Port design flange question

TheoM · 31st October 2003, 06:26 PM

Anyone. How does the flange impact a port length. Does the design length stop where the flange begins, or do I count the flange area?

Also, I have a situation where the port is close to the driver. Its a 4" x 2" port. Do I need to block the area between the rear of the port and the rear of the driver? I'm concerned about phase cancel.

Nuuk · 31st October 2003, 08:09 PM

Quote:

Anyone. How does the flange impact a port length. Does the design length stop where the flange begins, or do I count the flange area?

In short - it doesn't really matter!

Quote:

Also, I have a situation where the port is close to the driver. Its a 4" x 2" port. Do I need to block the area between the rear of the port and the rear of the driver? I'm concerned about phase cancel.

In theory, you are right to question this but I have heard a number of great sounding speakers with the port adjacent to the woofer with seemingly no ill-effects!

Personally, I prefer to keep the port as far from the driver as possible and after experimenting, I now prefer putting the port on the bottom of the speaker.

TheoM · 2nd November 2003, 06:52 AM

I'm sensitive to phase alignment problerms. I always put the port in the same plane as the driver. I think this improves the impact of low end. But.... this is one man's opinion. Punch. I like it. tvm

roddyama · 2nd November 2003, 07:15 AM

Quote:

Originally posted by TheoM
Anyone. How does the flange impact a port length. Does the design length stop where the flange begins, or do I count the flange area?

FWIW, my Bass Box Pro shows a ~5% length reduction for one end flared and ~10% length reduction for both ends flared (length includes the flare).

Quote:

Originally posted by TheoM
Also, I have a situation where the port is close to the driver. Its a 4" x 2" port. Do I need to block the area between the rear of the port and the rear of the driver? I'm concerned about phase cancel.

No, you don't need to block off the port from the driver inside the box. The air in the port will resonate at it's tuned frequency providing the proper low frequency output. The ports output is out of phase with the driver by design.

31st October 2003, 06:26 PM	#1
TheoM diyAudio Member Join Date: Mar 2003 Location: Ohio	Port design flange question Anyone. How does the flange impact a port length. Does the design length stop where the flange begins, or do I count the flange area? Also, I have a situation where the port is close to the driver. Its a 4" x 2" port. Do I need to block the area between the rear of the port and the rear of the driver? I'm concerned about phase cancel.

2nd November 2003, 06:52 AM	#3
TheoM diyAudio Member Join Date: Mar 2003 Location: Ohio	Port location and phase alignment I'm sensitive to phase alignment problerms. I always put the port in the same plane as the driver. I think this improves the impact of low end. But.... this is one man's opinion. Punch. I like it. tvm

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