Tweaking an 80s preamp
I have a Phillips Black Tulip 22AH280 preamp. It's quite a sophisticated circuit, not typical Phillips of the era - infact I believe it was designed and built in Japan. I've looked at the circuit, I don't want to make any major changes but some capacitors leap out at me as being candidates for improving:
Phono stage output: a series pair of 10uF electrolytics making them bipolar. Replace with one 4.7uF polyprop.
Linestage input: there's an NPN transistor fed by a 470nF electrolytic and a PNP fed by another 470uF electrolytic with the capacitor in reversed polarity. Could I replace these capacitors with polyprops or as I suspect is polarity important here? I'm confused by this configuration.
Linestage output: a series pair of 10uF electrolytics making them bipolar. Replace with one 4.7uF polyprop.
The service manual with the circuit is at:
https://www.vintageshifi.com/repert....ice-Manual.pdf
I'm thinking the series capacitors in particular could be changed, I suppose suitable film capacitors weren't available in the 80s or were very expensive. Is this wise?
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