Sealed Loudspeakers and Ported Subwoofers?

[sbo6]

It absolutely does NOT show that.

His own graphs show significantly less excursion around the tuning frequency. At same SPL, which is most important, the differences are larger.

Yes but only at the tuned port frequency which = ~35 - 20Hz. Where is most musical bass at?

 

[DaveC]

Total excursion would be the area under the graph, if you start at the tuning frequency and go up to say ~200 Hz you'll get the total excursion of the driver at those frequencies. Or you can restrict the signal in to the frequencies of interest, but the graphs Rob posted are misleading because they are zoomed way out and signal is shown down to 5 Hz when the tuning frequency looks to be just under 30 Hz. If you zoomed in on the the 25-100 Hz range you get a much clearer picture, but Rob didn't do that...

In any case, it's obvious from the graphs that excursion of the BR woofer is MUCH lower around the port tuning frequency and the resulting FR graph shows a large increase in bass extension and efficiency, which is exactly what you'd expect.

IMO Rob's argument is completely a semantic interpretation of the data and serves no useful purpose. Anyone can look at the graphs he posted, it supports everything I said, which btw does NOT include saying it's definitely going to cause any damage to plug a port! The tradeoff is lower efficiency and increased IMD due to higher excursion.

 

[sbo6]

I'm missing something. On the graphs at any power level, the slopes are easily visible so what does zooming in do? Also, the worse case scenario at 100 watts shows a cone displacement delta (sealed vs. ported) at ~28Hz which = 3.8mm or < 1/8". And that's at 98+DB! So in his simulation while the output is less by ~8DB for the sealed, that's the largest delta, and at 28Hz (little musical information). What would be interesting as I think you said earlier would be to simulate and graph SPL versus excursion for both.

 

[NorthStar]

I would hire a professional, there is one here, Mark Seaton.
? https://seatonsound.net/

 

[Robh3606]

Morning Dave

You need same SPL, not the same power input.

BR isn't used below tuning frequency.

No you don't not to make the point I was which was that a change of alignment would damage a driver at 10-25 watt power levels.

If you did the same SPL you would have to EQ the sealed box which was not part of the original comparison and would obviously increase excursion in a sealed design.

As far as BR not being used below tuning well that's a bit of a stretch. Smaller reflex boxes especially the smaller stand mounts, say with 6" woofers, are used full range by many people. Not everyone uses subwoofers.

The whole "premise" you completely took out of context. You're basically trying to argue a BR isn't more effecient vs a sealed design, and you're just wrong.

Bellow is my post before we had a disagreement discussing why you could save money compared to a sealed design. Post 52 this thread

Well actually it's not. It depends on how you look at it. For that same FR over the same bandwidth you get more bang for your buck using reflex enclosures. You don't have to waste amplifier power making up for the sealed subwoofers roll-off. You can also use a driver that doesn't have to put up with up to 12db of EQ so less expense there as well. So you are actually are using the bass drivers more efficiently using reflex enclosures.

But hey, rig the results just to make a point and try to make yourself look better. Your behavior is ridiculous. None of this is up for debate, if you don't understand the basics this isn't the place to argue it anyways, I'm not interested and don't want to spend the time or effort on this ridiculousness.

I never rig my results and will admit when I am wrong or have misspoken.

Rob

 

[Robh3606]

What would be interesting as I think you said earlier would be to simulate and graph SPL versus excursion for both.

Hello sbo6

It is already there?? You have excursion and SPL graphed over frequency at 4 power levels.

Are you talking about with EQ? If you are the sealed box is going to have an issue with excursion and potentially power as well. No free lunch.

Rob

 

[DaveC]

Lol, Rob. Your sig says it all.

I'm just NOT up for it, your argument is ridiculous. Buh-bye now!

 

[Robh3606]

Lol, Rob. Your sig says it all.

Not all of it

Rob