Full Range and the Semi-Open Baffle

[Capt Zach]

Hi All,

I'm wondering if anyone has any experience or opinions about the semi or quasi-open baffle concept. I've been pretty fascinated by the idea, ever since I read the rave reviews of speakers using this concept. Big examples that come to mind are the products of Ocellia, Tonian Labs, Auditorium 23. While these designs differ in certain respects, they have a few things in common:

1. Most use the PHY drivers with a relatively high Q.
2. They rely on relatively thin walled cabinets
3. Products like the Tonian and Ocellia come with a removeable/adjustable door to change the cabinet tuning.

I'm not an experienced speaker designer, but I get the impression these enclosures would be difficult to model, since they're not really open baffles of any standard type. Maybe the designers are doing everything by ear?

I also imagine that their response would be complicated, a combination of some kind of pipe or TL?

Any thoughts?

[becki200]

Hi do you mean something like the Saba Cello?

[el`Ol]

If implemented not correctly these enclosures are pipes with mussive bump at 80 Hz (seen such a measurement at a diy-forum). The fault was probably that it had a third frame in the middle. I once visited someone who claimed his speakers run fairly linear down to 40 Hz. When knocking on the side walls one can hear that these frequencies emanate from the resonances of the side walls, much like in a DML.
And there are no software tools for simulating that.

[Godzilla]

http://www.sonicflare.com/_audio_a23...mages_side.jpg

I've always thought this was an inspiring design but have no clue where to start other than an ppen baffle and some movable wings.

[Capt Zach]

Originally Posted by becki200

Hi do you mean something like the Saba Cello?

Hi becki200,

Yes the Saba Cello looks like a similar design.

[Capt Zach]

Originally Posted by el`Ol

If implemented not correctly these enclosures are pipes with mussive bump at 80 Hz (seen such a measurement at a diy-forum). The fault was probably that it had a third frame in the middle. I once visited someone who claimed his speakers run fairly linear down to 40 Hz. When knocking on the side walls one can hear that these frequencies emanate from the resonances of the side walls, much like in a DML.
And there are no software tools for simulating that.

Yes, all of the designers have chosen to break the rules and use very thin walls that "sing", or in the case of Ocellia, actually mimic the soundboard of an instrument using tonewoods.

[stevieg]

Oo-er break the rules! It'll end in tears! When designing a speaker enclosure, Is there any advantage at all to a non inert support/enclosure? Other than it's easier for us to predict/understand an inert body?

[TerryO]

Originally Posted by stevieg

Oo-er break the rules! It'll end in tears! When designing a speaker enclosure, Is there any advantage at all to a non inert support/enclosure? Other than it's easier for us to predict/understand an inert body?

Using a non-inert enclosure allows only the drivers to produce the sound and makes modelling and voicing much easier. Can a non-inert enclosure sound better...absolutely, IF the designer knows what they're doing and can control all aspects of the testing and construction of the enclosures.

The late John Wyckoff was one of those people that could actually do it, but he was a trained Violin Maker and also Wood Instrument maker. In conversations with John it became evident, to me anyway, that there's so many factors in such a cabinet construction that are inter-related and requires a lot of arcane knowledge, that it would be hard for a typical DIY'er, or even most speaker companies to keep track of. The cost would certainly be an issue as well as the properties of the materials can be different from one lot to another, depending on density, grain orientation, thickness...well, you get the picture. I'll just say that it would be very hard to mass produce something like this and maintain the absolute "tone" that was the original goal.
Can it be done? Yes.
Can it be done well? That's the real question.

Best Regards,
TerryO

[stevieg]

Thanks for that Terry. Very well put. Even if impossible to emulate for the amateur at home, the more holistic approach has a lot to commend it, rather than thinking speakers/crossover/enclosure as discrete components.

Thanks for the heads up about the late John Wyckoff. A thoughtful and interesting designer; a loss to us all.

Cheers Steve

[el`Ol]

Originally Posted by stevieg

When designing a speaker enclosure, Is there any advantage at all to a non inert support/enclosure?

The starting point was some kind of a religious belief that light paper cones don't like to be tortured by strong motors or encaged in massive enclosures.