You need to read up on the Raal foam because it does exactly the opposite of your assumption. Without the foam, the top two octaves are dispersed very narrow vertically. With the foam added, you get a much taller dispersion which would then bounce off of the top of that woofer hex tube and cause odd comb filtering. Kind of kills the whole idea of a free swinging driver.
See Goran's excellent measurements here:
www.audioexcite.com RAAL 140-15D
See Goran's excellent measurements here:
www.audioexcite.com RAAL 140-15D
Thanks Greg, I previously started reading that thread but I really didn’t understand the results, but suffice to say you gleaned from it that the purpose of the pads is to increase vertical response not decrease it.
I will make sure that I plan as best I can to avoid any panels that would create a direct reflection. Just thinking what about lower (larger) hexagon that is sat on its edge, if I can’t avoid having the tweeter close to a hex, having it angled away like that has to be better than a direct reflecting surface wouldn’t it?
I will make sure that I plan as best I can to avoid any panels that would create a direct reflection. Just thinking what about lower (larger) hexagon that is sat on its edge, if I can’t avoid having the tweeter close to a hex, having it angled away like that has to be better than a direct reflecting surface wouldn’t it?
Well, the basic info is on Raals site too...plus my own measurements follow Goran's very closely. It's Alexander's(owner of Raal) novel and simple approach to a common problem with ALL tall treble drivers, beaming in the top octaves. I'm thinking of trying my own larger pads to use with some Neo8 drivers I'm running as mid/tweeters.
Set at an angle would surely help some, but keep the creative wheels moving and maybe you'll come across something even better.
Set at an angle would surely help some, but keep the creative wheels moving and maybe you'll come across something even better.
Ok time for a new design... I call this one "the butt crack" 
It's a modified version of the Slot Loaded Open Baffle.
Rounded front exit to smooth the sound transition. Closed in back to reduce baffle size.
Figure this would be fairly easy to make, two symetrical sheets of 10mm folded acrylic, glued at the centre back join (nice solid gluing point), and top and bottom plates...
It's a modified version of the Slot Loaded Open Baffle.
Rounded front exit to smooth the sound transition. Closed in back to reduce baffle size.
Figure this would be fairly easy to make, two symetrical sheets of 10mm folded acrylic, glued at the centre back join (nice solid gluing point), and top and bottom plates...
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You could also use some flexible MDF like this. You should glue two sheets together (slice against each other)
An externally hosted image should be here but it was not working when we last tested it.
That flexible MDF would probably be an easy way to do a round tube..
But I do like the idea of using the clear acrylic. Just came back from the shopping centre and on the way out I spotted these.
Looked like 10mm so it gives me a good idea of how far it can be bent.
But I do like the idea of using the clear acrylic. Just came back from the shopping centre and on the way out I spotted these.
Looked like 10mm so it gives me a good idea of how far it can be bent.
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In the case of the bends shown, bear in mind that the acrylic is heated until it gets soft, and then bent at any angle needed.
The downside in your application is that the heated area will look wavy and distorted...
The smaller the radius(less than a couple of centimeters in the case of the shopping center bends), the less obvious is the distortion.
On a 20cm radius bend, unless you have specialty industrial grade equipment, getting it to look good will be quite a challenge.
The bendy MDF might be the best was to go.
P.S: have you thought about the acrylic's resonance? I have no idea what the intrinsic resonance frequency of such a tube would be, but it's a good idea to check it out first.
How about 2 of these per side?
Dayton Audio RSS460HO-4 18" Reference HO Subwoofer 4 ohm 295-472
Nice Qts @ .48 means not a lot eq needed while not being too flappy and resonant. Nice low FS and good price. Too bad they are 4ohms. You would need to use a good Crown or QSC that can handle 2 Ohms or run them in series which is not optimal.
EDIT: Just noticed the Mms, 425g! Ouch, if you believe that this makes a difference. For comparison, my B&C is 96g, but much less xmax and higher FS.
