Thanks Philippe and Wachara...
First I must admit that all of my efforts so far have been in completing the energizer, so I still have the headphones left to address. Wachara, I think with the parts you sent me the headphones will not be difficult and I have the film and graphite waiting to complete them. I would like to find some decent cable for the headphones but I really haven't been looking yet so I am sure I will find something.
Philippe, I think I see what you mean. These resistor values have been intentionally left blank so that the appropriate value may be inserted when the actual voltage is measured to ensure that the two voltage rails are at +300V and -300V and not something just "close". Thank you for the link with the Stax connection.
I do have one more question that came up when I looked at the Stax connection. On the Pro bias Stax phones the bias for both diaphragms is shared on a single pin. Would this be any problem with the bias supply shown in this schematic? Would the two 10M resistors which are connecting the bias supply to the stators need to change? I assume I would just have four 10M resistors connecting this part of the bias supply to each of the four stators?
I apologize for all of the questions but the truth is I am an artist, not an electrical engineer. I am able to craft something fairly carefully but some of the underlying reasons for doing so escape me.
Thanks,
Matt
First I must admit that all of my efforts so far have been in completing the energizer, so I still have the headphones left to address. Wachara, I think with the parts you sent me the headphones will not be difficult and I have the film and graphite waiting to complete them. I would like to find some decent cable for the headphones but I really haven't been looking yet so I am sure I will find something.
Philippe, I think I see what you mean. These resistor values have been intentionally left blank so that the appropriate value may be inserted when the actual voltage is measured to ensure that the two voltage rails are at +300V and -300V and not something just "close". Thank you for the link with the Stax connection.
I do have one more question that came up when I looked at the Stax connection. On the Pro bias Stax phones the bias for both diaphragms is shared on a single pin. Would this be any problem with the bias supply shown in this schematic? Would the two 10M resistors which are connecting the bias supply to the stators need to change? I assume I would just have four 10M resistors connecting this part of the bias supply to each of the four stators?
I apologize for all of the questions but the truth is I am an artist, not an electrical engineer. I am able to craft something fairly carefully but some of the underlying reasons for doing so escape me.
Thanks,
Matt
Hi Matt,
The single pin for biasing the diaphragms on both side is OK. You can connect it exactly like the diagram. There is no need to change the 20Mohm resisters. However, the number of electrical wires needed for the 2 sides still need to be 6 - 3 for each side. You put the bias voltage to the diaphragms, not the stators. If you want to, you can make higher bias voltage which will give you louder sound. I have tried 1200V and it worked fine.
Please post more pictures for us to see.
Wachara C.
The single pin for biasing the diaphragms on both side is OK. You can connect it exactly like the diagram. There is no need to change the 20Mohm resisters. However, the number of electrical wires needed for the 2 sides still need to be 6 - 3 for each side. You put the bias voltage to the diaphragms, not the stators. If you want to, you can make higher bias voltage which will give you louder sound. I have tried 1200V and it worked fine.
Please post more pictures for us to see.
Wachara C.
Hi Matt,
About the graphite powder coating, you can try it first. If the result isn't very good for you, you can try my glue formula. It works wonderfully.
http://www.diyaudio.com/forums/showthread.php?postid=1837517#post1837517
Wachara C.
About the graphite powder coating, you can try it first. If the result isn't very good for you, you can try my glue formula. It works wonderfully.
http://www.diyaudio.com/forums/showthread.php?postid=1837517#post1837517
Wachara C.
Hi Matt,
The single pin for biasing the diaphragms on both side is OK. You can connect it exactly like the diagram. There is no need to change the 20Mohm resisters. However, the number of electrical wires needed for the 2 sides still need to be 6 - 3 for each side. You put the bias voltage to the diaphragms, not the stators. If you want to, you can make higher bias voltage which will give you louder sound. I have tried 1200V and it worked fine.
Please post more pictures for us to see.
Wachara C.
Thanks Wachara, I think I understand...
The actual headphone cable still needs 3 conductors per side; 1 for + stator, 1 for - stator and 1 for the diaphragm(bias). From the point on the bias supply where it says +Vbias I need a single 20M resistor going to the bias pin on the jack (right?
), which will feed the + bias to each of the diaphragms. I still don't understand about the -Vbias side though, where it leads to two 10M resistors which appear to be tied to the same connections as the + and - stator connections. Is this correct? It would appear that I would have a 10M resistor (4 total) for each sides stators(+ and -) leading from the -Vbias point on the bias supply.Thanks for your help!
Matt
PS. I should be getting my computer back in a couple of days and I can post pictures then. Right now I am using my daughter's old computer and it is extremely slow
Hi Matt,
The audio signal (AC Voltage) will need to be limited with 10Mohm resister before attaching to the negative side of bias supply as per the diagram. In total I use 6 of 10Mohm resisters. 2x10Mohms are used on the positive bias supply that is attached to two diaphragms. 1x10Mohm is attached to the wire going to each one of the stator and also the negative side of the bias supply. Since there are 4 stators, 4 of 10Mohm resisters are needed here.
I hope you can understand what I try to explain.
Wachara C.
The audio signal (AC Voltage) will need to be limited with 10Mohm resister before attaching to the negative side of bias supply as per the diagram. In total I use 6 of 10Mohm resisters. 2x10Mohms are used on the positive bias supply that is attached to two diaphragms. 1x10Mohm is attached to the wire going to each one of the stator and also the negative side of the bias supply. Since there are 4 stators, 4 of 10Mohm resisters are needed here.
I hope you can understand what I try to explain.
Wachara C.
Hi Matt,
I don't bother to think about this issue. Since it is working by push and pull, I doubt if you can hear the differences.
