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My DIY electrostatic headphones - Page 48

post #706 of 1528

If stator rigidity is one of the major issues than you could try electroplating a different substrate. The imidiate material that springs to mind is corundum - it's very hard, very rigid, inert and non conductive. I have no idea where you would get it, or how you would machine it, but the rigidity means that you could get thinner stators that flex much less. I imagine that there are other materials out there with similar properties, so you could look at different materials to machine and electroplate. It seems to me that the standard PCB substrate might be one of the major things holding back these designs.

post #707 of 1528
Quote:
Originally Posted by n3rdling View Post

 

Silver is only like 6% more conductive than copper IIRC.  I don't think it'd be worth the cost difference.

????

 

Silver plating is only like 20 dollars more? Plus it is 9% more conductive. 

 

For other projects that need silver plating, I will go down to a independent jewelry store and see if they have scrap silver. Pawn shops work well too. I get like 15 bucks worth of silver. You could also spend a bit more and get silver wire. Make a coil to place your copper drivers in and you are good to go. 

 

Then silver nitrate is pretty easy to find online. You can get a bottle of the stuff for about 45 bucks, but the container is so big that you are pretty much set for life.  

 

 

On a separate note, I do not have access to a CNC machine. I have read that people have been having success with drill presses, but what about a plain old dremel tool with a 1mm drill bit and a lot of luck. Any chance that would work? 

post #708 of 1528
Quote:
Originally Posted by Tjj226 Angel View Post
Plus it is 9% more conductive.

 

5.7% more conductive, if the conductivity figures from Wikipedia are accurate.

EDIT: or 8.6% if you're comparing to IACS. I think the first is more accurate compared to the copper used in these headphones.


Edited by Salm0n - 12/30/12 at 5:07pm
post #709 of 1528
Quote:
Originally Posted by Salm0n View Post

 

5.7% more conductive, if the conductivity figures from Wikipedia are accurate.

EDIT: or 8.6% if you're comparing to IACS. I think the first is more accurate compared to the copper used in these headphones.

Yeah, my chem teacher I guess wrote down the figures wrong on the board. I went back to look for other metals and I saw that chart. 

post #710 of 1528
Quote:
Originally Posted by Salm0n View Post

If stator rigidity is one of the major issues than you could try electroplating a different substrate. The imidiate material that springs to mind is corundum - it's very hard, very rigid, inert and non conductive. I have no idea where you would get it, or how you would machine it, but the rigidity means that you could get thinner stators that flex much less. I imagine that there are other materials out there with similar properties, so you could look at different materials to machine and electroplate. It seems to me that the standard PCB substrate might be one of the major things holding back these designs.

 

The SR-009 is made of 3 layers that are "fused" together under high temperature and pressure. The main perforated surface is thin but it is stiffened by ribs that are significantly thicker. It's interesting to note though that you then get less viscous damping from the perforations so this can cause an issue with too little damping from the diaphragm (thin air layer damping is critical in this application because mylar resonances in the mid/highs are not particularly pleasant to hear I believe ;).

post #711 of 1528

@chinsettwong: I noticed your friends attempt at electrostatic headphones. They look cheap and right up my alley. Obviously they work, and they don't sound bad, but in your opinion, how well do they work/sound. Is it worth the effort to make a cheap test pair? Or should I just go for the gold and build a full scale electrostatic headphone. 

post #712 of 1528
PCB's are usually made with glass-reinforced epoxy laminate sheets, also known as FR-4, which seems to have reasonable strength. Wachara or Spritzer can confirm that, but I think one of them once posted that SR-007 stator is also an etched PCB.
 
Although we can find non-metallic materials with better strength (glass, diamond, graphene...), it seems to me that they are still not very suitable when we want to mass produce an electrostatic stator. 
 
