Home » Sponsored » Pi Speakers » Alternate port shape for Four Pi cabinet (What problems arise from 2 round ports instead of 1 rectangular port? )
Alternate port shape for Four Pi cabinet [message #88308] Tue, 03 July 2018 10:48 Go to next message
tubino is currently offline  tubino
Messages: 13
Registered: May 2009
Chancellor
The Four Pi plans show a single rectangular port of 3.5" x 6", or 21 sq in cross-section. An equivalent area round port would be 5.2". (If Pi*Rsquared - 21, r= 2.59, d = 5.2)

If I wanted the equivalent in two round ports, I calculate 2 ports of 10.5 sq in area, or diameter of 3.66" each. That's close to 3 5/8" inside diameter.

Does anyone see a problem with those numbers? Does anyone see a problem with using two round ports adding up to the same cross-section as the original?
Re: Alternate port shape for Four Pi cabinet [message #88311 is a reply to message #88308] Tue, 03 July 2018 14:20 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)

Look at the following two threads:
In the second thread, there is a modified design that was tested and so I feel comfortable with it. The builder's name is Nick, and he used two round ports. You might scroll to the beginning of that thread and read all about it.

The issue isn't so much the Helmholtz frequency, although that is important, of course. But that's the easy part. The hard part is making sure the standing waves line up right, and that we don't get a pressure node lined up with the driver or port.

Re: Alternate port shape for Four Pi cabinet [message #88321 is a reply to message #88311] Wed, 04 July 2018 06:16 Go to previous message
tubino is currently offline  tubino
Messages: 13
Registered: May 2009
Chancellor
Thanks, Wayne! I'm reading through the threads carefully and will go with a proven design.
Previous Topic: Eminence H290B vs. H290C vs H290S
Next Topic: 7Pi Plans request
Goto Forum:
  


Current Time: Thu Mar 28 10:58:36 CDT 2024

Sponsoring Organizations

DIY Audio Projects
DIY Audio Projects
OddWatt Audio
OddWatt Audio
Pi Speakers
Pi Speakers
Prosound Shootout
Prosound Shootout
Smith & Larson Audio
Smith & Larson Audio
Tubes For Amps
TubesForAmps.com

Lone Star Audiofest