Cardioid Subs in a Smaller venue.

[Evan F. Hunter]

Hey folks,

Just wondering if anyone has been using any cardioid sub setups in venues that are right around the 500cap mark? I have EV QRX 153s over JBL SRX 728s. When I only need 1 top per side I simply put one 728 on end, 153 on top. When I do not need more low end but I need more coverage I find myself bringing 2 subs per side for the sole purpose of getting the tops high enough. Now I understand there are several other options to get the tops higher, I can fly them but too much hassle for most of these venues even if I bring my own lifts, I dont want to invest in scaffolding or any such to lift them up, and I dont want to build cable trunks that double as extra height for the speakers, none of that is the question. Keep in mind that my overall goal is sound quality for live events. I want to setup my systems in the most professional manor I can, I strive for safety, neatness and the best sound I can get from each and every element of the system.

Are there any benefits to running cardioid subs in a smaller venue? I am not fighting any serious issues or any extreme build up of low end up the stages very often, and I never mind having more sub that I need, but If I can benefit then Id love to try it, if anything just to learn.

If there is a benefit, how would one go about setting this properly so it doesn't actually cause more damage than help? I usually see blocks of 3, two subs forward and one sub backward. Is it still possible with only two subs per side? What are the thoughts and opinions of people who use cardioid subs a lot more than me? Any links and such about cardioid subs are welcomed too, I know there are a ton plus Dave Rat has some videos and what not.

 

[Ivan Beaver]

Re: Cardioid Subs in a Smaller venue.

If you just need height-then I would bring the extra subs-hook them up as normal-and just turn the level down. That way they are not working as hard and will last longer.

You DO NOT want to use just one sub and leave the other one disconnected. It will cause a notch in the response.

 

[Jay Barracato]

Re: Cardioid Subs in a Smaller venue.

I have set them up, but the effect is not as big as you might expect because the primary reflections become a biger deal in a smaller venue.

 

[Evan F. Hunter]

Re: Cardioid Subs in a Smaller venue.

If you just need height-then I would bring the extra subs-hook them up as normal-and just turn the level down. That way they are not working as hard and will last longer.

You DO NOT want to use just one sub and leave the other one disconnected. It will cause a notch in the response.

This is exactly what I do when I bring both subs per side.

 

[Kevin Hayes]

Re: Cardioid Subs in a Smaller venue.

Cardioid sub configurations in small-midsize venues is really useful. Cutting down the amount of force reflecting off the back wall/going into mics keeps the stage quiet/clean, which helps your monitor and front of house mixes. It may not be a drastic difference depending how big the room is, but it should help.

That being said, in an ideal situation using your gear you would be limited to only having the force of the one 2x18", which may not be desirable for bigger events since you probably want to have at least two dual 18"s per side in action.

Theoretically cardioid subs work by throwing sound completely out of phase behind the subwoofer, so theoretically(I'm sure someone can elaborate on some of the intricacies), you should be able to achieve the effect by offsetting the timing of the rear facing sub in processing.

 

[Jay Barracato]

Re: Cardioid Subs in a Smaller venue.

Cardioid sub configurations in small-midsize venues is really useful. Cutting down the amount of force reflecting off the back wall/going into mics keeps the stage quiet/clean, which helps your monitor and front of house mixes. It may not be a drastic difference depending how big the room is, but it should help.

That being said, in an ideal situation using your gear you would be limited to only having the force of the one 2x18", which may not be desirable for bigger events since you probably want to have at least two dual 18"s per side in action.

Theoretically cardioid subs work by throwing sound completely out of phase behind the subwoofer, so theoretically(I'm sure someone can elaborate on some of the intricacies), you should be able to achieve the effect by offsetting the timing of the rear facing sub in processing.

A cardiod configuration does not change the amount of sound hitting the back wall or reflecting, it simply changes the timing of parts of the sound.

Cancellation is timing specific, therefore it is location specific.

The wave continues to travel past the point of cancellation, still transfering energy.

I have found that when the back wall is close enough that the wave does not lose a significant amount (usually considered 6db) of level before the reflection, than the amount of positive and negative reinforcement from the reflection is as large of an effect as the negative reinforcement from the cardiod setup.

 

[Tim Weaver]

Re: Cardioid Subs in a Smaller venue.

I've never done it with a 2 sub stack, but If you want to try it, I would revere the top sub instead of the bottom. The bottom sub couples with the floor at a higher frequency (getting closer to the center freq of the cardioid setup) and will have more forward output at those higher frequencies. The top sub will have a ground reflection that will cause a bit of a notch towards the rear anyway. Which is kinda what we want!

