New project: Usher 8137a, T-B W3-1335SB, SEAS 27TAFN. WMTM, open baffle mids.

[augerpro]

Good stuff Javier! I've been silently watching all these OB threads to learn what I can before tackling my own. You might find Rudolph's posts helpful because if I remember right he posted this horizontal polar effect and there was some discussion on how to fix it.

[fjhuerta]

Yes Bob.. you were right! The hump was there, in all its glory.

Ryan, yes, I did move the speaker away from the walls. Unfortunately, my room is not perfectly symmetrical. You can notice in my RTA measurements that one speaker is basically completely flat from, say, 180 Hz on up. The other is a lot more ragged. The flat one is near a corner, the other one isn't. I moved the speakers around until I had the flattest response (on average) from both, and then I started fixing the crossover. That's why I also think the speaker, as designed, can only work correctly in the room I tuned it in. I may be dead wrong (I hope I am), but the experience I've had seems to be that an open baffle needs a combination of careful positioning and slight crossover tuning for the specific room it'll be used in.

Brandon, I'll try to find Rudoplh's posts. What's the name of his design? I can't recall :s Thanks!

[augerpro]

I think he made some comments in Saurav's thread, and some similar posts at diyaudio, on a speaker he was working on. Sorry, that's all I remember.

[BOBinGA]

Rudolf (he posts as "Rudolf") has web site that has a lot of good information for dipoles. It's in German, so start up Google translator:

http://www.dipolplus.de/index.htm

I used a parallel LRC in series with the mid to take out the extra energy. I thought this might be safer since it increases the circuit impedance at that point instead of reducing it like a series LRC across the speaker terminals would. Since your two mids in parallel are already 4 ohms, a series notch filter across them would reduce the impedance into the 2 ohm range, which would be challenge for a lot of amplifiers (although I do see you have a series filter across the mids who's purpose I don't quite understand). Your solution with the added resistance looks like it worked just as well since your peak is centered on your mid's bandwidth. In my case, my peak was a little off center and a little higher Q, so the notch filter worked best to exactly hit the peak.

-Bob