Hi guys, slowly getting into this stuff and now wanting to start my first build using a 5,25" driver and a 1" dome tweeter into a tower.
Now I´ve been reading a bit on diffraction and baffle step and in my mind a diagonally cut baffle should help compared to a rectangular one. But it seems no companies are doing it.
So would it or would it not make sense to do the extra work of making the top of the tower more pointy?
Now I´ve been reading a bit on diffraction and baffle step and in my mind a diagonally cut baffle should help compared to a rectangular one. But it seems no companies are doing it.
So would it or would it not make sense to do the extra work of making the top of the tower more pointy?
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Definitely yes, worh of the effort! The angle should be 30-45deg, not more! With layered thick baffle you have more playroom and making the box is easier.
Check Avalon speakers! Avalon Acoustics | Music is the passion in our blood, and the muse of our intellect
Check Avalon speakers! Avalon Acoustics | Music is the passion in our blood, and the muse of our intellect
What I think I´m after is introducing as few problems in the frequency range as possible, that I would have to fix with crossovers later. And in my mind the rectangular baffle would trap more hig frequency notes than the cut-corners one.
In this case if the baffle was flat and large, then this kind of diffraction would not happen. The response would be the same as the manufacturers response. The diffraction happens when you cut the baffle away.
But isn´t that true for really big (infinite) baffles? In my mind, if you cant have an infinitely large baffle, a small baffle as possible is the next best, as the diffraction issues that will occur will only do so in the highest ranges where the least musical information is?
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This is not the point. The point is that the sound in this case starts, and wants to continue to travel along a baffle.
Once it gets to a certain width, other things change as well.
Ok, now you are getting to the issues. You've decided to change the baffle near the driver. Doing so will cause diffraction, but making it gentle helps.
Moskwich, this is a fundamental thing with loudspeaker construction and well documented, expalained and tested, also innumerable simulation programs are available!
At least 50 different threads about this can be found at diyaudio.com
Please do some homework with these key words
loudspeaker, diffraction, baffle dimensions, baffle shape
Baffle Diffraction
https://site.diy-loudspeakers.com/baffle-diffraction-step
Speaker baffle design, diffraction and baffle step | Audio Judgement
Diffraction from baffle edges
etc.
At least 50 different threads about this can be found at diyaudio.com
Please do some homework with these key words
loudspeaker, diffraction, baffle dimensions, baffle shape
Baffle Diffraction
https://site.diy-loudspeakers.com/baffle-diffraction-step
Speaker baffle design, diffraction and baffle step | Audio Judgement
Diffraction from baffle edges
etc.
Thanks, I know there is a lot to read about the topic, and I have read some, but I just thought this thread would in a short sense make it clear to me why manufacturers mostly do the rectangular style baffle, even in pretty pricey categories, even so the litterature seem to point to making as small a baffle as possible.
Basically it´s hard for a beginner to just read the litterature without having someone to clarify when you get lost.
Basically it´s hard for a beginner to just read the litterature without having someone to clarify when you get lost.
Well, designing a loudspeaker for mass production is business - you must make profit.
The big names of hifi loudspeakers like KEF, B&W, JBL etc., they know what they are doing, but still production costs are very important. Making angles other than 90deg or roundovers easily multiplies production cost of the box. Other important aspect for business is the look of teh speaker, brands must be identified easily. Some brands make series of different looking speakers.
Considering these business aspects, the measurable or audible effect of trapezoid or rounded baffle is still minimal. There are several other more important issues which can be done well or wrong.
With diy hobby, some designers who publish plans have mantras regarding baffle shape etc., some other try different shapes and concepts every time. You can for example check the variety of projects by these
Zaph|Audio
DIY-Loudspeakers
Speaker Design Works
DIY Loudspeakers Kimmo Saunisto
DIY Lautsprecher | Bausatze, Lautsprecher Entwicklungen
http://www.humblehomemadehifi.com/speakers.html
http://www.htguide.com/forum/forumdisplay.php?39-Missions-Accomplished
The big names of hifi loudspeakers like KEF, B&W, JBL etc., they know what they are doing, but still production costs are very important. Making angles other than 90deg or roundovers easily multiplies production cost of the box. Other important aspect for business is the look of teh speaker, brands must be identified easily. Some brands make series of different looking speakers.
Considering these business aspects, the measurable or audible effect of trapezoid or rounded baffle is still minimal. There are several other more important issues which can be done well or wrong.
With diy hobby, some designers who publish plans have mantras regarding baffle shape etc., some other try different shapes and concepts every time. You can for example check the variety of projects by these
Zaph|Audio
DIY-Loudspeakers
Speaker Design Works
DIY Loudspeakers Kimmo Saunisto
DIY Lautsprecher | Bausatze, Lautsprecher Entwicklungen
http://www.humblehomemadehifi.com/speakers.html
http://www.htguide.com/forum/forumdisplay.php?39-Missions-Accomplished
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There may be lots of diffraction, but it is close to the tweeter so you might hear it less.
What one really needs is a dinosaur egg of the right size, unfortunately we are 65 million years to late, but that's the shape you are after.
