fdd5d689_e_Notes_on_Coupling_Capacitors__Impressions_HV
[Brand] Surplus Soviet Paper in Oil K42Y-2 0.47uF/500V ~$2.00 [Impressions LV] . [Rating] 2½ (3 in ||) [Impressions HV] 
These, along with the Soviet Teflon caps, have been all the rage on the audio boards lately. They are super cheap, and for the money represent a pretty good bargain in audio. Unfortunately, while they are good for the money, they are not as good as some of the made for audio capacitors, or other surplus caps, that are available. Overall, they are flat sounding in the midrange, and they lack the resolution of some of the better caps. They also seem a little grainy and hard in the mids and treble. Their best quality is probably their bass resolution which is strong and punchy. These are a great value and good to keep on hand for experimentation, but they are not something I'd use in equipment I was listening to regularly. A sizeable step down from a Vitamin Q and on the low end of the "2" category. An update -- paralleling a bunch of these together seems to change their character considerably -- think of it as a home made multicap. Anyhow, I needed a 2uF cap for a project and paralleled four 0.47uF together, and the sound was warm and smooth and very detailed. I won't speculate on the why, but, at least so far, this seems to be working pretty well. This puts them in category 3.
ecp audio diy: Some Notes on Coupling Capacitors
Impressions HV