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RE: Electrostatic Speakers - Pros and Cons

WinterRacer wrote:

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."

I can feel a storm brewing..............

"We should no more let numbers define audio quality than we should let chemical analysis be the arbiter of fine wines."  Nelson Pass

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RE: Electrostatic Speakers - Pros and Cons

Sorry if it does, that wasn't my intention.  I thought the text was quite balanced, I.e., technically flawed, but can sound stunning.

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RE: Electrostatic Speakers - Pros and Cons

WinterRacer wrote:

Sorry if it does, that wasn't my intention.  I thought the text was quite balanced, I.e., technically flawed, but can sound stunning.

I found it informative......I knew about some of what was said, but not all. The subject can cause emotive reactions.

 

"We should no more let numbers define audio quality than we should let chemical analysis be the arbiter of fine wines."  Nelson Pass

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RE: Electrostatic Speakers - Pros and Cons

CnoEvil wrote:

The subject can cause emotive reactions.

if, by subject, you mean 'hi Fi' I agree! Smile

 

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RE: Electrostatic Speakers - Pros and Cons

It would be useful to have a thread for each of the main speaker types that were factual and ideally non emotive, as a useful reference for newcomers to the respective technologies.

This thread, so far has had some good info and I could see me at least trying something like planar or electrostatics in the future, just not yet and in my current house, as they would simply not be ideal.

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RE: Electrostatic Speakers - Pros and Cons

good thread OD. (finally something's happening on this forum). for the interested I think this article sums up very well advantages of ESLs over dynamic drivers. if you really love your dynamic speakers, be it active or passive, and you think you'd never swap them for anything else read this article only at your peril.

http://kenrockwell.com/audio/stax/electrostatic.htm

those who know me here know I don't like waxing lyrical over the "sound". hard technical facts is what matters most. and this article is quite technical. but also very approachable to everybody.

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RE: Electrostatic Speakers - Pros and Cons

oldric_naubhoff wrote:

good thread OD. (finally something's happening on this forum). for the interested I think this article sums up very well advantages of ESLs over dynamic drivers. if you really love your dynamic speakers, be it active or passive, and you think you'd never swap them for anything else read this article only at your peril.

http://kenrockwell.com/audio/stax/electrostatic.htm

those who know me here know I don't like waxing lyrical over the "sound". hard technical facts is what matters most. and this article is quite technical. but also very approachable to everybody.

 

Thanks for the link.

I liked his DACmagic review and it was partly responsible for its purchase, along with a special price of £250.

 

busb wrote:

I heard a pair of Quad electros around thirty years ago, probably driven by quad prem/power. They sounded stupendously good - no boxiness, beautifully integrated across their frequency range, smooth, detailed with good imaging. Their bass was their greatest weakness: not deep. Upper treble wasn't brilliant.

The nearest speaker I've heard recently was an oldish pair of column Grandiants that have to be up against a wall to produce bass which actually goes quite deep. These speakers are triangular in cross-section with the dual driver mounted on an internal frame, therefore no box that does give a clean sound with fewer artefacts than my Arros. For a speaker that needs a rear wall, they image well if not up to the standard of mine. So there are alternatives to electros.

 

Thanks for your views.

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RE: Electrostatic Speakers - Pros and Cons

Overdose wrote:

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

ESLs usually have inherently difficult impedance plot that stems from driver technology and not from using a passive crossover or not. connecting a power amp directly will yield no benefit. besides ESLs don't suffer from back EMF so no need for high damping factors. besides, the interface transformer windings would screw up nicely even the lowest of damping factors.

the bottom line is you really need a capable amp to drive ESLs efficiently. such that is stable into low impedances, even as low as 1 Ohm. the upside is that the usual impedance dip occurs in high treble region where is really little musical energy.

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RE: Electrostatic Speakers - Pros and Cons

BenLaw wrote:

 

Another interesting article on dispersion patterns and the cause and effect of comb filtering with dipole speakers.

 

hi BenLaw. the article is quite long and I didn't want to go through it all. could you post the excerpt explaining why dipoles would be comb filters? this is the first time I came across such a notion and I'd like to know where it's coming from. thx.

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RE: Electrostatic Speakers - Pros and Cons

oldric_naubhoff wrote:

BenLaw wrote:

 

Another interesting article on dispersion patterns and the cause and effect of comb filtering with dipole speakers.

 

hi BenLaw. the article is quite long and I didn't want to go through it all. could you post the excerpt explaining why dipoles would be comb filters? this is the first time I came across such a notion and I'd like to know where it's coming from. thx.

