Need advice on subwoofer freq. response measurement

[JasonB]

I have built a small subwoofer and would like to measure the actual response to see how close I am to the modeled response. Is there a way to take measurements indoors without room effects? I will be using Radio Shack hand held meter and a test tone CD and all my results will be adjusted using the correction values for the RS meter.

Thanks,

Jason

[PMazz]

Doing a nearfield measurement (hold mic right in front of the driver) would get you close. At least pull the sub out from a corner.

Pete

[ThomasW]

To expand a bit on what Pete posted. Nearfield you hold the meter about 1" in front of the dustcap. That will tell you what the driver is doing.

If the box is ported (you didn't provide specifics) then things get a bit more complicated.

[Nichol1997]

To expand a bit on what Pete posted. Nearfield you hold the meter about 1" in front of the dustcap. That will tell you what the driver is doing.

If the box is ported (you didn't provide specifics) then things get a bit more complicated.

I want to measure a subwoofer as well. It is a ported enclosure. Do you do two nearfield measurements, one in front of the dustcap and the other in front of the port and then just take the higher of the two at that particular frequency and graph it?

[JasonB]

The box is ported and the port is on the front of the box. The port is 2 1/4" away from the frame of the driver. If I take measurements with the mic between the port and the driver how far out from the baffle should I place it?

Thanks again,

Jason

[ThomasW]

Nearfield ported = 1 measurement 1" from dust cap, another measurement at the port . Now add them together. This isn't the best way but it will get you started.

A better way is with a PC that has a duplex soundcard and a freeware program like Room EQ wizard.