Electrostatic speakers?

[misterdog]

Service kits - https://eraudio.com.au/index.php?option=com_content&view=article&id=7&Itemid=118

US rebuild specialist Sheldon Stokes, very knowledgeable and approachable. - https://www.quadesl.com/quad_esl63.html

Full blog on the rebuild process - https://drmrehorst.blogspot.com/2025/02/quad-esl-63-resurrection.html

Various threads on DIY Audio inc. this - https://www.diyaudio.com/community/threads/quad-esl63-rebuild.426178/

The trickiest part is the panel rebuild, membrane tension and surface resistivity of the coating.

As an EE you will know that the 5kV can kill you !!! leave overnight to discharge before touching the innards.

Well set up they have few peers, though mine have taken 15 years to perfect.

Quads love low distortion amps and signal, that's what they were designed for. They are essentially voltage driven so require little power I'm currently using Topping B200's, going to try B100's set at 0dB gain.

PM/DM if you need more..

 

[Keith_W]

I have heard ESL-63's and more modern Quad speakers, but I haven't had the opportunity to take any measurements of them. The main characteristics are: (1) they don't make much bass, and (2) they don't go very loud. If you try to make them do either, they will distort - audible as very loud crackling. As for imaging, they definitely create a different stereo image to conventional speakers. I can't say it's better, it's just different. Some people like it.

Personally I would stay away. Not only because they have serious limitations - poor bass extension and are severely volume limited - but also because they require expensive maintenance.

 

[misterdog]

People need to hear correctly set up ESL's to avoid the misleading generalisations often made.

My Quad 989's have lashings of bass and dynamics, though to get 'the windows to rattle' I augment with 2x12" subs.

If you listen to stand mount or bookshelf speakers sat on the floor, how do they sound ?

When I first got my Quads and fed them from a poor source, badly set up, they sounded boring dull and lifeless.

They have now been described as the most ' accurate ' speakers heard, by someone who has heard more systems than most have had hot dinners, including systems into the six figure bracket.

 

[Purité Audio]

Never been convinced by them myself and I have heard quite a few examples, I remember the first pair of 57’s I heard the customer was kneeling in between the two speakers which were very close like large headphones, probably outstanding in 1957.
Keith

 

[misterdog]

Never been convinced by them myself and I have heard quite a few examples, I remember the first pair of 57’s I heard the customer was kneeling in between the two speakers which were very close like large headphones, probably outstanding in 1957.
Keith

Probably why Peter Walker always demoed them on chairs to elevate them.

 

[Frank Dernie]

If you don't have access to the recording chain, meaning being present both in the auditorium and during mixing process, this might lead to this or that error in judgement. I have done this several times, listening to the general rehearsal of a concert from behind the broadcast balance engineer, eventually experiencing the concert itself live in the auditorium. Differences are pretty pronounced, and in many cases I had to ask the balance engineer why they deviated from the sound impression in the hall that much.

It is very pronounced if the recording is a mix of many close-miked instruments balanced and adjusted by an engineer, not least because mechanical features of instruments at 1m distance and the tonal balance close up give quite different sound from that experienced in an auditorium at normal listening distances.
The old recordings with just 2 or 3 microphones several meters away are much more realistic IME, for obvious reasons.

Modern recordings using a mix of a large number of microphones are entirely a result of how the mixing engineer decides to manipulate the signals, whether acoustic or electric instruments.

It didn't used to be like that.
(you mentioned certain differences between cor anglais and oboe in a different post which may be apparent at 1m (when close miking) but are not at 10m IME.
Goodness knows how a realistic sounding mix could be made from a plethora of close miked channels of disparate instruments. IMO it usually isn't

 

[Arindal]

It is very pronounced if the recording is a mix of many close-miked instruments balanced and adjusted by an engineer, not least because mechanical features of instruments at 1m distance and the tonal balance close up give quite different sound from that experienced in an auditorium at normal listening distances.

This is how every modern recording is produced, and it is an absolute necessity in case you deal with instruments of different directivity (like woodwinds vs. brass or voice vs. piano), placed over a vast stage. Closely placed microphones are usually used as spot microphones only with very little actual contribution to the mix, the main picture is captured by an arrangement of main microphones. So directivity, tonal balance and character of each instrument in the room will always be captured in ´a natural way´ via main mic.

