Field Coils Anyone?

[Mr. Widget]

I was recently made aware of the new flagship Grande Utopia EM from Focal/JM Lab... Steve Schell should love the woofers at least. Sorry Steve no horns, but they claim to have been able to increase the sensitivity of these 16" woofers to 97dB /m and maintain a very low system resonance by using a massive electro magnet instead of a permanent mag. Sounds very interesting:

http://www.grande-utopia-em.com/en/technologies/em.php


Widget
.

[Guido]

Bl = 34 Tm !
Wow!

[scott fitlin]

Heres comes the NEXT craze, FIELD COILS!

I heard a pair of field coil speakers, old W.E., They do have a unique sound.

EVERYTHING OLD IS NEW AGAIN, and IMPROVED!

[Mr. Widget]

Bl = 34 Tm !
Wow!

Exactly!


Widget

[Jan Daugaard]

It gets really interesting when such woofers are made available as components and not just as a part of a complete system such as the Grande Utopia.

Does anybody know of modern field coil woofers that are available as components?

[Hoerninger]

Just for curiosity, how much power is needed to engage a field coil, I ask for an example?
___________
Peter

[Mr. Widget]

It gets really interesting when such woofers are made available as components and not just as a part of a complete system such as the Grande Utopia.

Sure, but don't count on it.

However, if it works as well as they claim, perhaps other manufacturers will build some for us crazy DIY types.


Widget

[spkrman57]

Just for curiosity, how much power is needed to engage a field coil, I ask for an example?
___________
Peter

With a variable power supple (PS) for the field coil the parameters (T/S) can be changed due to the different BL factor.

The amount of current flowing through the field coil will accomplish that.

Steve SCHELL can elaborate much better than me on that though!

I don't remember what voltage/current parameters are usually common.

Regards, Ron

[scott fitlin]

It gets really interesting when such woofers are made available as components and not just as a part of a complete system such as the Grande Utopia.

Does anybody know of modern field coil woofers that are available as components?

www.supravox.com.

They offer Field Coil, Permanent magnet in Alnico, also a silver wire VC as yet another option.

PRICEY, though!

[pos]

With a variable power supple (PS) for the field coil the parameters (T/S) can be changed due to the different BL factor.

The amount of current flowing through the field coil will accomplish that.

Steve SCHELL can elaborate much better than me on that though!

I don't remember what voltage/current parameters are usually common.

Regards, Ron

something in the ballpark of 10V (variable) and 5A

here you can see the T/S for different voltages:
http://www.supravox.fr/haut_parleurs/400_2000_EXC.htm

[Hoerninger]

... 10V (variable) and 5A

Thank you, Pos!
When going class A the extra amount of about 50 W per speaker is relativ small.
____________
Peter

[pos]

Plus you don't have to let it turned on all day long!

And with powered speakers you can even get rid of these nasty little 9V batteries in your cc networks

[scorpio]

www.supravox.com.

They offer Field Coil, Permanent magnet in Alnico, also a silver wire VC as yet another option.

PRICEY, though!

Besides Supravox, Fertin is another excellent French brand of Field Coil speakers, just as pricey as the Supravox...

http://www.fertin-acoustic.com

Cheers

[scorpio]

Plus you don't have to let it turned on all day long!

Mmh, I don't have the review around anymore, but this statement does not seem to hold true, Fertin Field Coilers are reported to take a couple of hours after being 'energized' to sound good, they are reported as flat and boring when cold.

I have no personal experience of that though, beyond having heard well run-in and warm Supravox ones (they were amazing...)

[Jan Daugaard]

There is a caveat about the BL factor: We don't know the DC resistance of the voice coil in the Grance Utopia woofer, and -- all other things being equal -- the BL factor increases with the square root of the DC resistance of the voice coil. A 16 ohm woofer will thus -- all other things being equal -- have twice the BL factor of a 4 ohm woofer.