With Acoustat panels, bumping the voltage up won't cause any damage. However, depending on the diaphragm tension in your particular panels, the higher bias voltage may cause diaphragm to collapse and stick to one the the stators. The symptoms of the collapse are reduced output and loss of bass. Remove or lower the bias voltage and the diaphragm will pull free of the stator and all is good again. Depending on how leaky your particular panels are, you may find you can use the increased bias on humid days but not on dry days.
See posts #7 and #8 here:
[http://www.diyaudio.com/forums/plan...eviews-includes-measurements.html#post4077083
(Now )I see all ESL panels the same.....if you can pull the bias AC pluge from the wall.......... an the panels play....at a nom loudness....for over 2-3 mins......more bias DOSE NOT sound better or even as good......as the stock 500meg res...an the 5k bias is right on the money.......Andy has said so minny time....not to speak for him.....ever...
For year I have added one more diode an cap mod.... to the Acoustat bias.....an droped the bias feeder res.......too 5-30meg.....but now I find my panels the way thay were setup....were vary leaky......if I pulled the bias AC plug .......thay stop playing....an have NO output.....with out that mod I had NO sound.....
just my two cent....
For year I have added one more diode an cap mod.... to the Acoustat bias.....an droped the bias feeder res.......too 5-30meg.....but now I find my panels the way thay were setup....were vary leaky......if I pulled the bias AC plug .......thay stop playing....an have NO output.....with out that mod I had NO sound.....
just my two cent....
Thanks, that's very interesting . Where I live, winters are very humid and the stats go right off song on wet days. I have a spare set of interface, I'll build a "winter" set with extra bias and see how that goes.
If that doesn't fix the problem, then I'll just listen to horns in winter and stats in summer!
Can you measure how fast the voltage drops on humid days?
Something like:
CBLoU,ojgbQ~~_1.JPG?set_id=880000500F)
$2 Digital Temperature Humidity Gauge
Something like:
$2 Digital Temperature Humidity Gauge
An externally hosted image should be here but it was not working when we last tested it.
The humidity meter is a great idea, but don't you need an electrostatic meter to read bias voltage accurately?
I've seen ads for these types of meters in ancient times, but no modern equivalent, surely they are available somewhere.
Dehumidifer
I live in Long Beach, CA, about 5 miles from the ocean. At night, the humidity can rise to 100 percent and often hits 90 percent. During these times of high humidity, I was lucky to have fully functioning 2 + 2s 10 percent of the time. One speaker would die altogether and the other would be about 10db down.
About a year ago a solution came to me: I removed the panels, dried the frames with a hair dryer, and sprayed them with two thick layers of Urethane. Problem solved! The reason that the panels were dying was not a direct a result of the nightly humidity. Instead, it was a function of the bare wood frames absorbing moisture over night. This moisture lingered throughout the following day and was replenished by more high humidity rolling through the following evening.
During periods of protracted rain, my speakers will still die; however, if I close the doors and windows and run a dehumidifier for about 45 minutes, they come back to life -- fully to life, not 10db down.
By the way, you don't have to treat the entire frame, just the lower half -- where the moisture collects.
Try running your finger tips over the wood supporting the bottom of the lower panels. If your experience was like mine, you will feel moisture. Now that my frames have been treated, they are dry to the touch. And my speakers are working in 90 percent plus humidity. Only consecutive days of heavy rain will knock them out.
I live in Long Beach, CA, about 5 miles from the ocean. At night, the humidity can rise to 100 percent and often hits 90 percent. During these times of high humidity, I was lucky to have fully functioning 2 + 2s 10 percent of the time. One speaker would die altogether and the other would be about 10db down.
About a year ago a solution came to me: I removed the panels, dried the frames with a hair dryer, and sprayed them with two thick layers of Urethane. Problem solved! The reason that the panels were dying was not a direct a result of the nightly humidity. Instead, it was a function of the bare wood frames absorbing moisture over night. This moisture lingered throughout the following day and was replenished by more high humidity rolling through the following evening.
During periods of protracted rain, my speakers will still die; however, if I close the doors and windows and run a dehumidifier for about 45 minutes, they come back to life -- fully to life, not 10db down.
By the way, you don't have to treat the entire frame, just the lower half -- where the moisture collects.
Try running your finger tips over the wood supporting the bottom of the lower panels. If your experience was like mine, you will feel moisture. Now that my frames have been treated, they are dry to the touch. And my speakers are working in 90 percent plus humidity. Only consecutive days of heavy rain will knock them out.
To measure the actual membrane charge in different places could this be modded with a carbon fiber brush tip?
designed for taking high voltage DC and AC measurements with a digital multimeter.
Specifications:
designed for taking high voltage DC and AC measurements with a digital multimeter.
Specifications:
- Input impedance:1000MΩAn externally hosted image should be here but it was not working when we last tested it.
