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My DIY electrostatic headphones
Oct 18, 2017 at 5:52 PM Post #2,821 of 4,059
But that takes all the fun out of it :triportsad:

And all of the "fun" when you do something dumb with the CNC machine.:wink:

Seriously, though, those are very well-made stators. I'm curious about the cause of the difference in efficiency, and the difference in capacitance.
 
Oct 19, 2017 at 11:18 AM Post #2,823 of 4,059
Well, frankly, I've been very busy with my day work and don't really have time to play much with my CNC machine anymore. Plus it's something that I have been wanting to find out for a long time after seeing the stators from Stax SR007 which are made from double sided plate through holes PCB. There is no way that I can make the plate through holes PCB by myself. :wink:

Anyway, I'm glad that they turn out great.

I've been A/B testing my headphones against SR007, SR009 and SR407 for several days now. These Stax headphones will go back in their boxes soon and I won't miss them at all. :)
 
Oct 20, 2017 at 6:43 AM Post #2,825 of 4,059
GvTT said:
Hello khbaur,

now you are whistling my tone!

I mentioned before in this thread that the tension of the diaphragm is directly indicated by it resonance frequency (eigenfrequency). Any impulse on the stretched membrane will activate a vibration in it's eigenferquencies, on a stretcher there will me more than one.

You could also use a loudspeaker with a tuneable output to make the membrane swing in resonance. But in this case you would need to monitor the amplitude (maybe with a laser?

BUT: this would only help you, if you intended to make many of the speakers. For setting up just one (as in DIY) I would not consider this relevant, as the size and shape of the diaphragm will be different for all the different designs.

We first need to define what we expect of tension of the diaphragm:
- prevent the diaphragm to stick to a stator (number one for me) -> the speaker is statically stable
- an interaction of the resonance frequency with the lower audible spectrum while listening? (e.g. bass increase while driving the speaker in a half closed surrounding? -> way beyond my thoughts)

So I suggest to test the diaphragm while being on the stretcher (before gluing) for static stability.

I have not had an idea how to do this in a safe and reliable manor. My thoughts go along the lines of applying an increased bias (maybe 780V [580 bias + 200V amplitude]) to speaker components only pressed (but not glued) to the membrane. But is this, what we want? Unconditionally stable? (I guess, that would be good, considering aging, different amps, air pressure, taking phones off, etc.)

Once you know what you are aiming fore (stability wise) you could use the eigenfrequency as a reference, but only for this one specific speaker design.

Greetings
Georg
Click to expand...

Hello,
I know the method you need which i was tested it. You must buy very small magnets 10 x 2 mm circular in shape. You will use them insted of plastic bolts. In this method you dont need to drill and glue the tensioned membrane. After tensionning the membrane you must apply the conductive coating as usual. Then you can assemble the electrostatic tranduccer carefully and use the small magnets insted of bolts. Then you can connecte the system to the electrostatic energizer / amplifier and make your measurements with your preffered instruments. If the measurements are not as you like ayou must apply more or less tension and make your measurements again. At last you will disasemble the system and glue the two spacers on tensioned membrane.

Regards
Theologos Sarafidis
 
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Oct 20, 2017 at 12:00 PM Post #2,826 of 4,059
Hi Theologos,

I've just played with your idea of heat treating the diaphragms today. I tensioned the diaphragms to really tight. They were so tight that the spacer rings were pretty badly bended up. I put them in my headphones, and there was not much bass at all. I took them out and treated them with the hot air gun. I tried to see if I could kind of relieve the tension on the Mylar a bit. By looking at the spacer rings, I could already tell that the tension had gone down quite a bit. I put them back in my headphones, and diaphragms sounded very nice, The bass after the heat treatment was quite a lot more than before. What happened here? My idea is that when you heat treat the diaphragm, the diaphragm tension is actually relieved when it's hot. Then when it cools down it shrinks a bit. This doesn't make the diaphragm under high tension becomes even more tight. It's actually doing the opposite. You can try it and see if you find the same result as what I get.
 
Oct 20, 2017 at 12:18 PM Post #2,827 of 4,059
Just an update for my new stators. Yes, I also try my JF clone with the double sided plate through holes PCB. For this time, I use 1.2 mm PCB with 2 oz copper. Well, the result isn't very good. I think because of the thicker copper, I really can't use 0.5 mm spacers with them. I just really can't make the diaphragms stable enough with that spacer thickness. Eventually, I have to put in the extra 0.1 mm plastic to make the total thickness of the spacer to become 0.6 mm. But other than that, the headphones sound very nice. So, if you guys were to make the PCB like what I do, don't use thick copper.

IMG_20171020_224007.jpg


Here is to David. The 100 mm leather earpads as per your recommendation look and feel really nice. I really like them.

IMG_20171020_223850.jpg


IMG_20171020_223920.jpg
 
Oct 20, 2017 at 12:46 PM Post #2,828 of 4,059
chinsettawong said:
Well, frankly, I've been very busy with my day work and don't really have time to play much with my CNC machine anymore. Plus it's something that I have been wanting to find out for a long time after seeing the stators from Stax SR007 which are made from double sided plate through holes PCB. There is no way that I can make the plate through holes PCB by myself. :wink:

Anyway, I'm glad that they turn out great.

I've been A/B testing my headphones against SR007, SR009 and SR407 for several days now. These Stax headphones will go back in their boxes soon and I won't miss them at all. :)
Click to expand...

Your Float Klone is quite amazing sounding...absolutely love your Orpheus Clone headphones as well!
 
Oct 22, 2017 at 11:26 AM Post #2,832 of 4,059
damn david that little battery thingy me like :D guess i have to make soon my stax connector to be compatible :wink: just made a test with new glue and licron spray sounds pretty good but still have the problem with too high highvoltage :/ and the my headband earcups only seal when i press them against head but then NICE bass :D

cheers janosch
 
Oct 28, 2017 at 8:07 AM Post #2,833 of 4,059
Hi !
I found another pair. I am very lucky because it is really rare. Well, in fact , as you can read, I found it one year after.
the headphones were presented as perfectly working. But they didn't work. But thsi time, I succeded in repairing them.
The result is absolutely awsome. I must say this is a real marvel. I compared them to my stax srxII pro, which were and still ar my favourite cans, but this is just close to it !
 
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