Love Is Always Better the Second Time Around: The Sanders Sound Systems 10e Hybrid Electrostatic Speaker

eslguy

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Nice to read from an electrostatic builder in WBF. In your experience what is the more durable and consistent resistive coating currently available to DIY electrostatic builders?

I learned a lot from his books and articles, but unfortunately Sanders has many white papers on its site, but none on resistive coatings.
Thanks for your interest but unfortunately I do not have an answer for you. Due to age I had to exit the DIY realm some time ago which is why I have the 10es. I would however share some of my thoughts. My original ESL project was very DIY. The stators were basically perforated "garden panels" from a hardware store. I used mylar sheeting and rub in graphite powder until a vacuum meter showed the required resistance. Sandwiched it in with Plexiglas spacers. Used a surplus photocopier power supply for the high voltages. Pretty low tech but they ran great for 10 plus years. Then developed arcing issues so tore them apart and did rebuild. The rebuild used Basically Eros panels. And they arced too. Conclusion was my amp upgrade couldn't power ESL's = new amp and problem went away. Another 10 ten plus years on iteration2 . Sold them as aging looked at downsizing . Bad mistake - but lead to the 10es. The 10e panels are incredible and I doubt there is any DIY project that could even come close. Having said that the DIYs provided 20plus years of great music and a great project for the "young and brave" The so called unreliability of ESLs is to my mind a total myth. They are definitely demanding but for those that appreciate their virtues well worth the bit of extra trouble. Even my original homebuilt rivaled most speakers I have heard.
 
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tmallin

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If you read my first couple of posts you will see that I, too, had problems with earlier versions of the Sanders hybrid electrostatics, the 10c. I think the biggest changes are the move to a better transmission line, aluminum woofers, and espcially the far, far superior dbx VENU360 crossover. I can instantly A/B the system with the woofers on or off and I honestly do not hear any change in directivity between woofer and panel with the 10e. All the sound appears to come from the panel in either case. With the woofers on, there seems to be bass coming from the panel while with the woofers off there is no bass. It's as simply marvelous as that.

Yes, the Quad 63 + Gradient SW63 is a good combo. It gets the Quads up to a good ear height (VERY important) without creating a midbass dip the way elevating them on high stands does and the woofer blends very nicely. If I were to own Quads and not be too demanding on bass power and impact, that would be something I'd want to try.

I lived with several full-range Gradient speakers over the years, and the last--Revolution Actives with triple Gradient sub modules arranged in tower configurations (a total of eight 12-inch dipole woofers per side) almost had enough bass power and impact to suit me, kind of like the quadruple 15-inch dipole woofers in the Legacy Audio Whispers I also once owned. Dipole bass requires Herculean efforts if the extension, power handling, and impact are to be more than mediocre at best.

I've never really cared for the larger Quad speakers like the 2905s. The bass still gives out far too soon for orchestral power music at decent levels and at least without EQ is rather "plummy" in the midbass, as the English say, not to mention the upper ranges sound not as coherent as with the smaller Quads, to my ears.

As Sanders and Martin Logan designs acknowledge, there is really no substitute for box bass, especially for material with a lot of low bass played at realistic levels. This is even more important if your musical interests are eclectic and go well beyond classical, as mine do. Electronic music will show you the problem with dipole bass drivers in just a few seconds if you crank it up to even levels peaking above 85 dB which is quite moderate for such music. The Sanders10e play any music magnificently at any volume from whisper to roar with lower apparent distortion from top to bottom than any other speakers I've had in my listening room.
 

kswanson27

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If you read my first couple of posts you will see that I, too, had problems with earlier versions of the Sanders hybrid electrostatics, the 10c. I think the biggest changes are the move to a better transmission line, aluminum woofers, and espcially the far, far superior dbx VENU360 crossover. I can instantly A/B the system with the woofers on or off and I honestly do not hear any change in directivity between woofer and panel with the 10e. All the sound appears to come from the panel in either case. With the woofers on, there seems to be bass coming from the panel while with the woofers off there is no bass. It's as simply marvelous as that.