 

If you just read the bits with 'dipole' subheadings it's all there, but no problem. There are also some decent, simple diagrams in the article. I'll include all the basic setup as an easy reference for all:

 

 

INTERFERENCE OF SOUND WAVES

 


Interference usually refers to the interaction of waves with each other, When similar independent waves are combined, the result can be either constructive or destructive interference, depending on whether the waves are in phase or out of phase. This interference occurs when the waves have the same or nearly the same frequency. Constructive interference will enhance sound. Destructive interference will weaken sound. If two identical waves are 180 degrees out of phase, they will cancel out. Whether the interference is constructive or destructive, the individual waves continue to exist separately. The interference itself is merely the effect of the waves together at one point in space.

 

 

THREE TYPES OF SPEAKERS

 


The direction that speakers radiate their sound depends on how the drivers are lined up in the enclosure, and also whether there are drivers or ports on the back of the speaker. If all the speakers are on the front, this would be called Monopole. If there are speakers on the front and back, and they are in phase (both speaker cones moving away from the magnet), this is called Bipolar, whereas if the cones are out of phase (one cone moving in towards the magnet, while the other cone is moving outwards, away from the magnet), the speaker design is called Dipolar.

 

Dipolar Speaker
Dipolar speaker arrangement is similar to bipolar. However, the front and the back speakers work in the same direction (out of phase). This can be useful in reducing the stimulation of resonant room modes at low frequencies. It also results in high frequencies being reflected from the rear wall, which can create more diffuse reverberation, though in theory it could reduce stereo localization. Here is how t

 

Dipolar Speaker Dispersion Pattern
The radiation pattern of a dipole is demonstrated in the following diagram. The left waves are equal and opposite to the waves on the right. Because they are firing out of phase, they cancel each other where these waves are superimposed off-axis (top and bottom, mostly lower frequency waves). This is called destructive interference and creates a figure 8 pattern. Dipole speakers are known to have weaker bass response.

 

In the above diagram, note that the bipole field shows a larger off-axis response (the middle part of the center diagram) compared to the monopole. This is because the drivers in the front and rear are in-phase, which constructively reinforce the sound waves. 

Dipole speaker arrangement, however, exhibits a smaller off-axis response (middle part of the diagram on the right) compared to the monopole. This is because a dipole arrangement has out-of-phase drivers which behave in a destructive manner and cancel the sound waves with the same frequency.

 

Reflections from the Back Wall for Dipolar Speaker
When the back-wave starts off from the rear of the speaker and reflects off the back-wall and travels back to the speaker where it recombines with the new wave just being started from the front driver. Because of timing difference, at some frequencies the two waves destroy each other and at other times they reinforce one another. This effect is called comb filtering A comb filter adds a delayed version of a signal to itself, causing constructive and destructive interference. Some dipolar users treat the back-wall with absorbent material that absorbs all frequencies except the long bass frequencies. That is one way to prevent comb filtering. Another way is to turn the dipolar speakers inward so that they are not parallel to the rear wall.

 

Music:

With stereo music, you are essentially creating images in space with two speakers. You can move instruments around in space, and expect the listener to perceive more than two speakers. Add two more speakers in the rear and you now create the ability to pinpoint the source of the music between all four speakers, so in theory you can place an instrument anywhere in 360 degrees around your head. By introducing dipoles/bipoles, you destroy that image. You are more at the mercy of the room. The room will most certainly color the sound and add its own signature. Some may actually like this effect, but the music is less accurate. Your room's acoustics will affect bipole/dipole designs more than conventional direct-radiating. Direct-radiating (monopole) models send sound directly toward the listeners’ ears.

 

Conventional direct-radiating monopole speakers place the listeners in a sound field in which the direct sound is more prominent. It is possible that the majority of people find stereo to be more attractive if the room reflections are strong. The sound tends to be open and spacious, with a good sense of depth like a real live concert. It has the advantage of making stereo listening region more enlarged. However, the specific images can be rather vague.

On the other hand, there are some listeners who do not like this kind of music reproduction, and prefer to have a very specific, almost pinpoint, sense of image position. Many recording engineers prefer this because they need to be able to hear, very precisely, the results of their manipulations. As a result, recording studios are often acoustically rather dead, and the loudspeakers are directional and identical. They use identical speakers so that they are perfectly timbre matched so that the sound is not affected by the differences between the speakers. However, these same people usually prefer the more spacious sound field at home.

 

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RE: Electrostatic Speakers - Pros and Cons

And an interesting comment from another forum dealing with this and other issues:

 

Quote:
I’ve spent the better part of a decade tuning a  custom room designed for MartinLogan speakers. And after much research and many measurements, I’ve come to the conclusion that absorption of the rear wave of a large, line-source dipole is the way to go. Many other MartinLogan owners have empirically validated this in their setups as well, as seen in this  discussion over in the MartinLogan Owners forum. 


One aspect not discussed yet is the fact that dipoles suffer from mid-bass (120 – 350Hz) cancellation due to their typically narrow profile. The right kind of absorption on the wall behind the speakers can improve that a good bit. Still won’t make them into a disco-diva’s favorite speaker, but definitely improves things.

