Separate but together is what I posted in my last Sketch Up pic… Are you saying that it is good to have some bass up high to disperse it better throughout the room like this? (modified photo of StigEriks setup)
I want to run a centre and surround channel (for movies only) so I can’t go crazy spreading bits around the room.
I want to run a centre and surround channel (for movies only) so I can’t go crazy spreading bits around the room.
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One of the challenges with an OB is trying to de-ugly it a bit, or trying to make it a bit more partner friendly... So I had an idea today that I have put down on paper.
Drawn to scale with 2 x 15", but could easily be switched to 2 x 18" without throwing the design out of whack. Drawing is 1.6 meters tall. (63")
Drawn to scale with 2 x 15", but could easily be switched to 2 x 18" without throwing the design out of whack. Drawing is 1.6 meters tall. (63")
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I think it's worth trying out. ... but I was thinking along the line of separate enclosure placement. Might work well near one of the mains ... another might be placed along a wall at some distance and elevated at that location might work better still.
When I placed mine I used that trick of putting the sub/woofer at the listening position and roamed the room till the bass sounded strongest ... one sub went there. I repeated the operation for the next sub.
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Couple of questions around a U or H box,
Do they need to be square? I have a router and could make them in round slice with some feet shaped on the bottom.
Do they need to be sealed both sides like a typical U or H box? If I made the tube round with a small gap all the way around I could suspend the driver in the middle of the tube.
Do they need to be square? I have a router and could make them in round slice with some feet shaped on the bottom.
Do they need to be sealed both sides like a typical U or H box? If I made the tube round with a small gap all the way around I could suspend the driver in the middle of the tube.
You can make it round I don't see any reason why it would behave much different. It's the depth or front to back difference that determines how it'll perform.
I wouldn't leave a gap though that will allow cancellation directly around the woofer. With an h or u frame the goal is to make the front to back distance greater for reasons stated a few posts back. I honestly don't see any good reason to go to the trouble of decoupling the woofers like you do the mid and hf drivers. I would instead make the h or u frame solid and look into damping it's walls.
I wouldn't leave a gap though that will allow cancellation directly around the woofer. With an h or u frame the goal is to make the front to back distance greater for reasons stated a few posts back. I honestly don't see any good reason to go to the trouble of decoupling the woofers like you do the mid and hf drivers. I would instead make the h or u frame solid and look into damping it's walls.
Ok thanks so direct driver cancellation is of a greater priority than driver vibration isolation…
That could be easy done by just make the mounting board slice with a slightly smaller inner hole to screw the driver to.
Is there a formula or calculator to determine the length / volume front and rear?
That could be easy done by just make the mounting board slice with a slightly smaller inner hole to screw the driver to.
Is there a formula or calculator to determine the length / volume front and rear?
If you go with dual 15's or even 18's, there will be significant vibration once EQ'd to play flat to even 30-40hz. I would use at least a U frame to get back some efficiency. It makes no sense to run the woofers nude since the wavelengths are so long. Mids and highs I can see the case for it, but it still does not guarantee a better result than some form of baffle.
I would not attach the mids and highs to the woofer panel without more significant bracing or isolation. That kind of defeats the purpose of running nude, so maybe make the mid and high support legs straddle the woofer frame without touching. Then you've got complete isolation the the ability to move them around relative to each other.
Taking a leaf out of StigErik’s book I would like to get as low as I can using OB, and if I was to use a 21” and a 15” there should be adequate bass there to do the job done, and if there’s not I could always add a single sub for movies.
There is still a lot of refinement work to be done on the current design. To do it in MDF slices would use up quite a number of 8’x4’ boards, so I am also playing with the idea of making clear hexagonal shapes in flat panels.
Figuring 6 x 60 degrees = 360 degrees, and halving 60 degrees is 30 degrees either side of the cut. A 30 degree bevel cutter would be easy to get for the router.
How do I determine the length required?
There is still a lot of refinement work to be done on the current design. To do it in MDF slices would use up quite a number of 8’x4’ boards, so I am also playing with the idea of making clear hexagonal shapes in flat panels.
Figuring 6 x 60 degrees = 360 degrees, and halving 60 degrees is 30 degrees either side of the cut. A 30 degree bevel cutter would be easy to get for the router.
How do I determine the length required?
Doing the tubes in mdf rings? Whoa, that's a lot of waste. Can you get heavy PVC sewer pipe down under? As long as you find a way to make a clean, square cut on the end, it is perfect for your design. Enough heavier than sonotube to actually support the structure that you are proposing.
Greg
Greg
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Greg I came across you sub build thread today, and decided to go to my local plumbing supplies after work today to see if I could get something like you have in your pics.
They are getting me a price on some 450mm that is about 9mm wall thickness, but they said it will be around $500. So not really looking that flash of an option.
They are getting me a price on some 450mm that is about 9mm wall thickness, but they said it will be around $500. So not really looking that flash of an option.
That DOES look cool! I wonder about sitting the Raal right on top of the upper hex tube though. You've got a good foot of space for the bottom firing radiation of the Raal to reflect off of. You either have to put a bunch of heavy felt or Bonded Logic up there on the top surface or maybe leave that top portion hollow. Can you mount both woofers together and have the MID/HF module on legs only?
Are you planning to run both woofers in parallel? Not sure if that will work given they may need different amounts of EQ.
Are you planning to run both woofers in parallel? Not sure if that will work given they may need different amounts of EQ.
I was actually wondering about the tweeter, but thought that the foam pads that come with it would stop upward dispersion. I haven’t got the new dipole RAALs yet (getting AM transformers fitted and being air freighted now), but from the PDF description I think they came with foam pads both front and rear. Nothing would stop me putting the top woofer higher or as you suggest opening it up on the bottom side.
If I run two of any size driver I would put them in parallel, if I run odd sized drivers I would probably run them as separate channels. Still need to finish reading up why StigErik went away from this kind of design that he had, to the line array. Don’t want to spend a lot of money only to find that I have followed an inferior design. If I was to put two woofers on the bottom the design goal would be to have the HF/Mid separately mounted.
Kind of like the idea of the clear hex tubes… kind of reminds me of the 70’s electric drum kits. Unfortunately there is no such thing as a bargain in Oz, if it is not commonly used that causes some kind of competition, then they figure that gives them license to rip you off. The internet is great for small items but post on large items like pipe would be crazy.
Got some prices on 10mm clear sheet the other day (2440 x 1220 – 8’ x 4’) $330 + GST for full sheet, $190 + GST for half sheet. Would 10mm be thick enough considering that it isn’t trying to seal the driver?
If I run two of any size driver I would put them in parallel, if I run odd sized drivers I would probably run them as separate channels. Still need to finish reading up why StigErik went away from this kind of design that he had, to the line array. Don’t want to spend a lot of money only to find that I have followed an inferior design. If I was to put two woofers on the bottom the design goal would be to have the HF/Mid separately mounted.
Kind of like the idea of the clear hex tubes… kind of reminds me of the 70’s electric drum kits. Unfortunately there is no such thing as a bargain in Oz, if it is not commonly used that causes some kind of competition, then they figure that gives them license to rip you off. The internet is great for small items but post on large items like pipe would be crazy.
Got some prices on 10mm clear sheet the other day (2440 x 1220 – 8’ x 4’) $330 + GST for full sheet, $190 + GST for half sheet. Would 10mm be thick enough considering that it isn’t trying to seal the driver?
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