[gitarretyp]

How top-heavy are they? I have an 8 month old daughter who'll be crawling soon and eventually walking, and I'm concerned that building open baffle speakers may create something that's easier to tip over.

What is the audible effect of the foam? It looks like the gray strips are glued to the side panels, while the white pieces are stuffed in there?

You could knock them over, but it would take a decent push. If you're worried about stability, you could make the base deeper.

The stips and foam provide acoustic damping for the u-frame, making the response more cardioid in nature. This site gives a more thorough explanation, as well as some general theory concerning dipoles.

[Saurav]

Thanks. I've thought about a deeper base, but unless I extent that out in front of the baffle, I'm not sure it'll help with tipping forward. I'll probably have larger woofers closer to the floor, which should help. Probably the best thing to do is to build a mock baffle and then see what kind of base it needs.

[gitarretyp]

Thanks. I've thought about a deeper base, but unless I extent that out in front of the baffle, I'm not sure it'll help with tipping forward. I'll probably have larger woofers closer to the floor, which should help. Probably the best thing to do is to build a mock baffle and then see what kind of base it needs.

Yeah, you'd need to extend the base forward for more stability. I'd build a mock-up out of cheap plywood or mdf to check stability. You should build test baffles to test responses anyway.

[gitarretyp]

I've made some revisions. I've improved the coolness of the tweeter and greatly improved the integration between the mids and woofers. I think i'm done at this point.

Gated response at 36" in 15 degree increments. White curve (30 degrees) is listening axis.


Ungated response at listening position

[D OB G]

Hi gitarretyp.

Looks very good!

With the GR Research M165X woofers having an Fs of 40 Hz, what do you think is giving the very low freq response?

The graph could be read as having a -3 dB point of 40 Hz, with low freq measuring artefact below that???

David

[gitarretyp]

Hi gitarretyp.

Looks very good!

With the GR Research M165X woofers having an Fs of 40 Hz, what do you think is giving the very low freq response?

The graph could be read as having a -3 dB point of 40 Hz, with low freq measuring artefact below that???

David

David,

I have the 165s high passed at 75Hz LR4 acoustic and Dayton RSS390s taking over below that. The 40/50Hz dip/peak is very location sensitive, so i didn't want to use a bunch of eq correcting something that would essentially average out if i measured at several locations near my listening seat. For example, see the listening position measurement in my first post. The sub 75Hz settings have not changed between those measurements, but the mic position is slightly different.

[D OB G]

Hi gitarretyp,

Fair enough! (as we say in Australia).

David

[Vapor Audio]

I don't get it ... is the tweeter firing through the dustcap?  From what I can tell that driver has a 1" compression driver, firing through the dustcap is all I can guess?  The response looks pretty decent, I'm guessing all the higher end bumps are from diffractions inside the driver itself, they're too high in frequency to be baffle end diffractions.  If all my assumptions are correct, you could probably realize some gains by removing the dustcap and trying some thin felt inside the pole area.

[gitarretyp]

I don't get it ... is the tweeter firing through the dustcap?  From what I can tell that driver has a 1" compression driver, firing through the dustcap is all I can guess?  The response looks pretty decent, I'm guessing all the higher end bumps are from diffractions inside the driver itself, they're too high in frequency to be baffle end diffractions.  If all my assumptions are correct, you could probably realize some gains by removing the dustcap and trying some thin felt inside the pole area.

Yes, the CD is firing though the "dustcap." This approach is pretty standard for prosound coaxial designs --reliability issues most likely. The dustcap is not your standard hard paper cap; it's more of a stiff fabric. Removing the dustcap has crossed my mind and would likely result in reduced diffraction above 3-5kHz as you suggest, but i'm a little hesitant to perform this surgery since i'm not sure what overall effect it would have on the driver --not to mention concern over damaging the cone.

As a little teaser, this project has morphed a bit. I received a quartet of AE IB15 to use in place of the M165s and my subs last week --i talked my significant other into allowing somewhat larger mains in lieu of mains and subs. In their current test baffles, i'm getting solid output to below 20Hz with minimal EQ . I'll post more on this project once i build the final baffles and get some final measurements --hopefully in the next couple of weeks.

[kyrill]

thx for posting yr wonderful looking OB
I am wrestling with a good looking OB design with a high waf
but yr design will find probably a home in my home

Kyrill