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Old 23rd February 2011, 02:19 PM   #441
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New challenge
Double 3015 @ 30hz to 120hz with max spl
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Old 23rd February 2011, 02:21 PM   #442
jbell is offline jbell  United States
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Quote:
Originally Posted by AndrewT View Post
I did not get much (any) interest in a the competition suggestion for a one and a half sheet design that could go lower and/or louder.

Is anybody up for that?
A Mars Bar for the winner if Customs allow it through.
sorry guys, haven't taken much interest in improving on the ss15 design -- it just works so well for my intended goal. I've found in reverberant spaces (gyms) that a gentle roll off from 60-40hz and a steep high pass at 40hz actually helps in the bass department. I have what I can subjectively say is 'cleaner' bass vs if I try to eq to flat. (testing 2.83v@1m) I've been known to add a couple db eq at 45hz, but only a couple, I don't try to get absolutely flat. I still get that really low satisfying bass feel, without some of the mud.

Unfortunately for a single sheet design -- it is a see-saw. Cabinet volume -- there is no replacement for displacement, hoffmans iron law, etc... When I try to maximize cabinet volume, I reduce the amount of wood available for interior panels, which limits the length of the horn, which limits the Fc. So to go lower, requires a smaller cabinet, which reduces overall spl.... and then figuring out how to cut it all out of a 4x8 sheet... It's kind of a maddening process...

you are all welcome to help me improve it..... (being serious here) I would appreciate the suggestions.
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Old 23rd February 2011, 02:24 PM   #443
Djim is offline Djim  Netherlands
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Quote:
Originally Posted by AndrewT View Post
I did not get much (any) interest in a the competition suggestion for a one and a half sheet design that could go lower and/or louder.

Is anybody up for that?
A Mars Bar for the winner if Customs allow it through.
1.5 sheet = + aprox 3dB ... or 1/2 octave lower

take your pick

Quote:
Originally Posted by jbell View Post
sorry guys, haven't taken much interest in improving on the ss15 design --
Even a couple inches that will give extra length will drop more dB than it will give that low extension you are looking for... As I said before you got the max efficiency out of an sheet already I think and maybe its time to move on (just a suggestion).

Last edited by Djim; 23rd February 2011 at 02:28 PM.
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Old 23rd February 2011, 02:25 PM   #444
AndrewT is offline AndrewT  Scotland
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I have decided to raise the prize fund.
A Mars Bar to the top ten designs, with a limit of one Mars Bar to each Member already posted on this thread. New Members attracted by the enormous prize fund are excluded.
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regards Andrew T.
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Old 23rd February 2011, 02:28 PM   #445
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by jbell View Post
sorry guys,
no need to be sorry. You have already contributed an enormous database to the Forum. Thanks.
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regards Andrew T.
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Old 23rd February 2011, 02:57 PM   #446
tb46 is offline tb46  United States
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Hi Y'all,

You can obviously improve on the documentation of the SS15, but making a meaningful difference in the output is not going to be easy, and you'll be leaving the single sheet concept behind. Also, looks like everytime you lower the F3 you will increase the excursion for a given input voltage.

Here is a 300L with a short coupling duct from throat chamber to S1/S2, by no means a single sheet:

Regards,
Attached Files
File Type: txt 3015_d_1.txt (463 Bytes, 49 views)
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Oliver
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Old 23rd February 2011, 03:17 PM   #447
jbell is offline jbell  United States
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Quote:
Originally Posted by Djim View Post
As I said before you got the max efficiency out of an sheet already I think and maybe its time to move on (just a suggestion).
Thanks djim: Your encouragement is always appreciated.

I agree at this point the ss15 design would most likely be spl diminished by trying to get more 40hz. If I could get a couple more db at 40-45hz, all else equal -- I would love to have it. I just don't know how to get there.
I've also tried other drivers in this cabinet, and haven't found any other driver that does more on the same input power. Any of the places that wholesale eminence sell the 3015lf for less than $110, so in terms of bang for the buck.. I sure can't find a better priced option.
So, either cabinet design or driver choice -- I agree -- I think the ss15 is about as good as it gets with the parameters that I originally set out.

(there's this little part of me... that is never satisfied however.....)
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Old 23rd February 2011, 03:20 PM   #448
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Say we use a speaker with a little more xmax that cost around $200
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Old 23rd February 2011, 03:33 PM   #449
jbell is offline jbell  United States
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Quote:
Originally Posted by soundhead View Post
Say we use a speaker with a little more xmax that cost around $200
that's what hornresp is for. You didn't mention the specific driver, but the hornresp for the ss15 is documented in this thread -- play around with drivers and if you find a winner, please post it.
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Old 23rd February 2011, 03:44 PM   #450
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Sorry jbell I am posting from my phone
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