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Author Topic: cardioid subwoofer ratio  (Read 562 times)

Peter Morris

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Re: cardioid subwoofer ratio
« Reply #10 on: July 12, 2019, 09:43:20 am »

I saw this over on a Facebook site. What does everyone feel about this ratio ? I've seen 2 with 1 inverted before but 1 sub trying to cancel the rear output of 5 subs?  What is your thoughts?

Douglas R. Allen

You will get a useful amount in the 70 - 80Hz region, which is probably where it will be most noticeable. Not so much at lower frequencies.
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Taylor Hall

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Re: cardioid subwoofer ratio
« Reply #11 on: July 12, 2019, 09:46:51 am »

Also, would't what little that one reversed buddy contribute to the front SPL get more shift in time since the pressure has to travel over/around at least one sub in either direction? It has no space to breathe around the cabinet. At least when I read the D&B CSA papers years ago they stated that there was need for some space between the stacks.
Most cardioid deployments I've seen have ~3ft or more between each stack, that seems to be the accepted minimum for proper radiation.  I can't remember who did it on here but someone ran a bunch of tests with different distances between the stacks, the results were quite noticeable.
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Tim McCulloch

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Re: cardioid subwoofer ratio
« Reply #12 on: July 12, 2019, 10:05:28 am »

Most cardioid deployments I've seen have ~3ft or more between each stack, that seems to be the accepted minimum for proper radiation.  I can't remember who did it on here but someone ran a bunch of tests with different distances between the stacks, the results were quite noticeable.

I think it was Merlijn van Veen or Timo Beckman.

It's about the path length from front radiator(s) to rear of array.
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Miguel Dahl

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Re: cardioid subwoofer ratio
« Reply #13 on: July 12, 2019, 10:09:00 am »

I think it was Merlijn van Veen or Timo Beckman.

It's about the path length from front radiator(s) to rear of array.

Where do one calculate the path length from? I'm rusty at this, center cone, or edge of cone? Or acoustical center of the box, which would be in between the cones if it's a double cabinet.
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Taylor Hall

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Re: cardioid subwoofer ratio
« Reply #14 on: July 12, 2019, 10:39:41 am »

I think it was Merlijn van Veen or Timo Beckman.

It's about the path length from front radiator(s) to rear of array.
Yeah Merlin rings a bell, but I'm having trouble finding the thread talking about it. Oh well, maybe I have something to put my fingers to work on over the weekend. :P
Actually, thinking on it a bit more makes me believe that it was actually an end-fire calculation thread I was thinking of rather than an array stack spacing calculation. Same general concept of waiting for the sound to radiate from one end of the cabinet to the other, but a different application of the concept.
« Last Edit: July 12, 2019, 10:43:13 am by Taylor Hall »
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Steve Ferreira

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Re: cardioid subwoofer ratio
« Reply #15 on: July 12, 2019, 10:48:55 am »

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Peter Morris

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Re: cardioid subwoofer ratio
« Reply #16 on: July 12, 2019, 10:51:35 am »

Most cardioid deployments I've seen have ~3ft or more between each stack, that seems to be the accepted minimum for proper radiation.  I can't remember who did it on here but someone ran a bunch of tests with different distances between the stacks, the results were quite noticeable.

Most I have seen are made by stacking 3 or more subs together with one facing backwards.  The distance is generally a compromise relating to the depth of the sub.
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Miguel Dahl

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Re: cardioid subwoofer ratio
« Reply #17 on: July 12, 2019, 11:25:38 am »

Most I have seen are made by stacking 3 or more subs together with one facing backwards.  The distance is generally a compromise relating to the depth of the sub.

Yes, but the distance is much bigger if there's no space between the stacks, as the pressure can't radiate "though" the adjacent subs, thus leaving "breathing space" between stacks if they have some distance apart. For the pic in the opening post the pressure would have to travel around or above at least one extra sub, instead of just around the rearward facing sub itself, if there would be space between the three vertical stacks.
« Last Edit: July 12, 2019, 11:28:31 am by Miguel Dahl »
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Dave Guilford

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Re: cardioid subwoofer ratio
« Reply #18 on: July 12, 2019, 09:53:28 pm »

Yeah but how did it SOUND?
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Peter Morris

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Re: cardioid subwoofer ratio
« Reply #19 on: July 12, 2019, 10:07:31 pm »

Yes, but the distance is much bigger if there's no space between the stacks, as the pressure can't radiate "though" the adjacent subs, thus leaving "breathing space" between stacks if they have some distance apart. For the pic in the opening post the pressure would have to travel around or above at least one extra sub, instead of just around the rearward facing sub itself, if there would be space between the three vertical stacks.

Usually like this ... but itís a compromise based on the sub dimensions, where you can put them etc. The delay time is adjusted accordingly to fine tune the array.  The advantage of the OP design is that the sound quality will still be almost like that of a normally array but with some reduction behind.  If they did two facing backwards they could get more reduction behind but it would sound as Ivan described.
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