Rational Acoustics



merlijnv
September 24th, 2014, 06:24 AM
Hi everybody,


One of the most common complaints about gradient cardioid subwoofer configurations is an apparent lack of impact?

I feel this is unwarranted an decided to write an article for my study hall section explaining in great detail the pros, cons and pitfalls of this specific approach from a musical, tonal and temporal point of view.

The article is rich with illustrations from Smaart v7 and finishes with carefully processed audio fragments to allow you to decide for yourself.

https://www.merlijnvanveen.nl/index.php/en/study-hall/76-lack-of-impact

luigichelli
September 29th, 2014, 04:56 PM
Great article,
thanks!

Harry Brill Jr.
May 1st, 2015, 01:32 AM
May I add tis to my handouts?

Harry Brill Jr.
May 1st, 2015, 01:46 AM
You may feel it is unwarranted, but it doesn't make it untrue. There are pros and cons. It's not a free lunch. If you are outdoors and you can pile the subs up in one place you will have the most impact on axis, that you are likely to get. When you make 2 stacks left and right of the stage you start running into problems off axis of the center line equidistant between the 2 stacks. In this scenario directional arrays may be a good trade off but you won't have the same impact you had with that pile of subs in the center. Even if you build a single center directional array. The best case is a 4 deep end fire on axis because you are just timing up those 4 sources, but when you go off axis the timing is off, which is what causes them to be directional in the first place. When you create a strong cardioid array with rear delayed, reverse polarity end fire arrays, you get a very very noticeable time smear that reduces the impact substantially, but it may still be a good option when you need that cancellation in the rear to avoid destructive reflections. The best case I have seen is a 3 tall stack with the bottom facing the rear, delayed, and pol inverted. The rear facing cabinet has little influence on the front third of the pie, but does cancel the rear third very effectively. You get the power of 2 subs, without the destructive interference you would have had from the reflection off a wall behind the subs, or the leakage into the mics on stage behind the subs, but you also retain 95% (arbitrary made up number) of the impact you would have had if you just had those 2 subs outside. And this is scalable to some extent. So much so that d&b uses it in there J Sub and Infra cabinets as an all in one box solution. I'm not disputing your findings from modeling this, but in the real world you are not always on axis., and what you feel in your chest and legs cannot be quantified with headphones. Also I think most of these models use continuous noise, not a fast attack impulse like a kick drum. It makes a difference.
If you want to create a folder of your article and send it to me, I'd be happy to include it in my handouts. Preferably it would be not a huge file.

merlijnv
May 1st, 2015, 04:49 AM
You may feel it is unwarranted, but it doesn't make it untrue. There are pros and cons. It's not a free lunch. If you are outdoors and you can pile the subs up in one place you will have the most impact on axis, that you are likely to get. When you make 2 stacks left and right of the stage you start running into problems off axis of the center line equidistant between the 2 stacks. In this scenario directional arrays may be a good trade off but you won't have the same impact you had with that pile of subs in the center. Even if you build a single center directional array. The best case is a 4 deep end fire on axis because you are just timing up those 4 sources, but when you go off axis the timing is off, which is what causes them to be directional in the first place. When you create a strong cardioid array with rear delayed, reverse polarity end fire arrays, you get a very very noticeable time smear that reduces the impact substantially, but it may still be a good option when you need that cancellation in the rear to avoid destructive reflections. The best case I have seen is a 3 tall stack with the bottom facing the rear, delayed, and pol inverted. The rear facing cabinet has little influence on the front third of the pie, but does cancel the rear third very effectively. You get the power of 2 subs, without the destructive interference you would have had from the reflection off a wall behind the subs, or the leakage into the mics on stage behind the subs, but you also retain 95% (arbitrary made up number) of the impact you would have had if you just had those 2 subs outside. And this is scalable to some extent. So much so that d&b uses it in there J Sub and Infra cabinets as an all in one box solution. I'm not disputing your findings from modeling this, but in the real world you are not always on axis., and what you feel in your chest and legs cannot be quantified with headphones. Also I think most of these models use continuous noise, not a fast attack impulse like a kick drum. It makes a difference.
If you want to create a folder of your article and send it to me, I'd be happy to include it in my handouts. Preferably it would be not a huge file.

Hi Harry,


Thanks for your interest. I'm very honored by your request. I've send you the article by email.

I agree with everything you said. It's TANSTAAFL as always. The emphasis of the article IMHO is how improper deployment might lead to unwarranted conclusions.


Regards,


Merlijn