Question About Port Velocity

[Kyblack76]

That graph is more of a relative measurement. The output numbers don't really matter, its the shape of the graph that is important.

SO what would be the "ideal" shape of the curve?

Up to you. What's ideal to you is meh to me. Vice versa

[DLHgn]

Up to you. What's ideal to you is meh to me. Vice versa

Ok, so what does the shape of the curve do? What does it mean?

[Triticum Agricolam]

The shape of the curve indicates how loud your box will be a certain frequencies relative to others. It may indicate that your box puts out 5 db less at 30 Hz than 50 Hz, or maybe you have a big 10 dB spike around tuning.

Like Kyblack said, there is not right or wrong frequency response, it a personal preference thing. For myself I like a smooth and gradual rising response between 60 to 30 Hz and I like my subs to have flattish response up to at least 120 Hz, but that's just me.

An important thing to keep in mind is cabin gain is going to change your frequency response by boosting the low end a LOT. It can be roughly approximated in WinISD, but the best thing is to measure it yourself using a calibrated mic.

[DLHgn]

The shape of the curve indicates how loud your box will be a certain frequencies relative to others. It may indicate that your box puts out 5 db less at 30 Hz than 50 Hz, or maybe you have a big 10 dB spike around tuning.

Like Kyblack said, there is not right or wrong frequency response, it a personal preference thing. For myself I like a smooth and gradual rising response between 60 to 30 Hz and I like my subs to have flattish response up to at least 120 Hz, but that's just me.

An important thing to keep in mind is cabin gain is going to change your frequency response by boosting the low end a LOT. It can be roughly approximated in WinISD, but the best thing is to measure it yourself using a calibrated mic.

Where do you think a good distance for the f3 point to be in relation to the port tuning?

[Joe X]

What is the volume velocity?

It's the volume displaced in a time interval, so that is easier to understand volume velocity units are cubic meters per second (m^3/s) if you divide that by area units (port area) in say square meters (m^2) you get meters per second (m/s) which are units of velocity (port airspeed).

[DLHgn]

It's the volume displaced in a time interval, so that is easier to understand volume velocity units are cubic meters per second (m^3/s) if you divide that by area units (port area) in say square meters (m^2) you get meters per second (m/s) which are units of velocity (port airspeed).

lol So literally the velocity of a given volume. I didn't know if you meant the volume of something specific like the port or the net volume.

[Triticum Agricolam]

Where do you think a good distance for the f3 point to be in relation to the port tuning?

Distance between the tuning and F3 is going to be different for different subs and different box specs, the F3 is usually below tuning but it can be above it as well. There isn't a "right" or optimal amount. The F3 shown in WinISD isn't really an important number because what you get in your vehicle is going to be totally different.

[DLHgn]

Where do you think a good distance for the f3 point to be in relation to the port tuning?

Distance between the tuning and F3 is going to be different for different subs and different box specs, the F3 is usually below tuning but it can be above it as well. There isn't a "right" or optimal amount. The F3 shown in WinISD isn't really an important number because what you get in your vehicle is going to be totally different.

Fair enough. I was just wondering if there was a goal to get it around but it makes sense that every situation is different therefore every box/driver combo will be different.

[Triticum Agricolam]

Yeah its really going to depend on what your goals for the system are and how you like your system to sound. For a more musical daily driver type system I have a frequency response curve in mind that I try to shoot for. For a straight up SPL setup I would design the box quite differently though. It all depends on the application.

[DLHgn]

Yeah its really going to depend on what your goals for the system are and how you like your system to sound. For a more musical daily driver type system I have a frequency response curve in mind that I try to shoot for. For a straight up SPL setup I would design the box quite differently though. It all depends on the application.

Would you mind posting an example of what both of those graphs would look like?