Worlds expensivest highest Efficiency '15 woofer: Goto SG38WN Series up to 110db/W/m - Page 2 - diyAudio
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Old 28th March 2010, 05:13 AM   #11
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So nobody even at JBL havent seen this opportunity?????
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Old 28th March 2010, 01:17 PM   #12
Dr_EM is offline Dr_EM  United Kingdom
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Quote:
Originally Posted by bear View Post
The usual problem with jacking up the sensitivity is that you reach a limit on the effectiveness of a bigger magnet, and then the only way to go is to make the gap thinner, which in turn means that it is easier to rub the VC, meaning the power handling is very limited in practice, and if you manage to make a driver that does this, you need a high slope HP filter to prevent LF over excursion which causes bottoming of the VC, the VC out of the gap or rocking which causes rubbing. You want the maximum number of turns in the gap as well, and this is a problem too...

So, still skeptical.

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This is what I'd assume. So it'd be a very high sensitivity driver but with very low Xmax and thermal power handling. In practise, probably outperformed by lower sensitivity more typical pro drivers running on more power?
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Old 28th March 2010, 01:34 PM   #13
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It hits that efficiency level drving the mouthpiece of a tuba. (with special reduction piston and cylinder, not included)

Last edited by Andrew Eckhardt; 28th March 2010 at 01:39 PM.
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Old 28th March 2010, 03:10 PM   #14
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Originally Posted by Andrew Eckhardt View Post
It hits that efficiency level drving the mouthpiece of a tuba. (with special reduction piston and cylinder, not included)
indeed. it's a compression driver, so it _NEEDS_ a horn
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Old 29th March 2010, 01:50 PM   #15
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tinitus... OT, but pure iron is very soft. I think they got chromium and vanadium from the meteors... fwiw, I think the Japanese who do that folded steel sword thing also got the same materials from the same source...

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Old 9th May 2014, 05:09 AM   #16
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looks like the prices have doubled,

since the turn of the century/millennium.

is the sg-38wn, the one that weighs 90 pounds ...?



Click the image to open in full size.













http://www18.ocn.ne.jp/~tnk/index.html

Last edited by tomtt; 9th May 2014 at 05:21 AM.
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Old 9th May 2014, 07:26 AM   #17
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Quote:
Originally Posted by tiefbassuebertr View Post
Unbelievable ! this efficiency from such '15 driver.

But 110db/1W/1m by the topmodel without horn - is this possible?

Are there experience about this transducer series? Thank you for your comments
Like too many manufacturers, they list the efficiency of the driver's break-up modes BW rather than the calculated efficiency that tells us the max mid band cab efficiency, which with rare exception is always < 100 dB/m.

Here's the measured specs of a SG38WNS that I calc a 98.82 dB/m using Fs, Vas, Qes and 98.89 dB/m using Sd, Mms, Cms, BL, Re and 98.80 dB/m using n0 = 4.7686 %; while they apparently measured 98.9839/m.

WRT what’s possible, the highest I’ve seen was a field coil Altec 515 with a ~55 Hz Fs [40 Hz advertised], ~1000 L Vas, 0.12 Qes = a calc’d ~113.28 dB/m = ~133.721 %, but it was from a decades old theater install, so its phenolic spider had to be pretty much beat to death, so figure its Vas was a lot smaller when new, ergo I assume its efficiency was around 109 dB/m = ~50 %.

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Old 9th May 2014, 07:35 AM   #18
GM is offline GM  United States
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Quote:
Originally Posted by tomtt View Post
is the sg-38wn, the one that weighs 90 pounds ...?
Dunno, if 90 lbs is the heaviest, then the one with the heaviest motor/highest flux is the SG38WNSSP.

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Old 9th May 2014, 07:50 AM   #19
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For bass, strong motor is positive only when matched with a proper load to the air. It can either be a mega 30" cone for driving more air directly, or a high pressure load like the throat of a bass horn.

A 15" cone and a regular box is not enough for finishing the job well enough. It's really not necessary to get too excited on a strong motor alone.

Yes it'd still be a good thing to have. But overall I think it's not a good engineering from engineers, and not a good buy for consumers.
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Old 9th May 2014, 10:00 AM   #20
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Originally Posted by Pano View Post
In fact it's so near - it's over 100% 1W of acoustic energy radiated into a sphere of 1M radius will be 108dB* at the "surface" of that sphere. So 110dB at 1W/1m is slightly more than 100% efficiency.
I thought efficiency equals:

Energy speaker in
------------------- x 100%
Energy speaker out

And that most speakers are only 2-4% efficient.
How can it be more than 100% efficient, that goes against the laws of physics I'd think?
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