Port tuning

[SMKSoundPro]

Dear Friends,

In my 4735 style of box, I am trying to tune the box and I found that the factory SR4735a is tuned to 45hz. I thought it would be closer to 40 or lower. I am using the "feel the cone movement" method.

Here are the box measurements: A= 33"; B= 21.5"; C= 13.5"

I am trying to include the "box" "driver" and Plot info and do not understand how to share those "pictures." Any help?

I am guessing that 40 hz would be a good place to start the tuning. The port is 6". I feel kind of lost here. The driver is a 2226G.

Help, please!

Scott.

[SMKSoundPro]

Now, without duct length, I am at 48hz. Nw I will add duct.

3" duct now at 40hz.

okay, doesn't sound too bad. Nice wet kick drum...thump, thump.

scotty.

[duaneage]

Final tuning must be done with the low pass coils in place or it will be off. The resistance in the coils requires the box to be slightly oversized.

If you have a voltmeter calibrate it for reading volts as ohms with a 10 ohm resistor that is spot on. Then you can determine F1, F2 and Fb as well as the min max Z for the system.

[Ian Mackenzie]

I had quick look and estimated the volume at 5 cu ft 3 with the dog box for the mid cone with some fibre glass on the walls

Plugging that into Bassbox tuned to 45 hertz looks like the best place to tune. 40 hertz is too low .

So use 1 1/2 inch long port 6 inches in diameter. I would not bother attempting to measure it by hand. If your internal volume dimensions are reasonably accurate the program is very reliable