That works, but i would avoid making it shallower. The vents have to be conidered separtely and, as shown, eats up a lot of gross volume. This is just a concept drawing (the 3rd iteration).
The idea was to show the 45° sides. If i were to redo this i would rethink the vents to get the shallowest package possible without sacrificing internal depth so that if hugs the wall as closely as possible. Top & bottom are less critical but they should have at least a minimum chamfer. Without tricky woodwork you’d just have to stick something solid top and bottom to create the chamfer.
Ideally we want the baffle wide enuff that that transition to the wall is “invisible”. Chamfer helps deal with edge diffractions and a gentler transition to the wall.
dave
+1
Me too; 'in for a penny, in for a pound'! 😉
Right, actual baffle width/height only big enough to mount the driver and why I posted the various Olson shapes as a general guide.
May I ask you all to suggest me a book to study these arguments? I feel a certain disappointment asking details on something I don’t understand. I do not pretend to know everything shortly, but at least to understand what you are talking about. Thanks in advance.
The acoustic compromises in this kind of enclosure would take an entire article to describe. Consider these points...
Here, so close to the wall any cabinet depth presents a problem because the waves will not blend with the wall unless they are large enough to make the 'jump'. So you can try to hold the baffle out nice and wide, then manage what's left at the edge. The way this is done is critical.
Don't forget that a large dimension can also set up modes inside the box at lower frequencies.
Here, so close to the wall any cabinet depth presents a problem because the waves will not blend with the wall unless they are large enough to make the 'jump'. So you can try to hold the baffle out nice and wide, then manage what's left at the edge. The way this is done is critical.
Don't forget that a large dimension can also set up modes inside the box at lower frequencies.
I guess, like in antennas, that it has to be lambda/4? So with an average room temperature of 20°C and then an average speed of 343 m/s, one meter is needed for 86 Hz?
Indeed! AFAIK, there's been no 'Acoustical Engineering Cookbook for Dummies' written, so will have to learn either by searching the net or reading the books 'we' did, so a good start would be Olson's late '30s seminal book, just one of many I've/we've learned from ['57 rev. I read] and where the illustration I posted came from IIRC: Acoustical Engineering - Harry Ferdinand Olson - Google Books
My 1st copy of that book was a photocopy. I don’t know if the reprint is still available from AxP/ Many of the Olson images out on the net came from that photocopy :^)
The transition at the edge looks like this:
The same dip is seen in a bipole, the back driver acting like the wall would. The angled edge spreads the transition and reduces the magnitude of any dip as well as lowering its Q. As you can see the wider the box relative to the depth the less the dip. At some point it essentially disappears.
dave
The transition at the edge looks like this:
The same dip is seen in a bipole, the back driver acting like the wall would. The angled edge spreads the transition and reduces the magnitude of any dip as well as lowering its Q. As you can see the wider the box relative to the depth the less the dip. At some point it essentially disappears.
dave
Thanks GM for the link, I’ve found an earlier print of around 360 pages, and not yet the 1957 one of 720 pages yet. I will continue to search.
Thanks planet10 for the plot!
Thanks planet10 for the plot!
Right, it's the foundation of resonant columns, so ideally requires a 1/4 WL radius.
edit: Resonances of open air columns
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You're welcome!
The link to it is on the link 😉; note the red block with white letters [READ EBOOK] on the left side of the page. I was posting while watching the Indy Car race, so just posted my Bookmarked link, not remembering it wasn't the actual link [now corrected].
Acoustical Engineering - Google Play
Unfortunately that book is not available in my country: there is no [READ EBOOK] red block on the browser, and from the Google store it clearly says "not available in Italy". Most probably is only available in the USA.
Bummer, the second link I posted IS the e-book. Oh well, learn something new every day; seemed reasonable to assume a Google link was just that anywhere Google was available.
edit: I have Google Mail, etc., on my computer, so maybe that's required?
edit: I have Google Mail, etc., on my computer, so maybe that's required?
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Hi GM,
I've done some research and it depends on the IP I currently have. Some nations have restrictions on available information. It is due to EU laws related to copyright on books et similia. Most probably a VPN would solve the issue.
I've done some research and it depends on the IP I currently have. Some nations have restrictions on available information. It is due to EU laws related to copyright on books et similia. Most probably a VPN would solve the issue.
Update: my GF wants to have shelves inside the wall on one side of the fireplace, so the speaker-on-the-wall idea is no more applicable.
I'll go back to something like the Metronome or Water Buffalo.
May I ask what is the difference in sound between the two?
I'll go back to something like the Metronome or Water Buffalo.
May I ask what is the difference in sound between the two?