Nelson Pass: The Slot Loaded Open Baffle Project - Page 3

boris81 · 1st September 2011, 09:31 PM

Quote:

Originally Posted by Rudolf

Not really. These polar diagram simulations show (from left to right) a closed box, an open baffle and a Ripole.
Rudolf

I don't think this design functions like a ripole. The idea is that the slot amplifies the front wave only. I expect something similar to cardioid behavior.

Nelson Pass · 1st September 2011, 09:32 PM

I thought that came out nice. Thanks to Steve for putting it up quickly -
I love instant gratification.

planet10 · 1st September 2011, 09:39 PM

Merged 2 threads on the same topic. If you have only been following one you might want to go back and read the posts you missed.

dave

Rudolf · 1st September 2011, 10:11 PM

Quote:

Originally Posted by boris81

I don't think this design functions like a ripole. The idea is that the slot amplifies the front wave only. I expect something similar to cardioid behavior.

The AMT-3 has a slot ratio of about 3 to 1 in the front. This is rather conservative. Some ripoles have up to 5 to 1 in order to get lowest bass. A ratio of 1.5 or 1 to 1 in the back is common for ripoles too. In simulations (or built ripoles) you hardly see any more change when going below 1.5 to 1. The air space between cone and back slot simply is too large to allow for that. The 9 dB front-to-back difference stated in the article doesn't really qualify as a cardioid pattern IMHO.

Rudolf

Tea-Bag · 1st September 2011, 10:46 PM

Did it mention what woofer driver was used? I didn't catch it.

PeteMcK · 2nd September 2011, 12:48 AM

slot loading like this would still work even if the rear was a normal BR box???

CLS · 2nd September 2011, 01:19 AM

That would tend to be a band pass.

Pano · 2nd September 2011, 01:24 AM

Does anyone remember a woofer project from about 5 years ago that was slot loaded with 2 woofers facing each other? The guy put it behind his sofa to get strong bass but not disturb the neighbors. I can't find the tread.

boris81 · 2nd September 2011, 01:41 AM

Quote:

Originally Posted by Rudolf

The AMT-3 has a slot ratio of about 3 to 1 in the front. This is rather conservative. Some ripoles have up to 5 to 1 in order to get lowest bass. A ratio of 1.5 or 1 to 1 in the back is common for ripoles too. In simulations (or built ripoles) you hardly see any more change when going below 1.5 to 1. The air space between cone and back slot simply is too large to allow for that. The 9 dB front-to-back difference stated in the article doesn't really qualify as a cardioid pattern IMHO.

Rudolf

Hypercardioid?

The slot ratio is one thing and then there is the polarity of the drivers. I might be wrong but I was under the impression that a ripole configuration implies both drivers move together in phase. Here they are reversed. I'm not quite sure what effect that will have on the radiation pattern.

A polar graph will be very informative. This is a very interesting design, I'm also curious to see if the sides can be curved without losing much of the 1:3 output ratio.

winslow · 2nd September 2011, 01:54 AM

Neighbor friendly dipole sub

I was just looking at it.

Quote:

Originally Posted by Pano

Does anyone remember a woofer project from about 5 years ago that was slot loaded with 2 woofers facing each other? The guy put it behind his sofa to get strong bass but not disturb the neighbors. I can't find the tread.

2nd September 2011, 12:48 AM	#26
PeteMcK diyAudio Member Join Date: Feb 2002 Location: Western Sydney	slot loading like this would still work even if the rear was a normal BR box??? __________________ Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency

2nd September 2011, 01:24 AM	#28
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	Does anyone remember a woofer project from about 5 years ago that was slot loaded with 2 woofers facing each other? The guy put it behind his sofa to get strong bass but not disturb the neighbors. I can't find the tread. __________________ Take the Speaker Voltage Test!

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1st September 2011, 09:32 PM	#22
Nelson Pass The one and only Join Date: Mar 2001	I thought that came out nice. Thanks to Steve for putting it up quickly - I love instant gratification.

1st September 2011, 09:39 PM	#23
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 5	Merged 2 threads on the same topic. If you have only been following one you might want to go back and read the posts you missed. dave

1st September 2011, 10:46 PM	#25
Tea-Bag not politcally affiliated diyAudio Member Join Date: Feb 2006 Location: Kennebunk Blog Entries: 7	Did it mention what woofer driver was used? I didn't catch it.

2nd September 2011, 01:19 AM	#27
CLS diyAudio Member Join Date: Jun 2005 Location: Taiwan	That would tend to be a band pass.