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Old 23rd February 2011, 04:00 PM   #451
Djim is offline Djim  Netherlands
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Join Date: Dec 2009
Location: 'Ollanda
Quote:
Originally Posted by jbell View Post
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.....)
Actually Jbell, it was your encouragement to join posting in the first place. Funny thing is I don’t post all findings as it doesn’t seem 'useful' around here. Sometimes I get the feeling some among us prefer to use their energy and knowledge to show somebody’s mistake instead of using their abilities to improve or find the correct answers...


Anyway, as you said yourself "I've also tried other drivers in this cabinet, and haven't found any other driver that does more on the same input power." Of course you can’t find that driver. The max volume displacement of the 3015LF is matched to the SS15 for the balance between usable frequency and SPL. Any change will cost…

Every driver has a maximum air displacement. This max air displacement can be used for max dB (efficiency) and usable freq. response (bandwidth) and both factors are linked to the volume of a system. More volume gives more efficiency and freq extension until the max air displacement of the driver is used (effective loading). From that point the efficiency factor or the freq extension will start to drop.

Therefore I’m saying leave the SS15 as it is. It gives max efficiency in a best ratio between volume and low frequency and economics (driver and one sheet). I know you looking for that fraction more low freq extension (like many others including myself). Like Oliver I also think it doesn’t look possible within the limitation you set out yourself. So that’s the reason why I think to move on and make new standards for another JBell winner. Oh and believe me I have watched this SS15 all over and over and... and over....
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Old 23rd February 2011, 04:06 PM   #452
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Well said djim. Well said
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Old 23rd February 2011, 07:36 PM   #453
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I well be making 8 of the SS15's the only changes will be to try and decrease the restriction at the last bend and make it out of 3/4" ply, so the over all box will be somewhat bigger. I will start a sketchup tomorrow and will post my progress.
Will this put me in the running for a Mars Bar?
Andy
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Old 23rd February 2011, 08:03 PM   #454
Chaps is offline Chaps  Denmark
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Quote:
Originally Posted by salzburgsoundsystem View Post
Can't say how often I've read these threads. The interest in the SS15 plan is increasing. Over at speakerplans.com someone is building the SS15, but no results reported yet.
That will be me .. I'm building four, and after a few more hours of work, they will be ready for paint and overall finish .. Really looking forward to it ! Results will be reported as soon as they are alive!
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Old 23rd February 2011, 08:15 PM   #455
tb46 is offline tb46  United States
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Hi 4pyros,

You might want to change the 13.5" board like this, but usually one change leads to another:

Regards,
Attached Files
File Type: pdf 2011_Feb23_mod_1.pdf (4.2 KB, 119 views)
__________________
Oliver

Last edited by tb46; 23rd February 2011 at 08:39 PM.
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Old 23rd February 2011, 10:04 PM   #456
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Join Date: Nov 2010
Quote:
You might want to change the 13.5" board like this, but usually one change leads to another:
Thanks tb46; I will look at that, but I was thinking of just dropping the bottom some. I have the change the hole box anyway to make it out of 3/4" ply and may add 1 or 2 inchs to all sides. This may make the path lenght a little longer so I will have to re-sim it too.
Anyway I will be using more than one sheet, maybe 1 and 1/4 or 1 and 1/2 sheets.
Andy
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Old 24th February 2011, 09:38 AM   #457
AndrewT is offline AndrewT  Scotland
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What I see as the "slight" limitation of the ss15 and similar 1sheet designs is restricted LF extension has been adopted as a compromise to maintain high usable SPL.

In a domestic situation high usable SPL is not usually the problem.
A flat response is similarly not a problem if some room gain is taken into account in the smaller and medium size rooms.
The low Q type of response, similar to a Bessel response, rather than a Butterworth works well in domestic listening.

I see some solution to the need for extended LF as a longer path length which will extend the response but as with all compromises reduce the max SPL at the lower frequencies.
If this reduced SPL were to follow the Bessel Q then we could end up with a better reproduction bass speaker for domestic listening.
A 1.5sheet design is still not big and for those wanting/needing more SPL simply stack a second 1.5sheet box alongside.
This is quite different target from Jbell's original brief.
If there is interest in such a domestic extended LF 1.5sheet TH with Bessel Q rolloff, it should probably be discussed in a new thread.
The question is
"is there interest?"
__________________
regards Andrew T.
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Old 24th February 2011, 12:21 PM   #458
jbell is offline jbell  United States
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Quote:
Originally Posted by AndrewT View Post
What I see as the "slight" limitation of the ss15 and similar 1sheet designs is restricted LF extension has been adopted as a compromise to maintain high usable SPL.

In a domestic situation high usable SPL is not usually the problem.
A flat response is similarly not a problem if some room gain is taken into account in the smaller and medium size rooms.
The low Q type of response, similar to a Bessel response, rather than a Butterworth works well in domestic listening.

I see some solution to the need for extended LF as a longer path length which will extend the response but as with all compromises reduce the max SPL at the lower frequencies.
If this reduced SPL were to follow the Bessel Q then we could end up with a better reproduction bass speaker for domestic listening.
A 1.5sheet design is still not big and for those wanting/needing more SPL simply stack a second 1.5sheet box alongside.
This is quite different target from Jbell's original brief.
If there is interest in such a domestic extended LF 1.5sheet TH with Bessel Q rolloff, it should probably be discussed in a new thread.
The question is
"is there interest?"
For a 'domestic situation' you are very correct, spl isn't the issue -- cabinet size and LF response typically are.
Room modes are dominant... but not as dominant as 'others' who get to dictate how big the subs can be that are built and brought in from the garage.....

For that situation, I think couple of mike's design is about perfect. Reed Exodus Anarchy 25hz Tapped Horn - AVS Forum

Last edited by jbell; 24th February 2011 at 12:23 PM.
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Old 24th February 2011, 12:31 PM   #459
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Default The dominant one

likes my pair of JBL control 1 Pro in the lounge... but would prefer something smaller.

Bose cubes are clearly made for...

...wait a moment, must not think sexist thoughts!

If doing a rebuild, you could sneak in a thicker wall or lower ceiling with a tapped horn in it. Might do some 'sound' renovation work when my fiance is away for 3 weeks this summer.
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Old 24th February 2011, 06:42 PM   #460
Djim is offline Djim  Netherlands
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'domestic situation' & ‘Lounge situations’, I thought we were talking PA or Sound Reinforcement here?
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