4 driver Design Opinions needed - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 10 Old 06-22-10, 07:02 AM Thread Starter
Shackster
 
Join Date: Apr 2010
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4 driver Design Opinions needed

Hi All,

I've been floating around for a long time, and also I've built some subwoofers. I'm very impressed with what I've produced so far, but the DIY bug bit me, and I need to ramp it up.

Being from South Africa, importing drivers are a tad expensive, but I did find local drivers that has 30mm xmax, but with FS of 37hz for a 12" and 34hz for a 15" driver, and they are affordable.

So for now my mind is set on 4 12" drivers. The 12" drivers TS measurements from the distributor wasn't too accurate, so I measured the driver parameters, see below.

Parameters Measured:
See pictures attached

I want to sacrifice SPL for low end extension, but still have useful SPL levels for low extension. This is what I've got so far:

SPL Graph:
See pictures attached

Air Speed:
See pictures attached
The port will have a 20mm flare

Xmax:
See pictures attached

My mockup in visio.

4 Vented:
See pictures attached

I want to build at least 2 of these boxes.
The port is a 43.6cm x 10cm x 306.8cm slot port.
Each box will be powered by a Behringer ep4000.
There is a 2nd order LPF at 30hz.
Everything will be built with 32mm MDF.

Any suggestions, or criticism welcome.
Attached Thumbnails
4 driver Design Opinions needed-4vented.jpg  

4 driver Design Opinions needed-airspd.jpg  

4 driver Design Opinions needed-spl.jpg  

4 driver Design Opinions needed-targa12_2.jpg  

4 driver Design Opinions needed-tfm.jpg  

4 driver Design Opinions needed-xmax.jpg  


Last edited by NoSnipeLimit; 06-22-10 at 07:51 AM. Reason: Uploaded Images to HTS
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post #2 of 10 Old 06-22-10, 07:37 AM
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Re: 4 driver Design Opinions needed

I can't see any images ?

Source: SB Duet, Pre/Pro: Integra DHC-9.9, Speakers: SGR MT3FSL (active), Sub Amp: Crown K2, Subs: 2x SGR Maelstrom-X (125L Sealed)
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post #3 of 10 Old 06-22-10, 07:54 AM Thread Starter
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Re: 4 driver Design Opinions needed

Attached using the forum, hope that is better.
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post #4 of 10 Old 06-23-10, 11:20 AM
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Re: 4 driver Design Opinions needed

What volume are the boxes internally? It looks ok except that your port length is over 3 meters. We generally try to keep this less than 1 meter. The reason is that you get a pipe resonance that corresponds with the length of the vent. Winisd will tell you what it is. a 3m vent would have a very low resonance that would put it in your subwoofers operational range and could cause responce issues there.
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post #5 of 10 Old 06-24-10, 03:16 AM Thread Starter
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Re: 4 driver Design Opinions needed

Hi Ricci, the Internal volume of the box is 143.7litres.
I am aware of the port resonance in the subs operational frequency, my previous sub's port resonance
was also in the operational frequencies, but I didn't notice anything strange because of that.

Any other advice you have for me ?
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post #6 of 10 Old 06-28-10, 02:13 AM Thread Starter
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Re: 4 driver Design Opinions needed

Here is a 3D model of the design.
Attachments
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post #7 of 10 Old 06-28-10, 07:30 AM
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Re: 4 driver Design Opinions needed

Quote:
NoSnipeLimit wrote: View Post
Here is a 3D model of the design.
That looks fantastic. I can't wait to see it built. South Africa is still my favorite country in the world.
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post #8 of 10 Old 06-28-10, 09:52 AM Thread Starter
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Re: 4 driver Design Opinions needed

Quote:
lsiberian wrote: View Post
That looks fantastic. I can't wait to see it built. South Africa is still my favorite country in the world.
Thanks it's my first attempt at using Google sketchup. I'll probably be starting with it very soon.
South Africa is a beautiful country, but every place has it's gems
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post #9 of 10 Old 06-29-10, 12:20 AM
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Re: 4 driver Design Opinions needed

Hi what brand are the drivers? cheers
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post #10 of 10 Old 06-29-10, 03:34 AM Thread Starter
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Re: 4 driver Design Opinions needed

It's not a common brand, believe it's made in Philippines. It's a car driver. Main reason for picking this driver is because it is cheap has 30mm excursion, and South Africa doesn't have home theater drivers available to the public. Importing is also very pricey. This driver is StreetSeries 1202DW which is a 12" dual 2ohm voice coil driver. I'm very happy with the quality of the driver, it's got a good surround that allows it the excursion it needs, also has a big magnet for a 12" the cone is made of Kevlar and paper.

I've built a subwoofer with these drivers before.
It's a downfiring sub, tuned to 13hz (was a calculation error), but still was very decent.
Here is a video of "Tippie the wonder sub" on Transformers 2 (used my camera to record so video quality isn't great)
The camera is stationary. Youtube uploading is blocked on my connection so sorry for that also.

http://www.2shared.com/video/8XOB4gjU/DSCF2826.html use the "click here" next to "Save file to your PC:" (at the bottom)

The image attached below was measurements done on Tippie
The blue was a bit away from the corner.
The Green is closer to the corner.
The purple is half filled with stuffing, same position as green.

I have a peak at 40hz because of my room. I've had several different subs, all with 40hz peak.
So the new one is 4 of these drivers in a bit higher tuned box, with better bracing, and thicker MDF.
I used 16mm MDF on tippie, and the cabinet kept making cracking sounds on low frequencies, so that is why I'm going with 32mm MDF this time round, It's also better to reduce box resonance, which was obvious with 16mm MDF box that was poorly braced.
Attached Thumbnails
4 driver Design Opinions needed-3compare.jpg  


Last edited by NoSnipeLimit; 06-29-10 at 03:36 AM. Reason: Clarification of were to click
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