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Driving ESL transformer more efficient on SS-amp
Driving ESL transformer more efficient on SS-amp
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Old 1st November 2017, 04:11 PM   #11
Joshcpct is offline Joshcpct  Germany
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Hi Calvin

While googlin around i noticed youre someone with a name reg. ESL Respect.
Ya its huge pitty Michael left the planet, I dont understand :....(
Was too good to remain true.

Serious polarization loss would mean ive overdriven (foil-stator contact) or the foil-coating aged away? I did lot of sine-log-sweep high level 60 seconds (hundret times), hope i dont regret that.

Do you know bout DIS elektrostaten, they do service, can u recommend or do you or whats good adress?


PS: bout response variation in distance i know them all, its smth totally new for a "normal speaker"-guy. It looks very reasonable. But SPL is 2,83/1M not 4 or 1 inch
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Old 2nd November 2017, 12:02 PM   #12
Calvin is offline Calvin  Germany
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Hi,

You cannot ´overdrive´ the polarization as its not part of the audio-signal-path, which runs via the audio-transformer wires to the stators.
Still though constant highvoltage stress can eat the membrane coating around the contact points.
Also some coatings don´t remain stable under constant HV and movement ... though I would rather exclude that for the coatings Michael used.
What You can override is the flashover treshold of the audio transformers .. especially when the panels begin to play softer and You push up the volume of the amp.
Unfortunately is the volume loss mostly going on slowly and unnoticed which increases the danger of pushing too much power from the amps into the transformers.

Regarding check and possible repair ... I don´t know if the company You named has gained sufficient knowledge over the years ..... my last contact with them is from years ago .... and at that time they didn´t seem to have deeper knowledge of what a esl is and how to construct safely and stable/reliable. I typically don´t repair non-mine esls, but as You are in the south west also, I can offer You to check them out.

jauu
Calvin
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Old 3rd November 2017, 03:49 AM   #13
bolserst is offline bolserst  United States
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Quote:
Originally Posted by Joshcpct View Post
… the ESL comes with a serial resistor of 6.7R (10%) MOX 10 Watt. The efficiency is pretty low, as usual. Thats what i just measured:
From looking at the available assembly manuals of the Capaciti ESLs, it looks like there were two different types of interfaces. I don’t know which one came first, but I will call them Type A and B. Type A you can see has a resistor internal to the interface enclosure( I believe it is 3.3 ohm). Then you can add in parallel to it a 6.8 ohm or 3.3 ohm depending on your preferred high frequency balance. Type B does not have an internal resistor, so if you don’t have an external resistor in place you won’t get any sound from the speakers. Type B uses resistors of 3.3, 2.2, or 1.5ohm depending on the desired HF balance. For nominally flat on-axis response with either interface type, the total resistance in series with the transformer primary should be about 2.2 ohm.

Which type of interface do your E160s have?
Based on the fact that they came with a 6.7 ohm resistor I am guessing Type A. But, looking at the impedance measurement and 1m frequency response you posted, it looks like there is no internal resistor in parallel with the external 6.7ohm. So either there is no internal resistor, or it has failed.

What signal level did you use when measuring the impedance?

Quote:
I guess 2-2.5 R they should survive. That should boost the highs many dB and I could skip the EQing. But... I can climb from 380 to 1000 Watts if i bridge the amps (got 2).
In that case Id need to increase the serial resistor to double, which leaves me with no big benefit other than heating the resistor
It would be best to not use more than 250W – 300W on these to avoid damaging the coating over time.
Attached Images
File Type: png Capaciti_E160_Interface_A.png (813.8 KB, 124 views)
File Type: png Capaciti_E160_Interface_B.png (923.0 KB, 120 views)
Attached Files
File Type: pdf Capaciti_E160_assembly.pdf (848.5 KB, 22 views)
File Type: pdf Capaciti-Element-Series-Assembly.pdf (287.8 KB, 21 views)
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Old 3rd November 2017, 03:54 AM   #14
bolserst is offline bolserst  United States
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Quote:
Originally Posted by Calvin View Post
Could be a major loss of polarization voltage (polarzing supply, membrane contact). Since You seem to have tried more and more powerful amplifiers it might even be that the audio transformers suffered from internal flashovers.
Looking at the impedance curve in post#1 taken with 6.7ohm series resistor, the primary inductance couldn’t be more than 6mH - 8mH. For a full range ESL I would expect 10 to 20 times that. Perhaps the transformers do have internal damage as you describe. Comparing measurements for both speakers may give an indication. If impedance and response match each other reasonably closely, it is unlikely damage has taken place.