About the cable, I read from somewhere that they should not be twisted wires. Because if they are, they will increase the capacitance of the headphones. That's why I use paired wires.
Wachara C.
I ordered the final parts for my energizer and have started preparing the parts of the headphone. Wachara, according to an earlier post (in another thread) you stated you used the white plastic spacer to adhere a film to to protect the diaphragm from sweat. Do you also put another film on the outside stator to prevent dust from becoming attracted to the diaphragm as Philippe did? If so, does this adhere directly to the plastic side of the outside stator?
Also, what gauge of ribbon cable are you using. I am having a little difficulty finding any in small quanitities that looks like it would withstand the voltages present.
thanks!
Also, what gauge of ribbon cable are you using. I am having a little difficulty finding any in small quanitities that looks like it would withstand the voltages present.
thanks!
Hi Matt,
Yes, I did put a plastic film on the outer side as well for dust protection. I think you can just glue film on the 3 mm cover that I sent you. Putting these two films on will change the sound a little bit. You might want to try to listen with and without the film to see how you like it. I am thinking that the outside film might not be needed if your listening room isn't all that dusty.
The ribbon wire that I used is rated at only 400V. Since I couldn't find anything better, I used it anyway. And so far so good.
Wachara C.
This stuff looks like it wold work even better than the drilled PCBs - the holes are roughly the same size, but spaced closer together and the material is thinner.
http://www.mcmaster.com/#9255t431/=3mr8oc
http://www.mcmaster.com/#9255t431/=3mr8oc
Hi Spasticteapot,
I'm sure that there are many other materials that are okay to be used for making headphones. However, what you need to be careful most is the electrical insulation. The reason why I choose to use a PCB as the material is that I do not need to insulate the fiberglass side. Since this is the side that will come into contact with my ears, I want to make sure that no electrical charge can ever make it's way to here.
Wachara C.
One more consideration: Bear in mind that while "thinner" has some advantages, you must also take into account the difficulty associated with keeping the stator truly flat. Some materials are very ease to dent, kink, or bend, and very hard to straighten out again. When the stator-to-diaphragm spacing is small (as in a headphone) small deviations from perfect flatness are even more important. PCBs aren't likely to get kinked out of shape unless they're really abused. Thin wires or thin sheets of perforated aluminum, for example, can be a real pain to keep dead flat. Maybe it's less of an issue with a stator of the size needed for headphones, but I found thin malleable material to be a pain when used in larger ESLs when I was also working with small stator-to-diaphragm spacing.
Few
Hey Wachara, I have a few pictures for you...
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[URL=http://img223.imageshack.us/i/img0681z.jpg/]
I have completed the energizer, but I haven't actually turned it on yet! I noticed one slight possible discrepancy in my build. I used two sets of the 75K and 10K resistors(a set for each channel) whereas I think you had them shared between the both channels. I don't know if this is going to cause a problem or not. Also, I am dissatisfied with the ribbon cable I have. I ordered some 28awg 9 conductor cable that I planned on stripping 3 conductors from to get the appropriate 6 conductors. Unfortunately I thought it was stranded, but it is solid core and I think this insulator may not withstand the voltage. The last thing I am concerned about it my graphite coating. I followed your recipe for the PVA glue mixture but when I look at it it doesn't look sufficient. I took a picture of the diaphragms against an image so you could see their opacity. I built a crude version of Philippe's tensioning mechanism which seemed to work fine. I did learn a valuable lesson after the third attempt to stretch a diaphragm. Cut the mylar with a soldering iron!! This apparently gives it a "beaded" edge which us much more resistant to tearing.
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I have completed the energizer, but I haven't actually turned it on yet! I noticed one slight possible discrepancy in my build. I used two sets of the 75K and 10K resistors(a set for each channel) whereas I think you had them shared between the both channels. I don't know if this is going to cause a problem or not. Also, I am dissatisfied with the ribbon cable I have. I ordered some 28awg 9 conductor cable that I planned on stripping 3 conductors from to get the appropriate 6 conductors. Unfortunately I thought it was stranded, but it is solid core and I think this insulator may not withstand the voltage. The last thing I am concerned about it my graphite coating. I followed your recipe for the PVA glue mixture but when I look at it it doesn't look sufficient. I took a picture of the diaphragms against an image so you could see their opacity. I built a crude version of Philippe's tensioning mechanism which seemed to work fine. I did learn a valuable lesson after the third attempt to stretch a diaphragm. Cut the mylar with a soldering iron!! This apparently gives it a "beaded" edge which us much more resistant to tearing.
Hi Matt,
The diaphragm coating is meant to be coated very, very lightly but evenly. So just only a little of the solution is required. After coating, the diaphragm should look only slightly change in color. Yours looks just fine.
About the energizer, you should just try it. I'm sure it's okay too.
I think the pictures you posted here are too large and we can't magnify them. Can you give me a link? I really like to see bigger pictures.
Wachara C.
The diaphragm coating is meant to be coated very, very lightly but evenly. So just only a little of the solution is required. After coating, the diaphragm should look only slightly change in color. Yours looks just fine.
About the energizer, you should just try it. I'm sure it's okay too.
I think the pictures you posted here are too large and we can't magnify them. Can you give me a link? I really like to see bigger pictures.
Wachara C.
Thanks Wachara, unfortunately something is going on with my energizer that I need to sort out. My filaments aren't lighting up and I am only measuring -51v on the negative side of the supply. The other side is measuring a little high at 319v. I need to revisit the schematic and compare it against what I have built. I wonder if it is happening where the diode and the negative half of the supply connects to pin 9 on the 12AX7. Oh well, I will get back to you when I have it working(I hate troubleshooting!).
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