[wakibaki]

I went to Malta for a week. I used to live there when I was 8~12 YO.

Some things arrived by the time I got back:-



These are the parts for the transformer-style amplifier I decided to take a flyer with. It's only ~8W into 8ohms, which is 8vrms, with a transformer ratio of 40, but I still think it should drive the phones.

w

 

[dude_500]

  Guys!  Any progress on your headphones and amplifiers? 
 
I bought a roll of 2 microns Mylar from Ebay and put it on my Omega clone.  I like it.  The trick is to not stretch the Mylar too much - just enough to get rid of wrinkles.

 
Interesting, I have my 2-micron mylar extremely tight - I think I hung about 12 pounds of weights on it for my last diaphragms, and it's not really enough. Works fine, and tighter didn't reduce bass (based on double blind testing... it certainly did reduce it by placebo effect). 
 
 

  All the single sided planars got me thinking.. Has anyone experimented with single sided electrostats or perhaps making the sides facing your ears more acoustically transparent (smaller stator surface area)? 

 
I believe this leads to charge migration in electrostatic drivers. Works fine in magnetic because there is no magnetic charge involved.

 

[chinsettawong]

   
Interesting, I have my 2-micron mylar extremely tight - I think I hung about 12 pounds of weights on it for my last diaphragms, and it's not really enough. Works fine, and tighter didn't reduce bass (based on double blind testing... it certainly did reduce it by placebo effect). 
 

 
Well, you just say it yourself that it's not really enough.  Then I don't think your Mylar is extremely tight already.  With inner tube stretcher, it's easier to get the diaphragm too tight.  When you do that, you get something like these:
 

 
When you say you use 12 pounds of weight on it, I assume you mean you put a total of 12 pounds of weight all together, right?  If that's the case, that might not be enough.
 
When I used water bottles as weight the last time, it's not really enough too.
 

 
I can't believe that you don't hear a sonic difference between very tight diaphragms and the ones that aren't too tight. 
 
I hear a lot better bass from the diaphragms below than the ones I posted above anytime.
 

 
Wachara C.

 

[dude_500]

   
Well, you just say it yourself that it's not really enough.  Then I don't think your Mylar is extremely tight already.  With inner tube stretcher, it's easier to get the diaphragm too tight.  When you do that, you get something like these:
 

 

 
Ok, in that case I think we just have different definitions of really tight. I've never even tried anything this tight, mine all look like your last picture for the most part. My bass comparisons would all be done at differences of 10-20% weighting. I imagine I'd have to nearly double to get up to the tightness you have pictured.
 
And yes, that is 12 pounds total distributed among 16 weights. At some point I will up that to probably at least 16 pounds since on a hot humid day I have to drop bias to about 500v right now. 

 

[chinsettawong]

   
Ok, in that case I think we just have different definitions of really tight. I've never even tried anything this tight, mine all look like your last picture for the most part. My bass comparisons would all be done at differences of 10-20% weighting. I imagine I'd have to nearly double to get up to the tightness you have pictured.
 
And yes, that is 12 pounds total distributed among 16 weights. At some point I will up that to probably at least 16 pounds since on a hot humid day I have to drop bias to about 500v right now. 

 

  I'm glad that we now understand each other better.  I just don't want others to get confused reading our posts. 
 
So, are you making any more amps or headphones?  As for me, I've been lazy these past few months and haven't done anything new. 

 
Wachara C.

 

[dude_500]

   

  I'm glad that we now understand each other better.  I just don't want others to get confused reading our posts. 
 
So, are you making any more amps or headphones?  As for me, I've been lazy these past few months and haven't done anything new. 

 
Wachara C.

 
No... I just graduated from college so it'll be some time until I get my life in order and have the tools to do much work on these things. I'm sure I'll get back to it at some point though! 

