I'm building an open baffle speaker based on Martin King's design on quarter-wave.com. I'm using an Eminence Alpha15 woofer and a Mark Audio Alpair12P for the midrange. For the crossover, I've used values for the components that match up to the Fostex 108ESigma as they most match up with the SPL of the ALpair drivers. (I've built this design with Tang Band 2145s and it worked great) I would like to add a GRS PT2522 planar magnetic tweeter crossed over at 3K hz to the design. I've made a rough schematic of the crossover. Can you let me know if I'm on the right track? Please be gentle, I'm a complete noob.
Thanks guys, that actually helps a lot. I'm brand new at this and knowing there are no glaring errors is good to know. Next steps are buying a PC so I can run windows and then get XSim to simulate the crossover. The good news is the lower portion of the crossover was designed by Martin King, so at least that part I know is solid!
Which drivers will be OB? OB will get strange in the measurements. Don't assume the filters shown will measure like the sim. You need to be able to measure everything, and then it can be a struggle to figure out what to do in the x-over.
I don't know if you are on a Mac or not but you mentioned getting a Windows computer to run XSim? If on a Mac, that may not be necessary as I've had great results using Kegworks Winery to run both WinISD and Hornresp on my M3 MacBook Pro. Haven't tried XSim but a quick search did turn up folks who have done it... YMMV/FWIW. When I need full Windows compatibility I use Parrelles and have Windows 11 pro arm installed. Works a treat...
Sorry if you don't have a Mac and this is just clutter on your tread...
Sorry if you don't have a Mac and this is just clutter on your tread...
I would do a actual simulation of the drivers on a open baffle, which will include the off axis measurements.
Driver position and resulting phase need to be correct.
Actually about 5 mins with the open baffle box selected will introduce you to the reality of " dipole"
Driver position and resulting phase need to be correct.
Actually about 5 mins with the open baffle box selected will introduce you to the reality of " dipole"
My pleasure. Remember, it is a simulation without the *.zma nor *.frd files, useful to have an idea but still a simulation. I'm also building an OB, the XO is a hard nut to crack, but nowadays "easy" with the help of computers and this forum. Good luck.
Yes. I'm sure we can get Adam off the ground, but there is more to consider with an open baffle. It's not the first speaker I'd expect a newcomer to take on, though many have and succeeded.
The response falls as the frequency goes down since it cancels around the baffle. Because of this, the frequency you choose for the lower cross sets the levels so you have to juggle both factors at once.
Here's another thread for the reading list 😉
