A simple roundover goes much lower than that, and even lower depending on size. The "It's only useful at frequencies where the roundover radius is significant" has been debunked repeatedly with measurements. I don't remember what specific articles/posts but there have been plenty and I've done plenty of my own measures around diffraction (though I generally don't save measures- they're used as datapoints during design and change as the design gets refined).
I explain above what I believe is the key reason roundovers work well below their 1/4 wavelength size limitations, with a diagram and everything.
What 15" driver do you have? Is it one of those audio nirvana beasts.
Coaxials and large full rangers all have off axis diffraction issues up top, at least I've never seen one that didn't. But the high directivity means there is no advantage to putting them in a wall over a large box. Basically it will sound similar either way.
Just my opinion but I prefer to sit further away the more directional the speaker is. Also a reflective room is better.
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Baffle diffraction
33Polkhigh:
I have not bought a coaxial of any size yet. I'm very interested in the Vortex 15" (Eminence) unit from DIYSOUNDGROUP. I travel to the St. Louis area for business, so could stop any time and check out the Nirvana stuff.
My issue is aesthetics of the room architecture. Big, lots of glass, lots of traffic patterns in and out of the room, etc. Check out my signature....Homebuilder. I cannot (personally) put speakers in there that don't go along with the whole theme of the project. There are currently high end stand mounted 3 way monitors and subs in the room now, and they look horribly out of place. I want to move them to a new audio room. They do happen to be coaxial designs.
The idea of building something into the wall is very appealing. This room is also over a dry, air conditioned and heated crawl space (a big one) so infinite baffle is also a consideration.
GedLees comments on diffraction got me thinking about a large, efficient coaxial in-wall speaker mounted with as big of a box as needed. I'm completely open to suggestions.
I had not looked at the sticky on open baffle speakers before, so I spent a couple hours going through the hundreds of photos of those designs. There were quite a few that were really attractive, looked like a nice project, and would work well in the room if we rearrange the layout, which is planned for this coming Spring anyway. Two very nice and elegant designs that I really liked were in posts #1078 and #2241. But to use them, they would be in front of a 36' long wall of glass. Not good, but not much I can do about that.
The search goes on.
33Polkhigh:
I have not bought a coaxial of any size yet. I'm very interested in the Vortex 15" (Eminence) unit from DIYSOUNDGROUP. I travel to the St. Louis area for business, so could stop any time and check out the Nirvana stuff.
My issue is aesthetics of the room architecture. Big, lots of glass, lots of traffic patterns in and out of the room, etc. Check out my signature....Homebuilder. I cannot (personally) put speakers in there that don't go along with the whole theme of the project. There are currently high end stand mounted 3 way monitors and subs in the room now, and they look horribly out of place. I want to move them to a new audio room. They do happen to be coaxial designs.
The idea of building something into the wall is very appealing. This room is also over a dry, air conditioned and heated crawl space (a big one) so infinite baffle is also a consideration.
GedLees comments on diffraction got me thinking about a large, efficient coaxial in-wall speaker mounted with as big of a box as needed. I'm completely open to suggestions.
I had not looked at the sticky on open baffle speakers before, so I spent a couple hours going through the hundreds of photos of those designs. There were quite a few that were really attractive, looked like a nice project, and would work well in the room if we rearrange the layout, which is planned for this coming Spring anyway. Two very nice and elegant designs that I really liked were in posts #1078 and #2241. But to use them, they would be in front of a 36' long wall of glass. Not good, but not much I can do about that.
The search goes on.
Baffle diffraction
Addendum: My comment on Post # 2241 of the open baffle sticky was not for the look of the front of the speaker, but rather how they utilized wood with solid banding around the edges. I like the back side of that speakers, and overall construction. No specific comment intended on the drivers.
As for project #1078, I like it for many reasons, but would probably go with something like mahogany.
Addendum: My comment on Post # 2241 of the open baffle sticky was not for the look of the front of the speaker, but rather how they utilized wood with solid banding around the edges. I like the back side of that speakers, and overall construction. No specific comment intended on the drivers.
As for project #1078, I like it for many reasons, but would probably go with something like mahogany.
I built a speaker from diysoundgroup before. Their stuff is geared toward the pro audio home theater side of things. They're ok, maybe not the most refined audiophile designs. THey're waveguides are good.
You don't need a speaker though just a driver. Also theres other coaxials besides the Eminence. Some people do like the big full rangers and something in the 8-12" range might work. You will need a crossover with an in wall coax but probably not with a full ranger.
Look in parts express catalogue. THere is also a new 8" tang band coaxial that looks nice and a new seas design that came out from madisound.