Quote:
Originally Posted by Calvin View Post
..don't know the actual values but the polarizing voltage should be >3kV, probably around 5kVdc.
I recall Capaciti mentioning his supplies were variable between 1kV – 4kV, so probably operation range in the 3kV-3.5kV range.
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Old 3rd November 2017, 11:47 AM   #15
Joshcpct is offline Joshcpct  Germany
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Hi all. Nice support so far, thank you guys.
Id be very happy to come back to your offer Calvin


Thx Bolsert for the PDF!!!! Great.
But funny, I have neither one of them. I drove to Zurich 2015 to 2nd hand dealer.
I got only 2 normal connectors, and a power in. No external resistor at all.


Inside the positive pin goes into the 6.8 resistor which leads straight to the transformer. That's it. Takin the resistor out leaves me with near 0 Ohm DCR.
With resistor 6.8.


I conclude lowering the resistor value will do the same as those versions, lift the highs few dB.


But also the poor 10 watt resistor has to stand a lot. Gets hot, changes value, bä.
I bought a bunch of 44 MOX with 47R each. Would give me 2.1 Ohm and 220 watts, wrapped in a cooler, with 0.45% eff tolerance. Not yet installed though. Nice idea?
Wouldn't work with bridged amp tough.




This damaging topic makes me nervous. New foils are 1000 bucks in some places.
New transformer.... ? guess not available anymore. And theyd go to the bin?? :..(


cheers
Josh
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Old 3rd November 2017, 12:00 PM   #16
bentoronto is offline bentoronto  Canada
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Driving ESL transformer more efficient on SS-amp
It might be helpful to re-state something Calvin said.

If you pump enormous voltages into the transformer in an effort to raise the loudness, you may cause shorting and burns in the high-voltage secondary.

So take care how much power you are running into the speakers. And check the bias voltage reaching the panels.

If you know about safety, it is easy to make a high-voltage probe for this application. Put together a chain of resistors to form a voltage divider adding up to say, 200-megOhms and a last one that is .2-megOhms. If you don't understand this clearly, don't try it.

B.
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Old 3rd November 2017, 12:16 PM   #17
Joshcpct is offline Joshcpct  Germany
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well considering that the official manual from the company sais it can run more than 100dB.... I think ive been usually faaaar away from that. Still the fostex amp with 150 watts easily clipped.
That sounds to me like some big problems exist.
Ill have to take care about it, thx.


The resistor question was just more a parallel generic thing to talk about out of interest. Making smth more efficient, makes easier life for amp, sounds better. Having more watts than needed too. So rather a finetuning than any intention to run a big party volume or ignoring the damage.
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Old 3rd November 2017, 03:41 PM   #18
bentoronto is offline bentoronto  Canada
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Driving ESL transformer more efficient on SS-amp
Quote:
Originally Posted by bentoronto View Post
If you pump enormous voltages into the transformer...
By "enormous voltages", I mean "enormous signal from the amp". I was not referring to the high-voltage bias.

B.
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Old 3rd November 2017, 05:57 PM   #19
bentoronto is offline bentoronto  Canada
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Driving ESL transformer more efficient on SS-amp
Or not realizing the time it takes to charge some ESLs.

Here's a time course for my panels*. I use a very large series resistor on the bias supply.

The divisions are 10 dB. The curves are:

before bias
10 minutes
8 hrs
17 hrs

Not shown is after turn-off of 10 minutes. Looks similar to the turn-on 10 minutes.

B.
*not sure where i put the mic so curves may not be representative of the listener's FR
Attached Images
File Type: jpg Bias time course.jpg (121.8 KB, 93 views)
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Old 4th November 2017, 06:32 AM   #20
Joshcpct is offline Joshcpct  Germany
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I think that issue xplains some ESL distortions. I read somewhere that:
driving high level or xcursion can significantly discharge the ESL.
On some u can even notice volume drop after loud impulse.
The Capaciti are normally quick settlers. Also they turn down the voltage when after few minutes no signal and jump back on input within a second.
Therefore i usually triggered with first sweep, then measured the second one.
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