Yes, the Quad 63 + Gradient SW63 is a good combo. It gets the Quads up to a good ear height (VERY important) without creating a midbass dip the way elevating them on high stands does and the woofer blends very nicely. If I were to own Quads and not be too demanding on bass power and impact, that would be something I'd want to try.

I lived with several full-range Gradient speakers over the years, and the last--Revolution Actives with triple Gradient sub modules arranged in tower configurations (a total of eight 12-inch dipole woofers per side) almost had enough bass power and impact to suit me, kind of like the quadruple 15-inch dipole woofers in the Legacy Audio Whispers I also once owned. Dipole bass requires Herculean efforts if the extension, power handling, and impact are to be more than mediocre at best.

I've never really cared for the larger Quad speakers like the 2905s. The bass still gives out far too soon for orchestral power music at decent levels and at least without EQ is rather "plummy" in the midbass, as the English say, not to mention the upper ranges sound not as coherent as with the smaller Quads, to my ears.

As Sanders and Martin Logan designs acknowledge, there is really no substitute for box bass, especially for material with a lot of low bass played at realistic levels. This is even more important if your musical interests are eclectic and go well beyond classical, as mine do. Electronic music will show you the problem with dipole bass drivers in just a few seconds if you crank it up to even levels peaking above 85 dB which is quite moderate for such music. The Sanders10e play any music magnificently at any volume from whisper to roar with lower apparent distortion from top to bottom than any other speakers I've had in my listening room.
Have you heard the Quads with the Entecs? I'm told the Entec 12-f20 was designed by Keith Johnson and Demian Martin specifically for the ESL 63. They are almost exactly the same width and the timbre matches the Quads beautifully. Mine measure, in my room, -6dB at 20.4 Hz. That's all the bass I need.
 

tmallin

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The Entecs were box woofers so, yes, they could provide a lot of bass in terms of extension, power handling, and punch. The problem then was setting the crossover to the Quads high enough to protect the panels from strong bass while preserving enough of that wonderful Quad-ness that they easily lost if you set the crossover high enough to really protect them and keep bass distortion low.

That's another thing that sets the Sanders panels apart. They are virtually indestructible no matter how hard they are driven and can take substantial bass boost without any apparent increase in bass distortion. The standard EQ of the Sanders panels through the dbx VENU360 control box as supplied by the factory is about plus 15 dB at the 172 Hz steep crossover frequency of the panel to the bass driver. The 48 dB/octave high- and low-pass digital crossovers are another reason why the bass driver blends so well with the panels, I think. There is very little overlap between the two drivers.

While the Sanders woofers don't go quite as low as the Entecs, they make up for that with the superb blend of the transmission line bass with electrostatic upper range. See Sanders' paper on this at this link.
 

kswanson27

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As I said, the Entecs blend with the 63s beautifully. I'm currently crossing them over at 75Hz and have gone down to 60Hz and up to 100Hz. That wonderful Quad-ness--great term btw-- is definitely going away at much over 90Hz and no, you can't hammer 100dB out of them but you can play mine all day long at 90-95 dB which I don't want any part of.

Based on your very well done write ups about the Sanders I have no doubt I could live with them happily. I was just trying to point out that the Quads, with the right rebuild and subs, are a very viable option today.
 

tmallin

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Yes, Quads are a reasonable option when properly implemented. But just remember that as nice as Quads can sound on first listen and even for a considerably longer time than that, eventually you will hear the inherent peak in the midrange and mid-treble response which shows up in most reported measurements and realize that this must be deal with through aftermarket equalization, either analog or digital. Before you hear this problem you will marvel at the Quad's apparent clarity and presence compared to other speakers. The big midbass helps to balance the upper range peak and adding additional bass via add-on woofers or subs further disguises the problem.

