While I think there are ways to manipulate designs to achieve narrow band high output, and there are certainly more designs there has to be a consensus of benchmarks... Considering optimum FR and single driver, how far off am I? OR is it innane to simply matters this much?
Sealed 90db
Ported 95db
TH 100db
FLH 105db
To expound, would anyone consider a TH design achieving 95db in passband but lower F3 in a smaller cab a successful design? Thanks in advance.
Sealed 90db
Ported 95db
TH 100db
FLH 105db
To expound, would anyone consider a TH design achieving 95db in passband but lower F3 in a smaller cab a successful design? Thanks in advance.
Given they've all got different frequency response shapes, its difficult to draw any conclusions.
For example, a sealed box can give more output than a ported box if you want to go below the ported box's tuning.
At port tuning, you get a lot of gain over a sealed box. It depends on a lot of factors as to how much gain, but there's definitely some. When the ports start chuffing, however, all bets are off, with some claiming performance is worse than that of a sealed box.
THs are similar to ported boxes, in that you get virtually no output below tuning. Above tuning, you can expect gain over a ported box, with the penalty of cabinet size. As a rule, double the size of the box will net you +6dB, as if you'd gone for two ported boxes.
FLHs are very variable, and are often built severely under-sized, with the aim to use multiple cabinets to get the mouth area up. A full-sized FLH is non-trivial to construct and transport, but would beat anything else on efficiency, with the ability to go as low as you like.
Chris
For example, a sealed box can give more output than a ported box if you want to go below the ported box's tuning.
At port tuning, you get a lot of gain over a sealed box. It depends on a lot of factors as to how much gain, but there's definitely some. When the ports start chuffing, however, all bets are off, with some claiming performance is worse than that of a sealed box.
THs are similar to ported boxes, in that you get virtually no output below tuning. Above tuning, you can expect gain over a ported box, with the penalty of cabinet size. As a rule, double the size of the box will net you +6dB, as if you'd gone for two ported boxes.
FLHs are very variable, and are often built severely under-sized, with the aim to use multiple cabinets to get the mouth area up. A full-sized FLH is non-trivial to construct and transport, but would beat anything else on efficiency, with the ability to go as low as you like.
Chris
Cabinet size is a cube function of the cut-off frequency, so:
40hz box size is 1x
32hz box size is 2x
25hz box size is 4x
20hz box size is 8x
If you keep the box size constant the efficiency goes down by:
40hz -0dB
32hz -3dB
25hz -6dB
20hz -9dB
A 2 cu ft 2nd order sealed box with an F3 of 30hz can only be 0.18% efficient (84.55dB).
A 2 cu ft 4th order vented box with an F3 of 30hz can only be 0.36% efficient (87.56dB).
A 2 cu ft 6th order vented box with an F3 of 30hz can only be 0.90% efficient (91.54dB).
http://i56.photobucket.com/albums/g196/dkleitsch/CoePA-2009.jpg
A 30hz 6th order PPSL stack. Two cabinets stacked are 107dB/2.83V/1M in 2Pi, each cabinet being 8Ω.
The stacked pair of FLH mids are 110dB/2.83V/1M, each cabinet being 8Ω.
The single HF horn is 113dB/2.83V/1M, and is 8Ω.
40hz box size is 1x
32hz box size is 2x
25hz box size is 4x
20hz box size is 8x
If you keep the box size constant the efficiency goes down by:
40hz -0dB
32hz -3dB
25hz -6dB
20hz -9dB
A 2 cu ft 2nd order sealed box with an F3 of 30hz can only be 0.18% efficient (84.55dB).
A 2 cu ft 4th order vented box with an F3 of 30hz can only be 0.36% efficient (87.56dB).
A 2 cu ft 6th order vented box with an F3 of 30hz can only be 0.90% efficient (91.54dB).
http://i56.photobucket.com/albums/g196/dkleitsch/CoePA-2009.jpg
A 30hz 6th order PPSL stack. Two cabinets stacked are 107dB/2.83V/1M in 2Pi, each cabinet being 8Ω.
The stacked pair of FLH mids are 110dB/2.83V/1M, each cabinet being 8Ω.
The single HF horn is 113dB/2.83V/1M, and is 8Ω.
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Fill a large cardboard box or a plastic tub with as many books as you can "easy up a flight of stairs", weigh it, then you will know what you would call portable.
I used to be able to easily lug 75 pounds up a flight of stairs, now that would be pushing it.
Hey, would you be interested in a 72 pound 26.5" x 15" x 15" 10" TH with an F3 of 60 Hz ;^)?
Art
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The POC3 checks in at about 55 lbs, but that's with double-thick top and bottom panels (required because of the cheap ply that I used), and a considerable amount of bracing (ditto). Being based on a 12" driver with 5mm Xmax, its output is limited compared to most of the other designs here though
.However, it is a "proof of concept", and if I was going to build one again, I'd do it a bit differently, i.e. incorporate cone-compensation into the design (which should reduce the size of the box a little) and use a more capable driver, like the 4 Ohm Eminence Kappalite 12". The end result should be a smaller, lighter box with considerably more output capability.
I work out at home and have iron, so I kinda have the weight limit... I'd say 75 -100# is OK but of course the lighter the better. It's a size issue. I think you guys know what I mean when you were saying it's easier to move taller cabs. There are small cabs that a b**** to move. Awkward sized stuff. Gonna measure some large stuff and see if that helps.
POC3 might not be loud (PA310) but the FR is great. Right now trying to determine of that 190L cab with Don Snyder's fold is "portable". WOW 3012LF is under 7 1/2 lbs... That's like 25 pounds lighter than the PA385!!! Might table this until POC5!
POC3 might not be loud (PA310) but the FR is great. Right now trying to determine of that 190L cab with Don Snyder's fold is "portable". WOW 3012LF is under 7 1/2 lbs... That's like 25 pounds lighter than the PA385!!! Might table this until POC5!
I used two Galaxy Audio 5" and an EV phenolic dome tweeter as used in the S-100 or S-200 speakers.
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