Semi Open Speakers

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opnly bafld

Re: Semi Open Speakers
« Reply #40 on: 12 May 2020, 04:10 pm »
The saving grace that I hadn't considered was that the time delay could be filtered out sub consciously provided the difference was great enough.

Filtered out is not how I would describe it; although I can understand you putting it that way.

If the reflected sound has a relatively short delay our brains go into overdrive trying to figure out what we are hearing, whereas when the delay is long enough we tend to find it pleasing and our brain can relax more.

Here is part of what Duke L (AudioKinesis) wrote about this subject some time ago:

"Researcher David Griesinger has studied what makes a great seat in a concert hall.  He found that two elements must be in play: First, a clear stream of direct sound; and second, a clear stream of reverberant sound.  The key here is that the two be separated in time, rather than smeared together."

diyman

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Re: Semi Open Speakers
« Reply #41 on: 12 May 2020, 08:17 pm »
Letitroll98 yeah most people here were helpful and for that I am grateful.  My pointed response was toward diyman who seemed to get offended by the term semi open baffle.

Diyman I understand now. I offended you when I asked about OB speakers and questioned their efficacy in relation to mid and upper range frequencies.  However the questions I asked were logical and the answers that I got back were reasoned.  I suggested that reflections would mess with the frequency response and guess what, I was right.  The saving grace that I hadn't considered was that the time delay could be filtered out sub consciously provided the difference was great enough.

I am still unsure as to whether placing shapes behind the open baffle to direct sound waves could improve the sound or not. Further delaying the reflection does sound like it would make it easier to separate the background noise.  Alternatively one could also absorb or scatter or some combination of the three.  All without closing in the driver thus keeping it SEMI OPEN.

First of all, I have not been offended by anything you have written.  But I’m afraid that you still don’t understand open baffle speakers or the principles behind them.  So, I’ll try to help you again.
 
Open baffle speakers are dipoles.  Some people use the terms interchangeably and some even prefer to just call them dipoles period.   When the drivers are mounted on a simple flat panel the dipole formed closely resembles a figure 8.  Sometimes wings are added to increase the effective baffle width and thereby lower the bass frequency extension.   Various wing combinations can be used with both symmetrical and asymmetrical configurations.  The wings change the dipole shape somewhat, but nevertheless it still remains a dipole.  The interaction between the dipole sound pattern with the nearby walls results in a sound field that when delayed by an appropriate amount and mixed with the direct sound creates the highly desirable spacious and transparent listening experience.

Nothing you have posted has anything to do with this phenomenon.  And particularly your ideas for enclosures as presented in the original post.  None of those could be considered even remotely close to a dipole, and therefore have no application whatsoever in an OB environment.

And your reference to delayed reflection as background noise just further demonstrates your lack of understanding of sound perception in a room.

Joe_Limon

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Re: Semi Open Speakers
« Reply #42 on: 13 May 2020, 03:39 am »
Why are you the only one attacking me for asking questions if you aren't offended?

I understand what an open baffle speaker is. I understand what a dipole is, not just acoustic dipoles but electric, magnetic etc.  If you cannot visualize sound waves creating various dipoles in the original three concepts. Then I cannot help you and perhaps you are simply dragging me for your own lack of ability to interpret what I have presented.

diyman

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Re: Semi Open Speakers
« Reply #43 on: 13 May 2020, 05:04 am »
Why are you the only one attacking me for asking questions if you aren't offended?

I understand what an open baffle speaker is. I understand what a dipole is, not just acoustic dipoles but electric, magnetic etc.  If you cannot visualize sound waves creating various dipoles in the original three concepts. Then I cannot help you and perhaps you are simply dragging me for your own lack of ability to interpret what I have presented.

I’m not personally offended at all by you asking questions or anything else that you have said.  It’s just that your posts show a serious lack of understanding with regard to open baffles and I’ve been trying to help you understand the subject better.

And I’m not the only one that has tried to help you.  Go back and read some of the posts by others who also tried to help you understand OB physics.

Yet you still don’t seem to grasp the concept.  You continue to maintain that your three enclosure designs in the first post will produce dipolar sound patterns.  It’s not a matter of my lack of ability to interpret what you have presented.   It’s a matter that you are totally wrong about it. You commented yourself that the second one is side ported and you believe it will not reflect any sound out.  Pretty hard to have a dipole with sound only coming out of one place.

FullRangeMan also tried to tell you that your first design was nothing more than a vented enclosure without a resonant duct.    But you pretty much ignored his post along with mine and others who don’t accept your designs as being even remotely related to OB.

