Rerurn to Romy the Cat's Site
In the Forum: Horn-Loaded Speakers
In the Thread: Deep End DIY - Australian take one Macondo.
Post Subject: TSP relatedPosted by martinshorn on: 8/31/2017
Hi Anthony. No miracles. Round shapes happen to be far more rigid than flat. That will also increase the pressure on the flat opposite plate, which has to be of quadruple stability. You can easily eliminate this by the so called impulse compensation of installing one more driver on the opposite of the pipe. Alternatively a long rigid metal bar tension connecting plate and magnet.
Anyhow this is less a wall instability interference, but rather a reflection. At 180 cycles lambda/2 equals about 3 feet. Stuffing eliminates that pretty good. Long layers in small closed cabins let the standing wave decrease way more than the free field absorband spec assume. Especially that absorbency of 0.3 are sufficient already.
Stuffing influences TSP easily predictable when u check via TSP calculator playing with your given cabine size multiplied by 1.1 or 1.2 up to 1.3 for heavy stuffing (proven to be most common values). How much it lowers the fs depends on the VAS, meaning indirectly the suspension stiffness. If you got low VAS, like 50 or less, it wont influence much anyway. But it gets you Qts down which may look like a hipass, but actually just lowers the knee of the filter while increases xcursion on the subsonics. Still a highpass second order, just lower Q.
A little side note from my side: i happened to find the Sound more boring and tired when stuffing, though the measures are better. Cant explain why. Id rather try to avoid stuffing but stay away from the resonance with my passband. Alternatively use little stuffing only which decreases the ringing already dramatically (ideally in the middle of the pipe just a piece of foam, most efficient in the middle!).
Cheers, Josh Rerurn to Romy the Cat's Site