Eminence Flux Density Modulation

[Diablo]

Looks like there are two methods to achieve the same outcome. Fluxtone is using field coil speakers and lowering the voltage to the electromagnet on the speaker. Eminence is mechanically adjusting the strength of a permanent magnet - maybe moving the magnet, maybe adding or removing an iron pole piece. The Fluxtone video sounds good to me. I couldn't hear any change in tone. I know Ted Weber was also working on the development of field coil speakers before he passed away. I like the concept of Fluxtone, but I don't like the high price...around $750.

[walkman]

http://www.fluxtone-speakers.com



I haven't any suitable mp3's at the moment, however i can tell you they sound great.

[J M Fahey]

Hey, that's interesting !!
Can you post some pictures?
And some MP3's of course !!
Can you link to some data/brochure/whatever?
Thanks.

[walkman]

I bought two fluxtone speakers , and i really like their sound. I chose them over an attenuator in part because, i'd read that most attenuators will require some sort of tonal compensation and that they interfere with the speaker to amplifier dynamics. At the time the eminence were not on the market. I find that use them a lot at quite a high level of attenuation , even with a 2-5watt amp and they sounds good to me. Sure i probably could have bought decent load box / attenuator / speaker simulator or isolation cab , but the idea of the variable flux from the field coil speaker , just made sense to me and seemed like less mucking about

[teemuk]

Also, although 9 dB might sound a lot (basically, it's approximately dropping the perceived loudness in half), it is not that much attenuation in practice. Sound from cranking a moderately powerful amp is damn loud. After cutting volume in half it's still damn loud. So, if the problem was excessive loudness, either at bedroom or at stage, then dropping loudness only to about half isn't overly helpful. You can find demo videos of the FDM from youtube and the effect of full attenuation is actually barely noticeable. Basically, picking dynamics can make far greater differences loudness-wise.

There's a similar product called "FluxTone", which is based on variable magnetic strenght of a field coil. It has a range of approximately 25 dB and that actually is starting to be useful. The problem of that product is that it requires an external power supply unit, though.

[J M Fahey]

Yes, exactly that.
The audible volume will go down, which is expected, but not in a flat way, you will lose more highs and high mids than everything else.
The sound becomes duller.
You also lose damping at the resonance frequency (around 100 Hz) and bass becomes flubby and undefined.
I know it's hard to define sound with words.
To be more precise, the speaker loses acceleration, if that means something, it loses its "snap".
See that the review states something similar.
I think an external attenuator is much better and those "Power-something" circuits which lower supply voltage are the best.

[walkman]

It should be obvious that a less efficient speaker will not bringing out the 'fragile harmonics' and presence that a more efficient speaker will and would sound duller, unless of course you stand closer to the speaker , which the listener may well be doing, which is why a less efficient speaker may be needed in the first place.

Are you saying, that at the same db level of sound, regardless of the distance to the speaker, that the sound made from a speaker of less flux, everything else within reason being the same, the speaker with less flux will of its own nature will produce a duller , or more mellow sound with less attack?

[J M Fahey]

Not personally, but from what they say, plus the described effect on the sound, I see that they somehow reduce the useful magnetic flux that actually reaches the voice coil gap.
The speaker goes from "normal flux-99dB efficiency" to "low flux-91dB" .
My experience is that lower flux also rises Q and lowers attack, which they obliquely describe as "becoming mellow" It works as a sort of built-in pad.
It's an interesting concept, although I do not find it *very* practical, because you need a combo or open-back cabinet to be able to reach the attenuation knob.
Anyway, if somebody actually tests one, please post results.
MP3s would be even better.

[walkman]

Eminence Introduces Flux Density Modulation Technology - Premier Guitar

" The method of lowering volume by altering a speaker’s magnetic flux strength is not a fix all in either the new Eminence speakers or the Flux Tone speakers. When the magnetic flux of a speaker is lowered either by electrical or mechanical means the most fragile harmonics, overtones and high frequencies are trashed in direct ratio of the level of attenuation. The more attenuation the more loss in the high frequencies, overtones and harmonics, go too far and you got mud! The best way to use these new eminence mechanical flux attenuation and the Flux Tone variable voltage electromagnet flux attenuation speakers is to minimize their effects. Use them with smaller type amps that are still to loud in home or bedroom situations. Use them with bigger amps in clubs as long as you don’t need to throw away to much volume, you still need a good sound. The best case scenario is to acquire three of four different tube amps designed for your varying power output needs and use these variable flux speakers attenuation features sparingly! "

[JoeM]

Eminence has some new speakers using what they call "Flux Density Modulation". Anyone here know anything about these or have heard them? Looks interesting.


Eminence - The Art and Science of Sound