I would be more interested in the type of PC that you used.
When I did my original little panels, My coater refused to do a third coat for me, but never explained why.
After doing some reading I found that only some coatings are able to be used for multiple coats and it takes a lot more voltage to get it to stick as the coating gets thicker.
Not only complications from getting it to stick on the already coated surface, But over baking of the first inner coating and this can cause gassing and/or a weakened first coat due to being burnt.
Since it was a freebe, I thought maybe he just didn't want to do it, he just said no I can't do it.
He just said a "Third coat can't be done", So figuring on he was a professional, he must have had a good reason and he did say "I can do two coats, But not three".
I just wish that he had given it a try anyhow since it was just window screen and not a metal sheet that can hold much more heat longer.
jer
When I did my original little panels, My coater refused to do a third coat for me, but never explained why.
After doing some reading I found that only some coatings are able to be used for multiple coats and it takes a lot more voltage to get it to stick as the coating gets thicker.
Not only complications from getting it to stick on the already coated surface, But over baking of the first inner coating and this can cause gassing and/or a weakened first coat due to being burnt.
Since it was a freebe, I thought maybe he just didn't want to do it, he just said no I can't do it.
He just said a "Third coat can't be done", So figuring on he was a professional, he must have had a good reason and he did say "I can do two coats, But not three".
I just wish that he had given it a try anyhow since it was just window screen and not a metal sheet that can hold much more heat longer.
jer
Hi Jer,
I don't have any idea what kind of PC they did on my stators. I just told them what I wanted and they gave back to me when they're done. They did say that they had never done that before, but they would try.
As far as I can tell, they have done a pretty good job. When I tried to solder the wire onto the stator, I had a really difficult time scratching out the paint. It's very tough and quite thick indeed.
Wachara C.
I don't have any idea what kind of PC they did on my stators. I just told them what I wanted and they gave back to me when they're done. They did say that they had never done that before, but they would try.
As far as I can tell, they have done a pretty good job. When I tried to solder the wire onto the stator, I had a really difficult time scratching out the paint. It's very tough and quite thick indeed.
Wachara C.
Thank You for the Info!!
I completely believe in the Powder coated method as long as it is done right.
I am very glad it worked for you !!!
I will be exploring a DIY method of PC with the little panels soon.
I sill use the heat treating method for shrinking the Mylar as this works well for me and utilizes less waste of material as my stock is only 12" wide.
This worked even on my First 7.5" wide panels although it did take a bit more to get them to stay stable.
I think most of the stability issues I did have were due to the Stator's not being completely flat due to my construction method of using plastic lighting grate.
I like having just enough tension to keep them stable and while having the lowest frequency of diaphragm resonance I can get.
It was once stated to get them as tight as you can for an increased efficiency.
This is simply not true and all this does is raise the resonate frequency of the diaphragm.
I think that if you do get them too tight it can actually reduce the efficiency a bit as it could limit the diaphragm from reaching large a excursion at the lower frequency's.
However this may be barely measureable SPL wise, But there may be a possibility of a raise in the THD or even a compression of the peaks of the waveform's at the low end do to the limiting factor of having to much tension.
But I think the raised resonate frequency will be the most noticeable effect.
Once I got the resonance up in to the 170Hz to 200Hz range and this caused a sort of coloration if you will, and I had to redo them as it was quite annoying.
I didn't get to do a lot of testing with my larger panels as I have done with the little ones because this was 11 years ago and I didn't have the methods and equipment that I now have.
A calibrated microphone and and FFT software sure helps a lot now days and was non-existent back then.
I have also ran into stablilty issues when the Bias Voltage wasn't high enough!
This was due to the stators not getting charged equally due a slightly different resistance factors of the coatings on the two stator's and/or unequal leakages.
I have found sometimes that the diaphragm would suck into one of the stators or even oscillate until I reached a certain voltage and then it would stablilize into the center as it is supposed to.
At that point I could reduce or increase the bias voltage and it would stay stable as I varied the bias voltage throughout the power supply's voltage range while staying completely silent with no noise whatsoever until a signal was applied.
And of course reducing the bias voltage also reduces the panel efficiency.
I have had experienced the same effects when paralleling panels that exhibit different leakage rates and qualities even though the were made exactly the same.
This is one reason why you should feed your panels separately through a resistor if you are using the same supply to feed both panels, This I have already documented in another thread.
This also reduces/eliminates any crosstalk between the left and right panels due to a common powersupply.
In fact I would even feed the ground sided centertap of the step up transformers with a resister as well to be sure, although may not be necessary.
I was quite amazed in how much effect the signal has on the bias voltage and was one reason I chose to build a regulated bias supply besides needing it to be variable for all of my crazy tests.
jer
I completely believe in the Powder coated method as long as it is done right.
I am very glad it worked for you !!!
I will be exploring a DIY method of PC with the little panels soon.
I sill use the heat treating method for shrinking the Mylar as this works well for me and utilizes less waste of material as my stock is only 12" wide.
This worked even on my First 7.5" wide panels although it did take a bit more to get them to stay stable.
I think most of the stability issues I did have were due to the Stator's not being completely flat due to my construction method of using plastic lighting grate.
I like having just enough tension to keep them stable and while having the lowest frequency of diaphragm resonance I can get.
It was once stated to get them as tight as you can for an increased efficiency.
This is simply not true and all this does is raise the resonate frequency of the diaphragm.
I think that if you do get them too tight it can actually reduce the efficiency a bit as it could limit the diaphragm from reaching large a excursion at the lower frequency's.
However this may be barely measureable SPL wise, But there may be a possibility of a raise in the THD or even a compression of the peaks of the waveform's at the low end do to the limiting factor of having to much tension.
But I think the raised resonate frequency will be the most noticeable effect.
Once I got the resonance up in to the 170Hz to 200Hz range and this caused a sort of coloration if you will, and I had to redo them as it was quite annoying.
I didn't get to do a lot of testing with my larger panels as I have done with the little ones because this was 11 years ago and I didn't have the methods and equipment that I now have.
A calibrated microphone and and FFT software sure helps a lot now days and was non-existent back then.
I have also ran into stablilty issues when the Bias Voltage wasn't high enough!
This was due to the stators not getting charged equally due a slightly different resistance factors of the coatings on the two stator's and/or unequal leakages.
I have found sometimes that the diaphragm would suck into one of the stators or even oscillate until I reached a certain voltage and then it would stablilize into the center as it is supposed to.
At that point I could reduce or increase the bias voltage and it would stay stable as I varied the bias voltage throughout the power supply's voltage range while staying completely silent with no noise whatsoever until a signal was applied.
And of course reducing the bias voltage also reduces the panel efficiency.
I have had experienced the same effects when paralleling panels that exhibit different leakage rates and qualities even though the were made exactly the same.
This is one reason why you should feed your panels separately through a resistor if you are using the same supply to feed both panels, This I have already documented in another thread.
This also reduces/eliminates any crosstalk between the left and right panels due to a common powersupply.
In fact I would even feed the ground sided centertap of the step up transformers with a resister as well to be sure, although may not be necessary.
I was quite amazed in how much effect the signal has on the bias voltage and was one reason I chose to build a regulated bias supply besides needing it to be variable for all of my crazy tests.
jer
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.