Sub enclosures

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These are not accurate in every situation, but are rather generalizations.

Sealed subs generally have better transient response, which is often attributes to their musicality. They have a gradual rolloff as the frequency goes down. They generally allow a bigger margin for error during the actual construction, and are simple to design and build. They generally have a higher power handling.

Ported subs can generally go a bit deeper depending on the frequency to which its been tuned. Rather than a gradual rolloff, a good driver will be fairly linear to the tuned frequency, and then drop like a rock. The margin for error in the construction is smaller than in a sealed.

Both designs have their tradeoffs, but when properly designed, you should have a good end result either way. A lot of it depends on the driver itself, and its paramters, particularly the q of the driver. I personally use a ported sonosub tuned to 16 hz and love it, but I've also heard a lot of sealed subs that are tough to top...
 
yeah im using 400 watt 18" PA subs in mine ive done lots of ported enlcosuree and some of the time i wish they were sealed and so with this one im thinking of making it so that it is sealed but if i dont like the sound of it that i can easly make it ported the only problem with this is that if i dont like the sound more with it ported i wont be able to make it sealed again :(
 
You could always make a cheaper test enclosure out of lesser materials first. If you did want to make it back into a sealed box after already having made it ported, they do sell port plugs to seal the box off. Or, you could port it with PVC pipe, thread the pipe, and use a screw-on endcap so you could have sealed or ported, depending on the mood :)
 
Super said:
These are not accurate in every situation, but are rather generalizations.

Sealed subs generally have better transient response, which is often attributes to their musicality. They have a gradual rolloff as the frequency goes down. They generally allow a bigger margin for error during the actual construction, and are simple to design and build. They generally have a higher power handling.


What kind of margin for error? one tenth of a liter volume, material used, bracing....? What might be the most common error for a complete novice?

Thanks in advance,

Ron
 

kelticwizard

diyAudio Moderator Emeritus
2001-09-18 2:33 am
Connecticut, The Nutmeg State
I think the margin of error Super was referring to was the fact that you can tune a vented box wrong. Also, the vent can tune it correctly but be too narrow and make "chuffing" sounds.

Of course, there are formulas that avoid that-or the novice can post here and we can set him/her down the right path. Building a ported box is not appreciably more difficult than a sealed, but like anything else, if you have another set of variables-in this case, the port-you have another thing that can theoretically go wrong.
 
The plus of a sealed box over a vented one is that with the better transient response the sealed box has a more gradual roll off. That coupled with typical room gain will usually make up for the supposed loss in efficiency gained by a reflex cabinet.
The loww bass will be better if you take into account that the reflex enclosure will cause serious distorsion just below the vent tuning frequency. The woofer will not be loaded by the box/port combination and will go into wild excusion that causes distorsion.
 
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