Question concerning "end fire subs"

Dick Rees

Dick Rees

Curmudgeonly Scandihoovian
Jan 11, 2011
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St Paul, MN
If I'm basing my positioning and delay measurements on 63hz, will a pure 63hz tone cancel 100% to the rear of the array? IOW, if I want to test my setup by ear, can I simply have a helper flip the polarity on the rear pair and hear a result? Will the result have the meaning I'm looking for: that the offset and delay are correct?

Or should I just dial up the delay a bit at a time until the test tone nulls?

Thanks for helping an old man out.

DR
 
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Re: Question concerning "end fire subs"

You can do it that way, but there likely will not be 100% cancellation. This is due to the different arrival times of reflections. Even outdoors you 'll have some reflections off of the ground or the staging that will be out of "time" and mess up your results.

It is, however, pretty easy to find the point of maximum cancellation and just roll with that.
 
No, you won't get 100% cancellation. The first half of the waveform will arrive at 100% SPL, before the out of phase sound from the distant sub arrives.

Plus reflections as mentioned.

Caleb
 
Re: Question concerning "end fire subs"

Caleb Dick said:
No, you won't get 100% cancellation. The first half of the waveform will arrive at 100% SPL, before the out of phase sound from the distant sub arrives.
Caleb
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And after the first half of the first wave of the constant test tone?
 
You asked about amount of cancellation, not how much at each point in time ;)

Over time, yes, reflections take over as primary. Also, to be nit-picky, any distortion/harmonics will still be present.

Caleb
 
Re: Question concerning "end fire subs"

Caleb Dick said:
You asked about amount of cancellation, not how much at each point in time ;)

Over time, yes, reflections take over as primary. Also, to be nit-picky, any distortion/harmonics will still be present.

Caleb
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I use Hohner harmonics exclusively.......
 
Re: Question concerning "end fire subs"

End fire or cardio?
With end fire, you delay the rear sub nothing, and add delaytime as you travel towards the audience for maximum addition. With end fire you preferrably go more than two deep
With a cardio setup, you delay the rear speaker, reduce by 2-3 dB and flip the phase. This should give you near 100% cancellation, including the first half wave, but to find the right delay, you have to play with the level at the same time, or start off at -3dB, set best delay and then tweak level slightly for better cancellation.
 
Re: Question concerning "end fire subs"

Per Søvik said:
End fire or cardio?
With end fire, you delay the rear sub nothing, and add delaytime as you travel towards the audience for maximum addition. With end fire you preferrably go more than two deep
With a cardio setup, you delay the rear speaker, reduce by 2-3 dB and flip the phase. This should give you near 100% cancellation, including the first half wave, but to find the right delay, you have to play with the level at the same time, or start off at -3dB, set best delay and then tweak level slightly for better cancellation.
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And when you turn down the rear cabinet a couple of dB-then you will ALSO reduce the front energy.

Endfire and "cardioid" arrays have different effects in the rear-and different sonic characters out front.

Typically the "cardioid" (rear sub delayed and flipped polarity) has the greatest amount of cancellation. BUT at the expense of less punch/impact out front and less output than an endfire array.

So the choice is sound quality/quantity out front or less sound level in the rear. Choose ONE. DIfferent situations would require different setups-depending on what is most important at the time-for the situation.

it is not a matter of which one is "best"-because they each have their own "best" aspects.
 
Re: Question concerning "end fire subs"

Since we are talking about directional control. How well behaved is a "typical" horn loaded subwoofer in this respect(lower level at the rear VS frequency)?

I've been using my labsubs for some gigs in vertical stacks 3 high and I've noticed a decreased level at the rear compared to ordinary front loaded boxes. It sounds like it affects the "higher" sub frequencies more than the lower ones, AKA it's partially "cardioid". Is this what you would expect from a horn loaded sub or am I way off in my thinking?

For some reason I've never gotten around to measure it. Might have to do that one day.
 
Re: Question concerning "end fire subs"

Helge Dr. Bentsen said:
Since we are talking about directional control. How well behaved is a "typical" horn loaded subwoofer in this respect(lower level at the rear VS frequency)?

I've been using my labsubs for some gigs in vertical stacks 3 high and I've noticed a decreased level at the rear compared to ordinary front loaded boxes. It sounds like it affects the "higher" sub frequencies more than the lower ones, AKA it's partially "cardioid". Is this what you would expect from a horn loaded sub or am I way off in my thinking?

For some reason I've never gotten around to measure it. Might have to do that one day.
Click to expand...

You're seeing a natural increase in directivity based on a larger(v. wavelength) source-the area of the horn mouth is increasing, causing better transfer of the energy to the air. Put another three Labsubs right next to the first three, and you'll notice the effect covering lower frequencies.

