MIGHTY DUB PASS

                                                  M I G H T Y    D U B   P A S S

MIGHTY DUB PASS has been designed. I will fill in more details as I get time, but here's the low-down:

MIGHTY DUB PASS is designed for use in singles or multiples. MIGHTY DUB PASS operates from 30Hz to 110Hz. MIGHTY DUB PASS shows a half-space sensitivity of 101dB standard conditions in half space (but my tool gives more conservative results than most).

MIGHTY DUB PASS is designed for Void V18-1200. It's probably good with RCF L18P300 and maybe some other drivers - I'll check later. Not suitable for PD1850 or V18-1000 unfortunately.

I will supply diagrams later. To build, make a cuboid outer shell 1220mm high by 636mm wide by 750mm deep external (just slightly smaller than Rog's super scooper). Use 18mm ply and brace well.

Make a double-thickness (36mm) shelf panel to mount horizontally inside the shell. Cut a hole to mount the driver centred 275mm from the back of the shell. Build a cylindrical tube structure out of layered bendy wood internal diameter 500mm, length 300mm, thickness 25mm and attach to the underside of the shelf on the same centre as the driver (driver will sit on top of shelf, and cone faces through the cylinder). Plug the cylinder with a circular double thickness panel 500mm dia. Note that the cyclinder should contact the back of the outer shell - glue here for reinforcement. The plug panel should contain a 300mm diameter hole at its centre for a reflex port.

Cut two additional port holes 175mm dia in the space available at the front of the shelf panel. The shelf panel should be mounted to leave 370mm clearance between top of shelf and bottom of shell top panel.

Make a hole in the front panel located 200mm from the bottom of the cabinet to a diameter of 325mm (this dimension might change) for the final output port.

Port lengths have yet to be specified; they should be determined to achieve cabinet resonaces (low Z) at 28.5Hz, 57Hz and 101Hz. Driver resonances (high Z) should be at 15Hz, 39.5Hz, 80Hz and 119Hz. I will supply the actual lengths when I have determined them.

MIGHTY DUB PASS has been created, at least in theory. Let me know if you want to build one, and I'll help with the port length determination (which requires a built prototype).
  Edit: slight tweaks to let the A and B ports be bigger (so they never exceed 5% speed of sound at 1400 watts, xover <= 100Hz). A port assumed half in A and half in C. B port assumed mostly in B (bottom of port level with bottom of A cavity). C port all in C.

Edited by jsg mashed - 24 October 2007 at 3:50pm

You're down on scoops already my friend.
most get between 102-105dB sensitivity within usable bandwidth. (in half space)
Just how conservative is your software?

Has this been built, tried and tested?

Hi all

Thanks for taking an interest

MIGHTY DUB PASS has been modelled using my proporietary software - which has also been used to model various similar subs which have been tested and check out. Diagrams to follow. MIGHTY DUB PASS is an 8th order design - I don't think WinISD even supports that...?

As regards sensistivity, remember that a scoop's frequency response gets messed up when used in singles, and the bottom end goes away, leaving a response to perhaps 40Hz -3dB (=pathetic). Only when combined in groups do you even get close to the specified response.

MIGHTY DUB PASS gets 106dB in mutliples of 4, and covers 30Hz to 110Hz -3dB with about 1dB ripple in-band.

Incidentally, this is one of the subtler problems with introducing new technology into an established domain. People (rightly) want to know the catches and what-ifs of the new ttech, but sometimes they have to be remineded that the *current* tech has it's own drawbacks too.

I found this on 8th order BP : http://www.geocities.com/f4ier/speaker.htm not you is it JSG?

mykey wrote: giant JBL tripple chamber band pass bin, anything like that?