does anyone use subwoofers in their setup?

[thumb5]

A question on the subwoofer experts regarding properly setting up delay to ensure acoustical phase.

If my SW is located 11.4 feet closer to my listening position than the main speakers, then I will need to delay the output to the SW by 10.08 millisecs (11.4 feet divided by 1.13 feet per millisec) to correct the timing between the mains, sw, and listening position.  I will also need to subtract the processing time of the sw dsp (1.5 millisecs per manufacturer) from this amount to arrive at a revised total delay of the subwoofer preout by 8.58 millisecs.

Is my thinking correct?

That's my understanding too.  Lucky for you that the manufacturer can tell you the delay through your sub-woofer.

I don't think I have that information so am trying to work out how it can be measured - if anyone can share any hints and tips that would be most helpful.  (I have FuzzMeasure and REW so I expect it must be possible using those tools, but if I can avoid working out a method from scratch for myself that would give me more confidence that I'll get the right answer!)