But once you hear this overemphasis, it's hard to unhear it. With the Sanders, equalizing any part of the frequency spectrum is a simple issue to address because the 10e speakers already come with the dbx VENU360 Loudspeaker Management System that can cope with any frequency response issues automatically or manually and which may be used in conjunction with a measurement program such as OmniMic v2. And the DSP correction applied by this dbx LMS seems to my ears at least, utterly transparent, allowing the Sanders 10e to sound even clearer and more transparent than any Quad even with no electronic equalizer in the sonic pathway of the Quads.

Part of this sonic impression is the result of the Sanders' extremely narrow dispersion in the mids and highs compared to Quads and most all other speakers. Yes, outside the sweet spot, the Sanders highs roll off severely. But listened to from the sweet spot the Sanders just sound cleaner (that cleaner sound is one aspect of the gigantic headphone effect I mentioned) because, with the back wave suppressed through foam damping, very little obnoxious coloration or distortion results from room surface reflections. Yes, you can somewhat similarly suppress room reflections from wider dispersion speakers like Quads or box speakers, but it takes a lot more room treatment to do so and at least in my small room even with the added padding other speakers never sound quite as clean as the Sanders 10e does with damping only the rear wave.
 

tmallin

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Returning to the "you are there" vs. "they are here" dichotomy.

I think that at base this is a matter of personal preference. The Absolute Sound magazine for decades trumpeted "you are there" as the rather obvious goal of home audio reproduction. That is not so much so today, although a couple of their reviewers, Robert E. Greene in particular, as still strongly in this camp.

But even REG acknowledges that given how recordings are made this is ultimately pursuing a will o' the wisp. Even if we had more channels so as to more fully envelop the listener and "overpower" the listening room's acoustics with recorded acoustics from far more than two speakers and angles, as long as almost all recording engineers believe that facsimile reproduction of the original event is not salable to the public, we will not have enough program material to make pursuit of this goal worthwhile. At least with current technology, it is not possible to use electronic equalization or other tools at our disposal to effectively undo the fact that recording microphones are too close to singers and instrumentalists or positioned at non-audience locations, for example.

And that does not even get at the vast majority of modern recordings outside the classical music field for which no original venue ever existed, those which are studio creations of mixing boards and associated processors employed by recording engineers to literally create from scratch imaginary acoustics for any given recording. There is no reference standard for playback of such recordings. We literally have no way of knowing what such recordings should sound like. Okay, as Toole and some others have suggested, we might be able to recreate at home what the final mastering sounded like to the mastering engineer if we were able to recreate the studio audio system and room environment at home. But do you know any recordings for which such information is provided? It seems it would be possible with some sort of Rosetta Stone-line sonic information included with the recording which could be used to tune your home system. But, still, how many such recordings include such test tones or other vital information such as room size, room treatment, reverb times, angular separation of all the speakers etc. Again, such information could be included, but rarely is.

All these shortcomings would seem to argue that "you are there" is an impossible goal to pursue. But then when you consider the "they are here" goal, that seems even more hopeless to me.

For one thing, it's literally impossible to fit a large ensemble into a small listening room like mine, much less imagining what a large ensemble should sound like playing in a small room. Even for small groups or solo musicians, who wants to hear a piano in an 11 x 13 foot room? Musicians may well practice in such environments, but no one thinks such a venue is favorable for a performance for an audience.

The perspectives are all wrong, also. Hearing instruments playing merely a few feet or even inches from your ears is not a comfortable environment. Musical instruments and voices seem not only too close, but also too bright and nasty sounding.

A bit more subtle, but something I've really focused on in recent years is how sonically ugly the reverberation of a small room sounds for most music. It's a constant slap echo added overtop of any recorded acoustics. It's a type of reverb one never hears in any real performance space because all those venues are so much larger than even a good-sized living room, much less my small converted bedroom audio playback space. The "second venue" sound of my bedroom simply MUST be substantially suppressed in order to enjoy music playback much at all. But once you suppress your listening room's acoustics, now you're moving away from any possibility of achieving a "they are here" sensation.

