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Hi everyoneJust like to ask some of you knowledgable ESL folks out there. I have read in a few places that the power supply for the Quad 57 is considered wimpy and weak!
Either way that does not really disturb me. I am curious though, what other approaches /power supplies were used to supply high voltage for other ESL's? Were they stiffer / stronger?
Regards
Follow Ups:
...that the original ESL EHT block is "powerful" enough to do the job it was designed to do when the block is charging a nylon coated diaphragm in a panel with minimal (there's no such thing as zero) leakage. The speaker will begin to hum if the leakage is too high or the EHT block is "weak" and cannot keep charge up to the panel. Both cases are a fault condition, not normal.Using a "stiffer" or "more powerful" EHT block does not solve the problem. If the panel starts to leak abnormally the panel will still hum. Usual cause is a track to earth through moist dust accumulated in the gizzards over the years.
The nylon coating give something over 10^10 ohms per square resistance. Adding resistors to the EHT path to any panel is a waste of time and not used in the original design for that reason. Such resistors offer no "protection" against stator-to-stator arcing. If you overdrive the panel it will arc from stator-to-stator and punch a hole right through the diaphragm. Diaphragm to Stator arcing is prevented by the high resistance coating.
Finally, do not let the 'classic' diagrams showing a resistor in the EHT path to the diaphragm fool you. This "resistor" in the original Quad ESL is, in fact, the distributed diaphragm resistance. This also lowers any harmonic distortions the panel might be producing as well.
Kent's EHT boards are very good because they use high quality components with good ratings (3kV and higher). I use them on all my own panels (FWIW) and they are the only boards I have used that can maintain a good 5 to 5.2kV on a loaded bass panel even when improperly measured with a HT probe and DVM - meaning that they deal well with current draw.
Regards,
Gary Jacobson
Nonsense. The EHT unit in the ESL is more than adequate for the task at hand. It only needs to supply enough voltage/current to keep the panels charged, and make up for the minimal leakage that is present in all electrostatic panels. Anything more would be overkill and a waste of money. PJW was a frugal man and built things to get the job done, nothing more.I have never heard any tweak, or improvement made to the EHT that had any sonic impact on the speaker. This is provided the EHT and panels are working to spec.
I build and sell replacement ESL electronics including EHT boards. If there was a way to improve on the EHT supply I would make that available and make some money on the 'upgrades'. There just aren't any improvement to made IMO. I have tried audiophile grade power cords, A/C line conditioners, split supplies for tweeter and bass panels, fancy caps and diodes for the supply, etc. None of these had any impact on the ESL. They can potentially have a nice impact on your wallet!
Hi KenThanks for your reply. I was perplexed that it was considered whimpy by some hence i asked the question. So thank you for clearing that up!
In case you dont see it...somewhere further down this thread i was asking you about the issue of charge migration. What is your take on some of us using diaphragm coatings that are less resistive then originally used. Do we need to worry about this charge migration then? Or it still wont happen? Do we need to add some "extra" series resistance using non orginal coatings for the diaphragms?
What are your views, Ken?
On a side note...i was talking to Dr. Quad just yesterday and he mentioned to me your boards....a picture of them can be found on Sandy's website. Well...Ken...they are very nice looking boards indeed!! Very clean....
Regards
mark
Thanks for the kind words on the boards. Nothing too fancy, but then they don't need to be!If you lower the resistance on the panels with non-original coatings, then yes adding some resistance on the output of the EHT supply would be in oder. I honestly don't know why one would want to do such a thing. Nylon is so easy to use and readily available, and it is exactly what PJW had in mind.
Dropping the resistance below the minimum will cause some charge migration and sparking with original ESL panels, even with the added resistance in my experience. This will only occur under extreme drive, but it does happen.
The original was designed with high resistance on the diaphraghm and going lower only causes problems.
