MT102’s with chocked up expos!

Everyone has mid-horns with phase plugs nowadays, so i've decided to retrofit a much tighter horn & phase-plugs to a couple of almost built MT102 sized cabs, anyway before i go any further & finish the first off & start modifying the second, tell me if i've just gone a bit mad.... I'm hoping to go from around 220hz to around 2.5-3K with these...
I did a sim on the horns & i reckon i can squeeze quite a few more dB's 500hz-2K by really restricting the throat & reducing the compression & rear chamber volume, here's the work so far....

and the back (not made the plugs to fit into the speaker cone yet...)
http://hosting.mixcat.com/toomuchbass/PICT2909_sm.jpg

the throat area is around 160cm2 & the rear chamber will be as small as possible (4 Litres for the whole cab rear volume seems good) the rest of the cab is basically an MT102...

don't hold back the comments/suggestions, i can easily remove the work & get back to the ole MT102 dimensions if ne1 really reckons these won't work

PS the T/S of the drivers are:
Fs : 67 Hz
Re : 5 ohms
Qms : 6,653
Qes : 0,192
Qts : 0,186
Vas : 28 litros (0,99 pés cb. )
Sd : 0,0314 m2 ( 48,6 pol.2 )
Xmax : 4 mm
Le : 0,28 mH
Bl : 17,37 T / m
no : 4,3 %
Mms : 28 g
300WRMS

I will put in the perameters later and have a look.

The only problem I can see is that with that much squeez going on the throat should be round. The ideal for a horn is to start round and then end up square. This couples the driver to the air much better.

But its a good idea what you are doing and you should easly get to 2.5 KHz.

Rog.

Centauri has worked with midrange horns and phase plugs

http://www.centauriaudio.com.au/diy

roborg they look good mate

could some please explain what a phase plug does and how it works

thanks i had a read, but im still rather confused. Coul you explain it in simplier terms please

 

cheers

 

mash

mashgwan wrote: roborg they look good mate could some please explain what a phase plug does and how it works

Thanks! The main purpose of these was to make the throat area smaller & also to reduce the front chamber volume. That should add extra sensitivity to the higher frequencies. As mentioned elsewhere the phase plug should also shape the wavefront from the speaker to suit the horn it's going into. In this design there was no real hard thought about that I just wanted to restrict the throat of some mt102's to cross out of them higher up (and more importantly to play around like a kid with my jigsaw & irritate the hell out of the neighbours, just that little bit more testing it late on sunday night )

cheers
Rob