Hi Arend-Jan,
Thanks for your explanation of the surface resistance. However, I do not understand how the low resistance can cause higher distortion.
If you look at the ESL like it is a capacitor, the lower the resistance would equal to the faster the charging time for the capacitor. Wouldn't that make the ESL's bias voltage more stable?
It's just my thought.
Wachara C.
Thanks for your explanation of the surface resistance. However, I do not understand how the low resistance can cause higher distortion.
If you look at the ESL like it is a capacitor, the lower the resistance would equal to the faster the charging time for the capacitor. Wouldn't that make the ESL's bias voltage more stable?
It's just my thought.
Wachara C.
Hi Wachara,
with a high conductive diaphragm the voltage remains constant (because of the power supply), but as a result the charge must vary as the capacitance formed by the diaphragm - stator changes with diaphragm position!
V = voltage
Q = charge
C = capacitance
Let's assume constant voltage operation:
Q = C*V => Q / C = V = constant, so Q must change if C changes. The power supply must supply (and discharge) charge to and from the diaphragm to hold the voltage constant.
Now with a high resistance diaphragm the charge can't move, so Q = constant (and V changes with C, but the power supply does not notice this because the resistance is so high).
So why does this matter?
Let's look at the force on the diaphragm. Simply put we can use F = q * E. So we can see that F is linear with E if q is constant. Hence we must keep the charge constant to get a linear motor.
I hope this clears things up.
P.S. Again I have been simplifying things to make them understandable. But the reasoning remains valid.
with a high conductive diaphragm the voltage remains constant (because of the power supply), but as a result the charge must vary as the capacitance formed by the diaphragm - stator changes with diaphragm position!
V = voltage
Q = charge
C = capacitance
Let's assume constant voltage operation:
Q = C*V => Q / C = V = constant, so Q must change if C changes. The power supply must supply (and discharge) charge to and from the diaphragm to hold the voltage constant.
Now with a high resistance diaphragm the charge can't move, so Q = constant (and V changes with C, but the power supply does not notice this because the resistance is so high).
So why does this matter?
Let's look at the force on the diaphragm. Simply put we can use F = q * E. So we can see that F is linear with E if q is constant. Hence we must keep the charge constant to get a linear motor.
I hope this clears things up.
P.S. Again I have been simplifying things to make them understandable. But the reasoning remains valid.
Hi Arend-Jan,
Thanks so much for your explanation. I will need to read a few times and try to digest it a few days to really understand it.
Anyway, to summarize, high surface resistance is good. A good range should be between 10E9 to 10E12 ohms.
Given so high resistance, I figure that a normal multimeter will not be able to measure it. Do you have an easy way to measure the resistance? Does it matter so much if the surface resistances are not the same on 2 panels?
Wachara C.
Thanks so much for your explanation. I will need to read a few times and try to digest it a few days to really understand it.
Anyway, to summarize, high surface resistance is good. A good range should be between 10E9 to 10E12 ohms.
Given so high resistance, I figure that a normal multimeter will not be able to measure it. Do you have an easy way to measure the resistance? Does it matter so much if the surface resistances are not the same on 2 panels?
Wachara C.
Hi Wachara,
if you can get the S/R around 1E7 or up this is fine. ( I see that I wrote 10E.. in my previous post but I meant to write 1E.. )
There are meters for high resistance also called insulation meters. A well known brand is Megger. Such a device can measure resistance up to 1E11 at high voltages like 500, 1000, 5000 Volts.
I'm not sure if it really matters if S/R is not the same on two panels (within limits of course), but I would try to get them as close as possible. With a good coating this should not be a problem.
@coloradosound
If you don't hear any mechanical noises from air going trough the pinhole (e.g. farting) then I would leave it well enough alone. No problem with a small pinhole that I can see.
if you can get the S/R around 1E7 or up this is fine. ( I see that I wrote 10E.. in my previous post but I meant to write 1E.. )
There are meters for high resistance also called insulation meters. A well known brand is Megger. Such a device can measure resistance up to 1E11 at high voltages like 500, 1000, 5000 Volts.
I'm not sure if it really matters if S/R is not the same on two panels (within limits of course), but I would try to get them as close as possible. With a good coating this should not be a problem.
@coloradosound
If you don't hear any mechanical noises from air going trough the pinhole (e.g. farting) then I would leave it well enough alone. No problem with a small pinhole that I can see.
I have good news for everybody. I've found a self doable coating material which is very easy to apply on the diaphragm and it gives very high surface resistance in the range of around 1E12. The test result is from a high voltage insulation tester using 5000V.
