Don't know how many of you out there will be interested but this may give cause for consideration. I just completed modifying a friends Acoustat one plus one's high voltage supplies. The mod that I did is docummented on the Izzy Wizzy Audio site (http://www.izzy-wizzy.com/audio/spkr.html). This discribes the addition of an extra high voltage filter cap on the HT supply multiplier section. This simple mod does everything stated and then some in my opinion. This mod can be applied to most similar multiplier supplies.
An additional mod/diognostic tool is the mod shared by Sheldon stokes several years ago. This involves a neon bulb which is bypassed (paralled) by a small value cap (to catch transients at lamp turn on). The combination lamp/cap is then placed in series with the output of the high voltage supply after the large megohm value load resistor. When the panel looses charge and draws upon the HT supply the lamp lights up to conduct the HT to the diaphragm. As soon as the diaphragm is fully charged the lamp goes out. The neon lamp presents infinate resistance to the supply under these condition and so effectively decouples the diaphragm from the supply. It is as if you had unplugged the supply and the speaker operates in constant charge mode. As soon as the charge on the diaphragm starts to disapate the lamp turns on and reconnects the supply to the diaphragm. In normal operation the neon lamp will flash on and off. The cool thing is if you should see the lamp on all the time then you know that there must be a steady drain on the diaphragm somewhere (probably dust or bugs between the resistive coating on the diaphragm and the stator on that side of the panel. A very cool diagnostic tool as well as a means to decouple as much as is possible from the supply while maintaining automatic charge management of the diaphragm. Thanks to Sheldon Stokes for that one. Best regards Moray James.
An additional mod/diognostic tool is the mod shared by Sheldon stokes several years ago. This involves a neon bulb which is bypassed (paralled) by a small value cap (to catch transients at lamp turn on). The combination lamp/cap is then placed in series with the output of the high voltage supply after the large megohm value load resistor. When the panel looses charge and draws upon the HT supply the lamp lights up to conduct the HT to the diaphragm. As soon as the diaphragm is fully charged the lamp goes out. The neon lamp presents infinate resistance to the supply under these condition and so effectively decouples the diaphragm from the supply. It is as if you had unplugged the supply and the speaker operates in constant charge mode. As soon as the charge on the diaphragm starts to disapate the lamp turns on and reconnects the supply to the diaphragm. In normal operation the neon lamp will flash on and off. The cool thing is if you should see the lamp on all the time then you know that there must be a steady drain on the diaphragm somewhere (probably dust or bugs between the resistive coating on the diaphragm and the stator on that side of the panel. A very cool diagnostic tool as well as a means to decouple as much as is possible from the supply while maintaining automatic charge management of the diaphragm. Thanks to Sheldon Stokes for that one. Best regards Moray James.
Izzy Wizzy explaination
I_Forgot has suggested that he thinks that the Izzy Wizzy mod does what it does not because of additional filtering of the bias supply but because the panel (older Acoustat 0ne plus 0ne) is probably a bit leaky as far as bias supply goes. So if that is the case the the additional 0.01 uf cap stiffens the supply and makes it better able to get more voltage on to the panel. I think that this makes sense. So to find out I will remove the 0.01 uf cap and decrease the resistance value of the load resistor (500M) to say 250M. If voltage on the diaphragn is really the issue then this mod should have an identical result. Any thoughts or suggestions from the forum would be welcome.
I_Forgot has told me that 10 to 50M ohms is plenty to do the job and to keep the speaker working in constant charge mode. This just makes me want a variable supply all the more. Will keep you interested Acoustat owners advised of how this goes. It would be my guess that the reason Acoustat chose such a high value resistor for this job was probably a combination of reduceing current in the event of a shock and a good price from some vendor. Best regards Moray James.
