Speaker modeling software

[ogp]

I am trying to model some speakers with software. So far I have tried WinISD and Unibox. I have one question concerning both of these and speaker modeling software in general, I guess. When you are designing speakers in these, it doesn't seem possible to add multiple drivers of different kinds/brands. Just multiples of one type of speaker. So in a two way design, is the tweeter not essential to the size of the cabinet? It seems logical that in a three way design that the midrange driver would contribute to the size of the enclosure. Am I thinking about this correctly, or am I using the wrong software? Are these programs specifically written for subwoofers or something? If someone could correct me or point me to easier, more effective software that is freeware/shareware it would be greatly appreciated. Thanks alot.

Dave

 

[Super]

Not sure about Unibox, but WinISD is a subwoofer design tool.

 

[GRollins]

Dave,
Nearly all tweeters are totally enclosed, so the volume of the cabinet is irrelevant to them.
Treat mids as a separate cabinet, built within the larger one. Plan it out--at least the volume--as though you were designing it as a stand-alone enclosure. That way you'll get optimal performance from the driver. Note that there is a fringe benefit, in that back pressure from the woofer will not modulate the mid cone, reducing distortion and other sundry nasties.
Woofers, of course, get the lion's share of the volume of the enclosure, but since the mid-range driver is in it's own space and the tweeter is self-contained, it also will be treated as a separate design problem. Just be sure when building the cabinetry to compensate for the volume that the mid enclosure takes up.

Grey

 

[Eric]

If you build a vented speaker (bass reflex) also be sure to account for the room taken up by the port. The numbers that WinISD will provide for you are NET volumes. When you build the actual enclosure, your GROSS volume will include the net volume that the actual driver needs to operate, plus the volume of the port, plus the volume of your midrange enclosure.

For example, WinISD tell you that for a specific woofer, you need to have 50 liters of volume for it to perform optimally. If the volume of the vent you use for a bass-reflex design takes up another 10 liters, and 15 more are taken up by the enclosure for your midrange, your final speaker enclosure needs to be 50 + 10 + 15 or 75 liters total.

 

[ogp]

thanks for all the replies. I have one more question regarding a three way speaker though. According to GRollins, you "treat mids as a separate cabinet, built within the larger one". When you actually build the speakers, do you have to enclose the midrange? Or is this only useful for calculating cabinet volume? Thanks for clearing me up on this issue.

Dave

 

[Eric]

YES! Enclose the midrange to seal off this space from the space used by the woofer. Otherwise the two will interact and cause all sorts of undesireable effects!