Pure metal (titanium) or metal alloys (for instance maraging steel, CO-CR etc) vary in strength and production process. I for one would love to know which metal alloy is used in the SR-009 stator. The metal alloy Stax uses might be suitable for mass production, but unless someone show up with a "poor man" process, they are not very suitable for DIY.
 
For that purpose (DIY), FR-4 PCB's seem to be the most convenient material available (which does not mean the best material available…).

Edited by jgazal - 12/30/12 at 8:40pm
post #713 of 1528
Quote:
Originally Posted by arnaud View Post

 

The SR-009 is made of 3 layers that are "fused" together under high temperature and pressure. The main perforated surface is thin but it is stiffened by ribs that are significantly thicker. It's interesting to note though that you then get less viscous damping from the perforations so this can cause an issue with too little damping from the diaphragm (thin air layer damping is critical in this application because mylar resonances in the mid/highs are not particularly pleasant to hear I believe ;).

 

I'm slightly confused by this reply. Do you mean that a thinner perforated surface provides less 'resistance' (not sure what the correct term would be) to the flow of air, thus reducing acoustic damping on the diaphragm, leading to an underdamped diaphragm with harsh high frequency resonance? That's what I think you're saying, correct me if I'm wrong.

Given that the SR-009 uses (at least this is what I took from your comment, once again correct me if I'm wrong) standard PCBs that are fused, the use of a material such as corundum may be senseless overkill. However, I still think that for small scale production, where quality over all else is most important, that using different materials would at least be worth some experimentation.

 

 

Quote:
Originally Posted by jgazal View Post

PCB's are usually made with glass-reinforced epoxy laminate sheets, also known as FR-4, which seems to have reasonable strength. Wachara or Spritzer can confirm that, but I think one of them once posted that SR-007 stator is also an etched PCB.
 
Although we can find non-metallic materials with better strength (glass, diamond, graphene...), it seems to me that they are still not very suitable when we want to mass produce an electrostatic stator. 
 
Pure metal (titanium) or metal alloys (for instance maraging steel, CO-CR etc) vary in strength and production process. I for one would love to know which metal alloy is used in the SR-009 stator. The metal alloy Stax uses might be suitable for mass production, but unless someone show up with a "poor man" process, they are not very suitable for DIY.
 
For that purpose (DIY), FR-4 PCB's seem to be the most convenient material available (which does not mean the best material available…).

 

Thanks for the info on PCBs. Just a side note, the strength isn't all that important, it's the rigidity that counts here. tht's assuming I understand the issue correctly.

What I'm thinking about is a pipe dream of what would be the best possible. When I find something new that interests me I almost always think immediately of what ridiculous ways it could be improved. For instance, when I first saw a carbon fibre dynamic driver I thought about doing the same with a tri-axial CNT weave, something that would be hideously expensive if even possible with todays technology.

So, while PCBs seem to be very good when properly implemented it's still possible that there is something better. I might not be easy for either mass production or DIY, but I'm just thinking out loud here. I find that thinking out loud means that you only have to come up with half an idea - others who are more experienced, knoledgable, or who are just thinking the right way at the time are able to either finish off the idea into something useful, or explain why it's stupid before too much time is wasted on it.

 

I freely admit that I likely don't know enough about electrostatic drivers to contribute anything that is of significant help, which is why I have thus far read and learned, rather than posted and cluttered, on this thread. I simply saw a number of posts discussing how stator flexion caused distortion and added my $0.02.

Throwing out another off the cuff idea, if a pure metal stator will work (ie one that is conductive in it's entirety rather than just a film on the surface) than BeCu would have the right mix of mecanical and electrical properties for the job. Again, it's expensive and difficult to source and difficult to work with. just a thought.

post #714 of 1528
Thread Starter 
Before we all get confused, I must say that there is nothing wrong with using PCB to make your stators. As I see it, it's strong enough for this application. Stax use it with their SR007, and SR007 is considered one of the best electrostatic headphones that is out there.

