Electrostatic Speakers - Pros and Cons

Also, perhaps we could keep this to electrostatics and maybe open new thread for other speaker types if required?

Cons:

There aren't many around, they cost a lot, they're difficult to drive, they need mains power, they're big, they often don't sound like they have much bass.

Pros:

People who use them won't use anything else due to lack of treble and midrange colouration.

Just Electrostatic speakers, or panel speakers that use other technologies like Ribbon and Planar?

Both have similar pro's and cons.

Electrostatics usually have quite low dips in the mid-treble impedance so need an amplifier that does not mind that, but they are relatively benign at low frequencies. They also require a power cable to energise the electrostatic panel.

An example of the Electrostatic speaker are the Quad speakers, like the ESL-57, 63 and the newer models. Martin Logan have Electrostatic mid-treble and hybrid dynamic cone active bass in most of their models, and some of their high end use Electrostatic bass panels I believe.

Some others are Kingsound, B&W made a hybrid back in the 70's and a few others.

Panel speakers like ribbons, or planar tend to have a purely flat and resistive impedance, thus making them very easy to drive, although usually at low impedance (4 Ohms) and are quite in-sensitive so require a lot of power. They do not require mains power to the speaker.

Magnepan uses both Planar technologies (bass panels in all their speakers, and hybrid treble in the MMG) and then Ribbon tweeters in the higher end models. This is the same configuration as the Apogee speakers.

Both types have advantages in that the whole panels are energised, so you have a line source that moves the air, resulting in a very large and quite lifelike soundstage. As most, if not all are dipole speakers which means they radiate to the font and back in a figure of 8 pattern. This means that bass acutallu cancels it self out at the sides of the panels, which means they can be placed near to side walls. They need a reasonable amount of space behind them as the the bass-mid-treble are radiated both ways so can muddle up the sound.

Both types also have limited vertical dispersion, the curved panels of the Quad ESL-57 help with this.

I am sure others will add more, thats just all I can think off at the moment.

Subjectively, IME with the Quad 57, Magnepan MMG and hearing other 57's, 63's and Apogees they have a great big soundstage, very natural presentation, open midrange and lightening quick bass with no overhang (dipole).

They tend to re-produce drums especially well, and vocals.

Size is a major factor but I think I could get away with them in my lounge  as there's quite low traffic and their position would be quite out of the way. 

I was speaking to somebody the other day who previously had some Quad ESLs, he said they had the sweetest of sweet spots but dropped off if you ventured out of it. 

Something like the Martin Logan hybrids are really interesting. I'd love to hear them. 

Given that electrostatics are/can be difficult to drive, wouldn't active amplification be better, perhaps active/powered electrostaics and planar speakers are available?

Regarding the problem with dipole transmission and placement near walls, could this be minimised with acoustic panels behind the speakers?

Hoopsontoast, you've described electrostatics and panels far better than I could, spot on. I've found them a bit less fussy (Maggies) than some have. Worth saying the bass cuts off absolutely at whatever the bottom level is.

Apart from the logistics of having active panels, why would you bother? They outperform most other speakers at their price and above.

Apologies for going off topic if you meant this thread for electrostatics only - they are radically different to  panels.

You could go active, but one good thing about a passive crossover, is it has protection for the very fragile (electically) tweeters. If in an active crossover, the amp went puff, it would take the tweeter with it. Often, like in the case of Magnepan speakers, they have an inline fuse to stop that happening.

Things like Quad 57's actually like being driven with valve amps, as long as its stable its a match made in heaven. They were designed to be used with Quad II's and even the 303/404 SS amps.

Acoustic Panels would certainly help with dipole radiation to the rear.

They need good space behind them to work well as they can produce almost as much sound from the back as front so need room to breath.

Done well they can sound superb.

A brief explination of Monopole Vs Dipole Radiation on speakers, remember that the rear wave will be out 180deg of phase with the front, and you can see the cancellation at the sides.

http://www.acs.psu.edu/drussell/demos/rad2/mdq.html

I have Martin Logan hybrids, driven by Krell amplification. 

Very fussy to set up, toe in, distance to rear wall and overall placement key to making them sound decent.  Sweet spot is small, both vertcally and horizontally. 

I have a relatively small room, so ended up placing acoustic panels on the walls behind the speakers because of the dipole effect mentioned above.

When setup well, particularly for female volcals, they do their amazing disappearing act.  5 minutes with a decently recorded CD, and all the hassle is worth it.

OD, I did something similar a while back, so in case there is some useful info, here it is: http://www.whathifi.com/forum/hi-fi/electrostatics-brilliant-answer-or-i...

http://forum.blu-ray.com/showthread.php?t=66471

Another interesting article on dispersion patterns and the cause and effect of comb filtering with dipole speakers. The way it's been explained to me is that this effect is at least partly responsible for the great soundstage and the feeling that the speakers disappear. This effect is particularly good for classical music as it replicates venue acoustics but in terms of high fidelity of a studio recording may not be the best. It also limits the sweet spot a great deal, so don't listen with friends, especially very short and very tall ones!

Thanks for the info Cno.

I asked this question on another forum as I remember hearing some large hybrid electrostatic/MC speakers many years ago, thinking they were amazing and wanting to know more.

"They have limited dynamic range, they tend to distort on LF, they are not terribly reliable and they beam, so there's only a narrow sweet spot.

They also suffer break up problems.  The Quad ESL63s are the most intelligent in this respect, because they use delay lines to excite annular rings that start in the middle and work their way outwards.

They idea is to excite the diaphragm (it's like a large sheet of clingfilm) from the centre outwards as a stone causes rings when you drop it in a pond. Trouble is that a pond may be large enough for the rings to disperse before they hit the edge, but an Electrostatic isn't. The ripples hit the frame the diaphragm is miunted in and bounce back inwards disturbing ones on the way out. This is distortion.

The long and the short of all this is that although they can be shown to be technically flawed, there is no question that they can sound stunningly good with material that suits them. They are very realistic.

The problems with Quads and Martin Logan's was that diaphragms harden with time and sensitivity drops, they attract dust that causes arcing, which blows holes in the diaphragm and so on, so they never were as reliable as cones."