I_Forgot has suggested that he thinks that the Izzy Wizzy mod does what it does not because of additional filtering of the bias supply but because the panel (older Acoustat 0ne plus 0ne) is probably a bit leaky as far as bias supply goes. So if that is the case the the additional 0.01 uf cap stiffens the supply and makes it better able to get more voltage on to the panel. I think that this makes sense. So to find out I will remove the 0.01 uf cap and decrease the resistance value of the load resistor (500M) to say 250M. If voltage on the diaphragn is really the issue then this mod should have an identical result. Any thoughts or suggestions from the forum would be welcome.
I_Forgot has told me that 10 to 50M ohms is plenty to do the job and to keep the speaker working in constant charge mode. This just makes me want a variable supply all the more. Will keep you interested Acoustat owners advised of how this goes. It would be my guess that the reason Acoustat chose such a high value resistor for this job was probably a combination of reduceing current in the event of a shock and a good price from some vendor. Best regards Moray James.
I use model 3s these days in a homebrew space frame.
The vibration (energy) is virtually all in one plane, so the stiffness needs really only to be very high perpendicular to the panels.
I suggest a mig welder and square tubing. Fill with sand or foam for damping as required.
I used threaded rod/carriage bolts to mount the cells a distance from the main frame... it is possible to adjust the angle of the outer cells. Be sure to use insulation where any metal goes through the cells for mounting, or you'll find things getting charged up...
You can apply felt treatment to the frame's surfaces if you are worried at all about reflections at HF.
I found the dumpsters at the local malls to be a treasure trove of premade shapes and after the application of a hacksaw, just stock of chromed & painted square and round steel tubing, btw...
The main effect was to clean up the highs compared to the stock frames. Also the interfaces have long ago had the fuse holders removed and the signal caps replaced with all polypropylene (essential), the internal wiring upgraded and the BPs changed for real ones... the interface sits on the base of the frames at the rear...
_-_-bear
PS. the drop on a neon bulb is ~100v... I'd expect it to "bleep" fairly often while playing? And neon is also a bit noisy, maybe the cap helps with that? Maybe an OB2,3,4 tube?? :- )
The vibration (energy) is virtually all in one plane, so the stiffness needs really only to be very high perpendicular to the panels.
I suggest a mig welder and square tubing. Fill with sand or foam for damping as required.
I used threaded rod/carriage bolts to mount the cells a distance from the main frame... it is possible to adjust the angle of the outer cells. Be sure to use insulation where any metal goes through the cells for mounting, or you'll find things getting charged up...
You can apply felt treatment to the frame's surfaces if you are worried at all about reflections at HF.
I found the dumpsters at the local malls to be a treasure trove of premade shapes and after the application of a hacksaw, just stock of chromed & painted square and round steel tubing, btw...
The main effect was to clean up the highs compared to the stock frames. Also the interfaces have long ago had the fuse holders removed and the signal caps replaced with all polypropylene (essential), the internal wiring upgraded and the BPs changed for real ones... the interface sits on the base of the frames at the rear...
_-_-bear
PS. the drop on a neon bulb is ~100v... I'd expect it to "bleep" fairly often while playing? And neon is also a bit noisy, maybe the cap helps with that? Maybe an OB2,3,4 tube?? :- )
Thanks for the reply Bear. You are righr about needing strong frames for the Acoustats. I have seen Two plus Two frames cracked right in half in the middle due to stress from the panels. I have also seen the lag bolts used to mount Acoustat panels pulled out of the Fir strapping they are mounted to by the force of the panels.
What do you think about the Izzy Wizzy mod to the high voltage supply? What do you think about I_Forgot's thoughts on what this mod is doing? I have the feeling that I_Forgot is right. I hope to have the time this weekend to check this out on the 0ne plus 0nes.
I have found that filling the outside edge louver cubes with Duct Seal helps deaden and damp the styrene louvre frame reduceing resonance and cleaning up the sound. It is easy to do , cheap and stays put. A layer of black felt over this row of cubes cleans up the look and makes handeling cleaner. Regards Moray James.
