Вот у элны классификация кондеров для аудио (за 15-16гг).
Биполярный только один для аудио - RBD, по которому вобще ничего неизвестно

----upd
Вот что в аннотациях к конденсаторам обнаружил:

Сообщение от
RFS silmic2
SILMIC series Silk fiber using audio purpose capacitor
ELNA developed new raw material for the separate paper which use a silk fibers.
Therefore, this capacitor can give you high grade sound for your audio design.
Due to the silk fibers pliability, the capacitor makes a dream of the high quality sound.
For examples:
To relieve the music*s vibration energy.
To decrease the peak feeling sound at high compass and rough quality sound at middle compass.
To increase massive sound at low compass.
For bipolar capacitors. consult with us.
Для биполярных нужно с ними говорить. Или уже где-то ходют. Т.е. они реальны.
Позабавило еще про шелковые волокна 

Сообщение от
ROA cerafine
CERAFINE series Fine ceramic adopted electrolytic capacitor for audio
This reproduces very clear sound with real concert-hall presence by depressing the generation of electrical noise due to external viration.
As the charging and discharging speed between the oxidized film of anode and field surface of electrolyte and the variation of potential due to unevenness of fibers of separating paper sheets are improved by the elector chemical action of super fine particle ceramic, this product realize high grade audio tone with excellent sound resolution power, good rise in the low-pitched sound region and no distortion in the medium and high-pitched sound region.
For bipolar capacitors, consult with us.
Тоже самое.
И здесь, но про керамическое напыление 
Offтопик:
и названия только заметил безхитростные)))
silmic2 - silk, material
cerafine - ceramic, fine
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