Open baffle speaker pitfalls

[ctrl]

Just a majorly ignorant question here, but isn't the room the baffle?

Whatever metaphor is used to describe the influence of the listening room, it is always better to use a loudspeaker without design flaws for listening. Therefore, the hint on what to pay attention on U, V, H OB speaker.

Such a design flaw would exist, for example, if the V-frame OB bass section of example 5 is used in a 2- or 3-way loudspeaker at a crossover frequency above 150Hz (or example 1 above 100Hz).

We can also look at the frequency responses of the example 5 simulation as a CTA-2034 presentation (Spinorama). Those who are here in the forum more often should be familiar with this data presentation - only difference is 40dB instead of 50dB scaling.
Once without XO, with slightly downward sloping PIR and with semi-flat on-axis FR:

No matter how you design the crossover, the radiated sound power and on-axis FR/listening window never match - this is shown by the DI.
What you don't want is an abruptly and severely changing directivity index DI (or early reflections directivity index ERDI), because that means a sudden mismatch of direct sound to radiated sound power - which happens in example 5 above 150Hz.

Such behavior, no matter what listening room, will always be a problem.

 

[Els]

I had luck with a phy style open baffle, 6' tall, center baffle 16", wings hinged about 24" deep.

Wife liked it, said it didn't seem to big (with the wings more than 45 degrees bent back).
Must be a trick of the eye, not seeming wide due to height.....

12" Philips full range with a mass corner (ib) of maybe 100hz.

It basically had no bass.
In theory, dip at 280, peak at 140, then bass rolling off...............
My mostly 70-80's rock, well, sounded sad without that bass.

Very clean mids, especially with a 3" thick foam box I had around the back of the driver.

Very nice instructions, I agree with just about everything, However the best advice I can give after experimenting with open baffles, is forget about it. It can give good results, but way too much trial and error and way too much room dependent.

 

[Ola]

For a two months I'm using these. 38 x 50 cm baffle, Eminence Beta-12CX:n and Eminence ASD1001 elements.
One great speaker guy in Finland discovered that these Eminences give good response 30 degrees off center.
Kit is sold by Uraltone store and it's 275 EUR with filter parts.

He measured response like this. I don't measure.

I use one subwoofer. Making right stands now.

 

[ctrl]

For a two months I'm using these. 38 x 50 cm baffle, Eminence Beta-12CX:n and Eminence ASD1001 elements.
One great speaker guy in Finland discovered that these Eminences give good response 30 degrees off center.
Kit is sold by Uraltone store and it's 275 EUR with filter parts.

Glad you're happy with your OB speaker, but could it be that you accidentally posted in the wrong thread?
General experiences with OB speakers are collected in the thread "Open Baffle speakers".

This thread is about what problems can occur, especially when deviating from the classic OB design (flat baffle).
That some manufacturers call their OB speakers the "pinnacle of open baffle loudspeaker designs", but the radiation is anything but that of a dipole (yet what buyers usually expect) and in some cases more like a speaker design nightmare.

 

[Ola]

Hmm, I thought the thread is right. No nightmares, sounds great. I can't think out any nightmares with it.
And it deviates from classic design for sure. And radiation is diapole for sure.
Of cource, it depends on someones's thoughts about sound.

 

[ctrl]

And it deviates from classic design for sure.

The baffle itself is classic (though small in dimensions). Unusual is the vertical inclination of the baffle, which provides for a flatter response of the direct sound on the reference axis of the speaker - instead of keeping the often very wavy on-axis frequency response of a coaxial loudspeaker as a reference axis.

For this, the vertically also pronounced dipole behavior of the woofer is also tilted by 30 °, which leads to more floor and ceiling reflections as a compromise.

...And radiation is diapole for sure.

Yep, that's right. Of course, only up to the crossover frequency of the compression driver, from there it's a normal monopole speaker.

 

[yodog]

So if I added a baffle step compensation crossover network, it goes to the woofer and it lowers the output of the woofer for the whole section on a frequency response graph where the woofer is emitting a dipole radiation pattern? Or a carotid? Carotid is a beamed / laser radiation pattern?

 

[Plcamp]

At the end of this article http://musicanddesign.speakerdesign.net/u_frame.html is the following, which indicates the damped uframe (if you are careful) is effectively as good as an hframe that is twice the size … it seems to me that a uframe like this crossed out just above 100 hz could hand off to another identical driver in a sealed box and provide extended low frequency response beyond 500 hz (assuming 15” drivers) with a good match on dispersion?