C.M
C.M
I'd recommend having a play with "The Edge" Home of the Edge
With a rectangular baffle, placing the driver in an optimal location from the three closest edges can give very flat response as the diffraction from each edge cancels out the diffraction of the other edges. Roughly, the correct placement follows the golden ratio (1.618:1) so the driver will be a certain distance from one edge, x1.618 that distance to a second edge and x1.618^2 to the third. The tweeter placement in Zaph's ZDT3.5 roughly follows this (close to the top, further from right side, even further from left side)
http://www.zaphaudio.com/ZDT3.5-system2.jpg
Placing the driver equidistant from all edges produces the worst diffraction, so the 'pointy' baffle may well be worse than the rectangular one, at least with your current tweeter placement, as the diffraction from the top edge and two slanted edges will be similar and therefore add up instead of partially cancelling each other out.
With a rectangular baffle, placing the driver in an optimal location from the three closest edges can give very flat response as the diffraction from each edge cancels out the diffraction of the other edges. Roughly, the correct placement follows the golden ratio (1.618:1) so the driver will be a certain distance from one edge, x1.618 that distance to a second edge and x1.618^2 to the third. The tweeter placement in Zaph's ZDT3.5 roughly follows this (close to the top, further from right side, even further from left side)
http://www.zaphaudio.com/ZDT3.5-system2.jpg
Placing the driver equidistant from all edges produces the worst diffraction, so the 'pointy' baffle may well be worse than the rectangular one, at least with your current tweeter placement, as the diffraction from the top edge and two slanted edges will be similar and therefore add up instead of partially cancelling each other out.
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TMM stated the case rather well. I made a graphic to illustrate this concept (see attached pdf file). Imagine a small driver mounted in various baffles. The sound wave radiates from the driver along the baffle. I illustrate 4 different frequencies (wavelengths) and super-impose these on various baffle shapes.
Starting with a driver centrally mounted in a square baffle (near worst case), the transition from 2-pi to 4-pi radiation happens over a very short frequency range. Even worse is a driver centrally mounted in a circular baffle... here the transition happens at abruptly at a single frequency.
Moving to a rectangular baffle, things improve quite a bit, and now the transition from 2-pi to 4-pi takes place more gradually. Even better is a rectangular baffle with the driver offset horizontally. The final graphic is a trapezoid baffle, and clearly this results in a very smooth transition, but is it really better than the rectangle with a horizontal offset? Maybe not. It is possible to select an optimal rectangular baffle with an optimal driver placement which will result in a very smooth transition, one that is hard to improve upon even with a trapezoid shape.
Considering the extra complexity and cost of making a trapezoid cabinet, it may not be worth the effort.
Of course, if you are in the business of selling $20,000 - $100,000+ speaker systems (like Avalon), any possible improvement is worth the effort. Your customer base expects you to "spare no expense" in the pursuit of the finest possible sound reproduction. Even if the a design feature is very expensive, if it has even the slightest possibility of improving the sound, your customer expects you to incorporate that design feature.
Starting with a driver centrally mounted in a square baffle (near worst case), the transition from 2-pi to 4-pi radiation happens over a very short frequency range. Even worse is a driver centrally mounted in a circular baffle... here the transition happens at abruptly at a single frequency.
Moving to a rectangular baffle, things improve quite a bit, and now the transition from 2-pi to 4-pi takes place more gradually. Even better is a rectangular baffle with the driver offset horizontally. The final graphic is a trapezoid baffle, and clearly this results in a very smooth transition, but is it really better than the rectangle with a horizontal offset? Maybe not. It is possible to select an optimal rectangular baffle with an optimal driver placement which will result in a very smooth transition, one that is hard to improve upon even with a trapezoid shape.
Considering the extra complexity and cost of making a trapezoid cabinet, it may not be worth the effort.
Of course, if you are in the business of selling $20,000 - $100,000+ speaker systems (like Avalon), any possible improvement is worth the effort. Your customer base expects you to "spare no expense" in the pursuit of the finest possible sound reproduction. Even if the a design feature is very expensive, if it has even the slightest possibility of improving the sound, your customer expects you to incorporate that design feature.
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Thanks all for contributions!
Since baffle reflections is another effect, wouldn´t the offset driver in a rectangular baffle "trap" lower frequencies on the baffle compared to the trapezoidal?
That is, if the transitions are smooth in both cases, shouldn´t the next objective be to lessen the baffle reflections as much as possible?
Since baffle reflections is another effect, wouldn´t the offset driver in a rectangular baffle "trap" lower frequencies on the baffle compared to the trapezoidal?
That is, if the transitions are smooth in both cases, shouldn´t the next objective be to lessen the baffle reflections as much as possible?
What is wrong with sound being 'trapped' on the baffle? Can you describe it so I'm sure what you're talking about.
Well correct me if I´m wrong, sound that is trapped on the baffle will increase the output in those frequencies in a forward direction, and lessen them in the off-axis response. Like when a driver starts to beam. It might be possible to suffocate that increase with the crossover, but the off-axis response will still suffer?
A horisontally offset driver should also give different off-axis response depending on which side of the cabinet you´re at? Possibly that woud introduce other problems?
A small source on a large baffle produces hemispherical radiation which will be evenly balanced at frontal off-axis angles.
Do you want 360 degree radiation, 180, 90? Thoughts on why?
Do you want 360 degree radiation, 180, 90? Thoughts on why?
Reading a lot of comments and articles, I get the impression that a wide radiation provides better imaging for the listener, don´t know if that is the case or why that would be.
Surely it should provide a better experience while moving around in a room, even if that is not the primary objective?