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ports and grills [message #34973]

Mon, 04 February 2002 06:12

uW
Messages: 14
Registered: May 2009

Chancellor

If I'm going to allow aesthetic concerns to overrule best engineering practices and use an inset front board covered with grill cloth,

1. Will the grill cloth have a showstopping effect on the port?
2. Does it make sense to shorten the length of the port to account for the thickness of the front board?
3. Can I get around consideration 2 by sizing the front board hole diameter larger than the port diameter? If so, any guess as to by how much?
4. Or are all of these things relatively minor concerns, once I've already set my stubborn head to build speakers with a front board?

Thanks very much,

-uW

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Question for wayne about ports [message #34974 is a reply to message #34973]

Mon, 04 February 2002 06:56

Garland
Messages: 269
Registered: May 2009

Grand Master

I thought I'd jump in here with a related question. I routed a 3/4" radius on the mouth of my 3.5" port in my Theater 4's. Is this OK?

Thanks!

Garland

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Re: Answers about ports [message #34976 is a reply to message #34974]

Mon, 04 February 2002 10:56

Wayne Parham
Messages: 18783
Registered: January 2001

Illuminati (33rd Degree)

Ports with radiused entry and exit help reduce turbulence through the port. In general, I think I prefer having a larger port so that airspeed isn't excessive in the first place. But it certainly doesn't hurt to radius the ends, and sometimes looks cool. It will usually raise the Helmholtz frequency slightly compared to a straight port with no radius.

You can put a grille over the port, but again, one should concern themselves with port airspeed and the possibility of choking the port. About the width of the front baffle and what effect it has on port length, the port length should be considerd to be the distance from entry to exit. If the port is glued on the back of a 3/4" baffle, then consider it to be 3/4" longer. Total length is all that matters, not what materials are used to make the duct.

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