Port: How long is too long?

[akuma4u]

Im building a test box using triticums port area calculator and aiming for optimal or as close to optimal port area as possible. This requires a port that is wide and long. Its so long in fact that after it bends, it stops leaving only half an inch of space between the end of port and the side wall of enclosure. So my question is..how much room between the end of port wall (the 2nd piece that runs the width of the box) and the side wall of the enclosure should be left to be safe? Cuz the way my design is now, the port is so long its almost created a sealed box within a ported box. 

 

 

[1point21gigawatts]

1 hour ago, akuma4u said:

Im building a test box using triticums port area calculator and aiming for optimal or as close to optimal port area as possible. This requires a port that is wide and long. Its so long in fact that after it bends, it stops leaving only half an inch of space between the end of port and the side wall of enclosure. So my question is..how much room between the end of port wall (the 2nd piece that runs the width of the box) and the side wall of the enclosure should be left to be safe? Cuz the way my design is now, the port is so long its almost created a sealed box within a ported box. 

 

 

I’ve been studying him and his formulas and have used that calculator before. I have found flaws in his formulas and his calculator. So much so, I wouldn’t reference them or use them for any of my builds or recommendations. 

[1point21gigawatts]

Send me some schematics and I’ll figure the port for you. I need to know specs on the enclosure and I need to know the subwoofer(s) and amp(s).  

[1point21gigawatts]

It can not be a half inch away from the side way. It has to be at least the same distance away from that walk as the width of the port. 

[akuma4u]

9 minutes ago, 1point21gigawatts said:

It can not be a half inch away from the side way. It has to be at least the same distance away from that walk as the width of the port. 

Damn thats what i thought. Regarding triticums port calcualtor... U r not the first person to tell me its flawed. I dont have the tools needed to build boxes so i send my designs to builders and they build for me. A few times i did use his calculator and of course made a huge port. Every one of the builders would stop and wouldnt build the box cuz they said i was using way too much port area. I would have to convince them to do it. One bix i have sounds ok however that is using like 18sq in a cube and is still close to manufacturers recommendations. I have never been able to build an optimal port according to his caluclator. The port will be massive! Im trying to do a test box and test this optimal port out and see if it really does deliver.

 

Im curious to know what flaws you have found?

[Triticum Agricolam]

9 hours ago, 1point21gigawatts said:

I’ve been studying him and his formulas and have used that calculator before. I have found flaws in his formulas and his calculator. So much so, I wouldn’t reference them or use them for any of my builds or recommendations. 

I'm always looking to make my calculator better.  Please, what flaws have you found?  Maybe I can find a way to fix them.  

[Triticum Agricolam]

10 hours ago, akuma4u said:

Im building a test box using triticums port area calculator and aiming for optimal or as close to optimal port area as possible. This requires a port that is wide and long. Its so long in fact that after it bends, it stops leaving only half an inch of space between the end of port and the side wall of enclosure. So my question is..how much room between the end of port wall (the 2nd piece that runs the width of the box) and the side wall of the enclosure should be left to be safe? Cuz the way my design is now, the port is so long its almost created a sealed box within a ported box. 

 

 

Yeah that's not going to work out well.  If you could draw a picture of what you are trying to do, we could probably help point you in the right direction.  

In general, you want at least two port widths of space between the end of the port and another panel.  When I say "port width" I mean whatever is the smaller dimension of a slot port.  For example if the slot port is 3" x 10" then you are going to want 6" (3" x 2) of clearance.  

Also, my port calculator isn't meant to give you concrete port area numbers than cannot be broken.  It gives you numbers that are recommendations to try to avoid port compression.  Port compression is but one of many factors that need to be considered when designing an enclosure.  Often it is impossible to make everything "perfect" and compromises must be made.  

As far as what makes a port too long, well you have to fit the thing in your box in such a way as to provide good air flow, that's the whole point of using enough port area.  It doesn't matter if your port area is perfect if it results in a port that has terrible obstructions near the ends of the port.  Also there is such a thing as too long of a port,  for myself I try to keep ports under 44" in total length for car audio purposes so as to avoid pipe resonance issues.  This is like everything else though and is just one of many factors that must be considered for a box design and sometimes going longer than 44" is just fine.  

[CstrokerV]

9 hours ago, akuma4u said:

Damn thats what i thought. Regarding triticums port calcualtor... U r not the first person to tell me its flawed. I dont have the tools needed to build boxes so i send my designs to builders and they build for me. A few times i did use his calculator and of course made a huge port. Every one of the builders would stop and wouldnt build the box cuz they said i was using way too much port area. I would have to convince them to do it. One bix i have sounds ok however that is using like 18sq in a cube and is still close to manufacturers recommendations. I have never been able to build an optimal port according to his caluclator. The port will be massive! Im trying to do a test box and test this optimal port out and see if it really does deliver.

