or feedback..

[@atech9020]

You have to understand that there is a small amount of destructive interference in the forward plane. The center sub is used to maximize cancellation in the rearward plane, so there must therefore be some amount of destructive interference in the forward plane, which reduces the SPL potential. Another downside is that there is a small amount of smearing going on in the forward plane too, so the resultant sound will not be as pure so to speak. That is the downside to this deployment.

[@josealfredfernandes]

@@atech9020 cool. Sounds interesting.

[@SuAmigoElilegal]

Thats is correct. Speakers are ment to be set in the position they come in and to follow the manual. What ever people do like like putting them opposite sides or facing them to the wall or to the ground it is very ignorant and stupid. Speakers are desing and tested in a spund proffesional room. These people just dont have nothing to do. I mean just pjt ur speakers how ever they are menat to be set and play music. If u want more power buy more powerfull ones or add more

[@QuicksilverSG]

Is it possible to configure a pair of stacked subs as a cardioid array?

[@MichaelCurtisAudio]

Absolutely. It's the same process as the inline gradient, but the sub on top is facing backward.

[@QuicksilverSG]

@@MichaelCurtisAudio - Thanks for your help. If there's a wall behind the stacked subs, could I turn one 90 degrees and still get the cardioid effect?

[@MichaelCurtisAudio]

@@QuicksilverSG You're welcome! And negative, the pattern would fall apart.

[@rkirby2001]

@@MichaelCurtisAudio Do you just add more digital delay since the rear facing speaker cone is not as far back from the front facing cone compared to both cabinets on the floor facing the same direction 4.15 feet apart?

[@jaken528]

So if I have a concrete wall 6 feet behind my steup.. I should not do this?

[@MichaelCurtisAudio]

I'd test it out if you have the margin, but I'd probably steer away from this setup if you have a concrete wall behind your rig.

[@sullivan44]

Is there any cardioid set up that can work with a wall?

[@MichaelCurtisAudio]

@@sullivan44 A single enclosure that's passively cardioid will work against a wall, according to Fulcrum Acoustic.

[@sullivan44]

@@MichaelCurtisAudio so like the QSC?

[@MichaelCurtisAudio]

@@sullivan44 This is honestly something I'm a bit confused on. The KS212 is an "all in one" cardioid solution, but is active. I'm not sure if there's any difference in the Fulcrum Acoustic box that's "passive cardioid", only in that it's driven by an amp instead of built in DSP. I do know that if the KS212 is using a rear facing driver to make its pattern that it will not work correctly when placed against a wall.

[@josealfredfernandes]

This is what I did

[@MichaelCurtisAudio]

Very cool! Did it work out for you?

[@josealfredfernandes]

@@MichaelCurtisAudio Yes!

[@dantonliam]

Or put the middle one in cardioid mode ....

[@MichaelCurtisAudio]

If the middle one indeed has a cardioid mode. These KW181's don't have that feature.

[@dantonliam]

@@MichaelCurtisAudio so if you had 6... you would do the same thing but double stack everything with the middle subs ( in cardioid mode) both facing the rear? If the sub in use does have cardioid mode is there any other adjustments necessary?