Best regards,

John
 
Re: Question concerning "end fire subs"

John Halliburton said:
You're seeing a natural increase in directivity based on a larger(v. wavelength) source-the area of the horn mouth is increasing, causing better transfer of the energy to the air. Put another three Labsubs right next to the first three, and you'll notice the effect covering lower frequencies.

Best regards,

John
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In other words, the exact same effect that gives a HF horn its directivity also applies to horn subs, it just takes a much bigger horn to have the same effect.
 
Re: Question concerning "end fire subs"

Ivan Beaver said:
And when you turn down the rear cabinet a couple of dB-then you will ALSO reduce the front energy.
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Which is why I prefer a 2:1 setup, or a mixed 2:1 and 1:1 so not to "waste" stuff by turning it down:
subtest_mix_rear.jpg

Endfire and "cardioid" arrays have different effects in the rear-and different sonic characters out front.

Typically the "cardioid" (rear sub delayed and flipped polarity) has the greatest amount of cancellation. BUT at the expense of less punch/impact out front and less output than an endfire array.

So the choice is sound quality/quantity out front or less sound level in the rear. Choose ONE. DIfferent situations would require different setups-depending on what is most important at the time-for the situation.
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:)~:)~:smile: Yeah, when the sound company carefully arrange a huge cardio array and then have to provide lots on subs on stage because the performer likes lots of thumping, gutwrenching bass :lol:

it is not a matter of which one is "best"-because they each have their own "best" aspects.
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If in doubt, go with loud, if that doesn't work, try louder :D~:-D~:grin:
Seriously though, maximum cancellation on stage often tends to clear up so much of the mud in the mix that a slight loss of low end performance out front is compensated by the better sonic quality of the mix
 
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Re: Question concerning "end fire subs"

The first time I deployed an end fire sub array I expected complete cancellation to the rear. The event was indoors but I had some concerns about keeping the residents across the street happy (~65' away from where the subs were). So I went about placing my array, dialing in the delays, making some measurements but the cancellation wasn't near what was predicted. So I check polarity, re check my delay times, make more measurements, re tweak the delays, play with level, still not great. Doors are opening soon so I decide to just use the predicted delay times, they would have to be good enough. Soon the event starts and sure enough I stand across the street and you would hardly know there was a party with DJs and lots of bass on the dance floor. Go to the other end of the building and it sounds like the steel siding is ready to vibrate off the building.

What I took away from this experience was that it takes a fair amount of space for the cardioid pattern to fully develop and it re-inforced for me the the unpredictable nature of walls or other boundaries where bass is concerned. My array was 4 EAW SB528 standing on end spaced 4' from grille to grille.

Matt

(edit clarity)
 
Re: Question concerning "end fire subs"

Jay Barracato said:
Here is the L/R + center cluster model. The center cluster is +6db and delayed 18 ms
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Given four subs and space to centre cluster, I would go for either 2+2 endfire, 2+2 cardio or 3+1 cardio

dbl-endfire.jpg Double endfire, 1.36m 4 ms delayed fronts, 3m spacing axis to axis
Dbl cardio rear -3.jpg Double cardio 1.36m 4ms delayed and phase inverted rears -3dB, 3 m spacing
3to1 cardio.jpg 3 to 1 cardio, 1.36 m 4 ms delayed and phase inverted rear, 1.5 m spacing

The 3:1 will not have the rear power for full cancellation, but that is the tradeoff for more power out front, endfire gives better frequency response out front
 
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Hi Per,

Sorry to have muddied the waters but the L/R plus center config I modeled was the result of an offthread phone call based on using the subs to support the tops. When I went to reply by pm I couldn't attach it so I threw it on the thread where I knew it would be seen.
 
Re: Question concerning "end fire subs"

Jay and Per.....

Thanks to you both for the modeling. I'll let you know what I end up going with and how it worked. Gig is on Sept 8th.
 
Re: Question concerning "end fire subs"

Jay Barracato said:
Hi Per,

Sorry to have muddied the waters but the L/R plus center config I modeled was the result of an offthread phone call based on using the subs to support the tops. When I went to reply by pm I couldn't attach it so I threw it on the thread where I knew it would be seen.
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Yeah, I do that all the time, use subs where I don't really want them because they are sturdy and look better than a wobbly stick tripod.
 
Re: Question concerning "end fire subs"

Dick Rees said:
Jay and Per.....

Thanks to you both for the modeling. I'll let you know what I end up going with and how it worked. Gig is on Sept 8th.
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I think a lot of the decision on what setup to use should be based on what it is that one wants the subs to do. If the main function of the subs is to give a kick the gut-wrenching quality that we crave, then a centre clustre/array is the thing. If the main function is to provide downward extension for several instruments, and the performance around crossover frequency is important, then it often makes sense to go with tops and subs together. It all depends on what frequency is most important, and wether considerations about power alley and stage volume are important or not.

Lykke til!!
 
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