Subwoofer design question

Kepler

Member
2004-10-13 8:10 pm
I'm using winisd to size a box for a subwoofer.

I'm looking at two possibilities:

1. Flat spl/fr curve response from crossover down to ~21hz where it drops like a rock with cone excursion exceeded at ~18hz

2. spl/fr curve drops ~1.5db/10hz starting around 55hz down to ~25hz and then drops fast, cone excursion exceeded at ~22hz

The sub will be vented. Case number 2 has a higher max. spl than case 1. Something like 106 vs 101.

My biggest concern was if the fr curve is level all the way down to ~20hz, will it sound boomey when you factor in the room response below 45hz or so. I used the room mode spreadsheet from FRD, but I'm not sure how to interpret and apply the data to the sub design. From what I gather, there is a peak around 40hz, ?magnitude.

Any feedback is greatly appreciated, as I'm hoping to start on it this weekend. :)

thanks,
Brady
 

ruerose

Member
2005-08-28 5:49 am
Where in WinISD does it show cone excursion? I was looking for that feature but couldn't find it.

on topic, if you design your sub flat, with no major peaks in the slope, you can compensate for any room modes (boominess) with moving your sub to different spots of the room, or adjusting your seating position. If you have a really bad room, it will be difficult to design a sub to compensate for it.
 

Kepler

Member
2004-10-13 8:10 pm
No the box sizes are different. Case 2 has a smaller box size.

Case 1 tuning was around 20-21hz. I think case 2 was about the same, I'll check when I get some time a little later today to make sure.

thanks

ps The sub will be sitting in a corner next to a couch with the driver and vents facing out into the room. I don't have the option of moving it around the room at this point.