Ground reference for ESLs - Page 3

bolserst · 3rd February 2012, 04:03 PM

Quote:

Originally Posted by tyu

bolserst
are you saying the panel wont charg all the way up?

The 2K resistance is small compared to the 10Mohm or more resistance between the bias supply and the diaphragm. These two resistance are in series when charging the panel, so the 2K resistance has little affect on how much the panel can charge up.

Quote:

Now as for the SE setup i use,The art on the right, all i have here is a Ratshak soundpresurmeter but i get almost 2db more output from 1'away with this setup .

I tested one more time last night and do not get any change in SPL between the two setups.
The output of an ESL panel is dependent on two things, 1) diaphragm charge and 2) stator voltage.
To get 2dB more output, one of those two things had to increase by 30%, assuming the microphone placement and test signal were the same.
Was there any other changes you made? I know you had posted elsewhere about a bias modification that increased the bias voltage.

tyu · 3rd February 2012, 05:15 PM

bolserst

I saw the Acoustat 11 you posted...thay used the 10m too the bias 0 That would let it flot up right....there nothing new ...it al l been done ...we just have to find the info

ML Spres do you have the schematic ? anyone CLX

I dont no about the more output...i trust you... i have seen your work here, Thanks for all of it
Yes what i have been doing is geting a good 10m res. an puting it in on the Logan a bias feed...thay have 5 15m1/4watt carbon...not bad sounding..but this dose give more bias..
but as for more out put...you can hear a change right off ...

The testing was done with the bias 0 in the setup ...no res. but this sounds hard..i put more res. 60m back in the bias feed that helpet...but when i went back two the 2k feed souned much better...this sound i am talking about sounded like you were driveing the 2k hard with a amp...but sweetins up with the 2k feed.Still working on it all
Thanks

tyu · 3rd February 2012, 07:41 PM

bolserst

Bingo...it was the 2k res...pulled them an now were back to your frist post I have C in now and.....
Does anybody have a good explanation why most manufactured ESLs have the secondary referenced to safety ground or the primary? It had been suggested to me that perhaps with the secondary side floating, it could build up considerable static potential relative to the primary and the rest of your electronics. Most likely, it is to cover some sort of safety concern like this, I'm just not certain of what. Thoughts?

Good sound ..mAX the output. OUT OF THE PANEL..i can dig this ... boy all those SL3 out there sounding hard ...it the 2k res. JUST LIFT THEM..

Now i have put the SL3 power supply up i no you have this but i would like you to look at this an tell me how i can bypass the turn on an juSt say on all the time ... it looks To me like the switch is just the bias 0...When the 0 in it truns on... can you give me some input....thanks

tyu · 4th February 2012, 12:28 PM

Ok It not the bias 0....looks like a cut at c19 an a cut at the winding that feeds the turn on board an jump too c19..an it looks like the switch is out of the mix an the bias is on all the time??

bolserst · 4th February 2012, 04:28 PM

Quote:

Originally Posted by tyu

how i can bypass the turn on an juSt say on all the time ... it looks To me like the switch is just the bias 0...When the 0 in it truns on... can you give me some input....thanks

There are many ways to force the SL3 bias supply to stay ON. Here are two.

1) Solder a wire as shown to bypass the TRIAC switch. The bias supply will stay on. The LED will still turn on with applied audio, and turn after 15 minutes or so after audio is removed.

2) Solder a wire as shown to short out C6. The bias supply and LED will stay on whether or not there is audio applied.

tyu · 4th February 2012, 04:55 PM

Thanks

Mike Beck · 6th February 2012, 08:58 PM

So, does anybody have a good explanation why most manufactured ESLs have the secondary referenced to safety ground or the primary? It had been suggested to me that perhaps with the secondary side floating, it could build up considerable static potential relative to the primary and the rest of your electronics. Most likely, it is to cover some sort of safety concern like this, I'm just not certain of what. Thoughts?[/QUOTE]

Perhaps there is concern over long-term reliability of the step-up transformer insulation with the HV bias leakage across the primary/secondary boundary. In theory there should be no leakage but floating charge can do strange things. Grounding the CT to the primary with a hard ground or through a resistance would prevent this.

arend-jan · 7th February 2012, 07:17 AM

I agree with Mike. We like to think in circuit diagrams but with high voltages like this leakage paths develop very easily. I once forgot to put the 'ground' wire between the high voltage supply and the step-up transformer, so the HT was left floating. The speaker was working just fine, it completed the loop with the wooden frame (about 30cm distance between HT and step-up).

Quad grounds the CT secondary and the core as well. The primary is left floating.

bolserst · 7th February 2012, 02:46 PM

Quote:

Originally Posted by Mike Beck

Perhaps there is concern over long-term reliability of the step-up transformer insulation with the HV bias leakage across the primary/secondary boundary. In theory there should be no leakage but floating charge can do strange things. Grounding the CT to the primary with a hard ground or through a resistance would prevent this.

Hey Mike,
Thanks for bringing this thread back on topic.
Hmmmmm...perhaps one could setup a buffered(ie extremely high input impedance) HV probe to measure the voltage across the primary/secondary boundary with the secondary floating to determine if this is the case.

