Broke_Audio_Addict Posted June 14, 2015 Report Share Posted June 14, 2015 Port compression. Same as acoustic compression. Please tell me how having over minimum area hurts the output of a speaker.. I don't care at all about location restraints. He's not asking if a little over the minimum required area would hurt it he's asking how much is too much and what would it effect if it was too much. That being said a lot of people's definition of "music" is a clipped 30 hz sine wave with some 80 IQ knuckle head grunting about committing crimes and his genitals. Link to comment Share on other sites More sharing options...
Kyblack76 Posted June 14, 2015 Author Report Share Posted June 14, 2015 Port compression. Same as acoustic compression. Please tell me how having over minimum area hurts the output of a speaker.. I don't care at all about location restraints. He's not asking if a little over the minimum required area would hurt it he's asking how much is too much and what would it effect if it was too much. or.. what happens if your AT MIN... and what is MIN? SMD SUPER SELLER The Burban Build Blazer Build sold Acura trunk build sold Link to comment Share on other sites More sharing options...
Broke_Audio_Addict Posted June 14, 2015 Report Share Posted June 14, 2015 An isobaric sub has no port to connect the chamber to the outside so port area in no was would cause that.At some point if the port is freaking huge the sub might as well not be in an enclosure right?Say 500sq in of port for an 8" sub what's going to happen? The port helps control cone movement right? So what happens when the port is too big to have an impact on cone control? How much bigger does it have to be for that too occur? That being said a lot of people's definition of "music" is a clipped 30 hz sine wave with some 80 IQ knuckle head grunting about committing crimes and his genitals. Link to comment Share on other sites More sharing options...
Kyblack76 Posted June 14, 2015 Author Report Share Posted June 14, 2015 also.. port area i know has no effect on volume ... sooooooooo why does changing the volume change my score? port not playing....?? Tuning higher i get.. but... SMD SUPER SELLER The Burban Build Blazer Build sold Acura trunk build sold Link to comment Share on other sites More sharing options...
Krakin Posted June 14, 2015 Report Share Posted June 14, 2015 Okay going to scratch over the too much since it isn't the question right now. Minimum port area can be found from a few variables of your system such as cone area in total, xmax and tuning frequency. Using this: Calculate the minimum port diameter from the following equations: Sd = pi*(Dia/100)^2/4 Vd = Sd*Xmax/1000 Dmin = 100*(20.3*(Vd^2/Fb)^0.25)/Np^.5 where, Dmin = minimum port diameter (cm) For vented type speakers operated at full power that is, full excursion, it is possible to end up with audible noise from the air rushing in and out of the vent. For a given speaker system, the smaller the vent opening the greater the velocity of air in the vent and the greater the vent noise. The main reason this ever became a topic is because Richard Small (the S in T/S Parameters) wanted to know the minimum velocity the air from the port could have without causing noise. This happens to be about 5% the speed of sound. That formula should get you close to it, but with modeling software you don't really need to use it, just make sure your port velocity is down. There are other negatives from port compression such as added heat from inadequate air transaction and poor frequency responses due to it as well. Krakin's Home Dipole Project http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370 Krakin, are you some sort of mad scientist? I would have replied earlier, but I was measuring the output of my amp with a yardstick . . . What you hear is not the air pressure variation in itself but what has drawn your attention in the two streams of superimposed air pressure variations at your eardrums An acoustic event has dimensions of Time, Tone, Loudness and Space Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears, thus no formula can achieve a definite effect for every listener. Link to comment Share on other sites More sharing options...
Krakin Posted June 14, 2015 Report Share Posted June 14, 2015 An isobaric sub has no port to connect the chamber to the outside so port area in no was would cause that. At some point if the port is freaking huge the sub might as well not be in an enclosure right? No Say 500sq in of port for an 8" sub what's going to happen? You have a large port The port helps control cone movement right? Yes So what happens when the port is too big to have an impact on cone control? That's like saying when does an engine have too much horse power to not move a car. How much bigger does it have to be for that too occur? All of that works the other way around, the port looses the ability to control cone movement with too little port area and playing below the tuned frequency. Krakin's Home Dipole Project http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370 Krakin, are you some sort of mad scientist? I would have replied earlier, but I was measuring the output of my amp with a yardstick . . . What you hear is not the air pressure variation in itself but what has drawn your attention in the two streams of superimposed air pressure variations at your eardrums An acoustic event has dimensions of Time, Tone, Loudness and Space Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears, thus no formula can achieve a definite effect for every listener. Link to comment Share on other sites More sharing options...
Kyblack76 Posted June 14, 2015 Author Report Share Posted June 14, 2015 Okay going to scratch over the too much since it isn't the question right now. Minimum port area can be found from a few variables of your system such as cone area in total, xmax and tuning frequency. Using this: Calculate the minimum port diameter from the following equations: Sd = pi*(Dia/100)^2/4 Vd = Sd*Xmax/1000 Dmin = 100*(20.3*(Vd^2/Fb)^0.25)/Np^.5 where, Dmin = minimum port diameter (cm) For vented type speakers operated at full power that is, full excursion, it is possible to end up with audible noise from the air rushing in and out of the vent. For a given speaker system, the smaller the vent opening the greater the velocity of air in the vent and the greater the vent noise. The main reason this ever became a topic is because Richard Small (the S in T/S Parameters) wanted to know the minimum velocity the air from the port could have without causing noise. This happens to be about 5% the speed of sound. That formula should get you close to it, but with modeling software you don't really need to use it, just make sure your port velocity is down. There are other negatives from port compression such as added heat from inadequate air transaction and poor frequency responses due to it as well. power applied ? SMD SUPER SELLER The Burban Build Blazer Build sold Acura trunk build sold Link to comment Share on other sites More sharing options...
Krakin Posted June 14, 2015 Report Share Posted June 14, 2015 Doesn't matter, you shouldn't be playing a sub past it's Xmax anyway. The Xmax is there to have it know your upper limit of excursion. If you use less power you'll have less excursion to cause less air to move. So you could use a smaller port area, but when designing you design around your speaker not your amplifier, because what if you get a bigger amp. If you could have too much port area then playing speakers at low volumes would sound absolutely horrible as the port area needed gets exponentially smaller as you use less power. Krakin's Home Dipole Project http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370 Krakin, are you some sort of mad scientist? I would have replied earlier, but I was measuring the output of my amp with a yardstick . . . What you hear is not the air pressure variation in itself but what has drawn your attention in the two streams of superimposed air pressure variations at your eardrums An acoustic event has dimensions of Time, Tone, Loudness and Space Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears, thus no formula can achieve a definite effect for every listener. Link to comment Share on other sites More sharing options...
Broke_Audio_Addict Posted June 14, 2015 Report Share Posted June 14, 2015 So a sub doesn't unload at high volume with too much port area because that's what I've heard in the past. I think we all know too small and you have port noise. That being said a lot of people's definition of "music" is a clipped 30 hz sine wave with some 80 IQ knuckle head grunting about committing crimes and his genitals. Link to comment Share on other sites More sharing options...
Kyblack76 Posted June 14, 2015 Author Report Share Posted June 14, 2015 arg..... SMD SUPER SELLER The Burban Build Blazer Build sold Acura trunk build sold Link to comment Share on other sites More sharing options...
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