[jgazal]

Thanks nikongod, wakibaki and dude_500 for taking the time to explain. You are great!

 

[wakibaki]

I was just pulling your leg.

w

 

[jgazal]

I was just pulling your leg.

w

 
I admit the idea of making a dielectric aluminum alloy is stupid. 
If one were so concerned about paramagnetism, would just use wood or plastic... 
Anyway, "quamquam ridentem dicere verum quid vetat?"

 

[wakibaki]

τὸν κρατοῦντα μαλθακῶς θεὸς πρόσωθεν εὐμενῶς προσδέρκεται.

w

 

[wink]

Quote:jgazal

 Anyway, "quamquam ridentem dicere verum quid vetat?"

"What prevents me from speaking the truth, though laughing?"
 
Quote:wakibaki

 τὸν κρατοῦντα μαλθακῶς θεὸς πρόσωθεν εὐμενῶς προσδέρκεται.
 

"God from afar looks graciously upon a gentle master"
 
Quote:jgazal

I admit the idea of making a dielectric aluminum alloy is stupid.  If one were so concerned about paramagnetism, would just use wood or plastic... 

The non-ubiquitous unobtanium would serve very well here.

 

[chinsettawong]

I'm so glad to see wakibaki still active with his DIY. 

 

[wakibaki]

Thanks.

Yes, I was a bit depressed for few weeks, but then you realise that you are still alive, and you still have to fill the remainder of your life, which is all any of us are doing anyway. What used to give meaning to my life still gives meaning to it, and although I build things to use, building is fun in itself.

I have built one side of the electrostatic headphones complete down to the cable and connector. The other side is just a little hand-fettling away.

Now I need an amplifier. I have completed the design work for the I solid state amplifier I talked about previously, with some small exceptions. I have designed a case to make on the cnc mill, it uses perspex and aluminium sheet. I ordered the wrong transformers, so I have not ordered the boards, because I always check the layout against the parts, because dimensions in data sheets can be hard to interpret. Building something like this is always quite stressful, because of the cost implications of a mistake, so I have a quick fix in mind.

I have bought a 15W (TPA20202024) amplifier and Meanwell 12V supply. I intend to build an EHT supply after the style of the one on Rod Elliott's site:- http://sound.westhost.com/project105.htm, and wire it up with a pair of centre-tapped transformers. I wonder if anybody would care to recommend some transformers for this service? I don't want to spend a lot, I just need something to prove the phones.

edit:

This is what I am thinking about:-

http://uk.farnell.com/multicomp/vtx-146-015-106/transformer-15va-2x-6v/dp/1675043

Fred

 

[wink]

Just get a good NAD, Yamaha, Sansui, or Pioneer amp and a Stax SRD7/SB and you're good to go.
Or, you could build a KGSS, KGSSHV, BHSE or DIYT2.
 
Or, even buy a Stax SRM-252s or SRM-323s.

 

[wakibaki]

Doh! I picked a tx with a CT secondary, when what is required is a CT primary. I must be a bit distracted.
 
Here is the latest iteration of the depletion MOSFET design. I have carefully made these stacking boards 100mm square, this is the best value/size on sites such as seeedstudio.com and iteadstudio.com. 10 ea. of these cost ~U$75.
 

 
The bottom layer, the amplifier, has a largely unbroken copper plane on the upper surface, the upper 2 layers have largely unbroken copper planes on their undersides. The power is supplied via vertical descenders as required locally by the amplifier. That's the theory anyway.
 

 
The schematic shows DN2540, but IXYS IXTP01N100D should be substituted for UK mains operation with ~650V bias available. I have all the parts excluding the transformers and boards. I have part-drawn an enclosure in 3D inAutocad:-
 

 
Dimensions are 5*5*4 interior. 2, 3 and 5mm acrylic and alu sheet.
This will enable me to figure the placement for the fasteners and controls. The back will be alu. plate to heatsink the active devices, the front smoked acrylic, to permit the digital bias voltage readout to be visible on the top shelf of the PCB stack. Top and bottom will have cooling slots. This has been designed to permit low-effort production on my CNC mill.
 
w

 

[wink]

The centre-tapped primary is not a problem as long as the secondary is centre-tapped too.

 

[chinsettawong]

I'm sure that Wakibaki knows what he's doing.

 

[wakibaki]

I found these:- http://www.ebay.co.uk/itm/Toroidal-230V-Mains-Transformer-15VA-0-6V-0-6V-/300976618233?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item46139abaf9
 
In this case the primary and secondary swap roles, but this is dual both sides.
 
This is the bias supply:-
 

 

 
w

 

[chinsettawong]

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.
 

 
Wachara C.

 

[Congo5]

does this count?
12ax7 / 5965 like post# 7
thanks for the update on the 2 microns Mylar....
its all I have to work with...good to know.

 

 

[davidsh]

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)?