- Division Ratio:1000 : 1
- MAX. Test Voltage: DC : 0 ~ 40KV, AC : 1 ~ 28KV ( 50 / 60 Hz )
- Safety APPL.: EN61010 UL3111-1 TUV / GS, IEC 1010 CAT II Pollution 2
- Polarity
ositive / Negative - Temperature Cofficient:≦ 200ppm / ℃
- Maximum loading Current:≦ 40μA ( at 40KV DC )
- Maximum loading power:≦ 1.6 watt
or is a dedicated and expensive Surface DC Voltmeter needed eg
Model SVM2 at $410USD
this measures the field in a non-contact way from 1" distance so seems ideal for ESL panels?
Model SVM2 at $410USD
An externally hosted image should be here but it was not working when we last tested it.
this measures the field in a non-contact way from 1" distance so seems ideal for ESL panels?
Interesting revelations here. In all my years in dealing with Acoustat, I don't recall ever hearing about such dramatic variations in performance due to humidity. I can't help but wonder if some other factors, unique to your particular speakers, (possibly age-related) may be causing these problems. After all, Acoustats were born in south Florida, one of the most humid places in the country. The 5kV bias voltage was chosen as a good compromise between efficiency and lack of issues with high humidity and high altitude.
I don't think it's necessary, meaningful, or even wise to attempt to measure the charge on the diaphragm itself. Even if there is a localized discharge, it should equalize quickly. If one needs to measure the bias voltage, that's best done with a high-voltage probe (like the one pictured above) directly at the bias connection at the interface, after the 500-M ohm resistor. Remember, that even with a very high impedance probe, supply loading will occur, so you'll only measure about 3500 volts when you actually have 5000 volts. The actual measured voltage will depend on the probe.
I don't think it's necessary, meaningful, or even wise to attempt to measure the charge on the diaphragm itself. Even if there is a localized discharge, it should equalize quickly. If one needs to measure the bias voltage, that's best done with a high-voltage probe (like the one pictured above) directly at the bias connection at the interface, after the 500-M ohm resistor. Remember, that even with a very high impedance probe, supply loading will occur, so you'll only measure about 3500 volts when you actually have 5000 volts. The actual measured voltage will depend on the probe.
I think your right, since I replaced the 500Ohm resistors it seems much better.
Here a pic.....of SOME of the stock type 500meg bias feeder res.....as you can see the small ends on some..... can be-come UNSCREWED....Get lose over 20-or more years...make you lose bias output to the panels.......this setup....has gave ME..... bias loss for me in the past......some time ok..then low output...
I post this because these ....are NOT a ezey res....to find off the shelf....
.....just one more thing to help with getting great sound out of some of the best ESLs ever made........
long live Acoustats...
I post this because these ....are NOT a ezey res....to find off the shelf....
.....just one more thing to help with getting great sound out of some of the best ESLs ever made........
long live Acoustats...
Attachments
replacement HV resistors from Ultra High Voltage Components
500M Ohm 2W 15kV 5% Non-inductive High Voltage Resistor Glass Glaze
Has anyone tried this?
Is the bath water "dirty" from years of dust attracted to the charged membrane of is that the carbon based coating dissolving?
I say more coating than dirt....less these panels were laying on there back....an open so that dust could get in......but still I would use air only
After haveing over 20-30 Acoustat panels in 30 years.......I say the only thing to do to Acoustat panels.... is use Compress Air to blow off-out the dust.....some try to use Vacuum....becase that what thay have..
The only way I would put any water on any ESL panels today.....knowing what I have seen......is if it was so full of drit....you could not see any of the mylar.....an that would be a new one on me....
For years I thought it was fine to put panels in water ....an use hot air blowers to pull the mylar tight......till I opened up a panels.....an saw what happens
See the pic...it may look like the mylar is ripet.....its not!.....an some Know... reshrinking mylar...................is that realy a thing??.........dose it work ...an how long well that last?.....here what hot air can-well do to the mylar....it can stop the panels from working to it full output
Look there are lot Old great ESL panels out there...... you own them do what you well....I did!....................long live Acoustat panels....
All just one mans finding
After haveing over 20-30 Acoustat panels in 30 years.......I say the only thing to do to Acoustat panels.... is use Compress Air to blow off-out the dust.....some try to use Vacuum....becase that what thay have..
The only way I would put any water on any ESL panels today.....knowing what I have seen......is if it was so full of drit....you could not see any of the mylar.....an that would be a new one on me....
For years I thought it was fine to put panels in water ....an use hot air blowers to pull the mylar tight......till I opened up a panels.....an saw what happens
See the pic...it may look like the mylar is ripet.....its not!.....an some Know... reshrinking mylar...................is that realy a thing??.........dose it work ...an how long well that last?.....here what hot air can-well do to the mylar....it can stop the panels from working to it full output
Look there are lot Old great ESL panels out there...... you own them do what you well....I did!....................long live Acoustat panels....
All just one mans finding
Attachments
![Nov20_2002_01%2020[1].jpg](/community/data/attachments/507/507867-142c92b0a1129df3501d6248ba82c0fa.jpg)
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Washing of Acoustat panels is not recommended. There is evidence that the conductive coating may be damaged, despite the fact that the coating is not a water-based compound.
The only time I might suggest washing an Acoustat panel is if the panel is so dirty that it doesn't work, even after blowing out with gentle compressed air. In which case, what do you have to lose?