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Note on the design of the ESL section
The Transformers
In principle, an energiser for electrostatic headphones is a trivial challenge. All we need are a pair of transformers to
create the very high signal voltages for the electrostatic headphones and some form of bias supply. Of course, what
seems simple usually hides unexpected complexity.
For example, to make transformers that can turn 20V audio signals into a 640V signal, with low distortion, a at frequen-
cy response and without obnoxious resonances is a serious challenge. Get it wrong and the sound will be coloured,
something especially objectionable with the crystal-clear sound of electrostatic headphones.
In addition, while making a high voltage bias supply seems easy, we must remember that this bias voltage provides one
part of the motive force that moves the diaphragm. Any noise on the bias supply will modulate the drive strength of the
moving diaphragm and thus the sound. Obviously, this must be avoided.
Given the high voltages involved even trivial jobs like circuit board design become challenging as we must avoid any
chance of these high voltages to get out of control. Therefore great amounts of spacing between voltage carrying traces
and pins are needed, making a simple circuit board layout suddenly very challenging.
Then we need to make sure we can select multiple sources, with minimal impact on sound quality from the switches and
good long term reliability, something that simple mechanical switches fail to deliver.
In order to produce the high voltages requires by electrostatic headphones, the iCAN Phantom employs custom-made
transformers of the highest quality
The extremely critical core of the transformers is a hybrid that combines ultra-thin GOSS with pinstripe permalloy
lamination. A 100% GOSS core suers from hysteresis at low levels causing distortion in quiet passages.
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