Beginner Q: any ct trafo for Stax adapter?


2006-08-15 9:46 pm
For the purpose of testing Stax "earspeakers" I would like to put together a transformers-based adapter.
(A basic "works-notworks" test, waiting to build or buy a dedicated amplifier.)

Did I understand correctly, that this adapter is made of center-tapped step-up tranformers, where the center tap is biased, as the diaphragm, to an appropriate voltage (580V for Pro, 230V for the Normal)?

If this is the case, here is my second question(s):

Can this be done with "normal" center-tapped output transformers?
I have two smallish transformers from an old ECL82 amplifier, that have say "3.5" on one side and 5000 Ohm" on the other sidez (this oen being center-tapped).
Can I expect these to withstand the bias voltage?

Could this be done with "100V line transformers" from a 100W PA amplifier?
I have two of these, and it seems like the taps are symmetric (I'll test more accurately) and function as step-ups.
These look "bulky" to me (2Kg weight and thick conductors) but again, would they stand 580V?

Thanks for any help.
I would normally "just try it and see what happens".
But in this case, even if I can keep the bias voltage low, it needs to be high enough to discourage such an approach; not ready to sacrifice those trafos, let alone the Stax-es...




2006-08-15 9:46 pm


...think I found the answer by myself...

The step-up transformer center tap is connected to the "zero" of the bias high tension, and the membrane at "ht" volts.
(I had a bad scan of a diagram, where the two looked connected, which wouldn't "bias" much...)

I think I now feel like "just trying".