Ported - With Bungs?

[matt scarlett]

Although I've never modeled them, i'm confused over ported subwoofers with bungs, which thereby make them sealed. Ported boxes are naturally going to be bigger in total volume to their sealed counterparts, let say by twice the amount for an example.

So effectively, with the bungs in, isn't the sealed sub then playing in an enclosure nearly twice the volume of a recommended sealed enclosure? Is this a good thing, or have i grossly misinterpreted the situation?

 

[just a guy]

Depends what you mean by "recommended".

The volume of the sealed box along with the t/s parameters will determine the qtc.

0.5 - 0.7 qtc is usually recommended as it will give a somewhat flat response in room to the lowest possible frequency.

There are pretty good reasons to shoot for other values of qtc to fit specific goals if you have different goals than those stated.

And if you have eq or dsp you can get any qtc you want so it doesn't really matter. In this case the amount of power it takes to use up your excursion may be much more important than the native qtc.

IB is usually best from a performance standpoint, and that's the biggest sealed box you can get. Qtc = qts in IB, it takes very little power to use up your excursion so power compression is low or not a factor at all and there are various other benefits.

BTW, I don't know what a bung is but I assume you are referring to a plug.

 

[matt scarlett]

I guess in this case whatever negatives there are for having a sub in an over-sized sealed enclosure are outweighed. And i guess within reason one can do many things with eq'ing. My experience with such designs have been in car audio i admit, and none of them really sat well with me.

BTW, I don't know what a bung is but I assume you are referring to a plug.

British dear boy .. we have differing terminologies

 

[just a guy]

The only real negative to a large sealed box is size and that's only a negative if you don't want a large box.

With IB you get lower qtc, less power compression, higher low frequency sensitivity, smaller amp requirements, less distortion, no reflections back through the cone (or at least very little compared to a small undamped box), no asymmetrical (non linear) excursion due to small box air spring, pressure on the cone is lower, etc, etc, etc. What's the negative?

 

[matt scarlett]

but a large sealed enclosure to be called IB would have to be a lot bigger than some of these dual purpose enclosures!

 

[just a guy]

Of course, but these characteristics are not a black and white all or nothing thing that kicks in exactly when your box size is 10x Vas, small incremental changes in box size will provide small incremental changes in these characteristics.

Anyway, you wanted to know if a box size bigger than "recommended" would be ok. As I see it bigger is better with the only drawback being physical size, and that's only a problem if you want a small box.