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Old 15th August 2005, 06:58 AM   #1
diyAudio Member
 
Join Date: Feb 2005
Location: Singapore
Default Newbie speaker builder needs advise

Hi all,

I'm a newbie trying to built my first speaker based on the Basszilla (http://store.hifiauthority.com/olsherkits.html) but I i'm using a lowther 55C and an Eminence Aplha 10 for the drivers.

Instead of using a sealed box or a simple ported box for the woofer, I'm using Martin King's MLTL worksheet to design the enclosure. I may have bit off more then I can chew.

The box volume is 1.9 cu ft with a 37 inch TL with a 1.75 inch port dia and 3 in port length. Here's the problem, there isn't much low frequency output coming out of the box. The port doesn't seems to be doing much coz there seems to be no output from it.

I'm open to any ideas or suggestions on how I can get more low bass from it. Thanks in advance for your advice.


Cheers
Rash
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Old 15th August 2005, 03:33 PM   #2
RJ is offline RJ  United States
diyAudio Member
 
Join Date: Oct 2004
You sure didn't give enough information.
Is it this Eminence speaker??
http://www.partsexpress.com/pe/pshow...03&ctab=2#Tabs

If it is - it models as such.
1.9 cu. ft. = 54 litres.
Closed box - Qtc=0.9 = F3 = 71 hz.
Ported box - F3 = 65 hz - Port dia.= 3" x 4 5/8" long.
TL= 50hz - Length of pipe= 67.7"
If tapered SO = 1 / SL = 7
Driver position on baffle 18.5" from top.
Length = 37" Stuffing Density = .25 lbs. per cu. ft.
Port = 1.5" x 3"
F3 looks to be 60 hz.

If it's not tapered the graph is horrible. There is a big peak at 100 hz and the slope dies quickly. There would be very little bass output.
If it's just a test box then you might want to rebuild it. Add a internal baffle to taper the Transmission Line. seal the port and stuff the inside of the box or add a bigger port (3" x 4 5/8")

All 3 slopes pretty much are mirror images of themselves.
The ported box looks the best to me, But if I was to do it, it would be a Dual-Chambered Reflex box.
http://www.diysubwoofers.org/prt/dual_chamber.htm
http://paginas.terra.com.br/educacao...negro/english/

The below resonance peak at 30 hz shows that it would self destroy with as little as 25 watts.
A DCR box wouldn't have this problem.

Let me know which direction you want to go?? Rudy
We're here to help not criticise.... L8'er
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File Type: jpg speaker-1.jpg (33.6 KB, 146 views)
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Old 16th August 2005, 07:23 AM   #3
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Join Date: Feb 2005
Location: Singapore
Default Unfortunately it is not a test box

Hi RJ,

Thanks so much for your response. I've attached the more info on the Eminence drivers. You calucaltion seems to be similar to what came out of the worksheet:

"Length = 37" Stuffing Density = .25 lbs. per cu. ft.
Port = 1.5" x 3""

Unfortunately I could not understand the graph much and this box is not a test box. I've folded the 37" TL and I cannot add a taper. Currently is sound very muffled with Stuffing Density = 1 lbs. per cu. ft.

I try your suggestion to increase the port size. Wish me luck and thanks again for your advise.

Cheers
Rash
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File Type: zip alp10.zip (86.4 KB, 3 views)
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Old 16th August 2005, 02:08 PM   #4
RJ is offline RJ  United States
diyAudio Member
 
Join Date: Oct 2004
Thanks for sending the driver info.
I plugged those numbers in and came up with a 4" port 9 1/2" long...
The F3 still comes out to 60 hz...
Good Luck!!
That alpha 10 looks like a good driver, let me know how it turns out.
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