The backwave is dead.Long live the back wave.

[Gregadd]

My preliminary toe in results indicate that best result is achieved with speaker parallel to the couch. For non science majors that means no toe in. The speaker is way to bright when aimed at me.

 

[RUR]

My preliminary toe in results indicate that best result is achieved with speaker parallel to the couch. For non science majors that means no toe in. The speaker is way to bright when aimed at me.

Do you have any room treatments, Greg? A bright, "smeared" high-end is common if you don't have any rear or first-reflection absorbtion.

 

[Dr.W]

Greg and Neil,

Since I am here now.

I think it is almost time for me to defend myself, and....... correct a few minor misstatements.

Wait for it.

I will this weekend.

 

[nsgarch]

Bruce, I don't know there's anything you have to defend; in fact, my crack about not turning it up too loud doesn't really apply here because your ears are exposed to such a relatively small percentage of the total panel surface.

Many people (and a LOT of 60's people ) have done the 'extreme nearfield' thing, with all kinds of speakers, and of course those ridiculous "speaker-chairs" However, I once took it a step further (not with Logans) and did the extreme nearfield thing outdoors! My logic(?) was, "if you want to get rid of the room effects, why not just get rid of the room?!"

I have two feelings about this kind of setup with electrostats; opposite sides of the same coin:
1. Since the ear is exposed to only a fraction of the panel's entire output, it's safer than if a conventional cone or dome driver were pumping its entire output right into the ear!
2. On the other hand, it's kind of a waste, because most of the panel's output is going right past the listener's head.

Of course, there are probably all kinds of interference conditions being created right at the midpoint where the two sides' waves collide. Though I doubt a listener sitting right in the middle would hear them, since the two channels are kept separate by the listener's skull ;--) Sort of like binaural recording in reverse.
.

Have fun . . . . that's what it's all about!

 

[Gregadd]

Do you have any room treatments, Greg? A bright, "smeared" high-end is common if you don't have any rear or first-reflection absorbtion.

No not yet. Maybe I should do that first. Any recommendations? It's bright but not smeared at all.

 

[vinylphilemag]

No not yet. Maybe I should do that first. Any recommendations? It's bright but not smeared at all.

Check out the stuff by Real Traps. Their stuff is pretty good.

 

[RUR]

No not yet. Maybe I should do that first. Any recommendations? It's bright but not smeared at all.

I use a mix of ASC and RealTraps products, and can recommend both without reservation.

 

[Dr.W]

Neil,

Thanks for that reply. Hey, I want to defend. As I look at this thread I realize my comments about the comment specific to my system and all my blathering about near field aught to be in another thread.

I started another thread for near field.

http://www.whatsbestforum.com/showt...f-the-why-nots-and-my-system.&p=4428#post4428

So, my comments here will about the back wave is dead.

A comment was made indicating that it made little sense to have a dipole and then kill the back wave. Certainly dynamic drives can be used as dipoles. Many very good examples exist. But the back wave of most dynamic drivers is killed.

Janzen and others made "box" speakers in which electrostatic tweeters and midrange drivers were used with the back wave killed in the box. The same applies to ribbons.

For me the ML is not about the back wave, but rather the front wave of our electrostats compared to the front wave of a dynamic driver. The detail, control, and physical difference of how the extremely lite diaphragm, driven over its entire surface area couples to the air.

The back wave simply bounces around in the room and adds some ambiance, but for me it causes the image to be less precise.

I have a number of DIY tube traps. One 9" version sits directly behind each of my Prodigy absorbing much of the back wave, just like a Soundlab Sallie. Now that I think about it, if I just had one more wife named Sally I could use the two of them as my DIY Sallie's.

 

[kach22i]

However, I once took it a step further (not with Logans) and did the extreme nearfield thing outdoors! My logic(?) was, "if you want to get rid of the room effects, why not just get rid of the room?!"

Speaking of, I just found these images today.
http://www-mddsp.enel.ucalgary.ca/People/madanayake/ghana_files/audio.htm

Of course, my electrostatic loudspeakers are not QUAD.? They are home made and is the next best thing to have (sounds nearly as good too!) .....................

Fortunately my living room was ideal for high performance dipole loudspeakers. An entire wall of the room is completely open to the garden and open area thereafter. This causes all the back radiated sound to escape to the surrounding area and be absorbed.? Therefore the issue of coloration from reflected sound is not a concern..............

air of ESLs? being tested. The greenery you see is the ?Sri Jayawardenapura Kotte Bird Sanctuary?. This is a protected marsh home to many wetland birdlife.