Dayton Audio RSS460HO-4 18" Reference HO Subwoofer 4 ohm 295-472
Nice Qts @ .48 means not a lot eq needed while not being too flappy and resonant. Nice low FS and good price. Too bad they are 4ohms. You would need to use a good Crown or QSC that can handle 2 Ohms or run them in series which is not optimal.
EDIT: Just noticed the Mms, 425g! Ouch, if you believe that this makes a difference. For comparison, my B&C is 96g, but much less xmax and higher FS.
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Nice looking driver. Just realize that with a Qts that low and higher FS than something like the Dayton will mean inherently less bass output before EQ. In other words, you will need a lot of EQ and will still only get to around 40-50hz. Good news is that with high sensitivity, you can do some downward EQing rather than boosted EQ to achieve the same results. Does this make sense?
How big is your room? Any idea what kind of spl you like to listen at?
Part of the problem is I haven't heard any of the drivers, so I am shooting blind. You have heard the B&C and others have commented on them, giving me some kind of idea of quality.
Just figured that the qts was slightly higher than the NDL and the FS slightly lower.
To be honest I think I am in the right ball park, but would nearly prefer someone just tell me what is the best driver to use after factoring in my needs.
How loud? loud!, you cant listen to AC/DC any other way
Most of the time I listen to music at quite moderate levels, but occasionally like to crank it up.
Room? moving into new premises within the next 6 months so cant really answer that one at the moment but will be shopping with home theatre in mind.
Just figured that the qts was slightly higher than the NDL and the FS slightly lower.
To be honest I think I am in the right ball park, but would nearly prefer someone just tell me what is the best driver to use after factoring in my needs.
How loud? loud!, you cant listen to AC/DC any other way
Most of the time I listen to music at quite moderate levels, but occasionally like to crank it up.
Room? moving into new premises within the next 6 months so cant really answer that one at the moment but will be shopping with home theatre in mind.
OK AC/DC loud and home theater. Man, you need to stick with a single, nice
15-18" on the bottom and just commit to some real sealed subs. It's the best choice IMHO.
If you want to make me jealous and be the first guy to do it, buy one of these for the OB, use it like that for a while and then add your subs later. I was very close to working out a deal to get a pair of these for a steal. Damn, that would have been sooooo sweet. It really would put your build over the top considering all of the other top-of-the-line drivers your are shelling out for. Do it do it do it!
Are you sitting down? Here it is:
TC Sounds Pro 5100 18" Neo Subwoofer Driver 293-674
15-18" on the bottom and just commit to some real sealed subs. It's the best choice IMHO.
If you want to make me jealous and be the first guy to do it, buy one of these for the OB, use it like that for a while and then add your subs later. I was very close to working out a deal to get a pair of these for a steal. Damn, that would have been sooooo sweet. It really would put your build over the top considering all of the other top-of-the-line drivers your are shelling out for. Do it do it do it!
Are you sitting down? Here it is:
TC Sounds Pro 5100 18" Neo Subwoofer Driver 293-674
With a recomendation like this how can I say no "Did I say crazy, I ment pull your underwear up over your head and have some one punch you in the face."
At 53lbs I can forget trying to mount them on 10mm acrylic.
All I can say is get ready to be jealous
Well ****, if I knew it was that easy, I'd have said you needed to buy 4 and send two my way. If I wasn't so happy for you right now, I'd be jealous. Gives me another reason to visit down under I guess.
Why bother visting I can just turn it up
If I was to leave these in the OB config, what would I then use for subs?
Do I U box these or H box?
Well duh silly, you'd use two more of the same thing in boxes.
With that much sexy driver to look at, I'd do a flat baffle prototype(heavily reinforced) to see what you get. No sense hiding those things down inside of an H or U. Maybe a wide enough panel to fit the 18" with some inches to spare on either side and some nice swept back wings in the sides to increase path-length while keeping the look relatively narrow. Or a nice rounded corner piece like these:
http://www.tapeease.com/4rounds.htm
Imagine if StigErik used these guys instead of the 21" he bought. Wow, that would be pricey. Takes my breathe away just thinking about it!
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