Charles
The list of legit tweaks for either ESL is small IMO. Some would argue even the small list!Naturally make sure the speakers are working to spec. And for me at least, they have to be off the floor. About 18" for the 63 and 24" for the ESL. This puts your head right in the middle of the panel. Huge improvement with both speakers in terms of soundstage, image size, etc.
Near-field set-ups seem to produce the best results with these speakers. Power amps with some heft to the supply.
In the case of the 63, get rid of the grille cloth. Taking off the screen, even the Monitor screen, makes a big improvement in resolution at the price of making the thing dangerous. And I have been known to pry off those dust covers which further improves the resolution, but off course there are contamination issues with no dust covers.
63 electronics can be updated/upgraded a bit. Quad made lots of changes over the run of this speaker including the electronics. Later Monitors eliminated the soft-clipping amp, in favor of a series thermistor! Argh. Get rid of that thermistor. Under heavy drive both the soft-clipper and especially the thermistor makes the speaker get very two-dimensional and glassy, hard.
The input circuit board and R/C network can be upgraded with better audiophile grade parts. Again, a subtle improvement in resolution, nothing earth shattering, but does show one your audiophile credentials!
Since you seem very knowledgable on the '63's; what is the function/purpose of the "bridge" resistors/varistors in the HV supply? why not just use diodes???Charles
This was the last revision to the ESL63 EHT board and the circuit used in the current 98/05 speakers. Quad has some fancy marketing name for this particule circuit, dynamic current sensing or some such thing.It helps to limit current flow to the panels under conditions of high humidity, i.e. above about 55-60%RH. As the panels begin to draw more current, the varistor heats and its internal resistance rises dropping slightly the current/voltage available to the panels. Does not completely solve the problem with operation of this speaker in high RH, but does help some. Best to keep them in a room where the humidity can be maintained at levels below at least 60%RH.
... surely a PS which was considered adequate in 1960? (or whenever the Quad 57 was invented?) is just plain not SOTA in 2006!!?? :-))So I'm sure a PS which makes them sound better can be developed today!
Regards,
Hi AndyThank you for replying. The Quad 57's can and do sound great when they are working as they are supposed to with their standard power supply. That i can attest to.
My question is not really about how to improve it. My question is what did other ESL manufacturers of the time use for their own ESL power supplies that make some people say the original Quad one was whimpy. Is there any real basis for some saying a Quad ESL power supply is whimpy?
Unfortunately, the Quad 57 is the only ESL i have managed to examine thoroughly, personally. I am thus curious how other companies generated their high voltages for their ESL's. There are hardly any other ESL's here in Malaysia for me to look at :(
As for your SOTA comments, my notions about audio progress today are perhaps somewhat different from yours and most audio magazines.....there's hardly any. In fact, i would generally say its more like SOTAR is going on, with A for audio and R for regression. Mind you Andy, that's just my own personal opinion and not a dig at you...
Regards
mark
Hi Mark,While I agree that there are a lot of amps - particularly tube amps - on the market today which seem to use circuits from 40 or even 60 years ago, I think progress has been made on other fronts.
Today's turntables, cartridges and arms leave those of the so-called "golden age" of vinyl for dead and the current incarnation of my Magnepan speakers (the 3.6R) is, likewise, a better speaker than my IIIAs from 1987.
Regards,
I don't see what the problem is.The power supply provides a high voltage to polarize the diaphragm. If the speaker is working properly, the diaphrahm draws no current, so the current capability (beefiness) of the supply doesn't enter into the picture. In fact, in the '63 there is a 10 megohm (thats millions of ohms) resistor in series betwen the supply and the diaphragm to, I believe ensure that it runs in a "constant current" mode.
The 10Meg resistor in series with the EHT supply helps suppress excess current to the panels when charge migration starts. This is not required with the original ESL given the extremely high resistance on the diaphgraghm and you see no series resistors in place with the original ESL EHT unit.Charge migration will never occur with the original ESL no matter the drive condition. This is not the case with the ESL63. Heavy drive will cause charge migration from the diaphraghm to the stator. The spark arrestor will stop the migration once it starts, but some migration and sparking will generally always occur under these conditions. The 10Meg resistor lowers the available current to the panel(s) and reduces the chances of punching a hole in the diaphraghm when charge migration occurs.
