Polar Response of OB with different length side wings

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Scott Joplin

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Hi. I recently watched Danny's YouTube videos called "Open Baffle Basics". I'm interested in acoustic solutions to obtain a smooth response and have come across "L-frames" before as a useful remedy to the problem of cavity resonance. What is the effect on the polar response of such a solution?

lowtech

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Re: Polar Response of OB with different length side wings
« Reply #1 on: 7 Oct 2020, 12:17 am »
This is really a great question that hits a fundamental design concept of "open baffle" speakers that's often glossed over (by ignorance or indifference).  In the video he's really careful (?) not to mention the importance of uniform off-axis response across the entire frequency range; something that a properly designed dipole is capable of and is a main design goal.

Scott Joplin

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Re: Polar Response of OB with different length side wings
« Reply #2 on: 7 Oct 2020, 09:50 am »
"Open baffle" is a very wide term and not all OB's are good dipoles, I agree this is the ideal goal for minimizing the effect of the room and getting the most out of the concept. I'd be interested to see measurements to get an idea of how much this ideal is compromised.

guest101973

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Re: Polar Response of OB with different length side wings
« Reply #3 on: 9 Oct 2020, 07:03 pm »
This seems to open up more questions than it answers.

For the novice considering open baffle what is the best option?  A plain baffle with no side wings providing a pure dipole, or a variation with side wings that is no longer a pure dipole?

Why would someone choose one of these over the other?

Scott Joplin

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Re: Polar Response of OB with different length side wings
« Reply #4 on: 9 Oct 2020, 08:44 pm »
A pure dipole is very difficult to achieve and not really something for a novice. https://www.linkwitzlab.com/models.htm

Wings are a way of effectively widening the baffle that further compromises dipole radiation, the question is, by how much and how much does it matter in a room?

guest101973

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Re: Polar Response of OB with different length side wings
« Reply #5 on: 9 Oct 2020, 10:28 pm »
Ignoring for the moment the difficulty in achieving a pure dipole, what is the best answer in terms of sound quality and listener enjoyment?  Pure dipole or modified polar response based on using wings?

Hobbsmeerkat

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Re: Polar Response of OB with different length side wings
« Reply #6 on: 9 Oct 2020, 10:43 pm »
I believe the side wings also help with L/R stereo separation, as well as providing bass extension & acting more like a "waveguide" than a typical wide baffle or box side panel.
Thats radically simplifying things, but is kinda how I've come to understand it.

guest101973

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Re: Polar Response of OB with different length side wings
« Reply #7 on: 9 Oct 2020, 11:26 pm »
So if side wings improve the sound and are better than a pure dipole why don't companies like Emerald Physics, Spatial Audio, and Magnepan include them in their products?

mlundy57

Re: Polar Response of OB with different length side wings
« Reply #8 on: 10 Oct 2020, 01:08 am »
Here's a link with measurements for the NX-Otica. Graphs for on-axis, vertical off-axis, horizontal off-axis, impedance, and a waterfall plot are in the first post.

https://www.audiocircle.com/index.php?topic=141654.0

As you can see, Danny's asymmetrical wing approach produces a very smooth response all around.

Mike

Tyson

Re: Polar Response of OB with different length side wings
« Reply #9 on: 10 Oct 2020, 05:41 am »
So if side wings improve the sound and are better than a pure dipole why don't companies like Emerald Physics, Spatial Audio, and Magnepan include them in their products?

Simple - cost and complexity. 

guest101973

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Re: Polar Response of OB with different length side wings
« Reply #10 on: 10 Oct 2020, 06:37 am »
I did think of that, but it doesn’t really have to be a lot more expensive or difficult.  Looking at the cost to manufacture a speaker that sells for $3K to $5K or more per pair, two pieces of additional flat material for wings per speaker should not add a lot to the cost.  And they could be very easily attached by the customer with a set of included screws using pre-drilled holes.

If that addition made a big difference in sound quality I would think that a manufacturer would want to offer it in order to gain an important advantage over competitors.  Even if it created a slightly more expensive product than the wingless model.  People are willing to pay for better sound quality if they can count on it really being there.

Scott Joplin

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Re: Polar Response of OB with different length side wings
« Reply #11 on: 10 Oct 2020, 07:35 am »
Here's a link with measurements for the NX-Otica. Graphs for on-axis, vertical off-axis, horizontal off-axis, impedance, and a waterfall plot are in the first post.

https://www.audiocircle.com/index.php?topic=141654.0

As you can see, Danny's asymmetrical wing approach produces a very smooth response all around.

Mike
Thanks for the link but I can't see any diagrams, I'm new here, is there something I'm missing?

Hobbsmeerkat

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Re: Polar Response of OB with different length side wings
« Reply #12 on: 10 Oct 2020, 12:05 pm »
I think Danny may have deleted his pics, cuz i have the same issue.

Dynky

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Re: Polar Response of OB with different length side wings
« Reply #13 on: 10 Oct 2020, 12:39 pm »
I guess it's something to do with your browser...all his pics are shown here as before in the first post of that topic.

Tyson

Re: Polar Response of OB with different length side wings
« Reply #14 on: 10 Oct 2020, 02:18 pm »
I did think of that, but it doesn’t really have to be a lot more expensive or difficult.  Looking at the cost to manufacture a speaker that sells for $3K to $5K or more per pair, two pieces of additional flat material for wings per speaker should not add a lot to the cost.  And they could be very easily attached by the customer with a set of included screws using pre-drilled holes.

If that addition made a big difference in sound quality I would think that a manufacturer would want to offer it in order to gain an important advantage over competitors.  Even if it created a slightly more expensive product than the wingless model.  People are willing to pay for better sound quality if they can count on it really being there.

Well, OB speakers are a hard sell in general.  And let's face it, the wings look weird.  Way more weird than the flat panel a traditional OB uses.  And thus have a lower WAF.  And as a manufacturer, WAF is important because you want people to actually buy your speakers. 

But from a pure performance standpoint, a speaker with a narrow baffle will out-image a speaker with a wide baffle, due to differences in edge diffraction.

Rusty Jefferson

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Re: Polar Response of OB with different length side wings
« Reply #15 on: 10 Oct 2020, 03:36 pm »
I guess it's something to do with your browser...all his pics are shown here as before in the first post of that topic.
That's interesting. I don't see them either, on my flat phone using Chrome.

Hobbsmeerkat

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Re: Polar Response of OB with different length side wings
« Reply #16 on: 10 Oct 2020, 04:15 pm »
That's interesting. I don't see them either, on my flat phone using Chrome.
Same here, so maybe that's the issue?
I can see most recent images, but those in older posts don't appear?

emailtim

Re: Polar Response of OB with different length side wings
« Reply #17 on: 10 Oct 2020, 05:00 pm »
That's interesting. I don't see them either, on my flat phone using Chrome.

I see a bunch of pictures and plots, but no polar plots. 

Love the duct tape !!!  No shop is complete without it.

Scott Joplin

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Re: Polar Response of OB with different length side wings
« Reply #18 on: 10 Oct 2020, 05:42 pm »
I've a chromebook. Polar plots would be nice but a range of off axis measurements would be useful

mlundy57

Re: Polar Response of OB with different length side wings
« Reply #19 on: 10 Oct 2020, 06:01 pm »
I've a chromebook. Polar plots would be nice but a range of off axis measurements would be useful

Not sure why some folks can’t see the graphs. The horizontal off-axis graph has plots at 0, 10, 20, 30, and 40 degrees off axis