What do you think about the Izzy Wizzy mod to the high voltage supply? What do you think about I_Forgot's thoughts on what this mod is doing? I have the feeling that I_Forgot is right. I hope to have the time this weekend to check this out on the 0ne plus 0nes.
I have found that filling the outside edge louver cubes with Duct Seal helps deaden and damp the styrene louvre frame reduceing resonance and cleaning up the sound. It is easy to do , cheap and stays put. A layer of black felt over this row of cubes cleans up the look and makes handeling cleaner. Regards Moray James.
moray james said:
I've not seen the cracked frames, or the bolts pulled out...
The mod is interesting, but I think not so important... the problem, iirc with the extra cap is that it pulls the voltage down, and doesn't really requlate or smooth very much... I like the neon idea best so far!
If ur going full bore and no-holds-barred why not just buy a regulated HV supply? They're small and often adjustable - sometimes you can scavenge them from copiers and printers... or buy them surplus. That solves the entire problem in one shot.
I like the idea of filling the outside cubes with goo...
I'll have to give that a try! Thanks for the the thought - good one!
Sil-Pruf silicone might work too... (no acetic acid release). Nice one.
_-_-bear
Acoustat bias supply ripple
I ran some simulations of the stock bias supply and the "izzy-wizzy" mod version. The Izzy-wizzy modification reduces ripple by about 20 dBV and somewhat increases the average DC output of the supply. 20 dBV sounds like a big reduction, but read on...
I put the results in an excel spreadsheet here:
Acoustat bias supply ripple I used excel because screen shots of the simulator output were just too big. I ran the simulation using SwitcherCad III (a free download from Linear Technology). I added the model of the 1N6533 rectifier to the library to run the simulation. The 1N6533 is a 5 kV, 50 mA rectifier that should be similar to the original parts in the Acoustat bias supply. The SwCadIII schematic file is here: Acoustat bias supply simulation file
Here is the spice netlist: Acoustat bias supply net list
The data includes the spectrum of the ripple so you can see what is going on.
With regards to audibility, I'd say a simple experiment is in order- place your ear close to the speaker with no music playing. If you hear buzzing, then the ripple makes a difference. If not, it doesn't. I have never heard any buzzing from any ESL, regardless of the bias supply configuration, so I'm inclined to think that the ripple really doesn't matter, at least at the levels that voltage multiplier circuits typically produce. The speaker is of balanced construction, so the ripple will cause the diaphragm to be pulled toward each stator, essentially ensuring that the diaphragm doesn't move due to the ripple.
Otherwise the average voltage out of the Izzy-Wizzy mod supply is a little higher, and the difference between the stock supply and izzy-wizzy supply increases as the speaker panel leakage current increases. That means a real leaky panel will show the largest improvement and one that is not leaky may show little or none by making the modification to the power supply. The difference in the output voltage is about 80V for a panel with 500 Mega Ohm leakage. I don't know if 80V is going to make an audible difference or not.
There should be no frequency dependent effects at all, higher voltage just means increased sensitivity (i.e. louder volume) at all frequencies.
I should note that the added capacitor in the bias supply makes servicing of the supply quite a bit more hazardous than the stock supply. If you do the mod, be careful- that extra cap storing the full output voltage (about 5200 V) will pack a real wallop. The fact that it has no bleeder resistor increases the hazard because charge on that cap may persist for weeks after turning the power off. Be careful!
I_F
I ran some simulations of the stock bias supply and the "izzy-wizzy" mod version. The Izzy-wizzy modification reduces ripple by about 20 dBV and somewhat increases the average DC output of the supply. 20 dBV sounds like a big reduction, but read on...
