mixed open baffle/sealed triune?

[dennymack]

I have all the parts to build the triunes, butnow I think I want to try an open baffle sealed mix.
For my "practice" speaker build I cobbled up some boxes for a set of blaupunkt component speakers (auto) that I had sitting around. built one sealed, sounded good. Just for goofs I installed the other woof and tweet on the baffle only, and I love the openness of the sound. Unfortunately, when I play the boxless alone it lacks bass. No surprise.
So that brings me to my harebrained scheme:
Can I build the triunes with half the box volume and have the top mid/woofer open backed?
The baffle would basically stick up above the box, so the drivers stay in the same relation to each other, with a sloping back starting behind the tweeter. I plan to have 12 dvc subs beneath each triune, so low end extension is not such an issue.
Am I nuts, or will this give me a mix of what I like about sealed and open?
Your thoughts, suggestions and caveats are all welcome.
Dennymack

[dthomas]

> I have all the parts to build the triunes,
> butnow I think I want to try an open baffle
> sealed mix.
> For my "practice" speaker build I
> cobbled up some boxes for a set of blaupunkt
> component speakers (auto) that I had sitting
> around. built one sealed, sounded good. Just
> for goofs I installed the other woof and
> tweet on the baffle only, and I love the
> openness of the sound. Unfortunately, when I
> play the boxless alone it lacks bass. No
> surprise.
> So that brings me to my harebrained scheme:
> Can I build the triunes with half the box
> volume and have the top mid/woofer open
> backed?
> The baffle would basically stick up above
> the box, so the drivers stay in the same
> relation to each other, with a sloping back
> starting behind the tweeter. I plan to have
> 12 dvc subs beneath each triune, so low end
> extension is not such an issue.
> Am I nuts, or will this give me a mix of
> what I like about sealed and open?
> Your thoughts, suggestions and caveats are
> all welcome.
> Dennymack

It would require a significant crossover rework. The dual woofers in the Triune work together from the bottom octaves all the way to the crossover point. If you configure one of them for dipole operation it will no longer help the other woofer and the speaker will as your tests showed have a lot less bass because only one woofer will be providing any significant output in the bass region.

I have done a couple of hybrid dipole designs and have found that 3 ways work best. Conventional box design for the woofer, dipole midrange and a dome tweeter. An added benefit of a 3 way approach is that it protects the dipole midrange from overexcursion.

What you want to do could be done but you will need to sacrifice a significant amount of sensitivity to get the drivers to play flat and there will be no protection for the dipole midwoofer so power handling will be much less.

Dave