What you need are:
1. PVA glue.
2. Water.
3. Graphite powder.
You add the mixture of 1 unit of PVA glue with 2 units of water and 1/10 unit of graphite powder. Take your time to stir the mixture well. It will become dark grey in color. Using a soft sponge, apply the material on the diaphragm. Only very light coating is needed. Once it's dry, it's good to go.
The only thing I don't know yet is its stability over a period of time. So far I have only use it for 3 days. But so far so good. Let's see.
Wachara C.
What you need are:
1. PVA glue.
2. Water.
3. Graphite powder.
You add the mixture of 1 unit of PVA glue with 2 units of water and 1/10 unit of graphite powder. Take your time to stir the mixture well. It will become dark grey in color. Using a soft sponge, apply the material on the diaphragm. Only very light coating is needed. Once it's dry, it's good to go.
The only thing I don't know yet is its stability over a period of time. So far I have only use it for 3 days. But so far so good. Let's see.
Wachara C.
chinsettawong said:Hi Philippe,
Nice work. It is just beautiful.
I wonder how you make the wires to stay that way.
Do you think if I use my CNC to machine a PCB similar to your pattern, will it be good?
Thanks for sharing.
Wachara C.
Hi Wachara,
Having a CNC to machine PCB is a good opportunity. Manual work of spacers, drilling electrodes, is tedious.
Philippe
Re: Piano wires
Hi,
Steel wires are called "piano wires" ("corde à piano" in french) :
http://en.wikipedia.org/wiki/Piano_wire
http://www.picomodele.fr/cordes-a-piano/C141.html
These electrodes are made with ø 1.5 mm steel wires.
Philippe
Audiofanatic said:Hi,
Maybe It should be "Like" piano wires instead of with piano wires!
Cause this looks like a flat metal plate that has been perforated with slots instead of holes.
Just my
Best regards,
Audiofanatic
Hi,
Steel wires are called "piano wires" ("corde à piano" in french) :
http://en.wikipedia.org/wiki/Piano_wire
http://www.picomodele.fr/cordes-a-piano/C141.html
These electrodes are made with ø 1.5 mm steel wires.
Philippe
How would you like to be convinced? All of my friends who have listen to my DIY version want one from me.
We had a meeting a few days ago, and we had a Koss and a Lafayette to compare with our 3 DIY versions with different Mylar thicknesses. All of our DIY versions sounded much better than the 2 brand name ones. Well, it's just our opinions of course.
For me the fun of DIY is not to make the best, but to be able to try what we want to and see if they work.
Wachara C.
We had a meeting a few days ago, and we had a Koss and a Lafayette to compare with our 3 DIY versions with different Mylar thicknesses. All of our DIY versions sounded much better than the 2 brand name ones. Well, it's just our opinions of course.
For me the fun of DIY is not to make the best, but to be able to try what we want to and see if they work.
Wachara C.
Ahh my old Koss, sounded like hell calling with my first kit on the front end (dynaco pat-4). Thanks for sharingI love that picture Wachara, I wish I could have been at that meeting!
I am undertaking my own electrostatic setup and will post pictures as I go. I have owned quite
a few nice dynamic headphones(Grado RS-1, Sennheiser HD-650, AKG K340(hybrid), Denon AH-D2000, etc) but my favorite headphones (earspeakers according to Stax) so far have been the older electrostatic Stax Lambda Signatures(better than SR-404). I am looking forward to building this and wish I still had the Stax to compare it to. You really can't beat an electrostatic for beautiful transparency and they have the capability of delivering excellent bass(think of all that surface area!).
Wachara, maybe you could start a new thread on the electrostatic panel you are building once
you have it to a point that you feel comfortable sharing it with others? I am thinking about the
possibility of building a hybrid speaker with MJK's 18" open baffle Goldwood woofer for bass and an electrostatic panel on top. I don't know if these would have good synergy but half the fun is finding out!
I am undertaking my own electrostatic setup and will post pictures as I go. I have owned quite
a few nice dynamic headphones(Grado RS-1, Sennheiser HD-650, AKG K340(hybrid), Denon AH-D2000, etc) but my favorite headphones (earspeakers according to Stax) so far have been the older electrostatic Stax Lambda Signatures(better than SR-404). I am looking forward to building this and wish I still had the Stax to compare it to. You really can't beat an electrostatic for beautiful transparency and they have the capability of delivering excellent bass(think of all that surface area!).
Wachara, maybe you could start a new thread on the electrostatic panel you are building once
you have it to a point that you feel comfortable sharing it with others? I am thinking about the
possibility of building a hybrid speaker with MJK's 18" open baffle Goldwood woofer for bass and an electrostatic panel on top. I don't know if these would have good synergy but half the fun is finding out!
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