[fackamato]

I'm considering building two identical subwoofers for use in my home. They will be ported, and of 200 litres volume. I'm using BassBox 6 Pro, and with a 200L enclosure with 2 vents (flared both ends), 100mm (4") diameter and 450mm long (18"), I'm getting this:

F3 23.12Hz
Max cone displacement: 15mm @ 32Hz / 600 watts
Max port airflow: 18.8m/s @ 13.51Hz / 600 watts

Is this a realistic build, or could I do better? The group delay is pretty good too, 15,26msec at 20Hz, then it just goes lower as the freq increases.

These woofers will be powered by a EP2500 (hence 600wpc at 4ohm). A question about the ports: should they be in the baffle, or in the back, or in the side, or one on each side? Does it matter? Also, the rule is to have at least (port diameter) free space around the port, to not interfere with the flow. Right/wrong?

Any tips would be heavily appreciated!

[Kevin Haskins]

If you are going to run them ported, you need a subsonic filter.    Without it, you will damage the drivers.   

I'd suggest just running them sealed in the same size boxes.   You don't have to worry about subsonic filters and the single EP2500 is a good match for a pair.     

[fackamato]

If you are going to run them ported, you need a subsonic filter.    Without it, you will damage the drivers.   

I'd suggest just running them sealed in the same size boxes.   You don't have to worry about subsonic filters and the single EP2500 is a good match for a pair.     

Hm, why is that? I can't (according to my simulations) push the cone displacement over 15mm @ 600 watts, no matter the frequency. What am I missing?

I think I want to go ported anyway though. And I'll probably be using a DCX2496 to EQ and filter the sub, I have no highpass filter otherwise. And I guess I could use the DCX2496 for the subsonic filter aswell...

[Kevin Haskins]

If you are going to run them ported, you need a subsonic filter.    Without it, you will damage the drivers.   

I'd suggest just running them sealed in the same size boxes.   You don't have to worry about subsonic filters and the single EP2500 is a good match for a pair.     

Hm, why is that? I can't (according to my simulations) push the cone displacement over 15mm @ 600 watts, no matter the frequency. What am I missing?

I think I want to go ported anyway though. And I'll probably be using a DCX2496 to EQ and filter the sub, I have no highpass filter otherwise. And I guess I could use the DCX2496 for the subsonic filter aswell...

Ignore your simulation for a second.    The DCX2496 is a pro-audio PEQ and while I don't own one, I don't know if it will operate under 20Hz.    Also, a PEQ band is not a subsonic filter.

There really isn't an option, you need a subsonic filter to run them ported.   Otherwise you will eventually blow the driver.   

Follow my original recommendation and run them sealed.   It solves your protection problems and you can use the DCX to modify your in-room bandwidth.    A pair of Tempest gives you plenty of output.   If you need more, just keep adding drivers and EP-2500s.   

[fackamato]

If you are going to run them ported, you need a subsonic filter.    Without it, you will damage the drivers.   

I'd suggest just running them sealed in the same size boxes.   You don't have to worry about subsonic filters and the single EP2500 is a good match for a pair.     

Hm, why is that? I can't (according to my simulations) push the cone displacement over 15mm @ 600 watts, no matter the frequency. What am I missing?

I think I want to go ported anyway though. And I'll probably be using a DCX2496 to EQ and filter the sub, I have no highpass filter otherwise. And I guess I could use the DCX2496 for the subsonic filter aswell...

Ignore your simulation for a second.    The DCX2496 is a pro-audio PEQ and while I don't own one, I don't know if it will operate under 20Hz.    Also, a PEQ band is not a subsonic filter.

There really isn't an option, you need a subsonic filter to run them ported.   Otherwise you will eventually blow the driver.   

Follow my original recommendation and run them sealed.   It solves your protection problems and you can use the DCX to modify your in-room bandwidth.    A pair of Tempest gives you plenty of output.   If you need more, just keep adding drivers and EP-2500s.   

It's just fun to simulate with different drivers and boxes, to see what they come up with. But yeah, I'll trust you and build two sealed subs, as per your Application Notes.

As you said, I can just up the lower frequencies if I feel the need for it.

Now I'm convinced. Thanks!

[Aaron Gilbert]

If you are going to run them ported, you need a subsonic filter.    Without it, you will damage the drivers.   

I'd suggest just running them sealed in the same size boxes.   You don't have to worry about subsonic filters and the single EP2500 is a good match for a pair.     

Kevin,

Is there such a thing as an inexpensive subsonic filter which can be added to any amplifier? I'm not totally convinced that I need one, based on our listening levels and the subwoofer's tuning frequency (12Hz), but if one can be added simply, why not? It would have to have a super-low frequency though - 10-12Hz at most.

[Kevin Haskins]

If you are going to run them ported, you need a subsonic filter.    Without it, you will damage the drivers.   

I'd suggest just running them sealed in the same size boxes.   You don't have to worry about subsonic filters and the single EP2500 is a good match for a pair.     

Kevin,

Is there such a thing as an inexpensive subsonic filter which can be added to any amplifier? I'm not totally convinced that I need one, based on our listening levels and the subwoofer's tuning frequency (12Hz), but if one can be added simply, why not? It would have to have a super-low frequency though - 10-12Hz at most.

I think Elemental Designs sells a $100 box but I'm not sure you can set it that low.    I wouldn't worry about it though.   With that low of a tune and with modest listening levels you won't have a problem with the driver unloading.   You also have to consider that most amplifiers have at least DC blocking, usually a capacitor on the input which effectively gives you a 8-10Hz filter.     Add to that there just isn't much content down that low (a couple movies and perhaps recordings where it is on there by mistake) and you have nothing to worry about. 


The people who should be concerned are those who are tuning a cabinet to around 18-22Hz.   Many movies have content that can pop the driver before you can get to the sub to turn it down.    Being amplifier limited is not necessarily a bad thing. 

[Aaron Gilbert]

Kevin,

Ok cool, thanks for the reassurance, I won't worry about it! At our normal levels, even the Dayton Quatro didn't unload that often. We usually are watching at -10dB from reference, sometimes -15dB. We did watch some Star Wars last week at -5dB, but that was bordering on too loud, and the driver only bottomed a few times, and not hard (the Dayton that is). The Tempest-X doesn't bottom at all even at -3dB, so I think we're good.

Cheers!