I put the results in an excel spreadsheet here:
Acoustat bias supply ripple I used excel because screen shots of the simulator output were just too big. I ran the simulation using SwitcherCad III (a free download from Linear Technology). I added the model of the 1N6533 rectifier to the library to run the simulation. The 1N6533 is a 5 kV, 50 mA rectifier that should be similar to the original parts in the Acoustat bias supply. The SwCadIII schematic file is here: Acoustat bias supply simulation file
Here is the spice netlist: Acoustat bias supply net list
The data includes the spectrum of the ripple so you can see what is going on.
With regards to audibility, I'd say a simple experiment is in order- place your ear close to the speaker with no music playing. If you hear buzzing, then the ripple makes a difference. If not, it doesn't. I have never heard any buzzing from any ESL, regardless of the bias supply configuration, so I'm inclined to think that the ripple really doesn't matter, at least at the levels that voltage multiplier circuits typically produce. The speaker is of balanced construction, so the ripple will cause the diaphragm to be pulled toward each stator, essentially ensuring that the diaphragm doesn't move due to the ripple.
Otherwise the average voltage out of the Izzy-Wizzy mod supply is a little higher, and the difference between the stock supply and izzy-wizzy supply increases as the speaker panel leakage current increases. That means a real leaky panel will show the largest improvement and one that is not leaky may show little or none by making the modification to the power supply. The difference in the output voltage is about 80V for a panel with 500 Mega Ohm leakage. I don't know if 80V is going to make an audible difference or not.
There should be no frequency dependent effects at all, higher voltage just means increased sensitivity (i.e. louder volume) at all frequencies.
I should note that the added capacitor in the bias supply makes servicing of the supply quite a bit more hazardous than the stock supply. If you do the mod, be careful- that extra cap storing the full output voltage (about 5200 V) will pack a real wallop. The fact that it has no bleeder resistor increases the hazard because charge on that cap may persist for weeks after turning the power off. Be careful!
I_F
I_F: wow thanks for the detailed explaination, that's a wack of research. Much appreciated, I would have never have learned that on my own! Very interesting and well worth a folder on my hard drive. Do you think I should put a bleeder resistor on that (Izzy Wizzy) cap? If so what is a good value?
This weekend has turned out to be a bust with respect to getting over to my buddies to experiment with the cap mod and your suggestion of decreaseing the load resistor value. I will post back with findings as soon as I gan get over to do the work.
What do the simulations look like with a regulated supply? I would think that there would be a larger difference than that seen with the Izzy Wizzy mod? Thanks again I_F. Best regards Moray James.
This weekend has turned out to be a bust with respect to getting over to my buddies to experiment with the cap mod and your suggestion of decreaseing the load resistor value. I will post back with findings as soon as I gan get over to do the work.
What do the simulations look like with a regulated supply? I would think that there would be a larger difference than that seen with the Izzy Wizzy mod? Thanks again I_F. Best regards Moray James.
moray james said:
A bleeder would have to be a very large resistor (maybe 1000s of Mega Ohms) or it would pull down the voltage of the bias supply and cancel the effect of adding the cap. Such a large resistor would result in a very long time constant, so its value as a bleeder resistor would be questionable.
There's regulated and then there's regulated. A regulated supply will maintain a constant average voltage, but the ripple might still be about the same as a charge pump multiplier, maybe even worse. When you look at the ripple in the stock supply, it's level is about 80-100 dB below the average output level. That's pretty good performance, even for a regulated supply. You can find the numbers in the excel file on the ripple spectra page- look at 0 Hz. That's the main output of the supply at DC (0 Hz). Now subtract the value of the 60 Hz output from that.
A regulator that could improve on that performance would be hard/expensive to make, and would not really add to the performance of the speaker, which is why no one does it.
I_F
One more thing...
Anyone can get this sort of data by learning to use a circuit simulator. I used SwitcherCAD III which is a full-featured spice based simulator that is distributed freely by Linear Technology on their web site.