Goodness knows how a realistic sounding mix could be made from a plethora of close miked channels of disparate instruments.

Mixing engineers have different ideals and strategies to mix main mic signals and spot mic signals, and that's fine. Some aim for a pretty enveloping, ambient and ´realistic´ picture, some don't, if they feel that capturing details of the performance is more important. Both ways are possible, and I see no reason to condemn one of them.

If one aims for ´realistic reverb soundfield´, stereo is anyways the wrong medium. Go for Dolby Atmos or Auro3D instead.

The old recordings with just 2 or 3 microphones several meters away are much more realistic IME, for obvious reasons.

Quite the opposite from realistic. 2 or 3 microphones are distorting differences in directivity of the different instruments (brass for example is usually highlighted, double basses, woodwinds and percussions ´in the abyss´), as well as overexaggerating the distances between groups of instruments and microphone leading to distorted depth-of-field (dominating strings, particularly 1st row violins, are an obvious outcome).

The claim of one-point-recordings being somehow ´realistic´, is 100% a myth and delusion. The only thing one can capture with 2 mics is a string quartet (or trio, quintet).

 

[Gwreck]

I have heard ESL-63's and more modern Quad speakers, but I haven't had the opportunity to take any measurements of them. The main characteristics are: (1) they don't make much bass, and (2) they don't go very loud. If you try to make them do either, they will distort - audible as very loud crackling. As for imaging, they definitely create a different stereo image to conventional speakers. I can't say it's better, it's just different. Some people like it.

Personally I would stay away. Not only because they have serious limitations - poor bass extension and are severely volume limited - but also because they require expensive maintenance.

I think that full range designs are flawed for bass and that older esl panel designs are flawed. New designs don’t have those limitations. I have a pair of Sanders model 10 ESL’s. The esl panel runs down to about 150hz and the bass is from a Transmission line enclosure. These speakers can play extremely loud with minimal distortion and the bass(not esl) is extended and clean. These speakers can play at ridiculous volumes but are so clean that it’s not perceived as loud as other speakers.

 

[Frank Dernie]

Quite the opposite from realistic. 2 or 3 microphones are distorting differences in directivity of the different instruments (brass for example is usually highlighted, double basses, woodwinds and percussions ´in the abyss´), as well as overexaggerating the distances between groups of instruments and microphone leading to distorted depth-of-field (dominating strings, particularly 1st row violins, are an obvious outcome).

The claim of one-point-recordings being somehow ´realistic´, is 100% a myth and delusion. The only thing one can capture with 2 mics is a string quartet (or trio, quintet).

So if 2 microphones distort the sound why ( and how) does it sound fine to the audience?

I have never heard a single commercial recording sound as realistic as the un-doctored recordings I have, recording during the concert on 2 microphones (probably about about 2 meters behind the conductor and 1m above his head) to a StellaDAT by a recording engineer who gave me copies.

Certainly 2 microphones too close to the orchestra would be expected to risk the shortcomings you list but the output of a close mike channel sounds as diabolical as if you stand where the microphone is placed so hats off to those who don't make a cod's head of the mix.

My experience is older than yours though, the last recording session I was at was 30 years ago.

 

[Frank Dernie]

The claim of one-point-recordings being somehow ´realistic´, is 100% a myth and delusion. The only thing one can capture with 2 mics is a string quartet (or trio, quintet).

I have literally thousands of recordings which show this to be quite wrong.

 

[tengiz]

...
PM/DM if you need more..

Thank you! I’ve read through some of it. At the very least, I need to be able to quickly assess what likely needs to be restored - assuming the seller allows me to inspect them more thoroughly. If it’s just a matter of routine electronic refresh, I’d probably go for it. But if it’s anything membrane-related, I’ll need to learn more before making a decision.

 

[MattHooper]

Even though I ultimately decided to move back to dynamic speakers I’m really glad I spent several years owning the Quads 63s. They provided plenty of magical listening experiences.

I view having owned different types of loudspeakers sort of like having taken different types of vacations or travel. I don’t regret any of them; I got something different and engaging out of all of them.

 

[tengiz]

I have heard ESL-63's and more modern Quad speakers, but I haven't had the opportunity to take any measurements of them. The main characteristics are: (1) they don't make much bass, and (2) they don't go very loud. If you try to make them do either, they will distort - audible as very loud crackling. As for imaging, they definitely create a different stereo image to conventional speakers. I can't say it's better, it's just different. Some people like it.

