Being reading up for the last few weeks and doing tons of research. Have looked and posted in HTS, AVS, Blu-Ray etc but not getting some critical info.
After seeing what JimGore and some of the local guys are capable of.... hoping some local talent can help me out.
I?ve decided to try and build a 15? dual opposed second sub to work alongside my Paradigm Sub15.
Current Sound Setup:
KEF Q towers front and back (5.1)
Sub ? Paradigm Sub 15
AMP Yamaha (no room auto-calb) (Used Radioshack SPL and actual distance)
SVS AS-EQ1
Usage will be primarily HT - 90% at least.
Room ? 6m x 5m x 2.60 high (+ 220mm false ceiling with 150mm isotherm)
All walls are double cavity - 220mm rib and block above.
We recently renovated and I have already a dedicated 20Amp plug point and 25mm PVC pipes in the walls and floor to the respective points.
Therefore I am limited in terms of placement. The pictures in my public Dropbox illustrate it better.
With the DIY Sub being so close to the second couch, I did not want it vibrating up against the couch.
I plan to have the woofers facing the front and back walls thereby leaving ample room instead of having the woofers face the couch and wall.
Driver Shortlist:
Dayton Titanic MK3 - $234 each
Similar local options ???
Amp Shortlist:
Behringer EPX4000 - ?279.00 (RMS power rating 2x 870 W at 4 Ohm) (Getting this in Sept)
Similar local options ???
From what I understand, the Amp would be able to give each channel about 800W RMS @ 4 Ohms.
Was thinking about wiring it such that the Amp is presented with a 4-Ohm load per channel per driver.
Would also replace the fans with low noise variants from Digikey (P14751-ND)
Phase 1 - What is the ideal box volume and size
I?ve used WinISD, Boxnotes and Unibox but still not sure what size box I should use. (Box must be sealed)
WinISD claims I need a 300 litre box for a Q of 0.700 and a 400L for a Q of 6.5 (Can?t go bigger than 300 without exceeding cone excursion)
Boxnotes does not like any box wider than 900mm (issues with resonant frequencies) ? possible bad idea anyway for dual opposed design.
Unibox calculates
Dayton Titanic - 235L for Q of 0.7 and a 280L for a Q of 0.675
Problem 1 - The tools all appear to give different values - which do I trust?
Problem 2 - I?ve read that a Q of 0.7 gives you the flattest response but you get room gain so if possible to aim for a Q factor that?s lower than 0.7. How low should I go?
Problem 3 - I can't seem to find or get an answer in terms of what the best practice is for maximum distance between drivers in a dual opposed design.
Internally the box would have panels with acoustic foam and be stuffed with polyfill.
I have most of the tools and access to those I?m missing. Clearly going to make a significant investment in clamps based on what I've seen.
Only concern is the cutting of perfect circles for the baffle. Might/Will have to outsource that locally in Cape Town.
It's going to have to have wheels as I can't move it by myself any other way.
I really require assistance in the box size calculation and look forward to comments and suggestions around the driver and amp selection.
With the Dayton Titanic MK3 was thinking about a 245L polyfill stuffed box. Hoping for a 25% increase in perceived volume giving me 306L.
750 x 750 x 550 (HxLxD) Outside dimensions
Thank you all for your time and :help:
Additional Info
Room - https://dl.dropbox.com/u/26125279/Visio-TV%20ROOM%20v10.pdf
Screenshots - https://dl.dropbox.com/u/26125279/Screenshots.zip
Dayton Driver - https://dl.dropbox.com/u/26125279/Dayton%20Titantic%20MK3%20Spec.pdf
Box Size - https://dl.dropbox.com/u/26125279/245L%20-%20Woofer%20BoxWizard.pdf
Cutting List - https://dl.dropbox.com/u/26125279/Visio-Cut%20Options%20v2.pdf
After seeing what JimGore and some of the local guys are capable of.... hoping some local talent can help me out.
I?ve decided to try and build a 15? dual opposed second sub to work alongside my Paradigm Sub15.
Current Sound Setup:
KEF Q towers front and back (5.1)
Sub ? Paradigm Sub 15
AMP Yamaha (no room auto-calb) (Used Radioshack SPL and actual distance)
SVS AS-EQ1
Usage will be primarily HT - 90% at least.
Room ? 6m x 5m x 2.60 high (+ 220mm false ceiling with 150mm isotherm)
All walls are double cavity - 220mm rib and block above.
We recently renovated and I have already a dedicated 20Amp plug point and 25mm PVC pipes in the walls and floor to the respective points.
Therefore I am limited in terms of placement. The pictures in my public Dropbox illustrate it better.
With the DIY Sub being so close to the second couch, I did not want it vibrating up against the couch.
I plan to have the woofers facing the front and back walls thereby leaving ample room instead of having the woofers face the couch and wall.
Driver Shortlist:
Dayton Titanic MK3 - $234 each
Similar local options ???
Amp Shortlist:
Behringer EPX4000 - ?279.00 (RMS power rating 2x 870 W at 4 Ohm) (Getting this in Sept)
Similar local options ???
From what I understand, the Amp would be able to give each channel about 800W RMS @ 4 Ohms.
Was thinking about wiring it such that the Amp is presented with a 4-Ohm load per channel per driver.
Would also replace the fans with low noise variants from Digikey (P14751-ND)
Phase 1 - What is the ideal box volume and size
I?ve used WinISD, Boxnotes and Unibox but still not sure what size box I should use. (Box must be sealed)
WinISD claims I need a 300 litre box for a Q of 0.700 and a 400L for a Q of 6.5 (Can?t go bigger than 300 without exceeding cone excursion)
Boxnotes does not like any box wider than 900mm (issues with resonant frequencies) ? possible bad idea anyway for dual opposed design.
Unibox calculates
Dayton Titanic - 235L for Q of 0.7 and a 280L for a Q of 0.675
Problem 1 - The tools all appear to give different values - which do I trust?
Problem 2 - I?ve read that a Q of 0.7 gives you the flattest response but you get room gain so if possible to aim for a Q factor that?s lower than 0.7. How low should I go?
Problem 3 - I can't seem to find or get an answer in terms of what the best practice is for maximum distance between drivers in a dual opposed design.
Internally the box would have panels with acoustic foam and be stuffed with polyfill.
I have most of the tools and access to those I?m missing. Clearly going to make a significant investment in clamps based on what I've seen.
Only concern is the cutting of perfect circles for the baffle. Might/Will have to outsource that locally in Cape Town.
It's going to have to have wheels as I can't move it by myself any other way.
I really require assistance in the box size calculation and look forward to comments and suggestions around the driver and amp selection.
With the Dayton Titanic MK3 was thinking about a 245L polyfill stuffed box. Hoping for a 25% increase in perceived volume giving me 306L.
750 x 750 x 550 (HxLxD) Outside dimensions
Thank you all for your time and :help:
Additional Info
Room - https://dl.dropbox.com/u/26125279/Visio-TV%20ROOM%20v10.pdf
Screenshots - https://dl.dropbox.com/u/26125279/Screenshots.zip
Dayton Driver - https://dl.dropbox.com/u/26125279/Dayton%20Titantic%20MK3%20Spec.pdf
Box Size - https://dl.dropbox.com/u/26125279/245L%20-%20Woofer%20BoxWizard.pdf
Cutting List - https://dl.dropbox.com/u/26125279/Visio-Cut%20Options%20v2.pdf