Quote:

Originally Posted by arend-jan

I once forgot to put the 'ground' wire between the high voltage supply and the step-up transformer, so the HT was left floating. The speaker was working just fine, it completed the loop with the wooden frame

Hello arend-jan,
I have had similar experiences where unconnected bias supply wires were actually charging up the diaphragm thru the resistance of the MDF base they were laying on. The HV bias supply doesn't need a low resistance connection to the transformer/Stators. The series resistance just defines the time constant for charging up the panel. Well, I guess in practice a portion of the bias supply voltage is dropped across the series resistance; the magnitude of the drop being propotional to the leakage current.

Quote:

Quad grounds the CT secondary and the core as well. The primary is left floating.

Yes, the original Quad ESL and the early versions of the ESL63 connected the secondary CT to safety ground.
I have always wondered why in later versions of the ESL63 the connection to safety ground was removed, and the secondary CT was connected to the primary.

Attached are early/later schematics of the ESL63 to illustrate this change.

arend-jan · 8th February 2012, 07:49 AM

I don't know the answer to that. But I'm willing to take a guess.

In the older models the high voltage section (stators, EHT) is referenced to safety earth and the whole input section, including spark detector, seems to be left floating (or actually referenced to whatever the amplifier is doing). Perhaps there were problems with the reliability of the spark detector? It seems preferable to have the spark detector referenced to the high voltage section in a predictable manner, not just by parasitics and whatever amplifier is hooked up.

In the later models the input section and the high voltage section are referenced to the same internal ground. Which means connecting it so safety earth would connect one of the speaker input terminals to safety earth. Not all amplifiers are going to handle that gracefully so that might be the reason to keep the whole speaker floating?

6th February 2012, 08:58 PM	#27
Mike Beck diyAudio Member Join Date: Aug 2005 Location: North Carolina	Secondary Ground Reference So, does anybody have a good explanation why most manufactured ESLs have the secondary referenced to safety ground or the primary? It had been suggested to me that perhaps with the secondary side floating, it could build up considerable static potential relative to the primary and the rest of your electronics. Most likely, it is to cover some sort of safety concern like this, I'm just not certain of what. Thoughts?[/QUOTE] Perhaps there is concern over long-term reliability of the step-up transformer insulation with the HV bias leakage across the primary/secondary boundary. In theory there should be no leakage but floating charge can do strange things. Grounding the CT to the primary with a hard ground or through a resistance would prevent this.

7th February 2012, 07:17 AM	#28
arend-jan diyAudio Member Join Date: May 2006 Location: Netherlands	I agree with Mike. We like to think in circuit diagrams but with high voltages like this leakage paths develop very easily. I once forgot to put the 'ground' wire between the high voltage supply and the step-up transformer, so the HT was left floating. The speaker was working just fine, it completed the loop with the wooden frame (about 30cm distance between HT and step-up). Quad grounds the CT secondary and the core as well. The primary is left floating. __________________ my Quad ESL website.

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3rd February 2012, 05:15 PM	#22
tyu diyAudio Member Join Date: Jul 2009	bolserst I saw the Acoustat 11 you posted...thay used the 10m too the bias 0 That would let it flot up right....there nothing new ...it al l been done ...we just have to find the info ML Spres do you have the schematic ? anyone CLX I dont no about the more output...i trust you... i have seen your work here, Thanks for all of it Yes what i have been doing is geting a good 10m res. an puting it in on the Logan a bias feed...thay have 5 15m1/4watt carbon...not bad sounding..but this dose give more bias.. but as for more out put...you can hear a change right off ... The testing was done with the bias 0 in the setup ...no res. but this sounds hard..i put more res. 60m back in the bias feed that helpet...but when i went back two the 2k feed souned much better...this sound i am talking about sounded like you were driveing the 2k hard with a amp...but sweetins up with the 2k feed.Still working on it all Thanks

4th February 2012, 12:28 PM	#24
tyu diyAudio Member Join Date: Jul 2009	Ok It not the bias 0....looks like a cut at c19 an a cut at the winding that feeds the turn on board an jump too c19..an it looks like the switch is out of the mix an the bias is on all the time??

4th February 2012, 04:55 PM	#26
tyu diyAudio Member Join Date: Jul 2009	Thanks

8th February 2012, 07:49 AM	#30
arend-jan diyAudio Member Join Date: May 2006 Location: Netherlands	I don't know the answer to that. But I'm willing to take a guess. In the older models the high voltage section (stators, EHT) is referenced to safety earth and the whole input section, including spark detector, seems to be left floating (or actually referenced to whatever the amplifier is doing). Perhaps there were problems with the reliability of the spark detector? It seems preferable to have the spark detector referenced to the high voltage section in a predictable manner, not just by parasitics and whatever amplifier is hooked up. In the later models the input section and the high voltage section are referenced to the same internal ground. Which means connecting it so safety earth would connect one of the speaker input terminals to safety earth. Not all amplifiers are going to handle that gracefully so that might be the reason to keep the whole speaker floating?