[JohnR]

For the purposes of the sticky resource lists, it would be helpful to have a definition of "open baffle."

Please note: This is not intended to limit discussion in this circle, only to help clarify and also to reduce work in constructing the sticky resource lists here.

An open baffle speaker:

• Uses cone drivers that emit acoustic radiation without the aid of a conventional (sealed, ported, bandpass, aperiodic, horn, ...) enclosure.
• Uses drivers as above for a substantial portion of the frequency range, and at least in the bass/modal regions. 
• Aims to accomplish a dipole radiation pattern over a significant portion of the frequency range.
• Are intended for home/domestic use.

Let me know what you think... with the caveat that I'd really prefer not to get into quibbling about things like e.g. what exactly constitutes "substantial portion of the frequency range"... thanks.... Helpful comments would of course be appreciated 

The following are therefore excluded (but may still receive an "honorary mention" in the listings if I think it's appropriate):

• Speakers built primarily using driver/s with a large thin membrane; for those, go to the Planar Circle.
• Speakers that are "open baffle" in the midrange but use boxes in the bass (although honorary mention possible if the crossover to monopole is low enough)
• Cardioids (although honorary mention possible).
• Pro-sound arrays etc
• Headphones

[Scott L]

Hi John,

   Please see below for what hopefully still meets your criteria. In my view, this design is done exceptionally well, as it addresses many issues, and does so exceedingly well:

http://www.perfect8.com/nav/pdf/THEPOINT_MKII_EVO_productsheet.pdf

[JohnR]

Hi Scott, this speaker does not quite meet the definition but got an "honorable mention" in the sticky list of commercial OB speakers.

[JohnR]

Actually I've decided to change the definition slightly (sorry). It's important to have a clear stake in the ground/line in the sand.

[ScruffyJasper]

I don't want to tick anybody off.

But as someone new to all of this I would like to ask what is to considered a "open baffle"  as far as I have heard a Sealed box would be a "infinite baffle".
Meaning a ported box would already be a "open baffle".

Now I understand the concept of a ported box,  what I would like some clarity on is when is a port big enough to consider the rest of the Housing a "folded baffle".

Maybe if the opening (port) is larger than the radiating surface?

sorry if this is a stupid question, i just want to understand the subject right.

[JohnR]

Hi, an open baffle speaker has no enclosure. So a ported enclosure is not that, nor is an inifinite baffle. Essentially, take a board and put a driver in it, that's open baffle

I'm not an export on ports but if you keep making one larger and larger I believe it would stop operating as a port well before you could consider the speaker to be open baffle.

[FullRangeMan]

Hi Jasper,
Sealed boxes can be Infinite Baffle or Acoustic Suspension.
Bass Reflex boxes have a tuned duct usually pipe shaped syntonized on some bass freq, a Bass Reflex box without the duct is called Ported, if the port is large they used to call Vented Enclosure, a Vented box will not do the bass freq reinforcement that characterizes Hi-Fi today.

Meaning a ported box would already be a "open baffle".
In this case the opening would have to be very big as most of the back side surface. Worth mention enclosures are used to make bass, mid and treble freq dont need boxes.

[ScruffyJasper]

Thanks for the replies I was just wondering because I saw those designs from GR Research.
And for example the NX-Treme,  they call open baffle  but compared to the amount of housing the opening in the housing isn't that big.

[JohnR]

The midrange and tweeter are open baffle. It doesn't meet the definition above because the bass is boxed, but that's nothing to do with big ports.

[Edit] Or is it? I can't tell. Maybe ask in the GR Research circle.

[WC]

Even the bass is open baffle on the NX-tremes. Danny prefers to use a smaller front baffle and smaller diameter drivers and wrapping the baffle to the sides. Different way to do it than large drivers on a flat baffle.

[JohnR]

Oh, actually they are covered in the Designs and Kits sticky, I updated the text to include them by name specifically.

[opnly bafld]

Thanks for the replies I was just wondering because I saw those designs from GR Research.
And for example the NX-Treme,  they call open baffle  but compared to the amount of housing the opening in the housing isn't that big.

Generally speaking open baffle can be flat, H frame, or U frame; for this speaker the bass sections appear to be a U baffle.

http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf

[ScruffyJasper]

Ok, I never saw a photo from the back side of the NX-Treme. 
Just found one (i think) and its missing the back wall so I guess U frame with a cutout at the side of the Tweeters and midrange?

I thought it was only that cutout (wouldn't have started asking if I would have known that).

[Bumpy]

I support the notion that U and H frames should be included in the definition of open baffles. They are, after all, just different ways to extend the baffle.

Bass that is fully boxed in, is outside of the definition. At best these speakers should be referred to as part open baffle.

A bass box without back is neither one thing nor the other. I can see how it extends the lower bass frequencies but this is tempered by additional internal reflections (one quarter wave?) where the low frequency extension is balanced by other negative issues such as echo.