 

[Art Welter]

Re: Cardioid Subs in a Smaller venue.

Are there any benefits to running cardioid subs in a smaller venue?
If there is a benefit, how would one go about setting this properly so it doesn't actually cause more damage than help? I usually see blocks of 3, two subs forward and one sub backward. Is it still possible with only two subs per side? What are the thoughts and opinions of people who use cardioid subs a lot more than me? Any links and such about cardioid subs are welcomed too, I know there are a ton plus Dave Rat has some videos and what not.

Putting sound where you want it and keeping it away from where you don't is always a good idea, regardless of venue size.

You can use a 1/1 rather than a 2/1 cardioid arrangement, though if you expand your system, you would find you only need about 2/1 ratio.
There is always some forward loss in cardioid arrays compared to "normal" forward facing arrays, but the sonic advantages may outweigh the added expense and complexity if maximum SPL is not your primary goal.
Rog Mogale has a good guide on bass arrays, cardioid starts on page 15:
http://www.voidaudio.com/pdf/bass guide.pdf

Modeling still is basically 2 dimensional, the lovely looking patterns presented don't always work as well in the real world of a smaller 3 dimensional stage box connected to a larger odd shaped big box, but they are a place to start.

More discussion here:
Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?

 

[Guy Graham]

Re: Cardioid Subs in a Smaller venue.

I've never done it with a 2 sub stack, but If you want to try it, I would revere the top sub instead of the bottom. The bottom sub couples with the floor at a higher frequency (getting closer to the center freq of the cardioid setup) and will have more forward output at those higher frequencies. The top sub will have a ground reflection that will cause a bit of a notch towards the rear anyway. Which is kinda what we want!

In Dave Rat's YouTube material he states that the primary reason he doesn't like/use cardioid subs is the detriment to sound quality that results from the sound in front of the stage, that is caused by the combination of the front firing sub in a cardioid array with the delayed out of phase bass coming from the rear-firing sub.

In a real-world situation where cardioid subs are deployed, is this impediment to the sound quality in the house as noticible as the theoretical combination of the forward sum of all the subs in the array, which ends up being a mix of the in-phase front-firing box combining with the out-of-phase rearward box signal?

In other words does the theoretical problem manifest itself in a noticeable degradation of sound quality, or in a real-world scenario are the benefits of using this bass-steering technique to clean up stage noise, reduce potential for standing waves and so forth, better to the point of negating the undesirable effect produced out front when mixed phase sub-bass frequencies are heard in the house?

 

[Kevin Hayes]

Re: Cardioid Subs in a Smaller venue.

My company has a venue with a small but very live stage thanks to a bandshell. We've had consistent noise complaints from neighbors and with a live band had trouble keeping things within our DB limits(95 peak a-weighted). Since we've switched to cardioid subs(D&B B4s), the stage noise has decreased significantly. The bands don't crank their amps as much, the monitors don't have to run as hot, and best of all no complaints from the neighbors.

That being said, when bigger acts come in we've been known to throw cardioid out the window because we do lose some energy out the front. For most events(corporate, galas, weddings) we don't need in your face bass, but I haven't heard a cardioid sub or configuration that's really wow'ed me.

 

[Per Søvik]

Re: Cardioid Subs in a Smaller venue.

I believe I prefer the rear-facing sub on the bottom, particularly if it is a non-solid floor, because more of the energy will be directed upwards into the room and the reflection patterns on stage will be better. At front, as long as the floor is absolutely solid, the front pattern might be better with the front facing sub on bottom, but it is quite marginal.
Depending on the room, with a left-right setup where the sidewalls are reasonably close to the stage and coverage is mainly in front of stage, I would go for a side-by-side setup, with the rear-facing sub on the outside.
As for delaytimes for rear-facing inverse phased sub, start with 2 ms and try it out in steps of 0.1mS up to maybe 2.5-2.9 mS. You'll probably find that 2.5 mS is about right.
And of course reduce the inverted sub by about 3 dB.

I would also prefer to push the rearfacing sub back a bit to put the quarter wavelenght frequency down, but that is obviously not an option if you need the subs to support the tops.

 

[Ivan Beaver]

Re: Cardioid Subs in a Smaller venue.

In other words does the theoretical problem manifest itself in a noticeable degradation of sound quality, or in a real-world scenario are the benefits of using this bass-steering technique to clean up stage noise, reduce potential for standing waves and so forth, better to the point of negating the undesirable effect produced out front when mixed phase sub-bass frequencies are heard in the house?

