Open baffle drivers configuration: time to ask the experts

[Peter Daniel]

Recently I got inspired by an open baffle system from http://www.warco.com.au/awar.htm. It is using Raven 3 ribbon and 2 Cabasse woofers 21NDC. It seems that it got good response from the listeners.

[Peter Daniel]

I was thinking about building something similar, since I have Cabasse woofers. Instead of Rven 3 I want to use Raven 2 and Triangle 5" midwoofer. Cressovers would be around 200 and 10K and probably active. Would this configuration work well? It's not MTM, but something slightly modified. Also is it better to place woofers as close as posible to tweeter and midrange or better space them?

The drivers would be mounted in a wall separating two rooms, so it's sort of infinite baffle design. Your input greatly appreciated.

[gilid]

Proac recently launched an open baffle series, the 'Futures'. I have heard only excellent things about them, so they can serve as a good starting point for inspiration.
Check out www.proac-loudspeakers.com/proacfut.htm for info.

Very expensive (more than the usual proac stuff), and they do not appear to use any propriatary 'black magic' techniques. They appear to be well within the reach of a determined DIY'er.

[transducer]

Keep the woofers as close as possible to each other, otherwise you will get comb filtering effects off axis vertically. Also cross over as low as possible. Another option is to put both woofers on the bottom. Your IB idea should work well, realize that the overall Qtc will be quite low, and therefore the bass will be on the thin side of things

Should be a nice system, you don't have to worry about baffle step response, edge diffraction, etc. Good luck and let us know how it turns out.

RonS

[transducer]

It's unfortunate that Proac chose to only use a dipole open baffle midrange, since it's in the bass region that the concept really shines, in reducing room/speaker interaction. I would imagine that the omnidirectional bass radiation coupled with the dipole midrange and line source forward radiating tweeter would make for a weird power response curve. Not my choice. I'd do something like the Linkwitz Phoenix or Orion. Peter's IB approach should make for a fine speaker as well, and get rid of many problems associated with box speakers. Of course it will do nothing for reducing room interactions, and he won't be able to move the speakers closer or wider for positioning

RonS

[Peter Daniel]

Originally posted by transducer
Keep the woofers as close as possible to each other, otherwise you will get comb filtering effects off axis vertically. Also cross over as low as possible. Another option is to put both woofers on the bottom.
RonS

Looking at Proac it seems very similar driver choice. They place the woofers at the bottom. Somehow I lean towards WTMW arrangement. What is better?
What do you mean by crossing as low as possible? I could cross mid-woofers at any frequency but ribbons can't go lower than 7-8k, they just blow when pushed too much (18dB slope).

[mrfeedback]

Hi Peter, your picture reminded me that I have not caught up with Pat for at least a year he is only about 10 miles away and has made some really good stuff.
I've heard the speakers that you mention and they really are very good.
Those boards are HEAVY, and the sound is solid and open and very nice depth and L/R imaging.
In a search I found these, http://www.enjoythemusic.com/ces2002/bonus/glackin.htm but have not seen or heard them, so cannot comment on these.

Eric.

[analog_sa]

I still have vivid memories from listening to the mid model of the Future range late last year. Open baffle has always been an attractive concept and cloning these ProAcs may be very rewarding if you like electrostatic type of sound coupled with reasonable impedance and efficiency. The bass is a bit weak but integrates very nicely. E-speakers claim the ribbon tweeter to be ATD LeRibbon. Any idea what are the other drivers?

cheers

peter

[capslock]

The Manger Zeroboxes (www.manger-msw.de or www.espeaker.com) have side drivers to deal with the limited baffle size (any idea why these would be more affected than other speakers?).

Using a very large baffle might be a neat way to deal with the problem using only one of these pretty expensive drivers. I've been dreaming about putting one to the wall that would hang there like a picture. My girl-friend would no longer complain about monstrous tower speakers in the living room...

However, they seem to require a damped volume of about 15 liters (don't remember the exact number). So even if I try to get spread this volume over a large area, they'd still have to be 5-10 cm thick.

Eric

[transducer]

Peter, cross the woofers as low as possible to the mid if you're going to do a WMTW configuration.

RonS