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In the Forum: Horn-Loaded Speakers
In the Thread: Deep End DIY - Australian take one Macondo.
Post Subject: Such trials are funPosted by martinshorn on: 9/2/2017
hi anthony, have fun with that, results are worth it.
Your findings don't need to match mine but i share my favorite briefly 
I found explanation from an famous german engineer. Hes calculating an Rms thiele small to indicate mechanical friction losses in drivers. He found that some sound tired and boring when having hi loss.Its got common ground with stuffing in my opinion and explained my impression. So if i had your tubes, id stuff a hi density foam disk into the middle of the pipe. Same diameter, maybe 10-20cm max depth. Hi density breaking fragile foam, like 10.000-15.000 density. Which is highly effective, eg sold by BASF as "melamine foam". That could be the minimum damping just to kill the ringing to a neglectable level. Rest of the pipe id keep blank. Also install the foam disk rigid in place not to move under vibration. Just my 2 cents. Was experimenting with a Lowther driver that got very "transparent " membrane and so very sensitive to cases and stuffing. Thick n heavy woofer may react less sensitive. Rerurn to Romy the Cat's Site