Want to kow the tuning freq of a vented box.

[ostie01]

HI, would like to know how can I measure the tuning frequency of a particular bass reflex box that is already built. which testing should I do. I have a woofer tester II from Dayton but not sure how to use it and how to read the result I'm going to get.Should I put the woofer in a seal box first to get some measurments and compare them with the woofer in my real design.I know how to get parameters from a raw driver with my woofer tester but not sure how to do this with the final design. I also have the harris tech bass box pro 6 but again, not sure how to use it when the box is done.My woofer is an Eminence Omega pro 15 in. 800watts in a 5.5 cubic feet with a 2 X 15 vent approx 6 in long. Fs is 39 Hz. What could be the best tuning frequency for this woofer, below or above 39 Hz. As always many thanks

[simon5]

To know what's the tuning frequency, just measure the impedance. You'll reach an impedance low at the tuning frequency.

[noodle_snacks]

http://www.bcae1.com/spboxad3.htm

outlines how to measure impedance, low voltage = high impedance. you need to find the low point of the impedance between two peaks either side of the vent tuning frequency. Follow the method on that page to do so. Attached is a picture of the point you actually want to find.