In my experience, and to my ears, while I realize I will not be able to achieve near perfection in pursuing a "you are there" effect, suppressing the second venue acoustics of my listening room, allowing recorded acoustics (natural or artificially created) to maximally shine through, seems much more enjoyable to me on a wide range of recordings. Tasteful application of electronic equalization can add to the pleasantness of the result. While most recordings will not allow facsimile reproduction of the original recorded event, I can get what seems to me "good sound" by pursuing a "you are there" effect much more easily and with much greater aural satisfaction than I get listening to the small room acoustics of my listening room in all their inglorious ugliness.

Yes, the means I've found most successful in pursuing "you are there"--the Sanders 10e set up as I've described--means that some recordings will sound rather lifeless in the sense of a lack of surrounding ambiance. And you MUST listen from the sweet spot. These are personal tradeoffs I acknowledge, but can live with.

If you don't want quite as much suppression of you listening room acoustics, there are several ways which can be used singly or in combination to pursue middle ground:

-Use speakers which broader vertical and especially horizontal dispersion (D&D 8c, Gradient, Harbeth, dipoles with undamped rear waves, very wide dispersion speakers like Ohms, or even omni speakers like MBLs or Morrisons)
-Use less acoustic absorption in the listening room (less coverage of room surfaces, and/or less thickness of the absorbing material)
-Listen from further away from the speakers
-Don't toe the speakers in to point exactly at your ears
 
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microstrip

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Where can we find full measurements of the Sanders Sound Systems 10e Hybrid Electrostatic?
 

tmallin

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Nowhere that I know of, if you are talking a battery of tests such as NRC anechoic chamber tests published by SoundStage, Klippel tests, or Stereophile-type tests. Because of their extreme horizontal and vertical directivity, they would measure quite poorly with 360-degree tests or even listening window tests. But that weakness is part of the beauty of the design in terms of its ability to ignore the listening room acoustics from 200 Hz up, the range of the electrostatic panel. Like I said, if you damp the back wave of the panel, you MUST listen on axis. The speakers must be aimed precisely at your ears. That means with your ears 12 inches or more above the bottom of the panel and with the middle of the panel aimed exactly at its respective ear as you sit in the listening position. If that's too much to ask, look to other speakers.
 

microstrip

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Nowhere that I know of, if you are talking a battery of tests such as NRC anechoic chamber tests published by SoundStage, Klippel tests, or Stereophile-type tests. Because of their extreme horizontal and vertical directivity, they would measure quite poorly with 360-degree tests or even listening window tests. But that weakness is part of the beauty of the design in terms of its ability to ignore the listening room acoustics from 200 Hz up, the range of the electrostatic panel. Like I said, if you damp the back wave of the panel, you MUST listen on axis. The speakers must be aimed precisely at your ears. That means with your ears 12 inches or more above the bottom of the panel and with the middle of the panel aimed exactly at its respective ear as you sit in the listening position.

Ok, I have now understood that buying them is a purely subjective driven action, with all its implications.

If that's too much to ask, look to other speakers.

I see. Thanks for being so clear.
 

tmallin

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I think I was too doctrinaire in my statement. I cannot stress enough how personal a decision my set up is. Many people love the sound of the Sanders 10e with not much damping of the back wave at all. In fact, this picture Sanders has on his website is apparently how he often uses his personal pair and other people also say they use them in or near a corner or at least right against the wall behind them because of the awesome bass and overall sound this produces.

In his review of the Sanders 10e in The Absolute Sound, REG said he used a combination of absorption and diffusion on the wall behind the speakers. His room is quite a bit larger than my 11' x 13" room. His is about 20' x 26'. He says that once you get the speakers at least 5 or 6 feet from the wall behind them, the back wave arrives late enough so as not to blur the direct sound. I think it has to be more like 7 or 8 feet. Even 5 feet is difficult to manage in my small room. In a former room which was 13' x 20' I could get dipole speakers about 80" from the wall behind them and this still wasn't quite enough to make the slap echo sound like pleasant added reverberation or space to my ears.