I would do some listening tests of whatever you get on a piece of plywood for a while and make sure you really like the sound. As far as diffraction, coaxes and full rangers all have some inherent diffraction as far as I know.
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Ignoring diffraction, if any, once you remove the frequencies below the localization tattle range (maybe 130 Hz on music) your decor option multiply since you only need a really quite small "enclosure" for the mid and tweeter. It should be easy for you to create hidden or camouflaged open baffles, for example. And the low freq driver (you need only one, at least minimally) can be tucked away anywhere - like inside a cabinet (with a fabric panel door) or under a sofa.
B.
B.
Baffle diffraction
"Ignoring diffraction, if any, once you remove the frequencies below the localization tattle range (maybe 130 Hz on music) your decor option multiply since you only need a really quite small "enclosure" for the mid and tweeter. It should be easy for you to create hidden or camouflaged open baffles, for example. And the low freq driver (you need only one, at least minimally) can be tucked away anywhere - like inside a cabinet (with a fabric panel door) or under a sofa."
Bentoronto: thanks for those comments. Those ideas are all possible in this room, except under a sofa. The fabric panel suggestion is kind of where I've been leaning. In that 24' x 36' room, there is an in-wall cabinet floor to ceiling in one corner. I could EASILY hide even a 21' sub in the bottom of that cabinet. But perhaps more interesting are the floor vents that used to be for forced air heat, scattered around the room. Over-top a huge crawl space. I've posted before about using those 2" x 14" vents (9 of them) to make some infinite baffle subs. Perhaps 2-4 small manifolds firing up through the floor.
There is also a large dropped soffit system wrapping around about 40% of the room, on the opposite side of the room from the floor vents. There is literally hundreds of square feet of ceiling area where-by an infinite baffle woofer manifold could be mounted above the ceiling. If we oriented the seating areas towards the South wall of glass, we could do anything from 2-?? channels of sound.
At dinner last night, one of my best friends and I talked about using his stone cutting CNC machines to make marble or granite tops to fit on top of our 3 12" powered subs. Probably make a matching piece for them to sit on, and turn them into coffee tables. Right now, I'm always paranoid they will get scratched. They are too pretty. They are 12" with a 12" passive design.
Patrick Batemans' projects with some of the various waveguides could be mounted in the ceiling, and throw sound far into this room. Lots of great idea. I'm just trying to get opinions from others on good, workable solutions. And of course, to have fun in the process.
"Ignoring diffraction, if any, once you remove the frequencies below the localization tattle range (maybe 130 Hz on music) your decor option multiply since you only need a really quite small "enclosure" for the mid and tweeter. It should be easy for you to create hidden or camouflaged open baffles, for example. And the low freq driver (you need only one, at least minimally) can be tucked away anywhere - like inside a cabinet (with a fabric panel door) or under a sofa."
Bentoronto: thanks for those comments. Those ideas are all possible in this room, except under a sofa. The fabric panel suggestion is kind of where I've been leaning. In that 24' x 36' room, there is an in-wall cabinet floor to ceiling in one corner. I could EASILY hide even a 21' sub in the bottom of that cabinet. But perhaps more interesting are the floor vents that used to be for forced air heat, scattered around the room. Over-top a huge crawl space. I've posted before about using those 2" x 14" vents (9 of them) to make some infinite baffle subs. Perhaps 2-4 small manifolds firing up through the floor.
There is also a large dropped soffit system wrapping around about 40% of the room, on the opposite side of the room from the floor vents. There is literally hundreds of square feet of ceiling area where-by an infinite baffle woofer manifold could be mounted above the ceiling. If we oriented the seating areas towards the South wall of glass, we could do anything from 2-?? channels of sound.
At dinner last night, one of my best friends and I talked about using his stone cutting CNC machines to make marble or granite tops to fit on top of our 3 12" powered subs. Probably make a matching piece for them to sit on, and turn them into coffee tables. Right now, I'm always paranoid they will get scratched. They are too pretty. They are 12" with a 12" passive design.
Patrick Batemans' projects with some of the various waveguides could be mounted in the ceiling, and throw sound far into this room. Lots of great idea. I'm just trying to get opinions from others on good, workable solutions. And of course, to have fun in the process.
Now that's quite an impressive array of creative smarts.
Data point: I used to have a Klipschorn corner horn sub in the corner of a large room yards from the main speakers and never heard a false localization peep from them with 130 Hz XO and 24db/8ave slope. But that is premised on sharp XO slopes and a clean sub with no give-away audible harmonics.
B.
Data point: I used to have a Klipschorn corner horn sub in the corner of a large room yards from the main speakers and never heard a false localization peep from them with 130 Hz XO and 24db/8ave slope. But that is premised on sharp XO slopes and a clean sub with no give-away audible harmonics.
