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Hey guys, I'm replacing some speakers in one of my Marshall cabs, and I was giving some thought to making a back panel with some type of porting. Have any of you tried this on a cab like this? If so, could you share your experiences? Any specifics would be appreciated.

The Allman Brothers used to open up the back of thier 4 x12 Marshall cabs. Makes them sound a bit more like a combo amp and the sound that comes out the back of the cab spreads out and gives the amp a little less focused and more dispersed tone. You do get a little more open tone but lose some bass.

A ported design is differant than an open back design in that if done right you'll get more bass. But there are mathmatical formulas you need to adhere to...it's a complex and scientific process.


Originally Posted by LewguitarA ported design is differant than an open back design in that if done right you'll get more bass. But there are mathmatical formulas you need to adhere to...it's a complex and scientific process.

That's what I know of it- it's not just a matter of cutting a hole in the front or back of the cab.

Porting the cabinet won't be a very good idea. The idea of a port is to 'tune' the enclosure to a certain frequency. Most ports are on subwoofers and tune the box to about 50-60 hz. This gives the enclosure an excellent response where the bass drum kick, regardless of the resonance frequency of the speaker ect.. You could do this to the guitar cabinet and tune the cab to (insert here what guitar frequency you want to stand out). This would hurt the signal because you would have an SPL jump at that frequency making every note not in that frequency attuenated (this could help if your cab has no low end and you DO IT RIGHT). Also in order to tune the cabinet to a guitar frequency you would need quite small port tube(s). As soon as you start to get your speakers moving serious air, the port tubes would not be able to handle it. This would either make the port sound like it isn't there or worse, it could make a loud whistling sound.

Then again it could work out great. I'm just a negative person. If you send me a PM i can give you all of the equations and crap.

My guess is that it's a cool thought, but in reality you'd probably ruin a good cab and wouldn't get much results. But I've always been a closed back cab guy, love that thump. Maybe run an open back cab next to it if you need to quot;airquot; it out some.

Dude, Ben is back this week, yeah! I'm guessing it'll be a slaughter for the Ravens, if cower is smart he'll run 2nd string in the 2nd half to prevent injuries. Not to de-rail your thread, I just get excited over them steelers, it's about time we got a good chance again!