I'm starting this thread to show visually what I mean when I refer to "optimizing" ported sub designs by maximizing port size by maximizing port length.
For these examples, I'm going to keep gross volume and tune the same. I'm operating under the assumption that this is the size box and tune that the designer wants. I'm reducing net volume for the volume taken up by the port, and I'm going to show why the effect of losing that volume is negligible compared to the benefit gained by increasing port size. I'm also using small boxes for these examples to make the negative effects of losing volume as significant as possible, in order to show that it still doesn't really matter.
So we've got an SQL-12 in a 6-6.42cf net box tuned to 15Hz, and a UM12 in a 4-4.5cf net box tuned to 20Hz. How much of a difference does the lost volume from the bigger ports make? As we see here, hardly any difference at all.
So everything looks roughly equal here, but it ignores port velocity, so what about when we look at that? Now we see it is a major issue in the SQL-12 boxes, and a minor issue in the UM12 boxes.
So what if we add some PEQs to the models to bring the SQL-12 velocities to around the same ~32 m/s, and to reduce the smallest port UM12 model to around 20 m/s?
Now we see the larger port versions of the SQL-12 boxes have a big advantage over the smaller port versions, and even in the UM12 case, if we compare the 4cf version with the 4.3cf version, we know port compression is already kicking in at 16 m/s, so I'd still prefer the 4cf version with the bigger port and lower port velocity.
So hopefully this shows visually what I mean when I am always talking about optimizing a ported design by maximizing port size, and the way to do that is to maximize port length. Decide how long of a port you are comfortable with as far as first port resonance, and try to use every bit of that length to maximize the port size for a given box size and tune. That will allow you to "optimize" the design and get as much real-life output from it as possible.
In the SQL-12 boxes, by increasing length from 26.4" to 35" to 45.5", I was able to increase the port size from 4" to 4.5" to 5" square, and the reduction in port velocity and resulting real output capabilities speaks for itself. In the UM12 boxes, by increasing length from 26.5" to 34.8" to 46.2", I was able to increase the port size from 4.5" to 5" to 5.5" square. I used this particular UM12 case to try to go toward the extreme of a smaller driver in a smaller box with a higher tune to try to reach the limits of where increasing port size is beneficial, and yet we still see even at that point, the lost volume vs the reduced port velocity is still close to a wash, so there's little downside to increasing port size, even in this extreme case. In the more typical cases we see with boxes with more capable drivers like a UM18, and box sizes that are 6cf+, maximizing port size just becomes more and more important, otherwise the design is unnecessarily limited by the port, and thus what I would call not yet optimized. Since it has no effect on the outside box size and tune, why not simply make the port bigger and get more output?
So even if someone is only comfortable with a first port resonance of, say 160Hz and thus a max port length of ~42", or a first port resonance of 180Hz and thus a max port length of ~37.5", or whatever, they should still be targeting that length in order to make their port(s) as large as possible, otherwise they are just leaving free output on the table.
Is it possible to go to even more of an extreme with a small box and small/weak driver, and high enough tune that it isn't necessary to go all the way to the max length? Sure, but it's going to be a really extreme case. For the vast majority of ported designs, it's going to have a huge impact, and the purpose of this thread is to help those in those scenarios.
For these examples, I'm going to keep gross volume and tune the same. I'm operating under the assumption that this is the size box and tune that the designer wants. I'm reducing net volume for the volume taken up by the port, and I'm going to show why the effect of losing that volume is negligible compared to the benefit gained by increasing port size. I'm also using small boxes for these examples to make the negative effects of losing volume as significant as possible, in order to show that it still doesn't really matter.
So we've got an SQL-12 in a 6-6.42cf net box tuned to 15Hz, and a UM12 in a 4-4.5cf net box tuned to 20Hz. How much of a difference does the lost volume from the bigger ports make? As we see here, hardly any difference at all.
So everything looks roughly equal here, but it ignores port velocity, so what about when we look at that? Now we see it is a major issue in the SQL-12 boxes, and a minor issue in the UM12 boxes.
So what if we add some PEQs to the models to bring the SQL-12 velocities to around the same ~32 m/s, and to reduce the smallest port UM12 model to around 20 m/s?
Now we see the larger port versions of the SQL-12 boxes have a big advantage over the smaller port versions, and even in the UM12 case, if we compare the 4cf version with the 4.3cf version, we know port compression is already kicking in at 16 m/s, so I'd still prefer the 4cf version with the bigger port and lower port velocity.
So hopefully this shows visually what I mean when I am always talking about optimizing a ported design by maximizing port size, and the way to do that is to maximize port length. Decide how long of a port you are comfortable with as far as first port resonance, and try to use every bit of that length to maximize the port size for a given box size and tune. That will allow you to "optimize" the design and get as much real-life output from it as possible.
In the SQL-12 boxes, by increasing length from 26.4" to 35" to 45.5", I was able to increase the port size from 4" to 4.5" to 5" square, and the reduction in port velocity and resulting real output capabilities speaks for itself. In the UM12 boxes, by increasing length from 26.5" to 34.8" to 46.2", I was able to increase the port size from 4.5" to 5" to 5.5" square. I used this particular UM12 case to try to go toward the extreme of a smaller driver in a smaller box with a higher tune to try to reach the limits of where increasing port size is beneficial, and yet we still see even at that point, the lost volume vs the reduced port velocity is still close to a wash, so there's little downside to increasing port size, even in this extreme case. In the more typical cases we see with boxes with more capable drivers like a UM18, and box sizes that are 6cf+, maximizing port size just becomes more and more important, otherwise the design is unnecessarily limited by the port, and thus what I would call not yet optimized. Since it has no effect on the outside box size and tune, why not simply make the port bigger and get more output?
So even if someone is only comfortable with a first port resonance of, say 160Hz and thus a max port length of ~42", or a first port resonance of 180Hz and thus a max port length of ~37.5", or whatever, they should still be targeting that length in order to make their port(s) as large as possible, otherwise they are just leaving free output on the table.
Is it possible to go to even more of an extreme with a small box and small/weak driver, and high enough tune that it isn't necessary to go all the way to the max length? Sure, but it's going to be a really extreme case. For the vast majority of ported designs, it's going to have a huge impact, and the purpose of this thread is to help those in those scenarios.