Fane 18XB 200l box design and modifications

Hi all,

I'm planning on building the Fane 18XB standard 200l design, found in the link below.

It'll be my first build and I'd like to make some slight modifications to the cabinet so it'll fit a little nicer with some other cabinets that I plan on building. I was trying to model it in in WinISD to help me with this but a I came across some strange numbers when modelling the original.

The actual plans state 4 ports of 108mm to obtain the tuning frq of 35hz whilst WinISD suggested the ports should be 310mm, slightly confusing... I'd rather go with Fane's designs as I'm sure they're tested I think but can someone explain whether I've missed something here or if it's just a quirk of the software?

Also is there anything that I should bare in mind about making the box slightly larger? Is it enough just to make the ports slightly shorter to keep the tuning frq the same relative to the increased volume?

Any help would be much appreciated.


From dim memory WinISD can't accurately calculate the vent's pipe end correction that shortens the basic single pipe 2pi space's 0.732r, so summing four and possibly factoring in that its vents are < 4" dia. i.d.can make a huge difference. Also, tuning/Fb isn't spec'd, just a 35 Hz low BW, so could be as much as a -24 dB cutoff.

What's the pipe's i.d. dim. and cab's net Vb with 4" o.d. pipes so we can view in HR?
Thanks GM!

Appreciate the response. That's interesting, I didn't realise I was looking at just the low BW limit at 35Hz rather than the f3.

The box that I'd use would be ~240lt and the pipes that I have have an i.d of 99mm, (3.89"), length of 111mm but I'm happy to cut these down to tune. I'm hoping to get the f3 down to about 35Hz, so also happy to just use two ports if that'll help me get down to that. Do you recommend HornResp over WinISD then?