. . . . . . . despite the ignorant/arrogant utterances of a certain gasbag audio magazine publisher! As Kinky Friedman once so eloquently put it: "Let's let Saigon's be bygones . . . "While the Innersound companies could not have survived the current economic recession, sales and income for Sanders Sound Systems have been growing during this time. This is proof that the Sanders' business model is successful. The future of Sanders Sound Systems is secure.
Hey Neil,. . . . . . . despite the ignorant/arrogant utterances of a certain gasbag audio magazine publisher! As Kinky Friedman once so eloquently put it: "Let's let Saigon's be bygones . . . "
Best of luck, and welcome to the WBF.
Neil
One piece that shows the "drum head" resonances dramatically is ELP's Lucky Man. Near the end there is a tone that I've heard both Mark Wright and SoundLabs electrostatics go into fits over.
I use a British pressing as a mainstay for speaker comparisons. I've found the richness of the vocal harmonies come alive dramatically in electrostatics over any of the cone speakers I've tested.
BTW, I heard this piece on the Hill Plasmatronics and the vocals were too harsh. Now that was an interesting speaker.
-Gary
While looking up information on that speaker I found this interesting exchange:Hill Plasmatronics? Now there was an interesting speaker.
josh358
Industry Professional
Posts: 486
Joined: February 9, 2010
So you don't hear the mylar? Interesting, wonder why. I've heard it in every planar magnetic or electrostatic I've ever heard.
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RE: Coherence and colouration, posted on March 6, 2010 at 18:38:59
DkB
Audiophile
Posts: 910
Joined: June 25, 2003
Certainly, I can hear "mylar clang" in many panel speakers, like Maggies and Martin Logans. In the Maggies, it is a plasticky undertone that underlies the music. In the Martin Logans, it is more like a tinny sheen.
I think you hear the tuning material because of the overall resonance of the mylar sheet, as determined by tension and mass (like the tuning of a drum skin.)
However, as mentioned in the above post, the Sound Labs have quite effectively dealt with this resonance by breaking up the panel's into a diversity of frequencies, spreading the resonances so there is no single overriding resonance frequency.
Certainly, there is no escaping the signature of any object producing sound, but for the SOund Labs, that trace has been suppressed to a highly miniscule level. More so than many transducers, panel or cabinet.
While looking up information on that speaker I found this interesting exchange:
http://www.audioasylum.com/cgi/vt.mpl?f=mug&m=149818
Has anyone heard "Mylar"?
The only time I have is in my DIY ripple speaker experiment, made a video/audio recording of it.
http://www.whatsbestforum.com/showthread.php?522-The-Point-Source-Principle-Ripple-One-Experiment
Roger-
Thanks for taking the time to give us insight into your speaker designs and philosophy. I also think it's interesting to see all the people in the industry who contributed to the ML design--and certainly taking estat reliability a few notches up.
I know you can't comment on other manufacturers designs but Roger West of Sound Lab also talks about estats' problems in the lows, namely the "drum head" resonance you referred to and dipole cancellation effects (like what the Maggies run into). But had you considered an approach like Roger took to the resonance problem?
reply from Roger
Hi Myles,
When you refer to Soundlab's approach to the resonance problem, I assume you are referring to Roger West's "distributed resonance" design. By way of review for readers who may not be familiar with this technique, this is where the speaker's diaphragm is broken up into sections of various sizes.
The idea is to produce several different, smaller resonant frequencies instead of one big one.
In theory, this technique should not only reduce the problem of extremely bad ESL bass frequency response, but it could be used to compensate for phase cancellation, which is a major reason that ESLs can't reproduce loud bass.
The different sized diaphragm sections are produced by using diaphragm to stator spacers that are at different distances from each other. Martin Logan also uses this construction method, although Soundlab claims to have a patent on it.
I have experimented with this technique extensively. Unfortunately, it has an unforeseen problem that prevents it from working as expected.
The distributed resonance idea works for isolated, widely-separated, electrostatic panels that can operate as individual drivers. Each will exhibit its own, unique resonance depending on its size and diaphragm tension.
But when you take those same drivers and bring them together to form a single speaker, something weird happens -- the panels now operate as one.
They no longer have individual resonances.
The reason for this is that the panels are immersed in air, which has significant mass. At audio frequencies, the air mass around an ESL takes on the consistency of a gel -- or at lower frequencies, a liquid. The air mass around the speaker then vibrates as a unit (as a bowl of Jell-O would vibrate as one mass), preventing individual resonances from forming.
