Hi. I try to build for myself a sub enclosure that plays around 20ish to 40hz with the possibly best SPL and a total volume of max 600 liters. I tried some builds on hornresp for a 6th order bandpass series enclosure and got two portlengths. Hornresp has one-sided flared ports and suggests me "port end" corrections. I tried to look up on google and on the help-window of hornresp itself without any explanation of what this port end correction is supposed to be and on what port geometry hornresp refers.
Can anyone tell me when you apply this port correction and wether you shorten or elongate the port with that suggested amount? I tried once to experiment with a port length of around 2cm but hornresp still tells me to correct it by around 10cm for my 1000cm² (just an example, idk if im right here) portarea. I cant imagine that hornresp tells me to shorten the port into an impossibly negative amount. Although i have never heard of port corrections on winisd to add any aditional length to a port for a tuning correction.
Can anyone tell me when you apply this port correction and wether you shorten or elongate the port with that suggested amount? I tried once to experiment with a port length of around 2cm but hornresp still tells me to correct it by around 10cm for my 1000cm² (just an example, idk if im right here) portarea. I cant imagine that hornresp tells me to shorten the port into an impossibly negative amount. Although i have never heard of port corrections on winisd to add any aditional length to a port for a tuning correction.
If you do a search within the main Hornresp thread here: https://www.diyaudio.com/community/threads/hornresp.119854/, I'm sure it has been discussed a couple of times.
The port end corrections shown in the status bar are for information only, they are not to be applied to your physical build of the enclosure and port. In other words, Hornresp is telling you that the port is acting like it is longer than the length you entered for Lp2 so it has added an end correction to the length before performing response calculations.
https://www.diyaudio.com/community/threads/hornresp.119854/post-6510545
The end correction lengths are a function of the port area and whether that end of the port is in free air or flush with a box wall. Formulas can be found in most acoustic texts. I have attached an excerpt from Leach. Attached also are pictures of Hornresp Sixth order bandpass enclosures(both Parallel and Series) showing where the end corrections are being applied by Hornresp during calculation. Note that there is no length correction applied to the end of the ports that radiate sound. This is because Hornresp uses a more complex radiation impedance model as the external airload on the ports which includes the effect of air moving as a mass near the port opening that the end correction factors are trying to approximate.