 

Im curious to know what flaws you have found?

ive used 24 sq inch per cube before didnt have a problem got loud and low huge ass box though lol oh wait never mind cant divide lol it was 19.2 lol

[akuma4u]

50 minutes ago, Triticum Agricolam said:

Yeah that's not going to work out well.  If you could draw a picture of what you are trying to do, we could probably help point you in the right direction.  

In general, you want at least two port widths of space between the end of the port and another panel.  When I say "port width" I mean whatever is the smaller dimension of a slot port.  For example if the slot port is 3" x 10" then you are going to want 6" (3" x 2) of clearance.  

Also, my port calculator isn't meant to give you concrete port area numbers than cannot be broken.  It gives you numbers that are recommendations to try to avoid port compression.  Port compression is but one of many factors that need to be considered when designing an enclosure.  Often it is impossible to make everything "perfect" and compromises must be made.  

As far as what makes a port too long, well you have to fit the thing in your box in such a way as to provide good air flow, that's the whole point of using enough port area.  It doesn't matter if your port area is perfect if it results in a port that has terrible obstructions near the ends of the port.  Also there is such a thing as too long of a port,  for myself I try to keep ports under 44" in total length for car audio purposes so as to avoid pipe resonance issues.  This is like everything else though and is just one of many factors that must be considered for a box design and sometimes going longer than 44" is just fine.  

Hey,.. so basically i have a box right now which i used your calculator for and i got minimum port area required.. its 2 cubes and 34hz and has a 3.25 inch wide port.. im using a sundown sub a u series 12 and giving it 2000rms. it sounds ok.. but i was wondering if i could get MORE output from it. so i called sundown. Their tech suggested since im overpowering the sub (its a 1500rms sub) they said i should go smaller on the box 1.75net and tune a lil higher and use 24 to 28sq inches of port area,, this way i can put MORE power to the box and get more output using a smaller box. so i had a test box built and im picking that up tomorrow. it actually has 21 sq inches of port area.. i had a discussion with the EMF audio guy about this and he told me to go smaller on the port area as it will give me a wider bandwidth and better roll off above and below port tuning frequency.. i actually told him about your calculator and he said some stuff about how the big port would be good for SPL but not for music heres what he actually said:

"Appropriate port area depends on the tuning, volume, usable bandwidth, and motor force. A bigger port area will narrow your usable bandwidth as you can't stray too far above or below tuning without reaching mechanical limits. For SPL applications that doesn't matter, for musical applications it does. While you might gain 0.5 dB at a peak you may lose the ability to keep a linear response and you may not be able to play below tuning at all where a smaller port area you could play 8-10 hz below tuning and be fine. Motor force is a factor because of the Qes. A higher Qes will control movement on it's own without relying on the enclosure as much. A bigger port reduces mechanical control from the enclosure."

 

"compression does happen before being audible, but that just means the port becomes less efficient. The concept is right for maximizing SPL, it's bad for music"

 

"I would do 24 sq in of port area. I'll give general specs, I will not do designs. I did look at that link you provided and I find there to be some issues with calculation, like not figuring in displacement in any form. Power alone will yield very different results of pressure in the enclosure which ultimately makes the port resonate to have compression to start with."

 

anyhow... i build a box based on what he said, 12 sq inches a cube,. and i wanted to build another box with as close to optimal of a port as possible as per your calculator which btw doesnt even work for me right now i dunno what happened... maybe take a peek it seems like its broken? , so ya when i tried to build a 1.75net with my MAX dimensions which are 13.5 tall x 32 wide x 17 deep, the port was coming in like at 40 inches or so and it was leaving like half an inch of space between the end of port and side wall. so i couldnt get it to work out.

 

so NOW, i guess i have to go for a smaller port..or as big or one i can fit in my max dimensions and keep a 36hz tuning while keeping 1.75net..

 

sorry no drawn diagrams ive just been using Torres to design at the moment..

 

 

 

 

[Joshdashef]

36 minutes ago, Triticum Agricolam said:

. . . .
In general, you want at least two port widths of space between the end of the port and another panel.  When I say "port width" I mean whatever is the smaller dimension of a slot port.  For example if the slot port is 3" x 10" then you are going to want 6" (3" x 2) of clearance.

. . . .  

Not to divert from ops topic, but what’s the impact of going between the port width and double the port width or more of clearance from a exterior panel and the port wall? 
 

I always figured a bare minimum of the port width would be needed, and anymore wouldn’t effect anything.