Greetings KenYou say..." Charge migration will never occur with the original ESL no matter the drive condition"
Ken...what prevents the total absence of this charge migration you mention? Is it due to the high resistance of the original nylon coatings? Or something else?
Why i ask? If we use "other" alternatives diaphragm coatings to nylon that have less surface resistivity (but no where near as little as graphite), do we run the risk of this charge migration occuring? Should we then look at adding in some series resistance?
Im curious if you have any insights into this.
AndyOne can only hope you might ask yourself one day just how generations before you absolutely LOVED buying and listening to music on such outdated gear. And if you ever decide to pickup reading, you might find it interesting what the great masters of a couple of hundred years ago had to say about notions of "progress".
Your analogue views and statement is somewhat too simplistic.
Do you have anything to say or ask about ESL power supplies Andy? That's what i would really like to talk about.
Mark,Re. "One can only hope you might ask yourself one day just how generations before you absolutely LOVED buying and listening to music on such outdated gear."
... you call ME simplistic!!?? :-))
Ever since I bought my Maggies 15 years ago, I have always loved listening to my system. But significant changes and tweaks have occurred to my system since then which, by comparison, give me significantly increased enjoyment NOW than what I had then.
Does that negate the enjoyment I've had over the past 15 years, compared to now ... of course not! It simply points to how naive I was 15 years ago in thinking "this is good"! :-))
Also, re: "And if you ever decide to pickup reading, you might find it interesting ...".
As they say in the comics "on the Internet, no-one knows you're a dog". You have absolutely no idea whether I read a lot or not, never having met me.
And as to: "... what the great masters of a couple of hundred years ago had to say about notions of 'progress'" - why stop at the last 200 years?
I've read a piece by one of the famous ancient Greek philosphers (Pythagoras?) that decries the behavious of the young - much as the press comments about todays teenagers. Plus ca change ... as the Frogs say! :-))
And do I have anything to say or ask about ESL power supplies? No, sorry, I'm not an electrostatic man ... neither am I a full-range driver man (both are too compromised IMO). Anyway, I think you've got all the information you need from Ken.
Regards,
Hi AndyMortimer J Adler wrote something called "How to read a book". If ever you get the chance...do try and give it a read. Quality of reading, not quantity is one of the main thrusts of it. It really is a gem.
To answer your questions,
No, i dont know exactly how many books you have read. To my mind, the Quality of books one reads and more so understands them is more important. But heck, that's just my opinion.
Why stop there? Well 200 years ago is when issues were raised on what progress really is about that have strong relevance to situations of today. I found the French writings of the day especially very enlightening and can relate to that time period more as the music, art and architecture are still visible to us today to relate the two.
Phythagoras was of a time i can not visualise or relate to to today.
Lastly you ask.. "you call ME simplistic!!?? :-))"...
Yes i do
The high resistance on the panels, along with the internal charge rings, keeps the charge in place. High resistance on the output of the EHT supply will not accomplish the same thing without a huge sacrifice in sensitivity, i.e. 200-300M. Best to have the high resistance on the panel.
Without knowing anything about electrostatic speakers, but a little about electronics, a series resistor does not lower current it lowers voltage. This is strictly a result of Kirchoff's laws which states that the current entering a point equals the current leaving. I don't doubt that the 10M resistor prevents damage to the diaphragm but not by lowering the current but rather the voltage.
I may be an egoist but at least I don't talk about other people.
As the spark occurs on a small part of the diaphraghm, the discharge current flowing in the areas adjacent to the spark area will cause the spark area to drop below the potential by which a spark can occur. The voltage drops momentarily to below the potential of sparking.
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