However, if you believe that your unusual designs have some sort of merit, then by all means go ahead and construct them and run tests.  At a minimum you should produce actual frequency response, impedance, harmonic distortion, and waterfall plots.  You’ll also need to do nearfield polar tests to see if see if a dipole pattern is produce.

Publish those results here and maybe you can show that all of us being critical about these designs are wrong.  I’d be surprised, but it’s up to you to demonstrate it.

FullRangeMan

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Re: Semi Open Speakers
« Reply #44 on: 13 May 2020, 07:01 am »
Gentlemen lets return to the technical aspect of the topic.
Thanks

Letitroll98

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Re: Semi Open Speakers
« Reply #45 on: 13 May 2020, 12:23 pm »
Let's all go over to Facebook, click on any news feed and read the comments so we can see what a real personal attack looks like.  Then when we come back here we can see that we're just talking about speakers and stop all the baloney about anyone being attacked.

Joe_Limon

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Re: Semi Open Speakers
« Reply #46 on: 13 May 2020, 12:35 pm »
This is ridiculous. I never claimed that these were open baffle speaker designs.  I claimed they were semi open and posted in an enclosures forum yet for some reason you have decided that since you have never heard a term to describe this novel idea that I must have no idea what I am talking about and have instead decided to take my posts as advocating that somehow closing in the rear of a driver maintains it as open baffle.

I maintain that these designs are dipoles.  The location of the inverse acoustic waves may not be perfectly mirrored around the central axis of the speaker, but neither are open baffle designs with a biased wing on one side which you admitted to being a variant of open baffle design.  I cannot figure out if you are arguing in bad faith or simply lack the visual spatial ability to comprehend the ideas as presented.


diyman

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Re: Semi Open Speakers
« Reply #48 on: 13 May 2020, 07:31 pm »
...
I maintain that these designs are dipoles.  ...

I think you are going to have a hard time convincing anyone that those designs are dipoles, but if you're convinced then just build and test them as I suggested above.  Let's see the data.  Then we'll all know for sure.  And please don't forget the test procedure description and photos to go with the data.

You also might want to learn more about dipoles first.   If the articles I referenced previously are too much here is a link to a simple description on Wikipedia.

https://en.wikipedia.org/wiki/Dipole_speaker

Joe_Limon

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Re: Semi Open Speakers
« Reply #49 on: 13 May 2020, 07:38 pm »
Did you even read the first paragraph of the wiki article you just posted?

A dipole speaker enclosure in its simplest form is constructed by mounting a loudspeaker driver on a flat panel. The panel may be folded to conserve space.

diyman

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Re: Semi Open Speakers
« Reply #50 on: 13 May 2020, 08:54 pm »
Did you even read the first paragraph of the wiki article you just posted?

A dipole speaker enclosure in its simplest form is constructed by mounting a loudspeaker driver on a flat panel. The panel may be folded to conserve space.

Sure.  I already talked about wings.  But your first diagram doesn't have simple wings.  It has the back so tightly closed that whatever sound can still escape will not be anywhere near 180 degrees from the front wave.  In fact, it will be much more perpendicular to the axis. Here is the next sentence in the article.

"The term dipole derives from the fact that the polar response consists of two lobes, with equal radiation forwards and backwards, and none perpendicular to the axis."

So again.  What you have proposed is not a dipole.

Joe_Limon

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Re: Semi Open Speakers
« Reply #51 on: 14 May 2020, 01:13 am »
So you invented qualifiers to narrow the definition of a word that doesn't even have to exist as a qualifier to a novel description of a design. And because I didn't instinctively understand your additional qualifiers to a word that you applied to my novel description... I therefore do not understand anything to do with what I am talking about?

Letitroll98

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Re: Semi Open Speakers
« Reply #52 on: 14 May 2020, 03:10 am »
Since we're just going in circles you guys have about two posts to bring it back before it goes to quarantine.

Joe_Limon

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Re: Semi Open Speakers
« Reply #53 on: 14 May 2020, 04:14 am »
It's fine, I'll probably revisit the idea and test when I have time/resources available to experiment.  Until then feel free to quarantine the thread.

diyman

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Re: Semi Open Speakers
« Reply #54 on: 14 May 2020, 05:07 am »
I agree also.  I think we are going around and around in circles as well.

For Joe or anyone who wants a better understanding of how open baffle works and its advantages without reading the papers I referenced, here are two recent YouTube videos featuring Clayton Shaw, the owner of Spatial Audio.  Clayton has a long and impressive background in open baffle and I recommend both of these videos as being very valuable to watch.

https://www.youtube.com/watch?v=lYaYCgwmHi8

https://www.youtube.com/watch?v=vYHjNc3kWAQ