Ported Cabinet or Not??

[OB311]

What are the significant differences between a ported cab, and a sealed cab?

[OB311]

of course i mean volume, tone...

[Mr. Foxen]

Sealed will tend towards smoother bottom end roll off, starting higher. So less lows basically. Anything higher than the bassy bit is down to the speakers themselves.

[Tagruvto]

I prefer a front firing ported cabinet for my onstage rig. The port allows extended low frequency performance. There is really nothing wrong with a nonported cabinet (often referred to as acoustic suspension). It's just that bass guitars have such low fundamental notes that most speakers won't efficiently reproduce these without some support in the acoustic design of the cabinet.

A rear ported cabinet will supply the lows, but I find the sound to be less defined.

[OB311]

I'm building a new rig. Starting with an Ampeg B2R, now looking for a cab. Just trying to decide between ported or not, aluminum cones or not, we play a good mix of rock and reggae.

I'm sure this all comes down to my personal preference....but I'm looking for some direction. Any thoughts??

[billfitzmaurice]

Originally Posted by OB311

What are the significant differences between a ported cab, and a sealed cab?

In most cases a vented cab will go lower and louder than a sealed cab of the same size using the same driver configuration, but not all. For every instance where sealed or vented cab displays a specific characteristic you can find another that doesn't.

I prefer a front firing ported cabinet for my onstage rig. The port allows extended low frequency performance. There is really nothing wrong with a nonported cabinet (often referred to as acoustic suspension). It's just that bass guitars have such low fundamental notes that most speakers won't efficiently reproduce these without some support in the acoustic design of the cabinet.

A rear ported cabinet will supply the lows, but I find the sound to be less defined.

A ported cab can give better lows than sealed, but not necessarily. An acoustic suspension cab is always sealed, but a sealed cab isn't necessarily acoustic suspension. AFAIK no acoustic suspension bass cab has ever been produced. There's no difference in the sound of rear versus front ported cabs based on the port location alone. If two cabs sound different and one happens to be front ported and the other rear ported other factors explain the difference.

[JimmyM]

All cabs must be judged on a case by case basis, and to assume generalities with regards to porting/sealed, size of speaker, etc., is to assume wrongly.

[Windreaper]

Originally Posted by billfitzmaurice

There's no difference in the sound of rear versus front ported cabs based on the port location alone. If two cabs sound different and one happens to be front ported and the other rear ported other factors explain the difference.

True. However, for conversation's sake, you do end up with some relative phase shift with a rear port (it's a different matter if anyone would be able to tell the difference). Also, one could argue that a rear port might help avoid midrange resonance problems but I haven't built enough cabs to have an opinion about that (I'd line the cab properly and use a shelf port before blaming front/rear placement for the problem). However, I have this feeling that most of the anti rear port sentiment comes from the counterintuitive function (ie. the looks) and people putting rear ported cabs too close to walls.

tldr; Place your cabs next to walls? Front port. Otherwise, meh.

[Windreaper]

Originally Posted by OB311

I'm building a new rig. Starting with an Ampeg B2R, now looking for a cab. Just trying to decide between ported or not, aluminum cones or not, we play a good mix of rock and reggae.

I'm sure this all comes down to my personal preference....but I'm looking for some direction. Any thoughts??

Aluminium cones tend to exhibit some nasty resonance imo, some people like how they sound though. Paper cones are good and in no way "cheap". Most modern cabs are ported and would be a good choice unless you're using a tube amp and/or looking for a specific tone. Just avoid cabs that stack drivers horizontally (like 4x10") and you should be fine.

[billfitzmaurice]

Originally Posted by Windreaper

True. However, for conversation's sake, you do end up with some relative phase shift with a rear port .

For phase shift to be of any consequence the distance from the port to the driver must be at least 1/4 wavelength. At 50Hz, where the bulk of port output lies with the typical bass cab, that's about 5 1/2 feet.

I have this feeling that most of the anti rear port sentiment comes from the counterintuitive function (ie. the looks)

Absolutely. For that matter in the vast majority of cases subwoofers will work better when aimed at a wall. Very few users do so, because they think that soundwaves work like lightwaves, and if the source isn't pointed at the listening area then it won't be heard. That's true in the directional frequencies, where PA tops operate, but in the frequencies where subs operate radiation is omni-directional, just as it is where ports operate.

[DukeLeJeune]

In my opinion a good ported box will give you more bass energy, and a higher max SPL in the bass region, than a roughly comparable sealed box. But match the speakers to the type of box you decide on - generally speaking, lower Qts woofers work best in a vented box and higher Qts woofers work best in a sealed box. If you don't know that that means, here's an article that will help:

Understanding Loudspeaker Data | Eminence Speaker

In case anyone would like to dig a bit deeper into ported vs sealed, one of Eminence's engineers wrote an aticle on sealed vs ported enclosures, with emphasis primarily on bass guitar applications:

Sealed vs. Ported Enclosures | Eminence Speaker