It's not the first time that Stax is using some reinforcement with their SR009's stator. The original SR Omega also has the similar backing for their wire mesh stators. It's simply for the purpose of making the stator strong and to avoid ringing in certain frequencies.

While the stators need to be conductive, we are better off to lightly insulate their conductive surface. With a very high diaphragm tension, high bias voltage, and a small air gap between the stators and the diaphragm, it's much better for your driver to operate more reliably by coating the stators with some plastic paint for insulation. For those who do not know about how the electrostatic driver operates, it might sound strange. But it's not the conductivity on the stators that matter much for efficiency. It's rather the bias voltage and air gap that really play important roles.

The good reasons for using PCB for making stators IMO are:

1. PCB is strong.
2. PCB is very flat.
3. The fiber glass side of the PCB is a good insulator. You want 100 percent sure that your ears won't be shocked by electricity. smily_headphones1.gif
4. It's cheap and easy to drill.

Wachara C.
Edited by chinsettawong - 12/31/12 at 10:25am
post #715 of 1528

After reading the entire topic, I am just curious how your tools are made that made your DIY tools that made your DIY CNC that made your DIY Electrostats spacers.......bigsmile_face.gif
 

post #716 of 1528
Thread Starter 
Quote:
Originally Posted by Nemeske88 View Post

After reading the entire topic, I am just curious how your tools are made that made your DIY tools that made your DIY CNC that made your DIY Electrostats spacers.......bigsmile_face.gif

LoL. All that you need is the will to do.

Wachara C.
post #717 of 1528
Quote:
Originally Posted by Tjj226 Angel View Post

 

Yeah, I read that post. But I don't know how to read a circuit map and turn it into a thing. frown.gif

 

I was wondering if there was more of a tutorial with pictures. 

 

Edit: Or a good guide on how to read circuit maps because all the guides I find aren't all that great. 

 

I'm considering building an ES amp kit loosely based on the ciruit in this thread.  Rather than assembling the amp Dead Bug style, where you wire components point-to-point between the tube socket terminals and other stand-offs, I'd make a board that you could just populate with components and put in a box.  I'm borrowing a set of SR-5s from a friend and the frequency response through the converter box really isn't very good for the majority of what I listen to.  I'm hoping that driving them directly without those huge inductors in series with the audio, would make it sound better.

 

As a SWAG, I'm guessing it would be in the range of $300 to $500 in parts (more of a WAG than a SWAG, I confess)  Is that something that would interest you?  Would anyone else be interested in such an ES amp kit?

post #718 of 1528
Quote:
Originally Posted by chinsettawong View Post

Based on the design from www.tubecad.com, I draw up a more detail schematic for the amp:

 

wholecct_RV41.jpg

 

Frankly speaking, I have no way to compare this amp to any other direct drive amp for electrostatic headphones as I don't have any other.  Oh,I just noticed that we have an eXStata DIY electrostatic amp in this forum, can someone point me to its schematic diagram, please?

 

Wachara C.

 

What modifications have you made to this circuit (if any), Wachara?  Are your phones still operating with the (220vRMS * 1.7vPtP/1vRMS * 2 (full wave)) = 748vDC BIAS?  I notice you don't have any DC blocking caps on the inputs, is that still the case?

 

Do you know if anyone has already made a kit for an ES direct drive amp like this one?  I'm not in it for the money, I just want the amp and it's cheaper to make circuit boards in quantity than one offs.  :-)

post #719 of 1528
Thread Starter 

Hi,

 

I haven't made any changes to the circuit.  But the bias voltage isn't as high as you calculated, I think.  I calculate out to be around (220 x 1.414 x 2) 622vDC.  

 

There was a group buy a while back on KGSSHV PCB.  I think it is a very good and easy to build amp.  You might want to contact Lilknight to see if he still has some left.

 

Here are a few pictures of my KGSSHV that I just finished building recently.  I really like it. 

 

 

 

post #720 of 1528

Wachara, this looks so cool!

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