Hi JonasKarud,
Yes, I had a chance to try the sound from a more conductive diaphragm. I coated the diaphragm with graphite spray. After rubbing the surface, I measure the resistance and I got just a few hundred ohms (can't remember it exactly). I tried it on and play some music. The sound was very distorted.
I also find out that it takes a longer time for a less conductive diaphragm to charge up. It might takes from a few minutes to about an hour before the loudness is stable. If the conductive material is too little, the loudness would never be loud enough. If you can measure the resistivity, I would say that the resistivity in the range of a few hundreds of M ohm to a few G ohm should be the target.
Wachara C.
Yes, I had a chance to try the sound from a more conductive diaphragm. I coated the diaphragm with graphite spray. After rubbing the surface, I measure the resistance and I got just a few hundred ohms (can't remember it exactly). I tried it on and play some music. The sound was very distorted.
I also find out that it takes a longer time for a less conductive diaphragm to charge up. It might takes from a few minutes to about an hour before the loudness is stable. If the conductive material is too little, the loudness would never be loud enough. If you can measure the resistivity, I would say that the resistivity in the range of a few hundreds of M ohm to a few G ohm should be the target.
Wachara C.
Hi Wachara
I'm hoping you are still checking on this thread...
I've finally put some time into rebuilding my energizer and will post some photos soon. I'm hoping you can post your schematic again so I can check to make sure I have the power supply wiring correct. It seems to have disappeared at the beginning of the thread.
I rebuilt the amp section of my energizer and found some tubes (12AX7's and 12AT7's) in my drawer to try it out. It made music for about 30 seconds but the transformer started humming and heating up so I shut it down. I guess it is possible I had a bad tube in there but I want to check the power supply wiring to be sure. Also, I have everything star ground right now, including the ground for the power cord. Should the ground for the circuit be isolated somehow?
I'm hoping you are still checking on this thread...
I've finally put some time into rebuilding my energizer and will post some photos soon. I'm hoping you can post your schematic again so I can check to make sure I have the power supply wiring correct. It seems to have disappeared at the beginning of the thread.
I rebuilt the amp section of my energizer and found some tubes (12AX7's and 12AT7's) in my drawer to try it out. It made music for about 30 seconds but the transformer started humming and heating up so I shut it down. I guess it is possible I had a bad tube in there but I want to check the power supply wiring to be sure. Also, I have everything star ground right now, including the ground for the power cord. Should the ground for the circuit be isolated somehow?
Hi Wachara,
I do have one question about grounding in this amp...
I see the input jack is shown with a traditional ground symbol. Should the other ground points also be taken to the same ground and grounded to the chassis/earth? Like the transformer center tap etc?
I think my transformer is fried
I'm not sure exactly why but apparently there is an excessive current draw somewhere. As I said I had it playing for about 30 seconds when the transformer sizzled and smoked. I quickly shut it off but the damage was done. I now get no reading on the HT secondary and the 6.3V tap is low.
In the power supply the power resistors on the two rails are not marked, should they be a particular value or are they selected to drop the voltage to 300v?
I am about to order another transformer but I am hesitant to try again without being certain. My wiring is all in order as far as I can tell but it is possible I had a bad tube that took out the transformer.
I'm not sure exactly why but apparently there is an excessive current draw somewhere. As I said I had it playing for about 30 seconds when the transformer sizzled and smoked. I quickly shut it off but the damage was done. I now get no reading on the HT secondary and the 6.3V tap is low.
In the power supply the power resistors on the two rails are not marked, should they be a particular value or are they selected to drop the voltage to 300v?
I am about to order another transformer but I am hesitant to try again without being certain. My wiring is all in order as far as I can tell but it is possible I had a bad tube that took out the transformer.
Hi Vaughn,
I'm sorry to hear that the transformer is fried.
The resisters on the two rails that are not mark are for dropping the voltage to 300V.
The current requirement for the amp is quite small. I use a transformer with 100mA HT secondary, and it's very stable. If you have any doubt, please refer to The Tube CAD Journal, Electrostatic Headphones . That is where I got the schematic diagram from. Oh, please check also that you do not ground the negative supply of the diaphragm bias circuit. If you do, that might cause a short circuit.
Wachara C.
I'm sorry to hear that the transformer is fried.
The resisters on the two rails that are not mark are for dropping the voltage to 300V.
The current requirement for the amp is quite small. I use a transformer with 100mA HT secondary, and it's very stable. If you have any doubt, please refer to The Tube CAD Journal, Electrostatic Headphones . That is where I got the schematic diagram from. Oh, please check also that you do not ground the negative supply of the diaphragm bias circuit. If you do, that might cause a short circuit.
Wachara C.
