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ESL Power supply question?
ESL Power supply question?
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Old 19th December 2013, 12:24 AM   #51
stokessd is offline stokessd  United States
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IF you folks still want an adjustable HV supply, I designed one that worked very well for me for years:

http://quadesl.com/speaker/diyesl/hv_supply.pdf

Sheldon
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Old 19th December 2013, 01:39 PM   #52
WrineX is offline WrineX  Netherlands
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Quote:
Originally Posted by stokessd View Post
IF you folks still want an adjustable HV supply, I designed one that worked very well for me for years:

http://quadesl.com/speaker/diyesl/hv_supply.pdf

Sheldon
thx looks pretty nice
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Old 10th January 2014, 05:48 PM   #53
bolserst is offline bolserst  United States
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Quote:
Originally Posted by X83 View Post
…I'm guessing that full wave rectifier high voltage multiplier has the larger capacitors on the positive AC wave form and on the opposite for the negative side… It also appears to have more diodes on the one side
The standard voltage multiplier using 2 strings of capacitors is a half wave series multiplier.
A full-wave multiplier requires a transformer with center tapped secondary and 3 strings of capacitors.
Voltage Multipliers, Inc. - Types of High Voltage Multiplier Configurations

Concerning the extra diodes…I think all they are doing is putting two diodes in series for each rectifier block to halve the peak voltages seen by the diodes. For an example, so the schematic linked to in post#51.
http://www.diyaudio.com/forums/plana...ml#post3744943

Quote:
Originally Posted by bolserst View Post
I've seen HV supplies where the first capacitor in the multiplier chain was increased in size to substantially reduce ripple at minimal cost, but increasing size of half the caps is new to me...not sure what the reasoning is.
As usual curiosity got the better of me and after a bit of experimenting on the test bench, there actually appears to be a very good reason for only increasing half of the caps in the multiplier. Looking at the example multiplier circuit shown in the attachments, let’s call the upper string of capacitors Ctop, and the bottom string of capacitors Cbot. The long term ripple is determined only by the size of the Cbot caps. The Ctop caps only affect the long term DC voltage magnitude and how quickly it gets there.

Rather than trying to tabulate and plot all my experimental results, I performed a few quick LTSpice runs to better illustrate the trends.
Attachment #1 Summary of Ctop, Cbot, Load, and Voltages for each run along with associated attachment pic.
Attachment #2 - 9 LTSpice screen captures for each run.
(Input voltage for each run was 100Vp = 70.71Vrms)

Some observations:
1) With a very light loading(10 Gohm) the output voltage is essentially Vp x number of capacitors. Voltage drops across diode junctions make it slightly less.
2) Every doubling of Cbot results in halving the ripple magnitude. Looking at the trend curve for ripple voltage at the bottom of Attachment #1 you can see that you may quickly ran into diminishing returns.
3) Increasing Ctop has no effect on ripple, but does increase the Vdc output. However, it would be just as easy to leave Ctop the same size and increase the input voltage to the multiplier by a small amount. I'm guessing this is the route that was chosen for the CLX woofer supplies.
Attached Images
File Type: png HVmult_summary.png (275.5 KB, 178 views)
File Type: png HVmult_Ctop-50nF_Cbot-50nF_R-10G.png (192.0 KB, 177 views)
File Type: png HVmult_Ctop-50nF_Cbot-50nF_R-10M.png (232.2 KB, 175 views)
File Type: png HVmult_Ctop-100nF_Cbot-50nF_R-10M.png (235.4 KB, 170 views)
File Type: png HVmult_Ctop-200nF_Cbot-50nF_R-10M.png (226.2 KB, 165 views)
File Type: png HVmult_Ctop-50nF_Cbot-100nF_R-10M.png (213.8 KB, 32 views)
File Type: png HVmult_Ctop-50nF_Cbot-200nF_R-10M.png (210.2 KB, 34 views)

Last edited by bolserst; 10th January 2014 at 05:54 PM.
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Old 10th January 2014, 07:36 PM   #54
geraldfryjr is offline geraldfryjr  United States
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Increasing the values of the caps also increase the output current capability of the multiplier stage as does increasing the input frequency.

I had found a few really excellent online calculators that take all of these factor in to detail.
I may have posted those links back in 2010 or I may not have, I will search for them later.

The one I liked in particular, you are able to adjust the input frequency and it would tell you the size of the caps to use and however many stages to use as per voltage and current output requirement.

It was fairly accurate as to the performance of my Variable HV supply and is what I used to plan it out.

jer
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Old 10th January 2014, 08:18 PM   #55
ticknpop is offline ticknpop  Canada
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ESL Power supply question?
The Martin Logan Stage uses a single inverter for power supply with 470 pf ceramic 6 kv caps. The ML Request used polyester caps as does the CLX in the HV doubler. A friends low cost ML uses a wall wart supply and ceramic caps in the step up. The diodes in the CLX low and frequency supplies are the same 1 amp 1 kv soft recovery types, while the Stage and Request used 1n4007.
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Old 10th January 2014, 08:32 PM   #56
bolserst is offline bolserst  United States
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Quote:
Originally Posted by geraldfryjr View Post
Increasing the values of the caps also increase the output current capability of the multiplier stage as does increasing the input frequency. I had found a few really excellent online calculators that take all of these factor in to detail.
Absolutely, ripple is inversely proportional to frequency as well.
Fortunately a properly operating ESL does not require much current capability.

I believe, all the calculators are based on formulas summarized(in grey boxes) on the Blazelabs page:
Experiments: Experiment 15
Calculations based on these equations certainly provide good guidance when deciding on frequency, number of stages, and capacitor size for your HV supply. Note that formulas are valid only for even number of multiplier capacitors/diodes with all caps of the same value. This point isn't particularly clear in the documentation.

@ticknpop
Thanks again for sharing details and pics of your ML products. Always new things to learn.

Last edited by bolserst; 10th January 2014 at 08:48 PM.
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Old 10th January 2014, 09:32 PM   #57
geraldfryjr is offline geraldfryjr  United States
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Yes, I believe that is one of the calculator's looks like they have added some color to it !!!

http://blazelabs.com/cw-brm-java.asp

jer
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Old 10th January 2014, 11:17 PM   #58
ticknpop is offline ticknpop  Canada
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ESL Power supply question?
I find it interesting that ML use film caps in the doublers of their higher end products and cheaper, smaller ceramic caps in their smaller, cheaper speakers.
i used Wima 2000V FKP caps in updating my Stage's step up caps and when I update the CLX's with Duelands for the crossover resistors I will also change the CLX's polyester step up caps to film and foil 2kv Wima FKP's.

i have Quad 63, Dayton Wrights, Acoustats and all used ceramic caps for the step-up multipliers
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Old 10th January 2014, 11:57 PM   #59
ticknpop is offline ticknpop  Canada
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ESL Power supply question?
correction - i said the Stage's doubler caps were 6kv ceramics, they were actually 2 kv ceramics.
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Old 15th January 2014, 08:14 AM   #60
ticknpop is offline ticknpop  Canada
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ESL Power supply question?
Here is the CLX music sense and power supply board
Attached Images
File Type: jpg image.jpg (479.5 KB, 73 views)
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