Open Baffle woofer what is important?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.

My audio buddy built u-frames with 2 Emince Beta 15 A in each frame. We measured FR with REW and he is getting bass more or less flat down to 30Hz without any EQ. He previously had magneplanar tympanis and acoustats in the same smallish room and I always found them a bit boomy. Be obviously he has some serious room gain around 30hz that just happens to offset perfectly the roll off of his u frame. Good luck rather than good management!
 
I think Vas has in itself less relevance in OB context, because Vas is a measure of equivalent air compliance that determines the a driver + enclosure Fs and Q. For OB, there is no enclosure.

Vas is given by the driver's stiffness and the latter is linked to the driver's Fs via it's mass. In the context of open baffle, it makes more sense to look at things from Fs and Qts perspective.


Bzfcocon, Vas as such may be irrelevant in OB, but since Vas is a direct function of stiffness (rather of compliance, which is reciprocal of stiffness), would Cms not be a factor to consider as far as how EASILY the driver would reach Xmax? For eg: if Cms for a given driver is quite high.. it might reach Xmax at much below required SPL.

Am i thinking on the right line?
 
... he is getting bass more or less flat down to 30Hz without any EQ. He previously had magneplanar tympanis and acoustats in the same smallish room and I always found them a bit boomy. Be obviously he has some serious room gain around 30hz that just happens to offset perfectly the roll off of his u frame. Good luck rather than good management!
I had a similar experience with a very large OB baffle.

Many members here are keen to be free of box sound and enhance the ambience and are pondering OBs. (See the discussion about ditching spatial localization in The Lounge forum.) But they are worried about the emanations from the rear of the drier sneaking around and annihilating the front emanations.

With an OB, you can install a driver with a low resonance and - unlike sealed boxes - it doesn't change. So you might be getting a boost in output at say, 25-35 Hz, just where you might like to hear it.

Hardly any "room gain" worth mentioning except in hermetically sealed cars. However, rooms have eigentones. But it depends on your seat location and the speaker location as to whether that will add or subtract at a given frequency. I think we notice the add-places more.

B.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.