The biggest benefit of absorption is the reduction in comb-filtering and the vast improvement in imaging and intelligibility.

I love electrostats due to their low-distortion and line-source properties; however, the fact that they are dipoles is actually a downside to be mitigated.
The ideal ‘enclosure’ for an electrostat is an infinite baffle. Basically, mount them in a wall between rooms, with the back-wave room containing absorption. That eliminates the rear wave problem, while maintaining the air-mass loading appropriate for the tech. My next custom room will be done that way.

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RE: Electrostatic Speakers - Pros and Cons

WinterRacer wrote:

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.

I wonder what forum that was because there were very few real facts that you were told.

WinterRacer wrote:

"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.

limited dynamic range - true. although I'm pretty sure if you heard decently sized ESLs you'd not feel like you miss something. it's true that ESLs wont go much more north of 100dB but do you really need 120dB output in your room. even though dynamic speakers are capable of such volume levels do you know what level of THD this feat is sacrificed with?

tend to distort LF - totally untrue! in fact you'd need to find some 18" dynamic bass drivers if dynamic drivers were to even start to compete with ESLs. large flat panels produce some of the least infested with THD artifacts bass that is available ATM. I saw measurements of THD in Magnepan MG3.7 (not an ESL but planar speaker none-the-less) and THD in deep bass (around 30Hz) was comparable to THD levels in mid-range in some dynamic designs.

not terribly reliable - whoever wrote it should say those words to some of the original Quad 57 owners that have used them for 40 or more years ROFL

they beam - this is true and this is a problem with ESLs. this happens because high frequencies are generated from a wide driver, in many cases. however, if you find ESLs with dedicated HF panels (will be then narrow) this problem is hugely mitigated. ribbons, like in Apogee style speakers, don't have this issue as they are very narrow.

WinterRacer wrote:

They also suffer break up problems.

total nonsense. how could a speaker with so limp diaphragm material suffer from any break-up modes? this is exclusively a dynamic driver's dilemma as the designers of such drives strive to reach two, mutually exclusive goals - infinite stiffness and lightness of the diaphragm. since the diaphragm will never be infinitely stiff, especially since it strives be infinitely light at the same time, break-up modes will occur in the diaphragm. ESLs avoid that issue ruling the stiffness condition out of the equation.

WinterRacer wrote:

The long and the short of all this is that although they can be shown to be technically flawed

of course ESLs are technically flawed in some ways. there's no perfect solution invented yet to artificially replicate sound creation. however, dynamic driver principle is flawed even more than ESL principle. but few hi-fi enthusiasts are aware of that fact.

WinterRacer wrote:

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."

diaphragm hardens with time - let's now assume this is true (although I doubt that mylar hardens with time, at least never heard of it). still I can't see how this could be any bad? the mylar in ESLs is tightly stretched over the frame so the diaphragm is actually quite stiff and moves uniformly within it's movement borders (which are very small compared to dynamic drives). if the diaphragm hardened I can't think how could this impede anything at all.

it's worth noting that ESLs are not bending wave principle speakers where the diaphragm is indeed flabby and the speaker itself takes advantage of this fact.

dust causing arcing - ESLs do attract dust. it's quite normal as they are electrically charged object. but this is not causing arcing! arcing is caused by over-driving the speaker where the membrane touches the stator. meaning; you should be careful with that volume knob. although don't need to panic. Quad specs their ESLs to be capable of taking 50V peak signal before shutting into protection. 50V means something around 300W into 8 Ohm.

were never as reliable as cones - that was already discussed above. but ever thought how a cone's rubber surround would look like after 40+ years? every mechanical component needs servicing every now and then.

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RE: Electrostatic Speakers - Pros and Cons

Any fully active types?

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RE: Electrostatic Speakers - Pros and Cons

I think it's fair to say that Quad Electrostatic owners should allow for a refurbishment every 8 to 15 years to keep them at their best. But even a tired Quad ESL will still have that midrange magic up to reasonable volumes.

 

But then coned speaekers with foam surrounds will need the foam replaced every 15 years or so. And conventional soft tweeter domes suffer from finger prod deformation.

 

I've also heard about Quad ESL's setting up an interesting magnetic field in a smallish room where lots of dust was attracted to the stylus of a turntable positioned 4 feet away.

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RE: Electrostatic Speakers - Pros and Cons

It doesn't make sense to fully active with Quad ESL's - unless you mean supplementing them with a subwoofer in actively bi-amped mode.

 

Quad ESL's have a step up transformer inside them to convert the signal to the very high voltage required by the plates to move the membrane. You could by-pass this transformer and connect them to a suitable valve amp with no output transformers - or a simplified transformer - to give the voltage required. Trouble is you'd have very high voltage in your speaker cables. Lethal voltages.

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