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Old 9th October 2012, 07:20 PM   #21
boris81 is offline boris81  United States
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Quote:
Originally Posted by studiotech View Post
I am going to experiment with trying to get more of a cardioid response from my woofer too. I've been using the Bonded Logic behind the Neo10s , but want to try several layers behind and around the woofer now too.
Greg
Quote:
Originally Posted by studiotech View Post
I'm hoping to add enough bonded logic around the lower backside of my baffle to get radiation somewhere less than a dipole and more like a cardioid. At least enough so that I get a smoother transition from full dipole to the omni of the subs that sit right next to them. Baffle to sub crossover is currently 60Hz.
I've been experimenting with cardioid using Bonded Logic.
Waveguie and Cardioid on a Slim Baffle
Achieving a cardioid response by absorbing the rear wave is difficult at low frequencies. I'd say you need at least 3 layers of Bonded Logic to get usable cardioid above 250Hz.


Quote:
Originally Posted by gainphile View Post
Yes, that's one way to doit.
Using w-frame, For dipole both the front would be (simplified):

Front | Back
(+) | (-)
(+) | (-)

The cardioid setup:
(+)|(+)
(+)|(-)

Hence it cancels at the back.
The cabinet needs to be acoustically small.
If you seal one of the woofers it should probably be:
(+)|
(+)|(-)

Do I understand correctly?


Quote:
Originally Posted by studiotech View Post
Yes, in an active set-up, one can play with the phase and delay of the rear woofer to tune the system to more of a cardioid response. Something like Meyer does with their PA subwoofers:

PSW-6 : High-Power Cardioid Subwoofer

Or in a passive U-frame style ala JohnK:

NaO U-frame

There are some great examples and explanations of cardioid bass on this site, including how to use a monopole driver in the back.
Cardioid bass
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Old 9th October 2012, 09:17 PM   #22
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Quote:
Originally Posted by boris81 View Post
I've been experimenting with cardioid using Bonded Logic.
Waveguie and Cardioid on a Slim Baffle
Achieving a cardioid response by absorbing the rear wave is difficult at low frequencies. I'd say you need at least 3 layers of Bonded Logic to get usable cardioid above 250Hz.


There are some great examples and explanations of cardioid bass on this site, including how to use a monopole driver in the back.
Cardioid bass
What thickness of BL are you using?

Thanks for that site! Lots of good info there.
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Old 9th October 2012, 10:14 PM   #23
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Quote:
Originally Posted by boris81 View Post
If you seal one of the woofers it should probably be:
(+)|
(+)|(-)

Do I understand correctly?
If the baffle is acoustically small, then it would radiate as omni (just like normal monopoles)

hence (+)|(+)
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Old 9th October 2012, 11:02 PM   #24
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Quote:
Originally Posted by Elias View Post
In theory I like cardioids too. They have the potential of allowing them placed very close to the room front wall.

I wish John K... manages to set up his mono-dipo-cardioid speaker and share some impulse responses.


- Elias
I will, but at the moment it is the unset of fall in New England a and I am preoccupied with thing other than stereo and music. Thus will be a littler different because I will be using digital eq and delays to make things absolutely identical.

If we get a couple of rainy days I may be able to throw the old CRAW together and see if it still works. I don't have the drivers it is supposed to be used but some that are pretty similar.
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Old 9th October 2012, 11:20 PM   #25
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Are you referring to opposite monopoles with delay?

I had been thinking of building one, should be very easy to do with DSP. What are the challenges here (e.g. does baffle step still apply?)
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Old 10th October 2012, 12:39 AM   #26
boris81 is offline boris81  United States
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Quote:
Originally Posted by studiotech View Post
What thickness of BL are you using?

Thanks for that site! Lots of good info there.
I'm using the rolls and they are 2 inch thick.
16 in. x 48 in. UltraTouch Denim Insulation Multi-Purpose Roll-60301-16482 at The Home Depot

I wrap a double layer around the driver basket, and then I use a double sheet on top of it. So it's actually 4 layers but there's some empty space inbetween. My measurements show a cardioid behavior to around 250Hz and it turns dipole below that.

Picture 001.jpg
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Old 10th October 2012, 01:25 AM   #27
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Ah yes, I thought what you were using looked thin compared to mine. I'm using the R13 rated stuff, so it is closer to 3.5" thick and rated for excellent acoustical absorption to below 100Hz. Doubling or tripling up should get me where I wanna be. I've even got some of the R19 at the studio if I need it.
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Old 28th January 2013, 11:49 PM   #28
kees52 is offline kees52  Netherlands
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Default dipole/cardioid

Do you now this? I did found it just whem googling.

http://www.kirchner-elektronik.de/~k...ARDIOIDeng.pdf

Hmm old topic, but not a problem I hope.
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Old 29th January 2013, 12:37 AM   #29
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Meyer has done this in pro PA app.: Meyer Sound News : Meyer Successfully Tests Unique Cardioid Subwoofer Design

Meyer Sound News : PSW-6: The First Directional Subwoofer in History

http://kpbonline.com/blog/2010/06/ca...woofer-array/:)

http://www.google.ca/imgres?imgurl=h...ch&um=1&itbs=1

Last edited by sergeloc; 29th January 2013 at 12:39 AM.
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Old 29th January 2013, 04:59 PM   #30
kees52 is offline kees52  Netherlands
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Hi All


I have drwan it in sketchup, it looks like that and I go build it to try it, because I am curieus about it and we have to try everything in live.
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File Type: jpg dipole-cardioid-front.jpg (64.0 KB, 419 views)
File Type: jpg dipole-cardioid-rear.jpg (80.6 KB, 404 views)
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