What are the advantages of electrostatic versus floor speakers w/wo external drivers?

tweak1,

I suspect you’re right. I’ve yet to hear any electrostatics that sounded balanced. Some things were very good, open airy and expansive mids, but some very bad, bass balance, dynamics and timing.

Even the original Quad ESL57s didn’t work out for me, but maybe I didn’t know how to get the best out of them. I’d still like to hear some Magnepans or Martin Logan’s though.

As for box speakers, there does seem to be a discernible ceiling on performance with them. Most have bandwidth/ resonance/ crossover / dispersion / drive unit integration problems etc.

I feel that most of these issues are down to the way the bass is interacting with everything else. As you say, most of the cost goes into keeping the cabinet inert so that it doesn’t interfere.

On the other hand I’ve not heard the KEF Blades, B&W 803s or any of the almost universally well regarded Revel range.

When you read so many good things about Revel speakers it almost sets up an impossible ideal for them to match up to when you finally get to hear them.

Open baffles also seem to have the same problem as electrostatics in one regard - domestic acceptability. Probably explains why box speakers remain the norm despite their box issues which the other two don’t have.

sokogear, As with most things in audio, there is more "different" than there is "better or worse". E-stats fall into a category I like to call "light membrane drivers" which also includes AMTs, ribbons, planar (like Analysis Audio and Magnepan) and others. One physical or mechanical advantage (relative to transducers) is their light weight. Music happens in the time domain and amplitude domain with phase response contributing. As long as a driver is used within its designed frequency range, displacement limits and baffle configuration, and is tracking the input signal, there really is no "fast" or "slow" driver. If a driver can't do a reasonable job then it's either broken or junk. If a driver is reproducing 500 Hz, that's its speed. If it was "slow" then it would not be reproducing 500 Hz. I believe what people are referring to as "a fast driver" is a driver that can accelerate and decelerate closer to the ideal, which is instant with zero lag. Basic physics tells us that "instant" is basically not obtainable. Basic physics also tells us (all else being equal) that a lighter membrane will accelerate and decelerate closer to the ideal. Many people refer to this as "transient response". The ability of a driver to  accelerate and decelerate closer to the ideal is important for the driver to be able to track complicated wave forms, music.

Line sources, panels, OBs, box speakers, long and short ribbons, AMTs line arrays and other designs is a different discussion.

Our speakers are an AMT line source design that are OB and have a sensitivity of 105dB. The OB woofer is separate. Harry Weisfeld, founder of VPI Industries and proud owner of our Apollo12 speakers describes them as" the fastest speaker he has ever heard". Our measurements tell me that their excellent transient and phase response is why they sound "fast".

Mike 

Are electrostatics considered the next level with a corresponding price bump, or just an alternative technology?

The latter.

One should be careful when driving ESLs if you wish to get the best out of them. Because they are a fundamentally different approach to transducers, the optimal way to drive them is different too. Most ESLs have an impedance curve that varies over a 10:1 or 9:1 range- the highest impedance being in the bass region, and then 1/9th or 1/10th of that at 20KHz. This is why Martin-Logans are only about 0.5ohms at 20KHz, since they are 4 ohms in the bass (which is often a cone driver).

Because of this impedance swing and because ESLs are based on a capacitor rather than a driver in a box, the usual voltage rules don't work so well on them. You can wind up with something that is really detailed and bright; what you are after is the former but not the latter. Now a speaker that is a driver in a box has an impedance curve that shows something about the resonance of that driver in the box- the impedance will be higher at those frequencies. ESLs simply don't work that way- the high impedance peak needs just as much power to make a certain sound pressure at 10 feet as it does at 1KHz where the impedance might be half of that of the bass. Conventional speakers don't work that way at all!

So if you are planning a solid state amp to audition the ESLs, be prepared for bright and weak bass. A tube amp is required to make the speaker play bass correctly, as with the higher impedances the amp can continue to make power where a solid state amp can't.

Its for this reason that on a set of Sound Labs you might need a 600 watt solid state amp to make enough sound pressure, but a 150 watt tube amp would be able to keep up with that 600 watt amp no worries! For more on how this works seehttp://www.atma-sphere.com/en/resources-paradigms-in-amplifier-design.html


The advantage of ESLs over many other speakers is that they use a power supply to operate the electrostatic field. Conventional speakers that use a permanent magnet have a phenomena where as you put current through the voice coil, the magnetic field weakens slightly. This creates a slower and less dynamic result. The kind of permanent magnet driver that does this the least are those equipped with Alnico magnets, but Alnico is also the weakest magnet structure (although they can be focused nicely in the voice coil gap). ESLs don't have this issue and so they sound obviously faster right away. With conventional drivers the only equivalent that exists are field coil powered drivers, where a power supply supplies the energy for the magnet.