A cardioid sub arrange has a top end rolloff-which can greatly affect the "punch" of the system. And endfire setup does not have this rolloff. However it does not have as much rear rejection as the cardioid-so you have to choose between what you want more-punch out front or rejection in the rear.

You also lose output as compared to the same number of subs all facing forward. Sometimes this is an issue if you don't bring enough subs. Yes the rear subs will add a little bit-but not as much as if they were forward facing with "zeros" delay.

 

[Per Søvik]

Re: Cardioid Subs in a Smaller venue.

In other words does the theoretical problem manifest itself in a noticeable degradation of sound quality, or in a real-world scenario are the benefits of using this bass-steering technique to clean up stage noise, reduce potential for standing waves and so forth, better to the point of negating the undesirable effect produced out front when mixed phase sub-bass frequencies are heard in the house?

Most of the time in indoor venues, the conclusion is that the cleanup on-stage far outweighs the negatives, and that the sound out front gets punchier even if the subs themselves are less capable of producing precise punch.
Even out-doors, it depends what the alternative is. I really think you need a sizeable end-fire array to beat a cardio setup. Unless of course the sound source is a DJ playing edm, in which case you just stack all subs together to get maximum interaction.

EDIT: Didn't see Ivan's response, agree totally with what he wrote (except I believe it is the timing, not any top end rolloff)

 

[Ivan Beaver]

Re: Cardioid Subs in a Smaller venue.

EDIT: Didn't see Ivan's response, agree totally with what he wrote (except I believe it is the timing, not any top end rolloff)

Yes it is the timing that CAUSES the top end rolloff.

If you measure one sub out front-then turn the "cancelling sub" on, you will notice that the top end (say 100ish Hz-give or take a good bit depending on spacing and delay added) will be lower than with one sub.

An endfire setup will not have this rolloff.-yet the same amount of delay is used-just on a different speaker and the relative polarities are the same-not reversed as in a cardioid setup.

 

[Per Søvik]

Re: Cardioid Subs in a Smaller venue.

Yes it is the timing that CAUSES the top end rolloff.

If you measure one sub out front-then turn the "cancelling sub" on, you will notice that the top end (say 100ish Hz-give or take a good bit depending on spacing and delay added) will be lower than with one sub.

An endfire setup will not have this rolloff.-yet the same amount of delay is used-just on a different speaker and the relative polarities are the same-not reversed as in a cardioid setup.

Yes, I don't disagree, but depending on x-over frequency, the rolloff isn't that significant compared to the delayed arrival of the wave from the rear-facing cabinet, making any rapid attack and release sound more diffuse than when everything is aligned.

 

[Evan F. Hunter]

Re: Cardioid Subs in a Smaller venue.

Im still here, reading and what not.

 

[Rob Spence]

Most of the cardioid sub arrays I have seen are made with conventional subs. What about horn cabs? Obviously timing has be different given the internal path length.
It interests me as some of my subs are horns.


Sent from my iPhone

 

[Per Søvik]

Re: Cardioid Subs in a Smaller venue.

Most of the cardioid sub arrays I have seen are made with conventional subs. What about horn cabs? Obviously timing has be different given the internal path length.
It interests me as some of my subs are horns.


Sent from my iPhone

It is a lot harder to get right, and would include some careful eq to the inverted signal to compensate for directivity at different frequencies (not that that isn't an issue even with conventional cabinets).

 

[Phil Graham]

Re: Cardioid Subs in a Smaller venue.

Most of the cardioid sub arrays I have seen are made with conventional subs. What about horn cabs? Obviously timing has be different given the internal path length.
It interests me as some of my subs are horns.


Sent from my iPhone

Actually, timing still works the same, assuming all the cabinets are the same, as the relative delay of each cabinet due to the horn length will remain consistent.

 

[Bennett Prescott]

Re: Cardioid Subs in a Smaller venue.

I have found that when the back wall is close enough that the wave does not lose a significant amount (usually considered 6db) of level before the reflection, than the amount of positive and negative reinforcement from the reflection is as large of an effect as the negative reinforcement from the cardiod setup.

I think this may have more to do with acoustic impedance and may even be fixable. However, I agree that the biggest problem with cardioid setups in small venues is when the environment seen by the rear woofer is dissimilar from that seen by the front woofers, e.g. too close to a wall. Seems that about 2M spacing from any boundary is sufficient, but that close small distance differences can have a large effect.