Lets start a thread on building DIY electrostatic transformer box.
I have one in work since who-knows-when. Never got to finish it up (yet), come to think of it, it is probably because of the ESP950 recable situation (still not fully done, waiting for stax extention cords). But anyway, I am using a pair of JRM M99B 1:50 transformers, originally intended for full size electrostatic speakers, the price was about $120 after shipping.
The M99B's are relatively large, the external dimensions are 76mm x 72mm x 64mm (h), weights exactly 2 LB each. Just so you have an idea how much bigger they are comparing to the stax ones, here is a picture of the M99B's next to a SRD-6 box (the transformers in a SRD-7 box are said to be the same as the ones in the SRD-6)....
Will post a review after I (eventually) finished the JRM box.
----- UPDATE: after about 2 years of use, the JRM box developed major channel inbalance (happened over night, about 2 weeks ago). upon trouble shooting, the "quiet channel" transformer's secondary DCR is a lot less than the good one: quiet= 200 ohms vs. good =330 ohms. The quiet channel transformer also gets warm during use (while the good one is cool), also the protector resistor for the quiet channel is hot (while the good channel resistor is cool). Looks like some kind of partial short has developed in the secondary winding.
I will not recommand JRM transformers due to this reliability problem.
I have one in work since who-knows-when. Never got to finish it up (yet), come to think of it, it is probably because of the ESP950 recable situation (still not fully done, waiting for stax extention cords). But anyway, I am using a pair of JRM M99B 1:50 transformers, originally intended for full size electrostatic speakers, the price was about $120 after shipping.
The M99B's are relatively large, the external dimensions are 76mm x 72mm x 64mm (h), weights exactly 2 LB each. Just so you have an idea how much bigger they are comparing to the stax ones, here is a picture of the M99B's next to a SRD-6 box (the transformers in a SRD-7 box are said to be the same as the ones in the SRD-6)....
Will post a review after I (eventually) finished the JRM box.
----- UPDATE: after about 2 years of use, the JRM box developed major channel inbalance (happened over night, about 2 weeks ago). upon trouble shooting, the "quiet channel" transformer's secondary DCR is a lot less than the good one: quiet= 200 ohms vs. good =330 ohms. The quiet channel transformer also gets warm during use (while the good one is cool), also the protector resistor for the quiet channel is hot (while the good channel resistor is cool). Looks like some kind of partial short has developed in the secondary winding.
I will not recommand JRM transformers due to this reliability problem.