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In the Forum: Audio Discussions
In the Thread: Macondo’s MiniMe or about Pilot Acoustic Systems
Post Subject: Ports of EntryPosted by Paul S on: 9/14/2008
The Thiels I have heard "load up" considerably as the cabinet is pressurized.  I suppose this is a strategy, but I will say again that I think the best results are when the driver is not pushed to Fs, and certainly the tuning should be well above Fs, IMO.  I think that if you guess right you should not get changing pitch or a tightening of the sound, nor "chuffing", up or down the range.  You might get small ports to work, but you might well fare better calculating a volume that allows somethig like 15% or so of the driver area and a port length that does not exceed 1/2 the depth of the cabinet.  IMO the port itself should be strong/damped, or cardboard, but not bare metal or bare plastic.  Maybe start with a mule; it's a lot less trouble than tuning/turning horns, but as with horns the math model will only get ypu in the ballpark (if you are lucky).  About anything in the port can change the sound, just like adding a little clay in a horn throat.  Laugh, but the "golden ratio" thing seems to +/- work for height, width, depth relationship of cabinet inside measurements.  Felt to taste.

Best regards,
Paul S

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