I wanted to share with the rest of the DIY community my experience with these capacitors, as I believe they are fantastic bargains bettering IMHO a lot of the exotica out there, but costing 'pennies'.
I first discovered them on EBAY several years ago, sold mostly out of the Eastern European/Russian community. I believe they are of military origin and in true fashion appear to be put together really well. I have been using them for several years now and have extensive experience with them. They are still sold as bulk buys on EBAY and cost 'pennies'
These caps mostly run from .001 to 22uf and voltages up to 1200v. They can therefore be used for tube projects as well as solid state.
I have used them in every type of electronic circuit that I have come across in my diy hifi adventures. They have never dissapointed. They bring great detail and neutrality to proceedings. But rather than go on about their sound i can perhaps best sum up their sound by the comparisons I have done with them
Audio note tin foil caps- petp was more dynamic and more detailed sounding probably equal in most other areas.
Jenson paper in oil caps - again a very similar finding
Sanyo's Oscon,the sanyo's sounded slower and less dynamic in comparison
Mundorf silver - the PETP matched it for detail and I believe was less strident and aggressive at the top end.
Black Gates - very similar sonic character, but the black gates had the edge for inner tonal detail.
Russian Teflon and PIO - again very similar finding as for the audionote and jenson paper in oils described above.
Still one of the best caps i have ever used for application in speaker crossover in which they are as good as if not better than the non polar black gates that cost a fortune.
The only capacitor I would probably prefer are the Audionote Copper paper in oils but not by a great margin. They tame the top end , bringing in more refinement and naturalness to the top end and midrange. So I guess if i were to criticise them then the top end needs to be matched a bit.