To use a simulator like this, you enter the schematic diagram- they have a very easy to use GUI, then you specify the type of simulation you want to do (in this case I used a transient simulation), and the start and stop times. Start defaults to 0. In this circuit, the caps take a while to charge up, so I started the simulation at 10 sec. and ended at 10.5 sec. This ensured there would be plenty of data for the fft spectrum derivation, though you really only need one complete cycle.
The voltage source is a sine wave source with the amplitude set to 1061V which is the 750 Vrms output from the transformer x sq root of 2. That gives a 2122Vpp sine wave which is 750 Vrms.
When using a spice-based simulator you must have a DC path to ground from each and every node in the circuit. That means you can't have two capacitors in series without there being a resistor to ground at their junction. In such a case you use a 1 Giga Ohm resistor or other extremely large value which will not affect the performance of the circuit but will satisfy the requirement of there being a DC path to ground.
There are some good books about using spice simulators and you can learn a lot from the help and example files that come with SwCADIII. The book by Tuinenga is a good place to start. It covers proper use, some tricks, and limitations of the simulator.
Of course, a simulation is a simulation and not reality. But a simulator can give you some insight into circuit behavior that might otherwise be very difficult of impossible figure out on your own. Also, a simulation is only as good as the models it uses.
I_F
Anyone can get this sort of data by learning to use a circuit simulator. I used SwitcherCAD III which is a full-featured spice based simulator that is distributed freely by Linear Technology on their web site.
To use a simulator like this, you enter the schematic diagram- they have a very easy to use GUI, then you specify the type of simulation you want to do (in this case I used a transient simulation), and the start and stop times. Start defaults to 0. In this circuit, the caps take a while to charge up, so I started the simulation at 10 sec. and ended at 10.5 sec. This ensured there would be plenty of data for the fft spectrum derivation, though you really only need one complete cycle.
The voltage source is a sine wave source with the amplitude set to 1061V which is the 750 Vrms output from the transformer x sq root of 2. That gives a 2122Vpp sine wave which is 750 Vrms.
When using a spice-based simulator you must have a DC path to ground from each and every node in the circuit. That means you can't have two capacitors in series without there being a resistor to ground at their junction. In such a case you use a 1 Giga Ohm resistor or other extremely large value which will not affect the performance of the circuit but will satisfy the requirement of there being a DC path to ground.
There are some good books about using spice simulators and you can learn a lot from the help and example files that come with SwCADIII. The book by Tuinenga is a good place to start. It covers proper use, some tricks, and limitations of the simulator.
Of course, a simulation is a simulation and not reality. But a simulator can give you some insight into circuit behavior that might otherwise be very difficult of impossible figure out on your own. Also, a simulation is only as good as the models it uses.
I_F
Izzy Wizzy Update
Well I made it back to my buddies Acoustat 0ne plus 0nes. I wanted to undo the Izzy Wizzy cap mod in order to compare it to the effect of a lower value load resistor. For the present my buddie is so happy with the Izzy Wizzy cap mod he would not let me remove it. So I paralleled a second 500 M ohm resistor to the factory 500 ohm load resistor to chop the resistance value in half to 250 M ohms. The result was much the same again as found with the Izzy Wizzy mod. This was a nice improvement in detail resolution and overall control. I think that I_Forgot was right about this from the start. I also think that 10 M ohms is all that is needed for saftey sake as well as to keep the panel operating in constant charge mode. While a lower value load resistor might just result in some small loss in overall output as a result of leaky dielectric in older Acoustat panels I do not think anyone hearing the improvements would not care to trade a little level for the benefits this simple mod will yield. Thanks to I_Forgot for his insite and willingness to share. Best regards Moray James.
