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Old 18th March 2005, 06:38 PM   #1
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Default Sub pointing down or forward

As I'm going to build some subs using 15" woofers, going from 20 Hz (eq'ed) to 80-100 Hz, I have some questions.....

For pure "cosmetic" look I would like to have the woofers pointing downwards in the cabinet, and I meen that I have heard that you can't point out the source/location for sound below app. 100 Hz due to the human ear...

Are there any disadvantages having the woofers pointing down ????
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Old 18th March 2005, 07:14 PM   #2
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Default Re: Sub pointing down or forward

Quote:
Originally posted by ACD
As I'm going to build some subs using 15" woofers, going from 20 Hz (eq'ed) to 80-100 Hz, I have some questions.....

For pure "cosmetic" look I would like to have the woofers pointing downwards in the cabinet, and I meen that I have heard that you can't point out the source/location for sound below app. 100 Hz due to the human ear...

Are there any disadvantages having the woofers pointing down ????
If the cone is heavy the suspension will tend to sag after some time.


Francois.
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Old 19th March 2005, 12:45 AM   #3
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The suspension needs to be sufficiently stiff for this to work. You lose a little excursion due to gravity. Adire has a paper on determining if a driver is suitable. I think most are ok. You lose a tiny amount of SPL on paper. I just built a small cheap downfiring sub for my parents - you don't have to make a grille, the driver is protected, and it's simple.
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Old 19th March 2005, 01:39 AM   #4
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Smile Re: Sub pointing down or forward

Quote:
Originally posted by ACD
As I'm going to build some subs using 15" woofers, going from 20 Hz (eq'ed) to 80-100 Hz, I have some questions.....

For pure "cosmetic" look I would like to have the woofers pointing downwards in the cabinet, and I meen that I have heard that you can't point out the source/location for sound below app. 100 Hz due to the human ear...

Are there any disadvantages having the woofers pointing down ????
hi ACD, i've got an Atlas 12 down firing in a 142.5L Shiva box tuned to 20HZ which has dual flared 4" precision port which seems to sound great! with no port noise problems with music, or HT. i think 5% cone sag is considered the max. which should be allowed from what i have read. i too, like the fact that no grill is required as it's safer, less cost, and less work. good luck with your project! crippledchicken


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Old 19th March 2005, 06:58 AM   #5
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Thanks for your replies
I'm going to have them firing down
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Old 19th March 2005, 07:21 AM   #6
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Jan, just do a quick check - have a look at the Adire paper on "driver orientation" I think it is called. There are a handful of calculations to determine how much sag you will get. It's good to have confirmation.
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Old 19th March 2005, 07:32 AM   #7
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Thanks Paul,
I got it right here
Attached Files
File Type: pdf driverorientation.pdf (8.6 KB, 100 views)
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Old 19th March 2005, 09:10 AM   #8
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That's all well and good for the short term but what happens a year or two down the road?

I've installed woofers facing down and they were fine at first. Years later they were working as diodes.
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Old 19th March 2005, 09:36 AM   #9
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Bill:
Your point is correct, however will horisontal mounting not also cause problems with the suspension, as the speaker weight will be carried by the upper part of the suspension.....
You can of course then turn your speakers a half turn every year
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Old 19th March 2005, 10:57 AM   #10
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Bill, what were the woofers you used? Have you run the calcs and if you did how much were they predicted to sag as a % of xmax? Maybe they weren't suitable. I think most of us on this forum will be upgrading before longeivity becomes a problem here.
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