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beun
Joined: 28 Jun 2006 Posts: 676
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Link Posted: Tue Apr 26, 2011 5:18 am Post subject: |
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Tom,
Yes, normally the HV-supply to bias the membrane is set to a fixed value and cannot be changed, in the case of the 3mm spacing for the ESL-1 and ESL-0.5 it is around 1800V. The customer liked to be able to play around with it a bit so I made it variable.
The step-up transformers I just ordered are for the audio signal and the outputs are connected to the front and back stators.
_________________ ESL-0.5 Full Range Electrostatic Loudspeakers | RTC2200 Component to VGA Converter with Gamma Boost
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beun
Joined: 28 Jun 2006 Posts: 676
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Tom.W
Joined: 09 Mar 2006 Posts: 6637
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Link Posted: Tue May 03, 2011 7:59 pm Post subject: |
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beun wrote: | The perforated metal arrived today, I will post some pictures later. Now I have to deburr them some more before they can go to the powder coater. |
What method do you use ?
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beun
Joined: 28 Jun 2006 Posts: 676
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Tom.W
Joined: 09 Mar 2006 Posts: 6637
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Link Posted: Wed May 04, 2011 2:50 am Post subject: |
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Well I must say this has been an interesting thread !
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beun
Joined: 28 Jun 2006 Posts: 676
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Link Posted: Wed May 04, 2011 4:54 am Post subject: |
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It is going to be a lot more interesting when I am finally going to put it together. I am also working on an update of the high voltage supply and I made an initial layout of the PCB.
Most of my time now is spent on getting ready for the 2011 Lone Star Audio Fest on 13th-15th of may at the Park Central Embassy Suites in Dallas, TX. Together with the customer that I am doing this built for we have been doing some experiments to better control the panel resonance and the measurements show we have made progress. If anyone is interested I can post the results.
_________________ ESL-0.5 Full Range Electrostatic Loudspeakers | RTC2200 Component to VGA Converter with Gamma Boost
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beun
Joined: 28 Jun 2006 Posts: 676
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beun
Joined: 28 Jun 2006 Posts: 676
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Link Posted: Sun May 08, 2011 2:22 am Post subject: |
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I have been a bit busy today and started to put a nice curve on the front of the base. To do so I glued a piece of lexan in the desired curve on the wood with some epoxy glue.
After drying I then used the miter saw for some rough cutting and the router with a trim bit to remove the wood until I have curve that is flush with the lexan strip.
After removing the strip and sanding off the epoxy glue I then copy this to three other wood pieces. Tonight I will stack two of these pieces on top to create the base.
I also finally took a picture of the perforated metal. The shop did a really nice job, also with the deburring it actually feels nice and smooth.
_________________ ESL-0.5 Full Range Electrostatic Loudspeakers | RTC2200 Component to VGA Converter with Gamma Boost
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Tom.W
Joined: 09 Mar 2006 Posts: 6637
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Link Posted: Sun May 08, 2011 6:15 pm Post subject: |
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beun wrote: | It is going to be a lot more interesting when I am finally going to put it together. I am also working on an update of the high voltage supply and I made an initial layout of the PCB.
Most of my time now is spent on getting ready for the 2011 Lone Star Audio Fest on 13th-15th of may at the Park Central Embassy Suites in Dallas, TX. Together with the customer that I am doing this built for we have been doing some experiments to better control the panel resonance and the measurements show we have made progress. If anyone is interested I can post the results. |
Please do !
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beun
Joined: 28 Jun 2006 Posts: 676
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Link Posted: Mon May 09, 2011 4:26 pm Post subject: |
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Ok, so here it is: the first frequency response is of the original ESL-0.5 with graduated vertical spacers only, narrower at the center and getting wider at the edges.
As you can see there is a visible major peaking of the frequency response at about 70Hz which is probably actually not that bad since the sub-woofer crossover frequency is supposed to be somewhere between 80 and 100Hz. There are also some minor peaks because of the purposely unequal distance in the spacers
The next response is of the same speaker but now there are additional horizontal spacers that divide up the vertical strip in 7 horizontal bands that get exponentially larger towards the bottom.
It is obvious that the resonance is now spread out over a much larger frequency range thereby reducing its peak by about 10dB or so. A subwoofer cross-over frequency of 80-100Hz will still be a very good choice.
Now a word of warning about the measurements, they are totally uncalibrated and the absolute vertical scale is meaningless. I took the measurements in the largest room I have using the audio output of a cheap netbook, I am pretty sure that its headphone output doesn't quite go all the way to 20KHz. The microphone used was a Dayton audio measurement electret from Parts-Express and again I used it uncalibrated, the microphone amplifier is a Blue Icicle and I don't know its exact frequency response nor do they publish a response curve.
The idea to use logarithmically sized spacers is not new by the way, it has been done by Soundlab a long time ago, but then again it is better to copy a good idea than to design a bad one.
_________________ ESL-0.5 Full Range Electrostatic Loudspeakers | RTC2200 Component to VGA Converter with Gamma Boost
Last edited by beun on Tue May 10, 2011 12:46 pm; edited 1 time in total
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beun
Joined: 28 Jun 2006 Posts: 676
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Link Posted: Tue May 10, 2011 5:58 am Post subject: |
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Some more info on the variable HV-supply. I think I have the schematic finished and the first cut of the PCB is finished as well. The output voltage has two ranges: 1.8kV - 3.5kV and 3.5kV - 7kV. For the original design with the metalized membrane the 1.8kV setting should really be the only one used, the rest is for experimentation purposes only.
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_________________ ESL-0.5 Full Range Electrostatic Loudspeakers | RTC2200 Component to VGA Converter with Gamma Boost
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beun
Joined: 28 Jun 2006 Posts: 676
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beun
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beun
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Tom.W
Joined: 09 Mar 2006 Posts: 6637
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Link Posted: Fri May 20, 2011 5:58 am Post subject: |
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beun wrote: | Well, my usual powder coater has ceased to be full service so I am on the lookout for a new one. This might take a few days. |
What ...Too much work ?
http://www.custompowdercoating.com/
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beun
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garyfritz
Joined: 08 Apr 2006 Posts: 12026 Location: Fort Collins, CO
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Link Posted: Fri May 20, 2011 1:50 pm Post subject: |
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Man. Seeing what you go through to build these things, I gotta believe you're doing it for fun and not for profit!!
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beun
Joined: 28 Jun 2006 Posts: 676
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beun
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Tom.W
Joined: 09 Mar 2006 Posts: 6637
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Link Posted: Fri May 20, 2011 8:23 pm Post subject: |
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How about the specs and the manufacturer ?
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