fdd5d689_e_Notes_on_Coupling_Capacitors__Impressions_HV
[Brand] Nichicon Muse ES series 4.7uF/50V Bi-Polar Electrolytic $0.45 [Impressions LV] Surprisingly, these are larger than the similarly rated BlackGate N series. They are reportedly favored by James Bongiorno of SAE, GAS, and Sumo fame as coupling caps. My experience is that their sound is very warm and full with a lot of deep bass. Really, if you like lots of bass this is your cap. However, they seem to lack dynamics, are a bit (just a bit) sluggish, and add a bit of a veil to the music. Unbroken in they also have that characteristic Nichicon Muse upper midrange hardness but this goes away after a few hours use. However, the treble resolution is not great. They are tons better than the Panasonic Bi-Polars, and tonally even compete with some of the film caps. Since they don't cost much they are probably worth experimenting with. [Rating] 2 ½ [Impressions HV] 
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ecp audio diy: Some Notes on Coupling Capacitors
Impressions HV