Well I made it back to my buddies Acoustat 0ne plus 0nes. I wanted to undo the Izzy Wizzy cap mod in order to compare it to the effect of a lower value load resistor. For the present my buddie is so happy with the Izzy Wizzy cap mod he would not let me remove it. So I paralleled a second 500 M ohm resistor to the factory 500 ohm load resistor to chop the resistance value in half to 250 M ohms. The result was much the same again as found with the Izzy Wizzy mod. This was a nice improvement in detail resolution and overall control. I think that I_Forgot was right about this from the start. I also think that 10 M ohms is all that is needed for saftey sake as well as to keep the panel operating in constant charge mode. While a lower value load resistor might just result in some small loss in overall output as a result of leaky dielectric in older Acoustat panels I do not think anyone hearing the improvements would not care to trade a little level for the benefits this simple mod will yield. Thanks to I_Forgot for his insite and willingness to share. Best regards Moray James.
HI
Thanks I_forgot to share his constatation.
My 2+2 were polarised via a 1gig (1000meg) resistor.
I try 20meg and the result was hurge! If the output drop, I didn`t hear any difference, so if a drop occur, this is not significant.
As for the Izzi Wizzi mods, I already use a "big" film caps (0.15uf) So I can`t comment
The best tweak I done were suggested by one friend of me, when I boosted the bias from 4600V to 6850V. (more than that and the panel will exibit some craking noise at high SPL)
The sound is way better and the sensility goes up too.
Martin
Thanks I_forgot to share his constatation.
My 2+2 were polarised via a 1gig (1000meg) resistor.
I try 20meg and the result was hurge! If the output drop, I didn`t hear any difference, so if a drop occur, this is not significant.
As for the Izzi Wizzi mods, I already use a "big" film caps (0.15uf) So I can`t comment
The best tweak I done were suggested by one friend of me, when I boosted the bias from 4600V to 6850V. (more than that and the panel will exibit some craking noise at high SPL)
The sound is way better and the sensility goes up too.
Martin
Etalon90: thanks for your reply with your experience. Lowering the value of the load resistor results in more volts on the diaphragm. The reason that I talked about the posibility of less output was that if your stator wires are a little leaky then as the diaphragm voltage goes up you will reach a point where peak playback levels will arc sooner than with a lower diaphragm voltage. That said as you have found the improvement is well worth the potential loss of overall output. It does not sound as if you have noticed any loss of output at all.
The Izzy Wizzy mod is an additional 0.01 (6KV) bypass cap on the high voltage supply. This will add about 80 extra volts to the supply output and reduce supply ripple. A nice mod why don't you give it a try? Best regards Moray James.
The Izzy Wizzy mod is an additional 0.01 (6KV) bypass cap on the high voltage supply. This will add about 80 extra volts to the supply output and reduce supply ripple. A nice mod why don't you give it a try? Best regards Moray James.
Snubberized HV Supply Xformer
I got back over to my buddies place tonight . I snubberized the secondary side of the high voltage step up transformer on his Acoustat 0ne plus 0ne's. I used a 10 ohm resistor in series with a .01 uf cap. This turned out to be a very nice little mod. Easy inexpensive and souns great. Give it a try. Best regards Moray James.
I got back over to my buddies place tonight . I snubberized the secondary side of the high voltage step up transformer on his Acoustat 0ne plus 0ne's. I used a 10 ohm resistor in series with a .01 uf cap. This turned out to be a very nice little mod. Easy inexpensive and souns great. Give it a try. Best regards Moray James.
Choke in HV supply
Rob in NZ has shared the mod of inserting a 10 H choke in series with the high voltage supply. Seems Rob has done the Izzy Wizzy mod to his Acoustats and then some. Rob said that the additional cap filtering was a worth while improvement but that the choke was a transformation.
It would seem that it would also be a good idea to replace the stock 500 Meg ohm load resistor with a (home made daisy chain) carbon resistor as this will be totally non inductive as well as haveing no capacitive component. 30 Meg ohms is a safe bet and your diaphragm charge will go up in voltage too. Check the idea out. A wide bandwidth choke with low capacitance is a bonus. Best regards Moray James.