Personally I would stay away. Not only because they have serious limitations - poor bass extension and are severely volume limited - but also because they require expensive maintenance.

Understood. My interest isn’t really about integrating them into my regular listening routine - it’s more like having a console tube radio. It doesn’t make much practical sense, but it’s still cool to experience.

 

[Arindal]

So if 2 microphones distort the sound why ( and how) does it sound fine to the audience?

Because in a three-dimensional soundfield we can identify localization and ambience separately thanks to HRTF-based perception of imaging, and both our visual senses and the fact that we can move our heads, help that. Two microphones cannot capture such a complex soundfield nor can two loudspeakers reproduce it.

Particularly when it comes to judging if loudspeakers like electrostats reproduce a ´realistic´ soundfield and imaging, it is important to know to which extent two-channel stereo can deliver that or not.

I have never heard a single commercial recording sound as realistic as the un-doctored recordings I have,

As mentioned, if you want ´realistic´ recordings, go for a format like Atmos or Auro. Stereo is per se not ´realistic´, and no-one said recording engineers are aiming for an unrealistic ideal of ´realism´. Most of them try to capture the music itself, keeping the core ideas of the composition and interpretation, balance between instruments, rhythmic aspects as close to the live performance, not the ´realistic´ reverb.

My experience is older than yours though, the last recording session I was at was 30 years ago.

I recommend to get some updated experience with what a good mix of several spot microphones with digital runtime correction can do. 30 years ago this technology was in its early days and mastered by some engineers, but not everyone.

I have literally thousands of recordings which show this to be quite wrong.

Link me an example please with several different instruments, I can tell you what is unrealistic about it. The vast majority of one-point-recordings is deeply flawed and lightyears from ´realistic´.

 

[MarkS]

Any Telarc recording.

 

[MattHooper]

I have never heard a single commercial recording sound as realistic as the un-doctored recordings I have,

Same here.

Nothing has sounded as completely realistic as the recordings I did of my own instruments being played in my own home, my kids practising their instruments, like saxophone and trombone, and the recordings of my family voices. In some cases, I borrowed some really nice equipment from our studio to do the recordings, but in others, it was just something like a handheld stereo field recorder. Of course the sound was influenced by the character of the microphone and the placement. But there’s just this documentary-like verisimilitude - they aren’t trying to sound like smoothed over professional recordings, they sound like raw sonic documents of a sound occurring in real space.

 

[Fidji]

Any Telarc recording.

Telarc is top class. With most of those Telarc recordings you also get great musicianship and top performances in good premises. So it is sometimes tough to attribute the pleaure of listening to just mic placement.

I am quite often in Berlin and I go for concerts, if possible. Actually here

Sounding Space

About acoustic and sounds of the Philharmonie

www.berliner-philharmoniker.de

they relay quite well, what is happening in the hall, especially in Atmos. I reallly think stereo is just not good enough and Atmos is way to go for classical music.

 

[misterdog]

Thank you! I’ve read through some of it. At the very least, I need to be able to quickly assess what likely needs to be restored - assuming the seller allows me to inspect them more thoroughly. If it’s just a matter of routine electronic refresh, I’d probably go for it. But if it’s anything membrane-related, I’ll need to learn more before making a decision.

Switch the system on, with no music playing the speakers should be dead silent.
Any buzzing, crackling or popping and the panels need attention.
The electronics are usually OK.

If the panels need work I would contact the US. guys I listed to see if they would sell you panels, as they are complex to remake without jigs and experience.

 

[Newman]

I have literally thousands of recordings which show this to be quite wrong.

So you have literally thousands of recordings with both a 2-mic mix and an excellent multi-mic mix made from the same session, and your feedback from independent listeners (literally thousands of times), every single time the 2-mic mix is preferred by everyone? Literally!

Or...have you been making your own recordings, and developed a cognitive bias in favour of that?

Or...have you been drinking the Kool Aid by labels that brag about their 2-mic technique as a point-of-difference, and you are hearing what their marketing tells you to hear, plus what your notions about the logical perfection of the 2-mic approach tells you to hear?

You see, it is not as easy as "oh I have been experiencing it this way for years and I am convinced it is better".

