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tiefbassuebertr 26th March 2010 09:21 PM

Worlds expensivest highest Efficiency '15 woofer: Goto SG38WN Series up to 110db/W/m
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Unbelievable ! this efficiency from such '15 driver. Not really cheap.
But 110db/1W/1m by the topmodel without horn - is this possible?

Are there experience about this transducer series? Thank you for your comments

price list for GOTO 38cm woofer SG38 series:
SG38WN $7125.00
SG38WNS $9375.00
SG38WNSS $11,125.00
SG38WNSP $15,000.00
SG38WNSSP $20,000.00

and some more URLs: - industry features: Goto Unit

bear 26th March 2010 10:09 PM

there's a problem with the specs on the listing of the SG-38WN series... the sensitivity changes, the flux changes but the Fs and the Qt does not. Perhaps a typo.

How they get THAT MUCH sensitivity out of these drivers when no one else does is a bit of a mystery to me... I'd like to see some real tests vs known drivers and some FFT results...


tinitus 26th March 2010 10:14 PM

Im not surpriced its possible to achieve the sensitivity
But it will be really surpricing if theres any bass from that driver
Probably mostly midrange
And may not even be spectacular

Pano 26th March 2010 10:50 PM

Very impressive if true.
But just remember, how much is 1 acoustic watt radiated into free space @ 1M? That would be your 100% efficiency mark.

bear 26th March 2010 11:39 PM

iirc, 110db/1w/1m is nowhere near 100% efficiency, nor 1 acoustic watt...

According to the specs it has freeair at 40Hz. and Qt of 0.25, so T/S alignments still work... if true it will not go flat to 40Hz in a ported box, but will be similar to some other Altec drivers that are <100dB/1w (like the 515?) but are highly regarded.

I am still skeptical about these specs, since even as a midbass driver those are specs that NO ONE else has matched, afaik, ever!!

Otoh, a certain British pro audio driver manufacturer used to pick a peak in the rather peaky frequency response as the "reference sensitivity" so that they looked "good". The reality was that the useful sensitivity was far lower than they featured in their specs and advertising - despite a big magnet and nice looking construction.

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.


tinitus 27th March 2010 12:33 AM

Its not so hard to find a driver with more than 100db, but its a non linear driver

MaVo 27th March 2010 12:41 AM

There are no measurements... if they are able to build a driver that is said to be this exceptional, one should think they would be able to also measure it - whats the point in building such a great device if you dont proove its greatness? Highly dubious. Besides, the materials used in the driver dont justify the price.

wahab 27th March 2010 12:54 AM

Best efficency possible in matter of money making...

tinitus 28th March 2010 02:13 AM


Originally Posted by MaVo (

Besides, the materials used in the driver dont justify the price.

Well, maybe it does
If its cobolt iron and such, it gets very expencive, considering the large size

Whether it really leads to significantly better sound is another matter

Btw, theres a funny story about very pure iron
The roman empire was partly based on their superiour swords
They didnt break in battles

In a small place in eastern europe there was small place where they made their living producing these swords
In fact it was a genuine industrial adventure

And how could they produce better quality?
Simply because the raw material they were using had its origine from meteors from space
A material from the universe
Its been proven lately
Ofcourse they had no idea back then, it was just luck
But the quality and purity of the iron they produced was on par with the very best you can get today

Problem today is that its difficult and exstremely expencive to produce pure high quality iron

Next may be drivers made of raw materials from Mars :D

Pano 28th March 2010 03:43 AM


Originally Posted by bear (
iirc, 110db/1w/1m is nowhere near 100% efficiency, nor 1 acoustic watt...

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.

Of course there is a catch. The 108dB figure comes from the energy radiating into full 360 space. AKA 4 Pi space. The woofer isn't going to do that. It will be radiating into less space, so the energy is more concentrated. How much more concentrated depends on a lot of factors. Too many to figure out here.

So Bear, I'm with you there. Color me skeptical, too.

* or 109dB depending on what source you read. I think it may be 108.5dB

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