HELPPPPPPPP!!!!! extending a port for 2nd order assist.

Tweakers' Asylum

Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ.

23 liter box.
Fs of driver is 38, Rot is deepest Fb assisted is 2/3 IE 26 hz,
the 'box' is a ~22" sphere (bass duties only in this case) with its baffle facing down, on to a 24 inch circular paver.
IE slot-loaded.
Can anyone suggest -
a height for the loading gap, with the existing port and what effect slot loading would have on the encl's current tuned frequency fb.
And, 'should it' go a good bit lower? Effectively makes the port 1.5 times as long!? Or 1.1 x ?
And, would I need active 2nd order boost to use the new effective tuning?
The port now is 6 cm's ID by 15.5cm - plumbers* UPVC pipe, all inside the encl. the remaining Vb is 23litres.
how long should the port be? to get to 26 hz? - NB taking into acount the slot loading and extending the port OUT of the box. IE we don't lose any Vb IE the 'extension' of it will be outside the box.
I will be using the encl to add .5 bass to an existing 2 way pr - same bass driver - same size spheres.
Why?
To get a 2(.5) way system, for BDD compensation without a filter in the main pairs feed, and - maybe - to get some additional extension into the lowest octave!
I do have a copy of 'Bullock ...... ' but I can't seem to find what I need to know, given this doesn't meet his assumptions, unless I play with losses or something else.
I could use a 90 degree bend insert to start, but won't the slot-load's gap-height need to increase, with the port across it? I could turn the flow down again with a second bend.
Do 'bends' screw with deep bass?
thoughst etc?

Warmest
Timbo in Oz
The Skyptical Mensurer and Audio Scrounger
'Still not saluting.'
Read about and view system at:
http://www.theanalogdept.com/tim_bailey.htm

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Kimber Kable

Topic - HELPPPPPPPP!!!!! extending a port for 2nd order assist. - Timbo in Oz 18:50:16 01/05/07 (1)

here's the only data I could get from Fostex. - Timbo in Oz 19:13:28 01/05/07 (0)

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