In other words, distributed resonance does not work. You cannot break up the fundamental resonance of an ESL into multiple discrete ones.
However, the different spacer distances do have an effect on the speaker's fundamental resonance because the diaphragm no longer behaves as though it were at a constant tension. This reduces the magnitude of the fundamental resonance widens its bandwidth. So it does help to improve the massive irregularity of the frequency response, although at the expense of making more of the audio bandwidth adversely affected by the resonance.
Note carefully that even if the technique of distributed resonance worked, the bass performance would still exhibit high Q behavior with its awful effect on bass quality. After all, by definition, all resonances are high Q, and by having more of them over a wider bandwidth, you would simply be introducing the bad, high Q behavior of a resonance over more of the audio bandwidth. This certainly degrades the performance of the speaker.
Finally, distributed resonance would not solve the problem of poor bass frequency response. Instead of having one resonance, you would now have many. So the frequency response would be ragged over a wider bandwidth.
In fairness, the case could be made that the magnitude of the multiple resonances would be smaller than that of a single resonance. Some might find that preferable. But the fact remains that the frequency response that consists of a series of resonances would still be far from linear.
In summary, I find that distributed resonance does not work as claimed.
Furthermore, it degrades the otherwise lovely, low Q, linear frequency response exhibited by ESLs over the rest of their frequency range.
There are only two ways I have found to eliminate the high Q behavior in the bass of an ESL. The first is to avoid driving the ESL near its fundamental resonance. A hybrid does exactly that. But there is a second method that can be used in full range ESLs to make them have low Q behavior over their entire bandwidth.
I have been experimenting with motional feedback. By measuring the motion of the diaphragm and comparing it to the musical signal, the errors caused by overshoot, ringing, and frequency response errors can be identified. An error signal is thus produced that can be fed to the amplifier that is driving the ESL's diaphragm to actively stop the ringing and overshoot.
This works quite well. It not only stops the high Q behavior, but can be used to produce perfectly linear bass frequency response. It will also compensate for phase cancellation. Nice!
But motional feedback has serious problems with implementation. The major one being that a microphone cannot be used to produce the error signal as the delayed sounds from room acoustics get into and confuse the electronic system.
A laser can be used to measure the diaphragm motion. It is immune from room acoustics since it is not measuring air motion, but the motion of the diaphragm directly.
Such a system starts to get very complex, expensive, and impractical for home use. So we have also been experimenting with simpler systems such as using the speaker's own capacitance changes (the capacitance changes as the diaphragm to stator spacing changes) to measure the motion indirectly. This is simpler than using a laser, but preventing the drive signal from influencing the measurement is tricky. More work is in order here.
While motional feedback can solve the frequency response and high Q problems of an electrostatic woofer, it still doesn't address the main issue, which is poor output. The fact remains that a dipole radiator suffers from extreme phase cancellation and radiation resistance losses in the bass that prevent it from producing deep, loud, dynamic bass.
There is no apparent solution to this problem of feeble bass output. Until there is, the dream of a high performance, full-range, crossoverless ESL will remain an elusive goal.
Fortunately, hybrid systems have now reached the point where they perform as well as full range ESLs with regard to detail and clarity. Integration of the two drivers is flawless. And unlike a full range ESL, a hybrid can produce very high output so that the full dynamic range of live music is fully realized. So while I continue to experiment with electrostatic woofers, I don't really see any need for them.
Great listening,
-Roger
Same for me.Roger: Thank you for a VERY informative and detailed response. I learned an awful lot from your post!!!
Roger: Thank you for a VERY informative and detailed response. I learned an awful lot from your post!!!
I think one issue is that many feel there is always a tradeoff between the "speed" of a dipolar bass system such as the Maggies and a dynamic speaker system. To my ears, the Maggies have an incredible ability to define say notes on a standup bass as opposed to the dynamics and amount of air moved by a cone driver. That said, what do you think the lower limit is and what factors might influence how low you could extend the frequency response on an electrostatic panel before crossing over to a dynamic driver or say your transmission line approach.
Well while we have your attention... I suppose I prefer electrostatic bass because of its transient response. That is to say I tend to prefer less ringing and slightly decreased output to increased output and more ringing. Many have tried a "servo" to get the woofer to start and stop properly. What role does a servo play?
Thank you for that informative explanation. I guess the next question was set up by you Roger. What is the difference between active and passive crossovers? Did I hear you say you prefer a brick wall crossover between the woofer and stat panel? At your leisure of course.
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