Karlson-ized port patent

[freddi]

for NEXO

https://patentimages.storage.googleapis.com/pdfs/4bc54951ae7cf8988ea3/US20150222984A1.pdf

I could see that working in something like my old RJ (18") where the inner two ports would have the cut

 

[Snickers-is]

I get a kind of feeling that we are reading this patent differently?

 

[freddi]

my RJ above has two fairly long shelf vents - one at the top and one at the bottom of its rear chamber, which feed the front "port". The patent's "V" cut port may be mainly appropriate for some regular bass reflex cases (?)

 

[Snickers-is]

Well, the way I read it is that this is supposed to solve two main things.

First of all, the cut in the port is supposed to reduce the standing waves in the port. This seem to work pretty well, and I believe it works the same way pretty much on your sub as well.

Secondly, if you look at the product drawing, they get a relatively linear output from the ports, but it is out of phase, and slightly delayed. With this placement of the ports, it gives a dispersion control to the speaker from the ports.

The really bad thing with this idea is that if you use it at low frequencies, they will get an extremely high velocity of air at the most narrow point. This will give turbulent noise. Even cutting a standard port at an angle can cause heavy noise compared to cutting the same port straight.

 

[freddi]

I've V-slotted a small round duct years ago and as expected it "wheezed" - (will have to read the patent) - is there enough info to start some empirical work? - wonder what the effective length of a V-slot shelf might be? is there a standard guesstimate?

I don't play much with reflex but it could be interesting with light cone midbass speaker.

for a small 20Hz tuned sub (cheap 12" speaker) I have a tapped pipe - if driven hard with sine then it would have some
turbulence - it seems ok with music

this is before it got a finish coat - its was built by Triticum Audio