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In Reply to: Quad's weak power supply question? posted by markzb on October 27, 2006 at 01:52:37:
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!
Follow Ups:
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.
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