Audio engineers themselves have put this matter to the test, and the feedback I have seen from them is that third party listeners tell them that the no-close-mic versions are relatively flat and lifeless. The one who comes to mind is Dr Mark Waldrep from about ten years ago, a musician and sound engineer and also a lecturer on recording who has published university texts on the subject. He has experimented plenty with close and no-close techniques and in an article comparing the two approaches he concluded (note: 'one mic' means no close mics, and is in quote marks because it is not literal):- "The “one mic approach” suffers from locked in balances, inconsistent tonal characteristics (presence), lack of depth, performance restrictions on the players, and the inability to present surround mixes. So be wary of promotional materials that brag about this or that recording technique based on uniformed opinions and unscientific claims."

In another article on mic techniques, Waldrep comes close to validating your preference, and describes it as sonic documentary, and while allowing for individual taste, he makes it very clear that there are sonic gains to be had in areas where the 'documentary' approach is lacking.

While there is no doubt that certain simple, live, acoustic, one-session, small-group performances are more suited than other musical forms to no-close-mic techniques and a degree of excellence can result, there is no reason to think that it is some form of pinnacle and things can only get worse when the far-field mics are supplemented with close mics and the result is expertly crafted. The engineer only has to turn the close mics down, up, down, up, and listen: he will keep the sound that sounds most effective. Those engineers who avoid close mics seem to be acting out of principle and a belief system, perhaps even bias, whereas those who do not avoid close mics seem to be acting out of pragmatism and experimental results. The sound engineer who doesn't even employ any close mics can't possibly know for sure what could have been achieved with their inclusion, whereas the pragmatist who does employ them can always turn them off and compare. And on so many occasions, they seem to be glad that they included them.

And then there are all the musical forms that simply don't lend themselves to no-close-mic recordings at all.

cheers

PS in recent years Waldrep has dropped his internet presence as personal life wasn't too kind to him in several areas.

 

[Frank Dernie]

Because in a three-dimensional soundfield we can identify localization and ambience separately thanks to HRTF-based perception of imaging, and both our visual senses and the fact that we can move our heads, help that. Two microphones cannot capture such a complex soundfield nor can two loudspeakers reproduce it.

Particularly when it comes to judging if loudspeakers like electrostats reproduce a ´realistic´ soundfield and imaging, it is important to know to which extent two-channel stereo can deliver that or not.



As mentioned, if you want ´realistic´ recordings, go for a format like Atmos or Auro. Stereo is per se not ´realistic´, and no-one said recording engineers are aiming for an unrealistic ideal of ´realism´. Most of them try to capture the music itself, keeping the core ideas of the composition and interpretation, balance between instruments, rhythmic aspects as close to the live performance, not the ´realistic´ reverb.



I recommend to get some updated experience with what a good mix of several spot microphones with digital runtime correction can do. 30 years ago this technology was in its early days and mastered by some engineers, but not everyone.



Link me an example please with several different instruments, I can tell you what is unrealistic about it. The vast majority of one-point-recordings is deeply flawed and lightyears from ´realistic´.

The best sound quality I enjoyed at home were BBC radio 3 live broadcasts of an evening concert every evening from the late 1960s, when I first discovered them, to when budget restraints stopped them altogether. They were my education into classical music, I recorded every concert and played it in my car to learn new music.
There are some superb Mercury, Philips and Decca recordings from early days.
I found Deutche Grammofon recordings unrealistic, though there are some great performances.

In fact many old recordings, but also my own un-doctored ones.

A few years ago one of the enthusiasts on a different HiFi forum was present at a recording of, iirc Handel's Messiah but my filing system has failed me and I can't quickly locate the CD, and he was authorised to send some clips from the recording, both from a multi miked mix and from an old school simply miked setup.
The old school sounded markedly better in instrumental timbre to me but was noisier.

It seems your idea of realistic is to do with spatial clues and reverb, which are of very little interest in my musical enjoyment.

My interest is in a realistic instrumental timbre and dynamic, probably because we have people playing music around here all the time on various instruments and voice (and have had for decades) and I am VERY familiar with how it sounds .
Getting a sound like the instruments I listen to is where the failure is.

I couldn't give a tuppeny f*ck about soundfield and imaging, and I don't know any of my friends who do either, but get the sound of the instrument inaccurate is obvious and irritating for me.