B.
I'm interested in hearing what more you think/discover in due course. The more I consider the apparent simplicity and advantages of something like Charlie Laub's naked OB the more boxes it seems to tick.
If I may, those comments remind me of this. The middle diagram, a side view using two sources. There is a discontinuity running downward and to the right, it is connected with the ceiling just above the speaker. It goes over the listening position, but how it gets that direction is not so intuitive.
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baffle diffraction
"I'm interested in hearing what more you think/discover in due course. The more I consider the apparent simplicity and advantages of something like Charlie Laub's naked OB the more boxes it seems to tick."
ScottJoplin: I think your comment is on the money. I spent time yesterday reading a summary of some of Linkwitz's thoughts on sound, and came away thinking that a dipole or similar might just be the best thing to deal with my situation.
One of the advantages I see to any type of open baffle/dipole/naked speaker is that you can save a lot of time and expense creating huge, boxy speakers, making 1.5" or more thick panels, etc. That money could be spent on other aspects of the speaker. Possibly better drivers, better room treatments, measurement, etc. And frankly, as you get older, you just cannot deal with boxes that end up weighing as much as a refrigerator.
Bentoronto: I love the thought of making marble or some other stone product "shields" to protect our subwoofers. But as anyone knows who has done a kitchen project recently, that stuff is really expensive. I'm doing that right now, and feeling the pain. I could come close to building new subs from scratch for the same amount as the marble, and just sell our subs. What is your opinion on subs mounted under the floor, and do you think it would work as well, or better than 1-3 subs located either in a nearly wall, or somewhere in the room? What about mounted in a ceiling?
"I'm interested in hearing what more you think/discover in due course. The more I consider the apparent simplicity and advantages of something like Charlie Laub's naked OB the more boxes it seems to tick."
ScottJoplin: I think your comment is on the money. I spent time yesterday reading a summary of some of Linkwitz's thoughts on sound, and came away thinking that a dipole or similar might just be the best thing to deal with my situation.
One of the advantages I see to any type of open baffle/dipole/naked speaker is that you can save a lot of time and expense creating huge, boxy speakers, making 1.5" or more thick panels, etc. That money could be spent on other aspects of the speaker. Possibly better drivers, better room treatments, measurement, etc. And frankly, as you get older, you just cannot deal with boxes that end up weighing as much as a refrigerator.
Bentoronto: I love the thought of making marble or some other stone product "shields" to protect our subwoofers. But as anyone knows who has done a kitchen project recently, that stuff is really expensive. I'm doing that right now, and feeling the pain. I could come close to building new subs from scratch for the same amount as the marble, and just sell our subs. What is your opinion on subs mounted under the floor, and do you think it would work as well, or better than 1-3 subs located either in a nearly wall, or somewhere in the room? What about mounted in a ceiling?
Naked speaker means maximum smoothness above the dipole peak and as far as diffraction goes seems to be best too, particularly if there is front/back symmetry. The only downside I see are the excursion requirements below the peak.
I talked with my advisor (PhD in nuclear physics) and gave him my thoughts and he couldn't add anything to what I am thinking - kind of seems like the cancellation is perfect at the edge of a disk if: the disk is perfectly round, flat and infinitesimally thin. Any one of these gets violated and there has to be some diffraction - greater deviation would lead to more diffraction. Some limitations might apply like infinity thick disk, or infinitely large disk, but those are not of much interest anyways.
As to "naked OB" there is no contest on enclosure simplicity, but a big contest in efficiency. To me the simplest solution to the whole problem of enclosure, is just an in-wall infinite baffle of a coax like a B&C 10". Done right (crossover, some subs) and this would perform amazingly.
Take a look at the polars on the second link- I don't know that there are other large-format coaxes on market even worth considering in light of this performance! Altec 604s can sound great but definitely don't control pattern nearly so consistently.
Denovo Audio Vortex-15
Vortex Speaker Kits | HiFiCircuit
Decent response, a little high in price when compared to the B&C's that I used, but that was a 10".
Take a look at 12CXN88 for example. One could make a very nice speaker out of that driver.
Ouch! Just looked up the list price on that! B&C prices seem to have gone much higher than I remember.
Take a look at 12CXN88 for example. One could make a very nice speaker out of that driver.
Ouch! Just looked up the list price on that! B&C prices seem to have gone much higher than I remember.
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Test Bench: B&C Speakers Pro Sound 12CXN88 12” Coax Driver | audioXpress
Nice driver- but if polars are a priority, the DIYSG driver seems to have it all over the B&C.
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