I Hate Ported Speakers!!!

[colofan]

The modeling I would reference is by LinearX in the help files 4.11 describes different models that does take into account the heating and non-linear motor aspects of suspension and voice coil technology. There is a demo mode that you can download and I might suggest looking at the help files for the reference material desired.

I have no connection with LinearX and merely a user of the product for the last 20+ years.

 

[a.wayne]

The problem with vented systems is that they require a larger cabinet than most designers are willing to give them. Run simulations and you will see that, once a woofer is chosen, the ideal vented box is roughly twice the volume of the ideal sealed box.

For commercially available systems that usually means that the vented alignments are typically undersized and boomy as a result. Years ago when I was at JBL they were selling a lot of products with the cabinet about right for sealed box, yet the systems were vented. The alignments were always on the boomy side (L150a excepted, which had wonderfully extended response).

If you have the right cabinet volume then you shouldn't need port loss, such as from a high aspect ratio slot vent. I would be concerned that such designs (including the Onken types) would be more prone to turbulence and noise. Resistive ports (including most "transmission line" types) are a very mixed bag, quickly losing the power handling and extension benefits that a well designed vented system should always have.

Regards,
David

+10

I have no connection with LinearX and merely a user of the product for the last 20+ years.

Comrade ....

Vented will be 4th order and sealed will be second. With the same cut off and corner shape (say Butterworth) then 4th order will ring a little more.

Now, interestingly, if you compare the same woofer in 2 ideal designs, the vented version will be double the volume with nearly an Octave of extension. It may have more ringing and group delay but it will occur at a much lower frequency. It can actually have a much cleaner response at the mid bass frequencies where the sealed box is ringing.

Which will sound cleaner?

This dichotomy exists for any comparison, even for systems of the same order. Push the cut off lower and the ringing is always longer (is a constant number of cut off frequency cycles) hence greater group delay. Yet if there is no program material in the vicinity it can have no effect.

Personally I would vote for lower excursion and distortion over a difference in group delay.

David S

This is usually the problem, the ideal speaker for a sealed enclosure is not really suited for BR, sticking one into the other will all ways result in unnecessary compromises, especially with BR systems ...