Notice that the ESL panels are almost completely transparent and the background can be seen right through the panels.

This is clearer in the left speaker due to lighting conditions at the time.?

 

[nsgarch]

Boy is that fellow passionate or what!? We Western audiophiles (USA, Canada, and Europe) have it too easy, just write a check. I truly admire people like him.

Yes, the rear wave is really a problem for panel speakers, however, outdoor operation eliminates room reinforcement (of the front wave) and may therefore require power levels neither the amp or the speaker can deliver. Many modern speakers with conventional drivers kill the rear wave just because (now) they can. High power ss amps have been largely responsible for that; it's easier to just throw away the rear wave, than deal with it via folded horns, bass reflex enclosures, etc. But with panels, it's hard to kill the rear wave (i.e. completely soak it up or bottle it up) I suppose it would be easy to build an "enclosure" onto the back side of the panel to completely damp out the rear wave but I haven't seen it tried, so there must be a reason -- I would guess having to do with overdamping the diaphragm. Capturing all of the rear wave after it's left the back of the panel is not really possible, so most solutions come down to "capture what you can and disable the rest." Absorption + diffusion.

 

[kach22i]

But with panels, it's hard to kill the rear wave.

I don't know how the JansZen does it.

Thread:
http://www.whatsbestforum.com/showthread.php?454-JansZen-electrostatic

 

[Dr.W]

I am not sure how they do it either, but Harold was doing it decades earlier.

http://www.bevaudio.com/history.html

 

[nsgarch]

It's really not that big a mystery Bruce and George. Physically the B and the J have something in common with each other that they don't share with other stats (except possibly the Final) and that something is the panel shape -- tall and skinny. As with most machinery, there are tradeoffs. On the pro side, Tall and Skinny provides better dispersion (like a ribbon) and a rear wave that is easy to capture and dissipate inside an enclosure. And you may have noticed these days that the more expensive speakers' enclosures, both cones and these stats, use curved shapes -- this is because by preventing standing waves inside the enclosure, substantial damping can occur in a smaller volume. And BTW the Beveridge doesn't completely "bottle up" the rear wave anyhow. The enclosure is made to resonate around 40Hz, reinforcing the panel output at the low end where it starts to drop off. The Janszen panel only goes down to 200Hz, so maybe they can completely kill the rear wave, I'm not sure. On the con side, a tall skinny electrostatic panel (as opposed to a tall skinny ribbon!) is a hard nut to crack in terms of output -- which was why the Final never took off, and why the Beveridge has to be as big as a Pipedream or the Infinity IRS!! If you try and get the necessary excursion/displacement (out of a tall, skinny electrostatic diaphragm) that you need to make some real noise, it will require a heavier membrane and higher voltages which means you lose transient response and encourage arcing -- two problems ribbons solve quite easily. The Janszen only puts out a tad over 100dB SPL with (they admit) some "negligable" distortion I hope George has time to go and listen to it for us. The Beveridge undoubtely costs a fortune, and in my opinion has always represented an attempt to make a full-height ribbon but using an electrostatic element.
At the time, it kind of made sense, ribbon technology being so primative in those days, but times have changed.

It has always interested me how certain audio pioneers have sometimes abandoned their own truly original idea as being inferior; and which were later developed by others: Joe Grado, the moving coil cartridge, and Roger Sanders, the curved electrostatic panel, to name two. I don't know much about modern moving iron Grado cartridges (compared to moving coils) but I have talked with Roger, who simply explained that he wanted to go in the direction of pure, fully optimised, engineering simplicity. Optimal panel size and shape, optimal diaphragm thickness, optimal charge voltages, etc. with nothing to compromise the purity of output he felt was possible. Of course that meant a flat panel, with no gimmicks to improve dispersion (curves, lenses, tall/skinny shapes, or Quad's time delay system), just a textbook perfect rendering of the basic engineering principles (the first thing Roger will tell you is that he's an engineer, not an audiophile) and let the other chips fall where they may. I mention all this with Bruce's ultra-nearfield setup in mind, because it seems to me that Roger's latest stat (which has virtually no horizontal dispersion ) would be the perfect candidate for a nearfield electrostat.

 

[kach22i]

Janszen..... I hope George has time to go and listen to it for us.

They know me as a bottom feeder over there picking some of their previously owned stuff, not sure I can get them to hook them up, but I can only try.

I'm getting my ears ready..............
http://www.a1nutrition.com/buy-similasan-ear_wax_relief/

 

[Gregadd]

"...It has always interested me how certain audio pioneers have sometimes abandoned their own truly original idea as being inferior;..."