But if your listening room is large enough, I'm sure you don't need to damp the back wave or use much other room treatment to get superb sound from the Sanders 10e. In the large-ish room Sanders usually uses at AXPONA, with the speakers set up to fire diagonally from corner to corner, Sanders regularly gets my vote for one of if not THE best in show with just drapes on the windows (exposed glass is a no-no for most all speakers) and a sheer curtain between the speakers to conceal the equipment behind the curtain.

In my very small listening room, however, the best sound to my ears is as they are pictured in this post #7 in this thread: well out into the room with the back wave damped with four-inch thick acoustic foam batts behind the speakers. An area 4 feet wide and 8 feet tall is damped along the side walls behind the speakers and an area 2 feet wide and 8 feet tall is damped on the front wall behind the speakers. The picture was taken from near the listening position and thus captures pretty well my view of the speakers from the listening seat. From my listening seat, the back of the panel is seen as being "aimed" at the center of that foam array to maximally absorb the back wave of the panel.

As I said in post #147, there are ways to get more of your listening room's sound back into the picture. With the Sanders the best way is to just undamp the back wave. It you do that, you will hear much better high frequency balance as you move around the room and if your room is large enough, more added reverberation, no matter how dry the recording itself might be. The sweet spot won't be as sweet, but for some/many/maybe even most listeners, that won't be an issue.

For me, I crave the sweetest sweet spot I can get for that gigantic headphones effect. That effect is hard to describe. Both ears hear both speakers, so it's really not like headphone listening where you have almost total inter-aural cancellation. With headphones your right ear can't hear much of what the left earphone is reproducing and your left ear can't hear much of what the right earphone is reproducing.

But, as with headphones, with the Sanders set up my way, the sound is tightly beamed toward your ears and from 200 Hz up the panels almost totally eliminate the effect of your listening room so that the sound takes on the extreme clarity and lack of listening room slap echo or listening room reverb that you usually only get with headphone listening. I've mentioned the "clap track" test track before: the Sanders, set up as I have them, reproduce this dry single handclap track closer to the way it sounds via headphones than any other speaker set up I've ever heard. With headphones there is absolutely no audible echo "tail" to this transient. With my Sanders 10e set up there is almost no audible "tail" to the clap transient.
 
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Ron Resnick

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That is a heck of a lot of toe-in. It does look like a giant set of headphones.
 

tmallin

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My guess is that the wide-angle lens I used for that shot exaggerated the apparent toe-in angle. I can assure you that the speakers are only toed in enough to point directly at my ears. How I accomplished that is explained in detail in this post #9 in the Speaker Set Up and Positioning section.
 
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mtcurrie

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Hi, my name is Mike Currie. I have just found this thread and have read through some, but certainly not all, of the posts. I have owned Sanders 10c since 2013…a record for me. These have been partially upgraded to 10e status (the crossover), but I have not replaced the woofers, for good reason. If you speak to Roger Sanders, as I have several times, he will tell you that the original woofers are at least as good as the aluminum cone version, if not better. He has kept those in his personal system. In other words, he talked me out of the change. I figure if a manufacturer suggests that I do NOT buy one of his products, I should listen. The switch was apparently made because some customers were overdriving them. The aluminum cone versions can handle a bit more in that regard. All I can say is that I’ve my system at some fairly ridiculous levels with nary a problem, and I fear hearing loss is in store for those who have had issues.

You have mentioned REG’s review several times. I couldn’t agree with you more. He absolutely nailed the sound and the many strengths of the speaker.

I cannot even begin to venture an explanation for your different experiences with the 10c and 10e. The range covered by the stat panels seems to be the source of most of those differences, yet as far as I know, those panels are unchanged. One thought (which may have been covered in a later post than I’ve yet gotten to). I found that the newer Dbx crossover was a mild improvement in a couple of areas, most notably eliminating a very mild ‘haze’ in the highs. Subtle, but a nice benefit.

