Anyone seen plans for an open baffle ribbon hybrid?

[wongstein]

Hi Folks,

I have a desire to make an open baffle two-way using a ribbon tweeter and a dynamic mid/bass. If you have seen such a DIY design please let me know. Or if you have some thoughts to contribute, certainly they would also be appreciated. I know it's quite ambitious for my first speaker project, but I think this is what I want.

My goals:
- should be fairly simple to build
- ribbons on top ('cause I love ribbon treble)
- simple crossover (hence a two-way)
- only need bass down to 50 or 40 hz. I can get a subwoofer for movies and techno
- sensitivity above 89db/w/m, preferably above 92db
- baffle can be large, but not huge

Is there a range of frequency where I should avoid trying to crossover? I'm considering maybe a Raven or Aurum Cantus ribbon crossed over at 3Khz with a 5" or 6" mid. For the mid I'm thinking maybe a ceramic Accuton, but to match the sensitivity of the ribbon I think I'd need the Neodymium versions which might be too expensive for me now. Any suggestions for a midrange driver that goes to 3Khz and still makes a little bass?

And does anyone know if any of the Accuton ceramic drivers are at all suitable for open baffle? All I know is that I've loved those drivers in plenty of commercial speakers.

The idea is to use top quality parts in a very spartan design. Active crossover and bi-amping would be part of the final dream, hence a two-way. Should I abandon this idea, and just do an open ribbon with some kind of transmission line mid/woofer? Or maybe use a fullrange driver with a ribbon super-tweeter?

Thanks,
Anthony

[Calvin]

Hi,

I´d suggest to use a larger Ribbon or Magnetostat like the Bohlenders
and try to crossover much lower than 3kHz, if possible even down to ~200Hz. Add to this a stacked array of 6 to 8 dynamic basses of 6"-8" in a folded dipole, drive the complete thing actively and enjoy

Something similar to the Dali Megaline, or the Force from Perfect8.com (which though looking beautiful sells for a ridiculous price, especially compared to far less costly electrostatic systems which outperform a magnetostat). Or think of a design like the big old Infinitys.

jauu
Calvin

[el`Ol]

Hello Anthony!

There are two problems I see:
*Getting 40-50 Hz with a big but not huge OB
*Getting an audiophile mainstream driver that is suitable for OB
The free Edge software allows you to simulate the first, the (not free) Basta software also the combination with the latter.
In Germany some people build (not simple) speakers between box an OB that work with resonating elements, mostly very thin poplar ply in tension. I think I will be trying a much easier to build alternative next time: use a polymer sheet and just mount it U-shaped behind a baffle. My problem is that I found a promising material (Forex classic, called Sintra in the US), but in my home town not in the right thickness.
A very big but not huge "enclosure" in combination with the room gain of a not too big room should allow you to get along with a simple crossover without a bafflestep-compensation.
Maybe you want to try first, but better with a cheap driver.
A fine driver for a final solution would be the Supravox 215 Signature.

Regards,
Oliver

[wongstein]

Thanks Calvin and Oliver,

I think you both understand very well what I'm going for, and what I'm hearing loud and clear is that I'll need to compromise some of my goals, therefore I need to determine which are the most important to me.

I think my goals are now:
- two drivers per speaker
- 92dB or better efficiency
- crossover below 1000Hz
- bass down to 80 or maybe 100hz for integration with a sub
- doesn't need to be open baffle either. A box would be okay

Another thing that I'm hearing from you both is that I shouldn't be foolish about using drivers in ways that they weren't originally intended (or proven to work), and that seems wise.

I think I'm going to start with the ribbon and see how low I can get the crossover, and then determine the woofer and baffle/box after. I'm considering making my own ribbon driver, but only up to about 18" because of limitations of my milling machine. I hope I can get the crossover below 1000Hz, as that will give me a lot of freedom with the woofer.

Mostly I want to do this for the learning, otherwise I'd just build a kit. Someone said "Experience is what you get when you don't get what you want" so even if my speaker is terrible, at least I'll have learned something

Thanks again,
Anthony

[Ang]

check out the threads in the main loudspeaker section on the Beyma tp150 - a guy has pulled the back off of it, and it would seem to meet your reqs for this project.

[Jeroenkv]

An example attached.

[Jeroenkv]

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