Does anybody have any experience or any ideas as to how you would go about eliminating as much of the backwave from a dipole as possible. I know this will minimize some of the benefits of a dipole, but I want to be able to put the units as close to a rear wall as possible. I am hoping to cover the midbass from where my tapped horns are not flat anymore (they are flat up to 60hz) up to 150-200hz or so.
With the drivers I have on hand, the only option of reasonable size is dipole since they have a weak motor and a qts of .7ish.
With the drivers I have on hand, the only option of reasonable size is dipole since they have a weak motor and a qts of .7ish.
Here is what I'm planning to do. The tapped horns will cover from 20-60hz and the OB arrays will cover from 60 up to around 150 or so. The OB array will act as a speaker stand for my mains.
http://i516.photobucket.com/albums/u328/xchris8sirhcx/BassDipole.jpg
Does anybody with experience with OB designs see anything wrong with this design?
Here are the t/s paramaters:
PARAMETERS
Re 7.20 [ê ]
Fs 44.26 [Hz]
F1 35.48 [Hz]
F2 56.23 [Hz]
Zm 53.74 [ê]
D 208.00 [mm]
Qms 5.80
Qes 0.90
Qts 0.78
Bl 6.76 [N/A]
L1K 1.47 [mH]
L10K 0.72 [mH]
Ms 20.47 [g]
Vas 101.85 [l]
dBSpl 92.34 [dB]
Cms 0.63 [mm/N]
Ma 48.00 [g]
FsMa 24.20 [Hz]
I was thinking about using some Wood Hardner on the cones of these to make them stiffer than they already are. This could also add a little bit more mass thus increasing the qts and lowering the fs along with the sensitivity some.
here is a link to a thread about the wood hardener:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=60652
http://i516.photobucket.com/albums/u328/xchris8sirhcx/BassDipole.jpg
Does anybody with experience with OB designs see anything wrong with this design?
Here are the t/s paramaters:
PARAMETERS
Re 7.20 [ê ]
Fs 44.26 [Hz]
F1 35.48 [Hz]
F2 56.23 [Hz]
Zm 53.74 [ê]
D 208.00 [mm]
Qms 5.80
Qes 0.90
Qts 0.78
Bl 6.76 [N/A]
L1K 1.47 [mH]
L10K 0.72 [mH]
Ms 20.47 [g]
Vas 101.85 [l]
dBSpl 92.34 [dB]
Cms 0.63 [mm/N]
Ma 48.00 [g]
FsMa 24.20 [Hz]
I was thinking about using some Wood Hardner on the cones of these to make them stiffer than they already are. This could also add a little bit more mass thus increasing the qts and lowering the fs along with the sensitivity some.
here is a link to a thread about the wood hardener:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=60652
Yeah, I have looked into the linkwitz transform before, but I really lose a ton of sensitivity. My subs will do 124db each at 20hz. There will be 8 of those 10's per side and they start out at 92 db each. I have tried 4 in a large OB before and it sounded very good. Would the lin. transform lower my total output potential at 40-60hz?
edit: I just messed around a bit in WinISD and came up with a 5.5 cubic foot box will get me around 114.5 db at 60hz w 200 watts with a linkwitz and will be good up to 115 hz or so. With a huge box im getting around 117db at 60hz w 50 watts and it is good up to at least 200hz. How soon does the Dipole start rolling off assuming that the 'wings' will go back a foot and a half or so?
edit: I just messed around a bit in WinISD and came up with a 5.5 cubic foot box will get me around 114.5 db at 60hz w 200 watts with a linkwitz and will be good up to 115 hz or so. With a huge box im getting around 117db at 60hz w 50 watts and it is good up to at least 200hz. How soon does the Dipole start rolling off assuming that the 'wings' will go back a foot and a half or so?
As SPL is simply a function of excursion and cone area, it's possible with the right box that the LT box may go louder than the open back sub as it can control the cone better and there is no rear wave cancelling stuff out. The LT should make no difference to "sensitivity" or SPL in other parts of the bandwidth of that box, however the amount of power required compared to open back will be greatly increased. I presume that's what you mean about sensitivity.
Xmax is not the problem, if it's a problem in closed box then it will be even more of a problem open baffle where excursion is wasted trying to overcome the rear wave cancellations.
People think you need big excursion for LT, that's not true. SPL is simply due to excursion and cone area, so whether the box is tiny and equalised like mad, or huge with no EQ, the attainable SPL is identical, it's just the power input requirement that changes.
With 30 watts you could be struggling. Could be worth a look with some software though. A dipole will need 6dB/oct boost anyway so you could be struggling even with that.
People think you need big excursion for LT, that's not true. SPL is simply due to excursion and cone area, so whether the box is tiny and equalised like mad, or huge with no EQ, the attainable SPL is identical, it's just the power input requirement that changes.
With 30 watts you could be struggling. Could be worth a look with some software though. A dipole will need 6dB/oct boost anyway so you could be struggling even with that.
starting at what frequency?richie00boy said:
here is the listed power handling:
30 watts RMS/60 watts max
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=299-721
I think he took down a lot of the design info as he was getting too much traffic that his hosting could cope with. It's available on CD for a fair price from him.
I can't remember whether the frequency is a full, half or quarter wavelength of the baffle dimension where you need to start boost from.
I can't remember whether the frequency is a full, half or quarter wavelength of the baffle dimension where you need to start boost from.
I have 16 of these things lying around, and I kinda want to get the giant box out of my room that has been sitting there for a few years. I think I will end up building a box that can have the back removed to make it into an OB. That way I can actually comare the two designs and I wont be stuck with one or the other.
My tapped horn (I actually have two of them) can be found near the very end of the huge tapped horn thread. There are plans, pictures, and a predicted spl graph. That 124db is only with ~100-141 watts. Each one can do ~103-104db with only 1 watt at 20hz. Never heard anything like it before, although I have never heard a full sized gigantic 20hz horn.
My tapped horn (I actually have two of them) can be found near the very end of the huge tapped horn thread. There are plans, pictures, and a predicted spl graph. That 124db is only with ~100-141 watts. Each one can do ~103-104db with only 1 watt at 20hz. Never heard anything like it before, although I have never heard a full sized gigantic 20hz horn.
That is 30W per driver, 240W for eight drivers, right?Chris8sirhC said:
You can simulate it with Edge. For a folded baffle you have to calculate the shortest way around the baffle from center to center. 20" wide with 18" wings at right angle should correspond to something like a 48.6" flat baffle. In your case not exactly, because you seem to be planning an M-shape.Chris8sirhC said:
Edge simulates the output of an ideal driver, with a linear frequency response. For real drivers there are unlinearities to take into account and the natural roll-off below the resonant frequency as well as at the top.
And you also should expect a resonance at the wing's wavelength from a folded baffle, if the wings are equally long. Maybe your M-shape is not so critical there.
Considering how big this subwoofer would be, how big are the boxes you want to replace?Chris8sirhC said:
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