Posted by AudioLapDance [ 216.106.106.8 ] on April 18, 2005 at 09:35:16:
Hi Wayne, hope the spring is finding you well!
I'm trying to figure out what the port of the 2 pi is tuned to. I'm using a spreadsheet with the equations from your Pi Align program. I can thus set the volume of the cabinet and then play with the port length and width to calculate different tuning frequencies.
Working backwards from your 2 Pi plans, I calculated an internal volume of around 1.44 cu ft. Problem is I'm not sure how much you subtracted from this (volume of drivers and ports etc) to get the actual volume.
If I set the volume at 1.25 cu ft then your 1.91" diam x 1.875" port is tuned for 42 Hz. If I set the volume at 1.0 cu ft then your port tunes for 47 Hz. I assume that you calculated the actual volume as around 1.1 cu ft and thus your port is tuned for 45Hz. Is this correct?
As well, given a certain volume I know that different port diameters can be tuned to the same frequency but with different Q. I assume this means that the resonant peak will have steeper or shallower slopes. Did you calculate the port for the 2 pi with this in mind or did you experiment with different diam ports ... or did you just use what you had at hand?
Thanks for the help,
Jeff
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