My listening room is pretty large at 15’ X 34’ X average 9’ (vaulted ceilings). I can confirm that moving the panels out at least 5’ from the back wall pays benefits. Farther than that, not so much. I actually have them 6’ out just because I have the room and achieve a very small improvement in imaging. Within limits, distance to side walls is virtually irrelevant. I’ve had them as close as a foot and as far as 3’. It just doesn’t seem to matter.

I’ve been listening to music now for almost exactly 50 years, and with one exception (Magnepan MG-1 that I bought when I was a graduate student), I have never owned a single piece of gear for this long. The Sanders 10c/e simply does it for me. I’ll repeat an earlier comment - read REG’s review. I certainly can’t say it better.
 

Ron Resnick

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Welcome to WBF, mtcurrie!

Thank you for telling us about your long experience with the Sanders speakers!
 

tmallin

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As to the woofer change, I think Roger Sanders has at least implied the same thing to me in private correspondence as to his opinion of the relative quality of the previous woofer versus the current aluminum woofer. He did state that the primary reason for the change was to prevent overzealous customers from destroying the woofers. He provided pictures of blown woofers of the earlier type and those pictures were not pretty. See this picture, for example:

woofer.jpg

As to the mechanical woofer noise problems I had with my prior 10c speakers in my former house, perhaps some of the noises were caused by interaction of the sharp spikes Sanders provided and the solid concrete slab floor beneath the carpet in my basement listening room. At the time, though, I attributed most of the problem to the amount of bass boost needed to bring the woofer up to the level of the panels all the way down to 20 Hz. Perhaps I was expecting too much bass extension. With the 10e's I have the bass boosted down to 25 Hz from which frequency it is allowed to roll off naturally.

The major problem with the 10c, in my opinion, was the high noise level--mostly quiescent hiss--generated by the Behringer DCX2496 crossover unit Sanders was then using. Honestly, I could clearly hear the hiss with no music playing from several feet OUTSIDE the music room door. Nothing I tried reduced this hiss. Sanders was at a loss to explain it since he heard no hiss from his own personal 10c system. He did admit, however, that he usually listened with his windows open, so that means his ambient noise level in the listening room was far higher than my very quiet, below-grade basement listening room.

This 10c hiss was totally eliminated when I eliminated the Behringer crossover unit and pressed my TacT RCS 2.2XP AAA into service to control the crossover and EQ. The sound quality notably improved in all respects and the hiss was totally gone--not audible at all even with my ear right next to the panel.

In my view, the current dbx VENU360 control unit is a HUGE improvement sonically and every other way over the Behringer. Overall it is by far the best equalizer box I have ever used, not to mention the most flexible crossover unit I've ever used. The fact that the 10e sounds so transparent is evidence enough of the dbx box's sonic transparency. And there is NO hiss when the system is properly gain structured, which the dbx controls easily allow--even from my near-field listening position.

In my view, the weakest aspect of the system--and this aspect is still very good--is the woofer driver and/or cabinet noise. It is still easy enough to induce mechanical noises which are very easy to hear at less than deafening levels and even with any additional bass boost eliminated--straight factory set up, in other words. I no longer use pointed spikes, just the flat feet Sanders also now provides.

To easily hear the noise, I just mute the output of the panels via the dbx controller app (takes only a couple of taps on my iPad screen) and listen to the woofers alone playing material with strong low bass. I can hear mechanical noise from the bass driver and/or cabinet at high but not unreasonable volumes beginning at between 84 and 90 dB or so. To be clear, however, this noise is not usually audible on any classical or jazz recordings, only with electronic music or heavy rock recordings.

Turn on the panels, however, and all such noise is totally masked even up to far higher volumes. Thus, the woofer is plenty "good enough" in my book for the volumes I use and my usual classical and jazz music fare, which generally don't exceed about 84 dB.