Neil maybe this should be a new thread. IMO Gayle Sanders abandoned the CLS basically because he was disatisfied with the bass. There was not an abundnce of subs on the market circa 1985. Certainly he could have bought or copied the Infinity sub which was remarkably similar to the Kinergetics that was supposedly built for the CLS, or made the Entec that was adopted by WATT fans. He could have hired somebody to do it. Just imagine 25 years of attention to the CLS.
It's not too late. if Gayle gets bored in retirement that could be a good hobby for him. Does anybody have Gayles phone number?

 

[MylesBAstor]

Nicholas,

Same can be said to some extent about the Audiostatics-and had even heard them in a tripled up config. And for some reason, the AS just didn't have a whole lot of top end extension.

 

[MylesBAstor]

"...It has always interested me how certain audio pioneers have sometimes abandoned their own truly original idea as being inferior;..."

Neil maybe this should be a new thread. IMO Gayle Sanders abandoned the CLS basically because he was disatisfied with the bass. There was not an abundnce of subs on the market circa 1985. Certainly he could have bought or copied the Infinity sub which was remarkably similar to the Kinergetics that was supposedly built for the CLS, or made the Entec that was adopted by WATT fans. He could have hired somebody to do it. Just imagine 25 years of attention to the CLS.
It's not too late. if Gayle gets bored in retirement that could be a good hobby for him. Does anybody have Gayles phone number?

Have his facebook page and he's raising a family on the East Coast. In fact invited him by if he was in NYC but haven't heard from Gayle

 

[kach22i]

I hope George has time to go and listen to it for us.

Done deal, I wrote a short review, but I may have to go back and hear the JanZen with the McIntosh 501's.

Link:
http://www.whatsbestforum.com/showthread.php?454-JansZen-electrostatic&p=5274#post5274

 

[Ztatic]

I am not sure how they do it either, but Harold was doing it decades earlier.

http://www.bevaudio.com/history.html

Ah, yes, but JansZen Laboratory was doing it decades before the elder Beveridge. In 1955, the first speaker from JansZen was a four-faceted, wide range, ESL tweeter array with a closed back, called the 1-30. It happens that A. A. Janszen also designed two dipoles, the first of which reached the market as the KLH Nine in 1959, with a single tweeter and 10 woofers in each speaker. You may note that this was essentially a point source configuration.

A variety of closed back, point source ESL hybrids with acoustic suspension woofers (Z-200 and so on) came from Neshaminy Electronic, which took the JansZen Electrostatic brand from 1959 through the mid 1970's. Electronic Industries then maintained it for another fifteen years or so, producing a series of similar speakers (Z-412 and so on), along with some that had JBL-style acoustic lenses ahead of the tweeters for widening the dispersion.

Since Harold Beveridge's name has come up, I feel compelled to mention that aside from the closed back, one of the things that he did that was most interesting IMO was his lens/diffractor, which allowed him to use a large, flat panel area for higher SPL without a dispersion penalty, rather the opposite of Roger Sanders' radiation ideal. I suppose a preference for when room ambience makes a significant contribution or not must be a matter of taste.

One could say that high SPL from a narrow quasi-ribbon is the more practical, modern way to meet the wide dispersion at high SPL challenge, but magnetostatic membrane speakers have significant moving mass, and thus do not function like ESL's as a virtually mass-less pistonic boundary.

Another interesting thing Harold Beveridge did was invent high impedance stators, polarize them, and drive the membrane. The basic driven membrane idea was patented by Williamson at Quad, but not Beveridge's way of doing it. His insight was that high impedance stators allow true, constant-charge operation in spite of a highly conductive membrane coating, and as a side benefit, nearly prevent arcing. He also invented a direct coupled amplifier that reduced ESL distortion by using feedback based on an ultrasonic signal for sensing membrane position. This was a brilliant stroke, but he seems to have ultimately preferred his high-impedance stator approach to getting low distortion, i.e., by way of constant charge operation, for its simplicity and the option of using any amplifier.

 

[kach22i]

It happens that A. A. Janszen also designed two dipoles, the first of which reached the market as the KLH Nine in 1959, with a single tweeter and 10 woofers in each speaker. You may note that this was essentially a point source configuration.

Great first post David, but how is the KLH-9 similar to a point source? I don't know a lot about the KLH-9, just before my time in the Hi-End.

http://eslrepair.com/gallery.aspx

KLH 9 Bass panel recoating

http://audiocircuit.com/index.php?c=KLH&m=Nine

KLH Model Nine loudspeaker
By J. Gordon Holt • June, 1979
http://www.stereophile.com/floorloudspeakers/666klh/