Thanks everyone for sharing ideas! I’m a newbie that’s very appreciative of all the advice posted by y’all. Been lurking for years so here goes…even though this thread is quite dated by now. Just sharing my SP-30 journey thus far:
Acquired a clean pair of SP-30 inexpensively almost two months ago not knowing much about them. Once home discovered one’s horn tweeter was blown and the other’s mid-woofer was performing poorly (leaking surrounds). Moral of the story is I don’t know how they originally sounded—then again 50-year-old speakers by now probably wouldn’t be so original sounding.
So I managed to obtain Sansui replacement drivers and recapped them with polypropylene “crossover” film caps. I was pleased that the pair sounded halfway decent but for some unexplainable reason I felt they weren’t performing up to their potential. I was surmising that Sansui engineers wouldn’t sell a product with a compressed presentation like that, even for a smallish 2-way system.
Then after reading online more AKer posts on the subject of electrolytic non-polar caps, which the SP-30s originally came with AFAIK, I made the switch from burning in the poly caps for a few weeks to now installing bipolar/non-polar Nichicon and Rubycon electrolytics. BINGO!!!
IMHO these electrolytic bipolar capacitors introduced far more pleasing SP-30 performance by noticeably opening up the soundstage and overall cohesiveness between high and low frequencies. There is appreciably more bass now to better match the show-off horn tweeters. And as many have already remarked the SP-30 really have a stellar midrange that excels with acoustic jazz and vocals. With the poly caps they struggled when playing electronic instruments (generally rock music), but with electrolytics sounds not so bad at all even though not as great as when playing recorded acoustic genres. Acoustic jazz IMHO plays great with the SP-30. YMMV.
Cheers!
