Superscooper 18 Discussion/Scoop Design

staiper wrote: This are two hypothetical variations of "same" scoop cabinet. (same cahmber/throat/mouth)

"A" version is 18" derivative from JBL 4520 layout; ASS style, reflection type fold (bit with negative "expansion" @ LEV smiley2 ) , overall slower expansion rate (in theory better suit for deeper bass)

"B" is 18" derivative from JBL 4530 layout; "purist" style, proper constant expansion, ~constant/expanding area fold, overall higher expansion rate (here theory suggests bit higher SPL and a bit more usable bandwidth)

Very nice Staiper...

One thing though, my experience of Scoops with negative expansion (SteveB/Shortman mini), is that they have much better SPL than most scoops.

Not knowing what is inside S118 is tricky, as somehow this does all the sub notes, and still throws inside or out very far.

Maybe Tony stopped selling them, because they were too good.. :lol:

bitzo wrote: done with pd1850 but pretty deeper.

Thought it would look like that, that's why I mentioned 45hz.. :lol:

bitzo wrote: Imho, the A version is so much solid then B version, only in the modded section for sure. The experiment could be obtain the same "solidity" with pure expansion. So.... we can find if this is an expansion issue or a construction one.

Yes I',m liking Version A too..

sorry for the questions just trying to learn abit more about how and why scoops sound like they do, in a standard horn if the throat size is made smaller then the SPL increases and Bandwidth decreases, So with a scoop would the first part of the horn dictate the freq bandwidth and then the the negative expansion bit dictate the spl...... smiley29

the pd1850 has a ratio of 1.6 to 1 so 103 db = 64.375 how do you convert this to measurments.........

maybee i should start a new thread about compression ratio.....

my approach isn't academic. I decide the general internal layout then I get the variables to play with. Then I model the horn path after that..... I'll try and try (like jimmy cliff teach ) until a I get a good spl and flattest as possible. With a good number of try you'll get what change to have the expected result. You'll have a plenty plans to get good measures.

staiper wrote: This are two hypothetical variations of "same" scoop cabinet. (same cahmber/throat/mouth)

"A" version is 18" derivative from JBL 4520 layout; ASS style, reflection type fold (bit with negative "expansion" @ LEV smiley2 ) , overall slower expansion rate (in theory better suit for deeper bass)

"B" is 18" derivative from JBL 4530 layout; "purist" style, proper constant expansion, ~constant/expanding area fold, overall higher expansion rate (here theory suggests bit higher SPL and a bit more usable bandwidth)

I have not built any of those (friend of mine have two version "B" and he is more than happy .. but unfortunately have nothing to compare with.. soooo do not ask me)

smiley2

Is not a simple of case of "just" scaling this up to acquire worthwhile 18" scoop, however layout and angles are a guide.

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I calculated the throat from db keele formulas and it's really smaller than 10 cm for pd1850, about 5 cm for pd186 is 9 cm so I get this result but the cab is really deep about 90 cm.


So I have to work another time on pd1850 but to get the best efficient throat using keele's formula I'm thinking to change the layout. Dogleg returns..... smiley15

bitzo wrote: I calculated the throat from db keele formulas and it's really smaller than 10 cm for pd1850, about 5 cm for pd186 is 9 cm so I get this result but the cab is really deep about 90 cm.

So I have to work another time on pd1850 but to get the best efficient throat using keele's formula I'm thinking to change the layout. Dogleg returns..... smiley15

@Bitzo, don't get too caught up with design theory/software.. Sometimes the theory/software get's it monumentally wrong in regards to scoops.

Eminence design probably has most negative expansion known to man, however only scoops I know that can match it for SPL+sub depth combo are ASS/SteveB/shortman mini...

levyte357 wrote: @Bitzo, don't get too caught up with design theory/software.. Sometimes the theory/software get's it monumentally wrong in regards to scoops.

Eminence design probably has most negative expansion known to man, however only scoops I know that can match it for SPL+sub depth combo are ASS/SteveB/shortman mini...

what do you think about stravens?

bitzo wrote:

levyte357 wrote: @Bitzo, don't get too caught up with design theory/software.. Sometimes the theory/software get's it monumentally wrong in regards to scoops.

Eminence design probably has most negative expansion known to man, however only scoops I know that can match it for SPL+sub depth combo are ASS/SteveB/shortman mini...

what do you think about stravens?

IMHO - They sound good.. But better outside.. Eminence/SteveB sound good near or far, in or out..

here's the value to complete the plan
For PD186
baf=50.5cm
panela=41.5cm
panelb=50.5cm
panelc=50.5cm
anga=30
angb=5
depth=85cm

For PD1850
baf=50.5cm
panela=41.5cm
panelb=54.2cm
panelc=50.5cm
anga=30
angb=5
depth=79cm

see the attachment for legend

bitzo wrote: here's the value to complete the plan
For PD186
baf=50.5cm
panela=41.5cm
panelb=50.5cm
panelc=50.5cm
anga=30
angb=5
depth=85cm

For PD1850
baf=50.5cm
panela=41.5cm
panelb=54.2cm
panelc=50.5cm
anga=30
angb=5
depth=79cm

see the attachment for legend

Interesting Bitzo,

What's the cab width, gap below rear baffle, throat volume (HR::S1), you are working with?