 

[ondesx]

Hello,
 
Can you tell me if the Topical antistat from Reztore will be a good candidate for Mylar coating ? Same product than Licron Crystal ?
 
http://www.charleswater.co.uk/CharleswaterCatalogue/FloorCareMaintenanceProducts/ReztoreCleaningProducts/TopicalAntistat/71035/#.U4O1n1h_sWs
 
Thank you for your answers,
 
OndesX

 

[dude_500]

  Hello,
 
Can you tell me if the Topical antistat from Reztore will be a good candidate for Mylar coating ? Same product than Licron Crystal ?
 
http://www.charleswater.co.uk/CharleswaterCatalogue/FloorCareMaintenanceProducts/ReztoreCleaningProducts/TopicalAntistat/71035/#.U4O1n1h_sWs
 
Thank you for your answers,
 
OndesX

 
I doubt there's any way to identify which is better than another from what the label says. And I imagine any spray will work reasonably well. The only variability I can think of would be long term stability of the coating.
 
Also I really hope you have a cheaper source of that stuff. $195 for 12L is probably not a logical purchase.

 

[ondesx]

Ooops ! I don't payed for the sample !...

 

[ondesx]

Otherwise are such products of any help (on the PCB) of the Cells ?
 
http://www.aclstaticide.com/acrylic_conformal_coating.html

 

[dude_500]

  Otherwise are such products of any help (on the PCB) of the Cells ?
 
http://www.aclstaticide.com/acrylic_conformal_coating.html

 
 
It might be, I don't know what finish that has but I assume glossy... I tried a spray paint with a glossy finish and it was very bad, loud squealing when hit by the diaphragm and actually decreased stability. I theorize that the glossy surface increases surface area of contact when hit by the diaphragm making it a bad situation. It could have been some other property of the paint I used, though. Now I only use matte finishes.

 

[chinsettawong]

I haven't noticed a problem with all the paints that I've used - glossy or matt.
 
It could be a problem with the certain brand of paint that you used though.

 

[ondesx]

Thanks Guys !...
 
Short questions perhaps already debated here or elsewhere :
 
- what is better for the diaphragm, too much tensioned or not. Obviously, the resonance frequency rises with the tension, but what about the sound quality ? Some of you have a quantified value in mind (in Newtons) ?

- as far as the coating of the diaphragm, one side or both must be prepared ? Will this have any incidence on audio quality ? 

- for the "track" on the internal face of the spacers for the polarization of the diaphragm, I suppose that smaller is the width of this track, better it is, since the capacity will be lowered this way ? If the diaphragm is coated both sides, a track on each spacer is perhaps advised...
 
Again thank you all for your help.

 

[dude_500]

  Thanks Guys !...
 
Short questions perhaps already debated here or elsewhere :
 
- what is better for the diaphragm, too much tensioned or not. Obviously, the resonance frequency rises with the tension, but what about the sound quality ? Some of you have a quantified value in mind (in Newtons) ?

- as far as the coating of the diaphragm, one side or both must be prepared ? Will this have any incidence on audio quality ? 

- for the "track" on the internal face of the spacers for the polarization of the diaphragm, I suppose that smaller is the width of this track, better it is, since the capacity will be lowered this way ? If the diaphragm is coated both sides, a track on each spacer is perhaps advised...
 
Again thank you all for your help.

-Well, too little tension is worthless because it goes unstable. So I guess too much is better than too little. But just right is better than too much, because too much will hurt bass.
-I think we mostly do one-side on the DIY ones. Hard to know what retailers do. If you run the math, coating both sides versus one is the same situation. What mathematically would greatly reduce distortion, at least in theory, is having both sides coated but insulated, and both having a few meg-ohm resistance to the bias supply. It'd be very difficult to implement this, I don't know if anyone ever has. I can't find the paper that talks about this at the moment, it's somewhere in this thread.
-I don't think the track size really affects anything. You're worried about capacitance between the stators because it affects the amp. The capacitance on the bias supply is basically irrelevant, it's DC.

 

[jcx]

one sided coating, the thickness of the diaphragm hardly matters to the E field, the force, balance since it is a small fraction of the spacing and the e_r of the Mylar even reduces the small effect of the thickness of the diaphragm more  - do you really get the spacing/centering/flatness within few microns?