Upgrade diaphragm for BA750

There's a whole chicken & egg & coop situation here. The first part of the problem is that the BA750 is, for whatever reasons, not commonly available. The second part of the problem is that the optimal waveguide to use with the BA750 - the SEOS18 - is also not commonly available. Complicating this is the fact that the exit angle of the BA750 and the entrance angle of the SEOS18 is not a great match.

To get the ball rolling on a BA750 diaphragm upgrade, somebody with a BA750 would have to first disassemble it and take precise technical measurements of the diaphragm. Not impossible. These measurements would then have to be forwarded to a company like Materion Electrofusion in Fremont, CA to see if they could manufacture a Beryllium diaphragm to those specifications. Assuming they could, the next course of action would be to get a quote at the minmum units ordered and try to drum up interest in a group buy situation through Materion. This is where the limited number of BA750s out in the world is not doing you any favors. To help remedy this, the demand for BA750s would need to increase, which is going to be hard because there are not yet any inexpensive (<$100) horns or waveguides that take advantage of the BA750's main strength - an extended lower range. As stated above, another complication is that there are no molds for the SEOS18 (at least not yet) with a throat angle that matches the BA750. Since there are folks who are satisfied using Radian compression drivers with the SEOS24, the driver/throat mismatch is not necessarily a deal breaker but it does seem to fall a little short of the goal here.

I, personally, would love to see a throat-matched poured resin SEOS18 / 16 Ohm BA750 joint offering at some point down the line. However, it looks like a lot of the folks who wanted a BA750 already got them when the getting was good so this is unlikely. Which is a shame - they would be a perfect pairing to sit atop some well-braced woofer enclosures for the TD15Ms I've been doing nothing with for the last year and a half.

 

I have the SEOS18/BA750 combo.I thoueasure the angles? How much are the angles off? Can this be rectified?
I too have the TD15M. I've built the cabinets and SEOS18/BA750/TD15Ms are making music now. Now if these angles are off, its really a bummer after all the work.......
That said, I'm not disappointed in the sound quality of the speakers.

 

I've always wondered about the entrance angle on those larger SEOS waveguides (the 18 and 24). What are the angles? There was much discussion about what driver to build the smaller SEOS stuff for, and a commonly used driver was chosen and thus the wg was built to match. How about for the larger 'guides?

 

I had lost track of this thread.

I've measured the angles with paper "plugs".

Unsaid in my OP was the hope that the BA750 had as its origins some other driver by a "mainstream" manufacturer.

 

Yes, I should PM erich and find out the model for the BA-750. Maybe it was designed from scratch. It would be nice if the 'phram measurements were the same as some stock Beryllium units and were available from a manufacturer. Maybe a group buy would be possible?

 

I have made accessories for sanding/smoothing the throat interface. Bwaslo used these on his unihorn project. I can also provide tapered wooden plugs to aid in the alignment of the horn throat to CD.
I'll use the Iwata 600 with either the BA 750 or the B&C DE250

 

How much of a mismatch is there between the BA750 and your Iwata 600? Do you know if there's a similar exit angle mismatch for the SEOS18?

 

Hi..as per my experience to get the ball rolling on a BA750 diaphragm upgrade, somebody with a BA750 would have to first disassemble it and take precise technical measurements of the diaphragm. Not impossible. These measurements would then have to be forwarded to a company like Materion Electrofusion in Fremont, CA to see if they could manufacture a Beryllium diaphragm to those specifications. Assuming they could, the next course of action would be to get a quote at the minmum units ordered and try to drum up interest in a group buy situation through Materion.

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