I've ordered a new transformer and will try to find the source of the problem while I wait for it to arrive. Here is a picture of the underside of the chassis, if there is anything glaringly wrong please let me know. I don't have the negative side of the bias supply grounded so I don't think that is a problem. It is quite possible that I grabbed a tube with a dead short out of my tube drawer to test this. Although I'm not sure how it would have played for the 30 seconds that it did if that had been the case...
http://img13.imageshack.us/img13/2241/img1364a.jpg
http://img13.imageshack.us/img13/2241/img1364a.jpg
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I rewired the audio section of the amp to make it more compact/cleaner. It wasn't working at all when I put it away last but I discovered during the rewiring that I did that there were a couple of cold solder joints that may have been causing problems.
When I went to try it out this time (after reworking it) I inserted a 3 amp fuse into the fuse block as it was all I had on hand. This was an expensive mistake and the amp ended up using the transformer as a fuse
I've got fresh tubes and a transformer on the way so I will give it another try when they arrive (with the appropriate fuse).
When I went to try it out this time (after reworking it) I inserted a 3 amp fuse into the fuse block as it was all I had on hand. This was an expensive mistake and the amp ended up using the transformer as a fuse
I've got fresh tubes and a transformer on the way so I will give it another try when they arrive (with the appropriate fuse).
No, but it is close... about 1 mm away. I'll trim back the lead just to make sure.
It is up and running!
I looked back and was surprised that it has almost been a year since I began this project.
I received my new transformer and tubes and switched them out and the amp and headphones have been working flawlessly. I must have grabbed a shorted tube out of my tube drawer and had the wrong value of fuse when I tested last. An expensive mistake I hope to never repeat.
Of course now that I have successfully completed one set I want to build another! Maybe a slightly different energizer, or perhaps a set of headphones with the wire stators like Philippe made. Hmmmmm...
As they are they sound very good. The bass is little loose on some electronic tracks but I could probably stretch the diaphragms with a heat gun. Overall I am very happy and would like to thank Wachara for his generosity in supplying me with the stators and housings for the headphones
I looked back and was surprised that it has almost been a year since I began this project.
I received my new transformer and tubes and switched them out and the amp and headphones have been working flawlessly. I must have grabbed a shorted tube out of my tube drawer and had the wrong value of fuse when I tested last. An expensive mistake I hope to never repeat.
Of course now that I have successfully completed one set I want to build another! Maybe a slightly different energizer, or perhaps a set of headphones with the wire stators like Philippe made. Hmmmmm...
As they are they sound very good. The bass is little loose on some electronic tracks but I could probably stretch the diaphragms with a heat gun. Overall I am very happy and would like to thank Wachara for his generosity in supplying me with the stators and housings for the headphones
Hi Vaughn,
I'm very happy to hear that everything works for you. I hope you enjoy the headphones as much as I do. I listen to mine almost everyday, and they sound better after a while. I would suggest that you keep your headphones charge at all time. Otherwise you might have to wait for a while before the sound actually sounds right.
Please show us some pictures.
I'm building another amplifier based on the design from The eXStatA Electrostatic Amplifier . Many people at Head-Fi.org - Headphone forums and reviews for audiophiles give a very good response on it.
Wachara C.
P.S. You might want to try different diaphragm thicknesses. I've tried 11, 6, 3, 1.4, and 0.9 micron film. So far I like 3 microns film the most. I actually feel that I'm having too much bass.
I'm very happy to hear that everything works for you. I hope you enjoy the headphones as much as I do. I listen to mine almost everyday, and they sound better after a while. I would suggest that you keep your headphones charge at all time. Otherwise you might have to wait for a while before the sound actually sounds right.
Please show us some pictures.
I'm building another amplifier based on the design from The eXStatA Electrostatic Amplifier . Many people at Head-Fi.org - Headphone forums and reviews for audiophiles give a very good response on it.
Wachara C.
P.S. You might want to try different diaphragm thicknesses. I've tried 11, 6, 3, 1.4, and 0.9 micron film. So far I like 3 microns film the most. I actually feel that I'm having too much bass.
Hi Vaughn,
I'm very happy to hear that everything works for you. I hope you enjoy the headphones as much as I do. I listen to mine almost everyday, and they sound better after a while. I would suggest that you keep your headphones charge at all time. Otherwise you might have to wait for a while before the sound actually sounds right.
Please show us some pictures.
I'm building another amplifier based on the design from The eXStatA Electrostatic Amplifier . Many people at Head-Fi.org - Headphone forums and reviews for audiophiles give a very good response on it.
Wachara C.
P.S. You might want to try different diaphragm thicknesses. I've tried 11, 6, 3, 1.4, and 0.9 micron film. So far I like 3 microns film the most. I actually feel that I'm having too much bass.
Hi Wachara,
That amp looks very interesting, unfortunately it looks like I just missed out on the group buy for the boards. I'd love to see how your amp goes! You are doing the solid state one right?
I will try different thicknesses of diaphragm, but not immediately. It has taken so long to get these going I just want to enjoy them for a while
I listened to a few CD's last night and stayed up too late enjoying the sound!Here are a couple of different pictures, I would still like to refine the look of the headphones. I wish I could find a supplier of the ribbon cable used on Stax headphones.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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