But many speakers exist which never produce any such mechanical or cabinet noise even with extension down to 20 Hz and the ability to play at high volumes down there. My Dutch & Dutch 8c speakers are just one example. I've never heard those speakers produce any spurious noise of any kind even at ear-splitting levels above 100 dB with any kind of music. By the way, I'm being careful to distinguish whether the bass-induced noise is coming from the speaker, or the structure or other contents items vibrating within the room. While the room and objects within it also can make spurious noises, the Sanders woofer driver or box itself is making some of the spurious mechanical noises I hear.

And, yes, read REG's review of the 10e!
 

tmallin

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Back in post #126 I mentioned the disturbing newly developed incompatibility between iOS software version 16.X and the wonderful dbx VENU360 app which controls the Sanders 10e speakers. That was October 2022 and this problem still hasn't been fixed and I've heard nothing more from Harmon about a fix date despite additional inquiries. The control app still works, but only on iOS 15.7.X and earlier. I have just turned off the automatic updating function on the iPad I use to control the Sanders 10e speakers and thus am holding the software on that iPad to iOS 15.7.X. The app works wonderfully on both iOs 15.7.X.

There are also versions of the VENU360 app for Android tablets as well as for Windows. I downloaded the Windows version onto my 2017 Microsoft Surface tablet and it works fine, just like the iOS version. I assume the Android version also still works, although I don't currently have an Android tablet on which to test it.
 

tmallin

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Cleaning the Sanders 10e

This need to clean all surfaces of the panel and the rest of the speaker may not be a problem in homes that have forced-air heat and air conditioning, especially where the air is filtered constantly by a constant or at least frequent operation of the HVAC fans and air filters. I also know from experience that other residential areas are not nearly so dusty as my current location. My former home, some forty miles away, was far from plane and train traffic and that home was on a cul-de-sac so there was not much pollution from autos, either. It had forced air heat and air conditioning, and an electrostatic air filter within the HVAC air circulation system. That home was relatively quite dust free. I had no problem with dust accumulation on the earlier Sanders 10c I owned while living in that home.

But the winter season has again reminded me of one of the unusual maintenance requirements of the Sanders 10e in my current home. The electrostatic panels are exposed to the atmosphere. The front and back metal stators attract a lot of dust because of the constant electrical charge on the diaphragm. The stator/membrane sandwich, in addition to being able to reproduce sound, is also akin to a large electrostatic air cleaner, attracting all the dust from the air of your home.

Those of you who may have experience with electrostatic air cleaners will know how those tend to deposit gray and black grime on nearby furniture and building surfaces, in addition to darkening the filter itself. This problem is worse for electrostatic filters without fans since the dirt is not dispersed by the fan but is concentrated on and very near the air filter.

My current home is exceptionally dusty due to its proximity of a lot of commuter rail traffic, commercial airline overflights from O'Hare, and vehicular traffic down my street. My home's heating system is a hot water boiler feeding baseboard heating pipes. It produces very uniform, noiseless heat, with warm floors and six separate thermostatically controlled zones, but the lack of a fan and its associated filter in this heating system means that in winter, the home's air is not being drawn through an air filter and thus the interior air is more dust-filled in winter than in summer when the air conditioner is on.

That's a long way of explaining why, over time (which in my house can take only a few weeks), especially in winter, the dark black stators of the 10e panel get uneven gray dust deposits all over them, making for a non-uniform appearance which, frankly, is not attractive. You don't want to use a vacuum cleaner on an electrostatic panel since this will certainly unduly stress the thin film membrane. You definitely don't want the membrane to touch the stators as it might if the vacuum has enough suction.

In addition, I've found that this dust deposit is not readily removed by a dry dust cloth. The dust-removing tool needs to be moist to break the hold of the grime from the stators.

I've also found that you don't want to use any cloth with knap to it, such as microfiber or terrycloth. The fibers of the knap tend to get into the slots of the stators, intermittently contacting the membrane and producing noises which are a bit startling and which I sense are not good for the membrane.

