Porting a 2X12 Cab

[timc]

I have a Tophat 2X12 cab, speakers are semi diag. I am wanting to open part of the back to open up the sound a bit, make it less directional. It does have what I've always called a sound post, or a brace like the Marshall 4X12's in the center, so I did not know if I would just 1) cut two boards, 2/3 of the back and leave the center section open, and either just remove the sound post or leave it hanging, or 2) cut 2 say 12" round holes on each side of the cab, centering the holes on each side, leaving the sound post to make contact with the center. Any thoughts?

Edit - When I say port, I actually mean just opening part of the back.

Tim

 

[pfflam]

Just cut nice round holes back there . . . do it from the back if possible so that you can remove the tolex and fit it around the holes.

 

[beej]

In an older thread, John Suhr cited a software package that's ideal to determine the characteristics of a port/cabinet so that it's tuned properly. Might want to do a search and look into that.

 

[timc]

Just cut nice round holes back there . . . do it from the back if possible so that you can remove the tolex and fit it around the holes.

Thanks. I am actually going to buy a piece of wood ( same type, dimen as the orig back panel) and use that. This way I can switch back if I don't like it.

Tim

 

[FFTT]

Before you cut anything, try removing one speaker
and rewire for that one speaker and of course switch
your amp to the correct impedance.

In other words, try running it as a detuned cabinet first.

As far as porting, remove the back panel and use it as a template
for a completely new semi open back.
The original back can be clamped to the new back so you can line up all the holes
for drilling.


This set up gives you 3 variations from the same cabinet

Closed, detuned and semi-open back.

 

[jay42]

Also, try DIY beam blockers, like a couple coffee can lids stuck to the grille cloth with a bit of duct tape -- nothing permanent. Evaluate what you mean when you say too directional. It helps soften the on-axis peakiness and may be enough.

 

[rockon1]

Also, try DIY beam blockers, like a couple coffee can lids stuck to the grille cloth with a bit of duct tape -- nothing permanent. Evaluate what you mean when you say too directional. It helps soften the on-axis peakiness and may be enough.

+1 Beam blocker will do the most to affect a directional problem. I use them on all my cabs/amps for sound dispersal. You could do both but I'd definately explore the BB option. Bob

 

[timc]

I'll try two approx 12" holes, so I can keep the sound post (not sure why) then go from there (larger oval, rectangle, BB's).

Thanks for the respones.

Tim