Rob in NZ has shared the mod of inserting a 10 H choke in series with the high voltage supply. Seems Rob has done the Izzy Wizzy mod to his Acoustats and then some. Rob said that the additional cap filtering was a worth while improvement but that the choke was a transformation.
It would seem that it would also be a good idea to replace the stock 500 Meg ohm load resistor with a (home made daisy chain) carbon resistor as this will be totally non inductive as well as haveing no capacitive component. 30 Meg ohms is a safe bet and your diaphragm charge will go up in voltage too. Check the idea out. A wide bandwidth choke with low capacitance is a bonus. Best regards Moray James.
Guys,
A choke operates by storing energy in a magnetic field. It takes current to set up a magnetic field. There is virtually no current from the bias supply to the speaker diaphragm unless the speaker is shorted - in which case you have a problem that requires something other than a choke to fix- so there virtually no energy stored.
If you're concerned about the impedance of the bias supply at audio frequencies, the resistor (maybe 20-50 Megs ohms) is the component that defines it. The reactance of a 10H choke at say, 120 Hz is minuscule compared to the resistor.
If you are hearing changes in the speaker's sound by adding a choke to the bias supply, I think it is because you expect to hear a change.
When you replace the resistor in the bias supply, be sure you get a HV rated resistor. "Normal" resistors (any resistor that doesn't specifically say "high voltage" in the specs) will self destruct when high voltage is applied. It is a slow process that will take weeks, but your speakers will get steadily quieter until they eventually go silent. You will then discover that the resistor has opened up. This happens even though there is almost no current through the resistor. I found this out the hard way. I think the HV allows some chemical reaction to take place that doesn't normally occur, or occurs much more slowly at low voltages.
I believe Caddock makes HV resistors.
I_F
A choke operates by storing energy in a magnetic field. It takes current to set up a magnetic field. There is virtually no current from the bias supply to the speaker diaphragm unless the speaker is shorted - in which case you have a problem that requires something other than a choke to fix- so there virtually no energy stored.
If you're concerned about the impedance of the bias supply at audio frequencies, the resistor (maybe 20-50 Megs ohms) is the component that defines it. The reactance of a 10H choke at say, 120 Hz is minuscule compared to the resistor.
If you are hearing changes in the speaker's sound by adding a choke to the bias supply, I think it is because you expect to hear a change.
When you replace the resistor in the bias supply, be sure you get a HV rated resistor. "Normal" resistors (any resistor that doesn't specifically say "high voltage" in the specs) will self destruct when high voltage is applied. It is a slow process that will take weeks, but your speakers will get steadily quieter until they eventually go silent. You will then discover that the resistor has opened up. This happens even though there is almost no current through the resistor. I found this out the hard way. I think the HV allows some chemical reaction to take place that doesn't normally occur, or occurs much more slowly at low voltages.
I believe Caddock makes HV resistors.
I_F
Choke in HV supply
The choke is in series after the load resistor, between the resistor and the diaphragm. Rob says that bigger is better when it comes to chokes in this application. The suggestion is that the choke helps to damp low lever diaphragm modulation which is caused by energy stored in the stators dielectric. I have a couple of 7 H chokes which I plan to try out in this position. Rob has done a lot of mods to his 0ne plus 0ne's and say this is the real deal. Right or wrong it cannot hurt to give it a try and find out for sure. It will be another week before I can get to my buddies to try this on his speakers. Will post results as soon as I give it a try. Best regards Moray James.
The choke is in series after the load resistor, between the resistor and the diaphragm. Rob says that bigger is better when it comes to chokes in this application. The suggestion is that the choke helps to damp low lever diaphragm modulation which is caused by energy stored in the stators dielectric. I have a couple of 7 H chokes which I plan to try out in this position. Rob has done a lot of mods to his 0ne plus 0ne's and say this is the real deal. Right or wrong it cannot hurt to give it a try and find out for sure. It will be another week before I can get to my buddies to try this on his speakers. Will post results as soon as I give it a try. Best regards Moray James.
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