I've tried various damp sponges, but sponges tend to leave tiny bits of sponge on the stators since the stators abrade the sponge as you move the sponge across the relatively sharp edges of the slats in the stators. Then you're faced with how to remove the tiny bits of sponge deposited on the surface of the stators, or worse, wedged in between the slats of the stators.

In my experience, the ideal cleaning cloth appears to be a damp men's handkerchief, the ordinary white cotton variety. It has no knap, is about the right size, and is easily rinsed clean from time to time as the cleaning project progresses.

The dust deposits on the stators are the most obvious problem because of the black color of the stators. But the electrostatic membrane also attracts dust to other surfaces nearby, which includes the grill cloth over the woofer, the woofer itself, and all wooden and metal surfaces of the speaker.

I currently operate the speakers without the wooden trim strips which cover the metal rails and without the woofer grill cloth. When I first purchased the speakers, I was using these parts. But it soon became apparent that keeping the woofer grill cloth looking uniformly black was a losing battle without frequent removal of that grill for thorough vacuuming of it, front and back. Even then, the vacuuming was not able to remove all the crud. Thus, I abandoned the woofer grill as well as the wooden trim strips.

Yes, the speaker looks much better with those parts in place as long as they are clean. But repeated vacuuming of the grill cloth not only couldn't keep it really black, but the fabric began to stretch, making it look a little saggy/baggy.

Without those parts in place, the speakers actually sound a bit better to my ears, and it's much easier to keep everything clean. The look is more utilitarian, but I soon came to appreciate or at least not mind its now more business-like appearance.
 

atmer

Well-Known Member
Jan 26, 2014
2
0
231
Hi Tom,

Regarding your issue with dust/dirt accumulation, do you know if the bias supply is connected to AC ground, and if so, is the wood frame/esl panel connected to the bias supply ground to provide a conductive path to bleed off any charge that would build up?

Also, why not just leave the speakers unplugged/turned off when not in use? At least that would eliminate dust/dirt buildup between listening sessions. If your panels are like my Sound Labs the
panel should be fully charged within moments of the bias being applied.

BTW, I've enjoyed reading your experiences with the Sanders over the past year.

John
 

tmallin

WBF Technical Expert
May 19, 2010
868
304
455
70
Chicagoland
Thanks for your interest, John.

The power cord is a standard three-wire IEC affair, but I have not taken anything apart to examine the wiring of the bias supply.

There is no wood in the frame. The trim strips are the only wooden parts above the wooden woofer box. The long heavy and stiff metal rails holding the panel bolt to the woofer box with eight bolts into metal sockets along the full height of the woofer box.. The ESL panel, which is some kind of metal sandwich (anodized aluminum, perhaps?) containing the diaphragm is merely velcro-attached to the rails along the entire 40+ inch length of the rails above the woofer box. There is a three-wire connection between the panel and the wooden woofer box facilitated by mating keyed connectors at the bottom of the panel and the top of the woofer box. This connection is ordinarily hidden from view by the woofer grill, but since I'm not using that grill I can see it at the top of the woofer box.

I leave all my equipment on 24/7 and thus am predisposed to leave the panels charging 24/7 as well. I have not read instructions for other electrostatic speakers other than the Quads. At least one Quad dealer recommends leaving the Quads plugged in for at least a couple of days before serious listening because, he says, it takes quite a while for the charge to even out over the surface of the panel. See the "Purchase Considerations" paragraph at this link. I don't know whether other electrostatic panels would need similar 24/7 operation to maintain best sonic quality. The Sanders manual does not discuss the AC power connection at all. The Sanders manual does acknowledge that the panels may get dusty and recommends a damp sponge to clean them. I discussed the damp sponge method in my post #158.

I think some other electrostatic panels may have at least a grill cloth covering the stators and that may cut down on dust accumulation on the stators. The Quads and Sound Lab do, for instance. But the Martin Logan and Sanders do not, allowing them to appear transparent/translucent in normal room light.
 

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