sealed vs ported

[gattiboy13]

What is difference? I have an SA X 10" and was thibkn sealed to save space.

[jarrius]

Sealed can be smaller and provides a different type of bass. Ported will be louder most of the time and requires more space. Also you have to look at your sub to make sure it can be used in a sealed or ported box. I think the sax can but some one should double check me on that. Now both boxes can sound really good if you build them correct. Just don't get a prefab and expect much from that sub

[Rail]

Sealed box if you are trying to save space, looking for an easy/simple build, or don't know what you are doing with ports. You won't have much low end because you will have a rolloff of 12dB per octave. Basically this means that it will be more than twice as loud at 60Hz than it is at 30Hz. That is not balanced at all. However one advantage is low group delay.

Ported is the way to go in terms of both loudness and hitting the lows, you just have to know what you are doing with ports (or find someone else who knows). Don't even mess with prefab ported boxes, they are terrible. Ported enclosures roll off at 24dB per octave, but not until you get below the tuning frequency. If you tune high, you will get very loud but not be able to hit the lows loudly, and your subs will reach their mechanical limits quickly the lower you play below the tuning frequency. If you tune low then you can design it to get a relatively flat response and the low notes will be MUCH louder, but there will not be a huge peak in the response then so you will overall not be as loud.

Ported boxes do take up more space, but low notes are fun. I would rather listen to crazy low notes than a loud system for burping, low frequency notes are the purpose of subwoofers after all, I don't want to be worried if I'm going to be able to hit that low note or not. If you tune low and it still isn't loud enough, then you just have to go with a bigger setup.

[Triticum Agricolam]

Sealed box if you are trying to save space, looking for an easy/simple build, or don't know what you are doing with ports. You won't have much low end because you will have a rolloff of 12dB per octave. Basically this means that it will be more than twice as loud at 60Hz than it is at 30Hz. That is not balanced at all. However one advantage is low group delay.

Like you said, a sealed box is going to have around twice the output at 60 Hz than it does at 30 Hz, but cabin gain does flatten out how the box will sound quite a bit. Here is a chart of a Sundown SA-12 in a sealed box. The yellow line is the response without cabin again and the red line is the response with approximated cabin gain added in.

The tricky part is trying to figure out just how much cabin gain you are going to get. The best you can do is an approximation, but it will still give you an idea.

[Rail]

Like you said, a sealed box is going to have around twice the output at 60 Hz than it does at 30 Hz, but cabin gain does flatten out how the box will sound quite a bit. Here is a chart of a Sundown SA-12 in a sealed box. The yellow line is the response without cabin again and the red line is the response with approximated cabin gain added in.

The tricky part is trying to figure out just how much cabin gain you are going to get. The best you can do is an approximation, but it will still give you an idea.

But how did you approximate that cabin gain? I didn't think it would be nearly that much or over such a broad range of frequencies either. Also how did you enter that into WinISD, through a Parametric EQ just to change the response curve to what you think it would be?

With each vehicle the cabin gain will be different. I can tell just by ear that in my Tahoe I have a significant amount of cabin gain from roughly 38Hz to 48Hz. This is not from bass boost or EQ, and my enclosure is tuned to 26Hz yet around these frequencies it gets noticeably louder, which leads me to reason that it is cabin gain. I don't have any numbers though because I unfortunately have not been able to get this thing metered yet.

[rockFord_Expedition]

If you are new to all of this

SEALED:

• Requires less space
• More forgiving than ported if you don't get things exactly right
• Safer for less experienced builders when running at or above RMS handling of subs
• With next to no wood working skill you can still sound good (good response across wider freq range)

PORTED:

• More efficient than a sealed enclosure resulting in more output at the tuning frequency
• Louder when done right

Just to name a few things

[Triticum Agricolam]

But how did you approximate that cabin gain? I didn't think it would be nearly that much or over such a broad range of frequencies either. Also how did you enter that into WinISD, through a Parametric EQ just to change the response curve to what you think it would be?

With each vehicle the cabin gain will be different. I can tell just by ear that in my Tahoe I have a significant amount of cabin gain from roughly 38Hz to 48Hz. This is not from bass boost or EQ, and my enclosure is tuned to 26Hz yet around these frequencies it gets noticeably louder, which leads me to reason that it is cabin gain. I don't have any numbers though because I unfortunately have not been able to get this thing metered yet.

I learned about modeling cabin gain in WinISD from a thread in their web board, here is the link: http://linearteam.proboards.com/index.cgi?board=winisd&action=display&thread=283

Like you said, each vehicle will be different. Whenever possible, I like to measure the longest internal distance of the vehicle I'm going to be designing & building an enclosure for so I can get the best approximation of cabin gain. For the example I did above I had the cabin gain start at 60 Hz, which is about what you would get in a moderate sized sedan or small SUV.

I'm sure you are right about your Tahoe, its cabin gain is probably going to start kickin' in around 55 Hz or so, so I'm not at all surprised by what you have experienced.