Advice needed re: porting a 4x10 cab

[Griz]

I'm thinking of having an alternate back panel made (a proper job, with tolex, etc) for a Marshall 1965B cab (4x10 straight front).

It's great little cab, though a bit boomy. In fact, you get a tone just by tapping on the back panel lightly.

So what I intend to do is first of all to attach a reinforcing post to the new birch-ply back panel, similar to what you'd find in a 4x12 but attached to the back panel instead of the speaker baffle - so the mod is fully reversible.

But I'm wondering whether it might just take things up a notch to also add a bit of porting. A number of manufacturers produce semi-open back cabinets these days.

What are your thoughts on the sonic advantages/disadvantages of a semi-open back 4x10 cab?

Also wondering what difference the size and location of a port makes.

Thanks in advance for your advice. :AOK

[Griz]

Anyone... anyone...

(crickets) :eek:


I'll try over in "Amps and Cabs".

[JJman]

I have the slant version. I put in the center post to reduce vibrations. (Front) porting is a science and will make it sound bad if not done right. IMHO opening the back (even only somewhat) will cause the low end to be reduced although would increase the “fullness” and reduce the “directional” nature of the cab.

Not sure if rear porting (with an actual port-tube) is ever done. I know that "partially closed/open" backs exist and employ separate panels.