akuma4u Posted September 27, 2016 Report Share Posted September 27, 2016 Hey just wondering the following. What happens if you use less sq inches of port area than whats recommended by the manufacturer? For example if they say use 32 sq inches but you have 28 sq inches. Conversely, what would using more port area than recommended cause? Thank you Link to comment Share on other sites More sharing options...
ckeeler11 Posted September 27, 2016 Report Share Posted September 27, 2016 Port compression which robs you of output and can also cause chuffing. Link to comment Share on other sites More sharing options...
akuma4u Posted September 27, 2016 Author Report Share Posted September 27, 2016 Ah i see I did some forum research on this and one member said using less port area would increase bandwidth? Link to comment Share on other sites More sharing options...
akuma4u Posted September 27, 2016 Author Report Share Posted September 27, 2016 LoudNLow931: Ive always been a fan of smaller port area/less port per sq in, can play a much wider range. Even though im tuned to 23hz i can play 10-50hz no problem. Link to comment Share on other sites More sharing options...
ckeeler11 Posted September 27, 2016 Report Share Posted September 27, 2016 hmmm new to me. changing port length affects bandwidth. The longer the port the lower the tuning. the lower the tuning the flatter the response. Higher tuned boxes tend to be more peaky which is why SPL boxes are tuned into the forties and SQ boxes in the 20's. Link to comment Share on other sites More sharing options...
mothra Posted September 27, 2016 Report Share Posted September 27, 2016 I've had verbal arguments on several night about sq in per ft^3, mainly DD guys argue the sq in per ft^3. I've had guys tell me several times that my ports are too small yet when people hear those boxes I always get told how awesome it sounds on "da lowz" and how much air it moves. I'm all about port velocity and not tuning above 32hz. there are several other factors that come into play but when it comes down to it. if you don't tune low and have a port velocity between 25 and 30 m/s it won't matter anyways. if nothing changes, nothing changes You don't know what you don't know, till you don't know Link to comment Share on other sites More sharing options...
akuma4u Posted September 27, 2016 Author Report Share Posted September 27, 2016 Extending or reducing length and its effects on tuning i understand. But using a smaller or larger sq inch port area i dont. In my case the manufacturer says 32 sq inches but my design came out to 30. The only way to fix this is by increasing the port width by 10th of an inch I dont want to do that really. Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted September 27, 2016 Report Share Posted September 27, 2016 LoudNLow931: Ive always been a fan of smaller port area/less port per sq in, can play a much wider range. Even though im tuned to 23hz i can play 10-50hz no problem. This person isn't entirely wrong, but they don't understand how ported boxes work either. Like others have said, undersizing a port can cause port noise and port compression, which robs you of output. An undersized port also increases cone excursion. If the subwoofer would otherwise have peaky output around tuning, undersizing a port COULD flatten out the frequency response. However its only going to work at max volume, where port velocity is the highest, and its a really terrible solution to a peaky box problem. Its like purposefully undersizing the exhaust on your car so you stop breaking the tires loose in 1st gear. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted September 27, 2016 Report Share Posted September 27, 2016 Extending or reducing length and its effects on tuning i understand. But using a smaller or larger sq inch port area i dont. In my case the manufacturer says 32 sq inches but my design came out to 30. The only way to fix this is by increasing the port width by 10th of an inch I dont want to do that really. That's probably close enough to ther recommended amount its not going to make a big difference, unless you are pushing way more than rated power to the sub, then you may have issues. Also, you asked what happens if you have more port area than recommended, the answer is nothing happens. You just take up a little more space in the box. Until ports get ridiculously huge there really is no bad side effects. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
akuma4u Posted September 27, 2016 Author Report Share Posted September 27, 2016 Ah i see ok thanks for the insight. Im starting to learn more about box design and i really got to say that torres box calculator has helped me learn a lot. The only thing i wish i could do is learn how to plot the curve graphs. I tried on winisd but i dont have all the input data for the sub and dont know what many inputs mean. Can you help show me some curve graphs for the zv3 12. 2000rms 1.75 net 32hz 2000 rms 1.9 net 32 hz 2000 rms 1.75 36 hz 2000 rms 1.9 36 hz Many thanks Link to comment Share on other sites More sharing options...
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