Full Range and the Semi-Open Baffle

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Capt Zach

Member
Joined 2004
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?
 
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el`Ol

Member
Joined 2005
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.
 
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Capt Zach

Member
Joined 2004
el`Ol said:
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.
Click to expand...

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.
 
TerryO

TerryO

Member
Joined 2002
stevieg said:
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?
Click to expand...

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
 
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stevieg

Member
Joined 2009
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
 
L

LineArray

Member
Joined 2008
dipol-audio.de
el`Ol said:
...
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.
....
Click to expand...

Maybe those resonant enclosures can be seen as a kind of "DML light" ...

I am rather prejudiced i must admit and have difficulties imagining such
an enclosure can be implemented with low coloration.

How was your impression ?
 
L

LineArray

Member
Joined 2008
dipol-audio.de
el`Ol said:
...
The one who built it listened to that typical slow audiophile music, so there was not much danger of getting the bass smeared.
...
Click to expand...

Slow and low complexity material - i listened once to fullrangers on
thin and large open baffles at a music show. Those baffles were neither
damped nor reinforced.

The room was full of ugly resonances while the audience was listening
to an LP with a blues singer, harmonica and guitar.

When playing an orchestra later, the tube amp and speaker salesman
told us, that the sonic result is so bad because the recording was
made digitally, giving the audience a knowledgeable smile.

I left the room and i knew exactly why.

This is not meant to disregard tube amplifiers or fullrange
speakers or even analog gear since i am very open to mostly
anything. But sometimes things go beyond my personal limits
of ridiculousness.

But why discuss, if there are people who enjoy such kind of
equipment ?

As long as they do not try to evangelize me, i also abandon
in doing so.
 
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stevieg

Member
Joined 2009
The one who built it listened to that typical slow audiophile music, so there was not much danger of getting the bass smeared.
Click to expand...

This is the curse of the "reference recording". If you are not careful, you tune to specific tracks. Much better to grab some random tunes and give them a spin. If you enjoy them, all is well; if not investigate.
DML=TLA (three letter acronym)?
 
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