which capacitor can change to improve the sound?

which capacitor can change to improve the sound?
my  合併式膽機 contain 2 x EL34, 2 X 6sn7 , Now i want to change 4 capacitor. which band is suitable ? After change , the sound become better[img][/img]

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thank to jimmison1 & accphoto , i will study all information and try to modify my amp.

i have already changed the capacitor to m- cap which is m-cap silver/gold(0.47uf 1200V) , after this change , the sound becomes rich and solid but not enough (通透). i think that need boiling it.
i buy the  m-cap silver/gold(0.47uf 1200V) in shamshuipo , the price is $1700 for 4, i feel "very painful in my wallet" ..............Now i want to ask every C HING that where to buy the parts is cheaper?   thank s

Sorry , it is 0.47uf 1200v ,Jensen copper foil is $6xx per one, i chech it in shamshuipo (wing X), where u found the $200 of Jensen copper fiol, pls tell me. do u buy it though internet market...(e.g. http://store.tubedepot.com)

After boiling the amp , (通透) of the sond has a great improvement. nice ...
the 2nd diy project is power cord. i want to ask that what is the perfect lenght of power cord .....(4M,5M,6M)? different lenght has different effect?

請問原本電 容值 是0.47uf630v現在改為0.47uf1200v當中電流電阻有什麼改變,聽說這樣會影響音質?
thanks

i see
thanks