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# My DIY electrostatic headphones - Page 55

I saved your picture with the uhu por tube a while back but didn't remember it until now ... Have you tried the two other type of glue I mentionned as well ?

I am so very tempted to make a pair of Jacklin Float clone.  What do you guys think?  My guess is that the dimension of the diaphragm is around 12 cm x 10 cm.  Can someone confirm it?

I have some 0.75 mm PCB which I think should be perfect for this.  The bias voltage should be around 1,000V.

To get good bass, I think 3 or 6 microns Mylar should be good.

Wachara C.

Quote:
Originally Posted by bidoux

I saved your picture with the uhu por tube a while back but didn't remember it until now ... Have you tried the two other type of glue I mentionned as well ?

Yes, I've tried so many different types of glue in the past.  I like contact cement the most.

Wachara C.

How is the electrical connection to the diaphragm itself made? I was under the impression that the wire went to the copper on the PCB ring.

w

That's funny you ask, I spent half an hour worrying whether I screwed up my last cell, then I realized the diaphragm wasn't electrically connected to the spacer. So I put a tiny amount of solder on the other stator, the one on which the diaphragme isn't glued on, so this blob of solder insure the electrical connection. But I think there are more elegant ways of doing this ...

I though this new version would improve the sound a lot but I am quite disapointed with it, though it is only a naked cell. It still has this "plastic like" (not sure how to describe it) sound which is not good enough, even my SR30 sound better

Quote:
Originally Posted by wakibaki

How is the electrical connection to the diaphragm itself made? I was under the impression that the wire went to the copper on the PCB ring.

w

Wow, coming this far and I thought you had learned all about how to make electrostatic headphones.

Anyway, the way I do it is that I glue the diaphragm on one of the spacer and use the other spacer as a charge ring.  Remember, I use PCB to make stators and spacers.  So, it's very easy for me to do that.

These pictures hopefully can give you better understanding of my arrangement.

Don't use the conductive glue.  Your glue doesn't need to be conductive.  And it should not be.

Wachara C.

So you apply the antistatic fluid to one side of the diaphragm only? I would have thought you could double the force on the diaphragm if there is twice as much charge distributed on it...

w

Quote:
Originally Posted by wakibaki

So you apply the antistatic fluid to one side of the diaphragm only? I would have thought you could double the force on the diaphragm if there is twice as much charge distributed on it...

w

The equation that rules the way the diaphragm moves only considers the difference in voltage thus it is not necessary to double coat the diaphragm.

Edited by bidoux - 4/16/13 at 1:54pm
Quote:
Originally Posted by bidoux

The equation that rules the way the diaphragm moves only considers the difference in voltage thus it is not necessary to double coat the diaphragm.

No, this is not true. The force is proportional to the charge. See Coulomb's law.

w

Well yes but the parameter that you can easily control and impose to the headphone is not the charge, it is the voltage. You have to see an electrostatic speaker as a capacitor, but since the diaphragm is mobile, the capacity is not constant. Once you have imposed the voltage, you can deduce the force applied to the diaphragm by using the law that links the charge and the voltage in a capacitor :

$C= \frac{q}{v}$

(v is imposed, q is linked to the position of the diaphragm and the geometry of your cell)

Finished up a new pair of headphones this weekend (with the exception of the top band which needs some work).

Since I had some laying around, they are built with the HD600/650 earpads. They are built with 2uM mylar with 0.5mm spacers. I have them biased at 400V since that's what my amplifier puts out, but I'm sure they could go higher its not even close to instability. Open-air resonance is 175hz.

I'll have to do a lot more listening before I do any real comparisons to my SR007 clones, but upon first impression they seem to be more forward in the midrange (might be hearing the 7khz dip that's always been in my other pair that is not present in these). The soundstage is quite a bit wider than the SR007 clones which is good.

Some pictures of construction:

Edited by dude_500 - 4/16/13 at 3:45pm
Quote:
Originally Posted by bidoux

Well yes but the parameter that you can easily control and impose to the headphone is not the charge, it is the voltage. You have to see an electrostatic speaker as a capacitor, but since the diaphragm is mobile, the capacity is not constant. Once you have imposed the voltage, you can deduce the force applied to the diaphragm by using the law that links the charge and the voltage in a capacitor :

$C= \frac{q}{v}$

(v is imposed, q is linked to the position of the diaphragm and the geometry of your cell)

Yes, a capacitor. The capacitance is dependent on the plate area. If you have charge distributed on both sides of the diaphragm instead of one, you effectively double the plate area. For any given voltage the charge will be doubled. This is why the foils in capacitors are rolled up, to take advantage of both sides of the plates.

w

Quote:
Originally Posted by dude_500

Finished up a new pair of headphones this weekend (with the exception of the top band which needs some work).

Since I had some laying around, they are built with the HD600/650 earpads. They are built with 2uM mylar with 0.5mm spacers. I have them biased at 400V since that's what my amplifier puts out, but I'm sure they could go higher its not even close to instability. Open-air resonance is 175hz.

I'll have to do a lot more listening before I do any real comparisons to my SR007 clones, but upon first impression they seem to be more forward in the midrange (might be hearing the 7khz dip that's always been in my other pair that is not present in these). The soundstage is quite a bit wider than the SR007 clones which is good.

Some pictures of construction:

Wow, those look awesome!  What is the size of your diaphragm?  Your holes look big and are very close to each other.  I think you must have a very high open area.  Do you like them better than your previous pair?

Congratulations!

Wachara C.

Quote:
Originally Posted by chinsettawong

Wow, those look awesome!  What is the size of your diaphragm?  Your holes look big and are very close to each other.  I think you must have a very high open area.  Do you like them better than your previous pair?

Congratulations!

Wachara C.

The active area is a 3.225 x 2.2075 oval. The open-area is somewhere around 60%, haven't precisely calculated it. The stators are 1.6mm instead of my typical 1mm in order to keep them plenty rigid.

I don't think I like them better, although not necessarily worse either. I think both will probably remain in my active headphone collection. They are much, much brighter (too much for my taste), but I really love the sound stage which is so far beyond my old pair. I need to experiment with damping foam, as right now they are wide open, which might help a bit to calm the brightness. I'll probably also play with lower tension, since I have a ton of headroom on stability.

Quote:
Originally Posted by dude_500

The active area is a 3.225 x 2.2075 oval. The open-area is somewhere around 60%, haven't precisely calculated it. The stators are 1.6mm instead of my typical 1mm in order to keep them plenty rigid.

I don't think I like them better, although not necessarily worse either. I think both will probably remain in my active headphone collection. They are much, much brighter (too much for my taste), but I really love the sound stage which is so far beyond my old pair. I need to experiment with damping foam, as right now they are wide open, which might help a bit to calm the brightness. I'll probably also play with lower tension, since I have a ton of headroom on stability.

You used to make much larger active diaphragms.  Why do you make them smaller this time?

With the driver of this size, you won't get much bass and the sound would certainly be brighter - due to less capacitance.

How muh weight have you put on this time?  If I were you I would increase the bias voltage instead of lowering the tension.

This was how much weight I used with my 3 microns Mylar with active diaphragm size of 78mm x 118mm.  The spacer thickness was 0.5 mm and 580V bias voltage.  The tension was only barely enough.  If I were to to it again, I would use use a few more water bottles or increase the weight of each bottle to around 1 kg (1000 ML).

Wachara C.

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