Open vs Closed back cabinets

[MikeS]

Generally speaking, what are the tonal characteristics of the two designs? I'm building a 2x12 for my new DSL 50, and can't decide whether I should go with an open or closed back. I know that typically speaking, an infinite baffle will sacrifice punchiness and accuracy for volume, but given the frequency range of a guitar cabinet and the t/s parameters of the drivers, a 3 cubic foot box is going to share a lot of the same properties as an infinite baffle.

So, any input? I've exhausted my limited knowledge of enclosure design here.

 

[Lewguitar]

Re: Open vs Closed back cabinets

Close back cabs sound deeper and tighter. Open back cabs don't have quite the depth but have a brighter, less compressed and livlier tone.

Why not build two backs for your cab: one that covers the whole back and one that has a square hole cut out of the middle or a two piece back so the middle third could be left open?

Then you can have both tones!

Lew

 

[PUCKBOY99]

Re: Open vs Closed back cabinets

I've got a closed-back Marshall 1960A 4x12 w/Celestion G12T75s....and a Marshall 1966A 2x12 w/Mojo G12V30/G12H30. It came with a closed back panel but I did like Lew suggested: I made rear panels where I can take the middle out & have an open back....now, I don't know if it's the speakers, the panels or a combination of both, but the 2x12 is MUCH louder than the 4x12. Perhaps the "fuller" sound just seems to be louder, but that little box booms!

I think the 3 panel option is a good way to go & you can see for yourself which way is best.

Good luck & have fun!!!

 

[some_dude]

Re: Open vs Closed back cabinets

Same info as above, plus open back designs are less directional (which is why I think they sound louder). On alot of close back cabs it seems like once you step to the side the volume drops big time.

I still prefer closed backs for their thump, but open and partial open cabs are great if you need to fill a large space and can't garuntee (sp?) that the audience will always be to your front.

 

[MikeS]

Re: Open vs Closed back cabinets

Awsome! I hadn't thought about a removable panel. Question is, how air-tight does it need to be? I know the sub enclosures that I've built have been as air-tight as you can get with wood (the long excursion and smaller volume creates enough pressure change in the enclosure to create whistling if it's not sealed)... just wondering how crucial air sealing is since there won't be much change in air pressure in the box.

 

[3 cent hero]

Re: Open vs Closed back cabinets

would it be posible to have, say a 50/50? as in the bottom of a 4x12 is closed, and the top half is open?



sorry to invade your thread bro
william

 

[some_dude]

Re: Open vs Closed back cabinets

Awsome! I hadn't thought about a removable panel. Question is, how air-tight does it need to be? I know the sub enclosures that I've built have been as air-tight as you can get with wood (the long excursion and smaller volume creates enough pressure change in the enclosure to create whistling if it's not sealed)... just wondering how crucial air sealing is since there won't be much change in air pressure in the box.

It's not as important as in a sub enclosure. In a sub box if there's even a tiny little hole the air will create enough noise to annoy the f*ck out of you. But in a cab you're looking at much lower pressure levels. Besides the fact that a loudspeaker generally has substatially less excursion, the cones are much softer and volumes are much bigger:

ie. If I put four 12" subs in an enlosure the size of a standard 4x12 guitar cab, the subs wouldn't be supported by the air at all and probably wouldn't cause enough of a pressure change to whistle through a leak. And since loudspeakers force less air than a sub.....

The back of my cab (Mesa 4x12) is only screwed on, with the tolex (I think that's what you call that stuff) acting as a gasket between the back and the sides & bracing.

I don't think most cab builders seal (with glue or calk) their cabs at all.

 

[dystrust]

Re: Open vs Closed back cabinets

would it be posible to have, say a 50/50? as in the bottom of a 4x12 is closed, and the top half is open?

This is possible. The old metal grill Mesa/Boogie cabs from the 1980s were made this way.

 

[Hot _Grits]

Re: Open vs Closed back cabinets

One quick way of getting some open-back response from a Marshall cab is to remove the plastic side handles. No permanent modification, and a definite loss of boxiness.

I play through one like this at rehearsal. Sounds good.

 

[Kent S.]

Re: Open vs Closed back cabinets

One further thing that you may want to try MCM (and others) have telescoping tube ports, for a sealed back cab, they are nice for tuning the low end of the cabinet. Of course for an open back (semi open back they wouldn't do much of anything. I vote for the halfback where the bottom two are sealed and closed back, and the upper two are open back, telescoping port(s) in the bottom [ maybe one up top if you planned on making the top were you could closed it up if you wanted]. I personallly am an open back guy myself, the sound sounds much more natural, the bass is fuller, and the mids smoother ... and of course the highs brighter. That directionality thing is dead on, as sealed back are really only made to focus the sound in one direction,hence why most half stack users need a slant to hear themselves correctly, the off axis high end response rolls off big time.

 

[Hellion]

Re: Open vs Closed back cabinets

My main guitar cab is a 212 custom job from a company that doesn't even exist anymore out of Pennsylvania. It's a wonderful sounding cabinet, but it is a solid back cab. The speakers load from the front and don't focus until you're about 15 feet in front of the cabinett. So, while it may sound quiet to you in front of it, 20 feet away you're parting hair and ripping heads off. And it's very directional, like a light beam. I've gotten away with using it because I stand in front of it a lot of the time and that helps disperse the sound, but I also have another open back combo and that thing is so omnidirectional that I don't even have to send it through the system to be heard.